New Warming Breakthrough for Cryopreserved Organs?

Although not of immediate concern to cryonics, warming has always been more of a challenge than cooling for cryopreservation by vitrification. This is because the initial formation of ice crystals is most rapid at very low temperature, such as -120°C, but crystal growth is faster at warmer temperatures. Tissue being warmed from the very cold temperatures of vitrification therefore often contains many tiny crystals that are ready to grow during passing through warmer temperatures until the melting point is reached. The warming rate required for successful recovery from vitrification therefore tends to be about ten times faster than the minimum cooling rate.

Since Fahy first proposed vitrification for organ cryopreservation in the 1980s, it was envisioned that a technique called radiofrequency warming (RF warming) would be used to recover organs from vitrification. In RF warming, a rapidly oscillating electric field at a frequency ranging from tens to hundreds of megahertz is applied during warming. The oscillating electric field causes water molecules to vibrate and heat the organ uniformly from the inside similar to a microwave oven. However RF warming uses frequencies much lower than microwave ovens to achieve more uniform heating without “hot spots.” Ruggera and Fahy at the U.S. FDA and American Red Cross published the first paper specifically studying RF warming of vitrified organs in 1990. In the decade that followed, Pegg, Evans and their research group at Cambridge University published numerous papers on technical aspects of RF warming of organs. In 2013 Wowk, Corral and Fahy resumed development of RF warming for recovery of organs from vitrification at 21st Century Medicine, Inc.

In 2014 Etheridge and Bischof et al at the University of Minnesota published a new idea for warming of vitrified organs. Magnetic nanoparticles were to be added to the cryoprotectant solution inside blood vessels, and the nanoparticles warmed by a radiofrequency magnetic field instead of electric field. This new method, called “nanowarming,” received a great deal of publicity in March of this year in connection with a new paper about it in the journal Science Translational Medicine. While having the disadvantage of warming occurring only in blood vessels, which could cause overheating of very large blood vessels, the method has a distinct advantage over classical RF warming. The energy absorption efficiency, and therefore heating efficiency, of classical RF warming varies with viscosity and temperature of tissue. This can be used beneficially to maximize warming rates during the most critical phases of rewarming. However classical RF warming is unavoidably inefficient at very low temperatures, below -100°C.
Nanowarming, in contrast, warms smoothly and efficiently at all temperatures, even the very lowest. Nanowarming may therefore be especially useful for uniform warming through the “glass transition” – the very low temperature at which vitrified organs change from being solid to liquid in their behavior – a critical phase of warming for avoiding thermal stress injuries.

With the development of nanowarming, there are now two independent technologies for achieving the necessary rapid warming of organs from the vitrified state, bringing us closer to an era of transplantable organ banking. The relevance of these technologies to cryonics remains speculative at this stage. In one envisioned resuscitation scenario, repairs of the brain and/or body would be conducted at cryogenic temperatures. It is reasonable to assume that these molecular machines would also introduce novel (ice-blocking) technologies that completely eliminate the risk of ice formation upon re-warming.

Another concern is cost. At this point adding high-quality nanoparticles to the perfusate would be prohibitively expensive.

This column was written with extensive  input from a notable cryobiology researcher.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, July-August, 2017

Advances in Cryoprotectant Toxicity Research

There is little disagreement among cryobiologists that the biggest limiting factor to reversible organ cryopreservation is cryoprotectant toxicity. It is actually not that hard to create vitrification solutions that completely inhibit ice formation at even the slowest cooling rates. The problem is that such highly concentrated vitrification solutions are too toxic to permit recovery of complex organs. The least toxic vitrification solution for complex mammalian organs as of writing is M22. M22 is the culmination of many years of experimental and theoretical work by cryobiologist Greg Fahy and colleagues.

Studying cryoprotectant mixtures on rabbit kidney slices, Fahy and colleagues came to the following conclusions:

1. High concentrations of a cryoprotective agent (or a mixture of different cryoprotective agents)
can prevent ice formation during cooldown and warming.

2. The toxicity of some cryoprotectants can be neutralized by combining them with other cryoprotectants.

3. The non-specific toxicity of a cryoprotectant solution can be predicted by calculating a quantity (“qv*”) which is intended to measure the average hydrogen-bonding strength of the cryoprotectant polar groups with the water molecules in the solution.

4. Within limits, non-penetrating agents can reduce the exposure of cells to toxic amounts of cryoprotectants without reducing vitrification ability.

5. Synthetic “ice blockers” can be included in a vitrification mixture to reduce the concentration of toxic cryoprotective agents necessary to achieve vitrification.

While M22 is a low toxicity solution, its toxicity profile still necessitates minimizing exposure time and introduction and removal at low (subzero) temperatures. If we had a better understanding of the mechanisms of cryoprotectant toxicity, vitrification solutions with no toxicity at all could be introduced at higher temperatures and exposure times could be increased to optimize complete equilibration of the tissue with the cryoprotectant.

Two major reviews of cryoprotectant toxicity were published in the last 5 years; Gregory Fahy’s“Cryoprotectant Toxicity Neutralization” (Cryobiology, 2010) and Benjamin Best’s “Cryoprotective Toxicity: Facts, Issues, and Questions” (Rejuvenation Research, 2015).

Greg Fahy’s paper is a rigorous exposition of experimental results concerning the phenomenon of cryoprotectant toxicity neutralization. The paper is mostly limited to the discovery that DMSO can block the toxic effects of amides such as formamide. The combination of DMSO and formamide (or other amides such as urea and acetamide) is indeed one of the building blocks of M22 but this combination cannot be used without limit and the paper includes data that indicate the maximum molar concentrations (and ratios) that still permit full viability. In theory, if two (or more) cryoprotectants would completely neutralize each other’s toxicity they could be the sole components of a vitrification solution. But as the formulation of M22 shows, it is still necessary to add weak glass formers such as ethylene glycol, extracellular CPA’s, and “ice blockers” to supplement the toxicity neutralization obtained with formamide and DMSO. An important finding in Fahy’s paper is that n-methylation abolishes toxicity neutralization for amides and combining methylated amides also does not lead to toxicity neutralization between
them. In fact, Fahy found that the presence of n-methylated compounds renders even small amounts of DMSO toxic. The remainder of the paper discusses the mechanisms of cryoprotectant toxicity and Fahy now favors protein denaturation as a plausible mechanism of (non-specific) toxicity. While other cases of toxicity neutralization have been reported in the literature, no rigorous studies have been done to produce a body of knowledge that is comparable to what we know about amide-DMSO interactions.

Benjamin Best’s paper is more general in scope but discusses a lot of experimental data from other papers and also critically discusses Fahy’s work on cryoprotectant toxicity. As Ben Best points out, different (and seemingly contradictory) results do not necessarily mean that cryoprotectant toxicity is a species or cell-type dependent phenomenon. One could imagine a meta-analysis of cryobiology data in which variables such as concentration, loading and unloading protocols, exposure temperature, exposure time, and the type of viability assay are matched to ensure methodological consistency. It is also important to compare cryoprotectants at their minimum concentration to vitrify to make meaningful toxicity comparisons.

If the work at 21st Century Medicine is an indication, universal low-toxicity cryoprotective solutions should be feasible. Perhaps the most interesting part of the paper is where Best offers a critique of Greg Fahy’s “qv* hypothesis of cryoprotectant toxicity,” which aims to show that non-specfic toxicity concerns the degree to which cryoprotectants leave water available to hydrate macromolecules. This discovery allowed for the substitution of ethylene glycol for propylene glycol in Fahy’s lower toxicity vitrification solutions, despite the resulting higher CPA concentrations. Best observes, “it seems contradictory that water remains available for hydration, but not available for ice formation.” A potential rejoinder to this observation is that so called “bound water” does not participate in ice formation but can be disturbed by strong glass formers. Best also suggests a potential refinement of qv* that allows for more precise calculation of the hydrogen bonding strength of the polar groups that are used to calculate qv*. It is conceivable that such a refinement would eliminate the few remaining outliers in the data that support the qv* hypothesis. The paper also draws attention to the possibility of kosmotropic co-solvents and changes of pH and microenvironment polarity to mitigate cryoprotectant toxicity.

Neither of the papers discusses cryopreservation of the mammalian brain, but there is good reason to believe that in the case of this organ, modification of low-toxicity vitrification solutions is required. Conventional cryoprotective agents such as PG, EG, and DMSO have poor blood brain barrier (BBB) penetration and the brain may not tolerate the CPA exposure times that other organs do. For example, while M22 can be used for cryopreservation of the brain, many of its component have poor BBB penetration and PVP and the ice blockers (X-1000 and Z-1000) are assumed not to cross the (non-ischemic) BBB at all. One potential solution is to (reversibly) open the BBB with so-called BBB modifying agents like detergents or perhaps to search for cryoprotective agents that can cross the BBB.

The most fundamental question in the design of vitrification solutions remains whether it is possible at all to introduce high concentrations of cryoprotectants without creating any kind of irreversible molecular and ultrastructural adverse effects. Understanding what specific and nonspecific cryoprotectant toxicity exactly is should enable us to answer this question.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, August-September, 2016

Scientific Proof for Cryonics?

A cryonics advocate makes an eloquent case for cryonics. Then a scientist is called upon to dismiss the idea of cryonics because there is “no proof” for it. Unfortunately, such a statement reveals that the “scientist” in question does not know the difference between empirical science and logic, and also does not understand the difference between cryonics and suspended animation.

As the evolutionary biologist Satoshi Kanazawa writes in a November 16, 2008 column for Psychology Today “The knowledge that there is no such thing as a scientific proof should give you a very easy way to tell real scientists from hacks and wannabes… Proofs exist only in mathematics and logic, not in science. Mathematics and logic are both closed, self-contained systems of propositions, whereas science is empirical and deals with nature as it exists. The primary criterion and standard of evaluation of scientific theory is evidence, not proof.” He goes on to write that “all scientific knowledge is tentative and provisional, and nothing is final. There is no such thing as final proven knowledge in science.”

What is the proper role of science in cryonics? Let’s say that a person proposes that if we freeze a person after clinical death there is a reasonable expectation that more advanced medical technologies can reverse the freezing damage, the medical condition that gave rise to this person’s critical condition, and also the aging process that caused this medical condition in the first place. We can respond to this proposal by asking a number of questions. What will freezing do to the fine structure of the brain? How will future medical technologies infer the original state of the brain from the frozen state? What kind of technologies are required to repair the brain and restore the person to a healthy and youthful state?

These are the kinds of questions where science (and reasonable extrapolations of where science will be heading) is important in evaluating the idea of cryonics. And we are not limited to just consulting existing science, we can also push science in the direction of minimizing the damage incurred during cryopreservation so the odds of revival for the typical cryonics patient will increase. For example, in 2000 Alcor changed its protocol from limiting freezing to eliminating it through a technology called vitrification. Advances in gene editing, virus modification, and nano-scale 3D printing can make the idea of cell repair more plausible. Advances in science and technology of this nature can make people update their prior (subjective) estimates about the probability of cryonics being successful.

What such advances in science cannot do is to provide “proof ” that cryonics will work. They cannot do this because all scientific knowledge is “tentative and provisional,” but it also cannot do this for a more fundamental reason. Cryonics is not suspended animation. Cryonics concerns
stabilizing people for whom no successful medical treatment is available to permit them to benefit from future advances in medicine. By definition, it is not possible to prove that these technologies will become available.

What people who insist on “proof ” for cryonics want to see is evidence of reversible cryopreservation. Human suspended animation is indeed a research- and clinical objective that a credible cryonics organization should aim for. But it cannot be emphasized enough that while “proof ” of suspended animation would provide strong support for the practice of cryonics is it is not necessary for the cryonics idea to be plausible. What is necessary for cryonics to work is that the brain (and rest of the body) of a person are preserved to a degree that the original, healthy, state of the brain can be inferred from the preserved state. Perhaps future “neurological archeology” technologies will reveal that even freezing of the brain without cryoprotectant allows for complete revival.

A proper understanding of cryonics requires that scientists recognize the difference between providing proof and updating expectations based on empirical evidence. But it also requires the scientist, as the great cryonics writer Thomas Donaldson once recognized, to make peace with the unknown because the capabilities of future science remain a matter of debate and we cannot say for certain when a person is dead by information-theoretic criteria.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, July-August, 2016

Human Biostasis Options: Advantages and Limitations

On February 9, 2016 the Brain Preservation Foundation announced that the cryobiology company 21st Century Medicine had won their small mammal brain preservation prize. The team at 21st Century Medicine used a procedure named Aldehyde-Stabilized Cryopreservation (ASC) to preserve the ultrastructure of the brain in a “near-perfect” condition. It is important to understand how ASC differs from both conventional cryopreservation and other human biostasis alternatives to understand its merits and limitations.

In conventional cryopreservation (which is the procedure Alcor currently uses) the blood (and cell water) in the brain is replaced with a vitrification agent that permits long term storage at liquid nitrogen temperature without further degradation. The advantage of this method is that it seeks to both preserve viability and the fine ultrastructure of the brain. Currently, the disadvantage of this method is that it produces (severe) cerebral and cellular dehydration, which alters the ultrastructure of the brain and renders some components of the brain difficult to observe in electron micrographs.

A radically different alternative to cryopreservation is to chemically fix the brain with aldehydes (formaldehyde, glutaraldehyde) and store the brain at room temperature or in a fridge in the liquid state. While some people consider such a procedure “better than nothing”, Alcor does not support this kind of “chemopreservation” as a long term care option due to concerns about long-term degradation and  sub-optimal preservation in ischemic cases. An extensive critique of liquid state chemopreservation can be found in my article ‘Chemical Brain Preservation and Human Suspended Animation.’

What is notable about the procedure that won the small mammal brain preservation prize is that it combines both aldehyde fixation and vitrification. In short, first the brain is perfused with glutaraldehyde, followed by perfusion of a high concentration of cryoprotectant to protect the brain against ice formation during long term care. This idea is actually not new and was discussed in in the mid-1980s in Eric Drexler’s book Engines of Creation. The renewed popularity
and technological development of this idea was recently triggered by the formation of the Brain Preservation Foundation and its emphasis on ultrastructural preservation. The protocol that won the small mammal brain cryopreservation prize has shown indeed a degree of ultrastructural preservation that has not yet been achieved with conventional brain cryopreservation.

Alcor’s biggest concern with aldehyde-stabilized cryopreservation is that it renders the tissue completely dead by contemporary viability criteria by creating irreversible crosslinks between bio-molecules. Despite claims to preserve the “connectome”, at the molecular level structure is fundamentally altered. In terms of research aimed at reversible biopreservation, this is a dead end.

Conventional cryo, conventional chemo, and a combination of the two are the three most discussed options of human biopreservation. Other, hypothetical possibilities include (a) vitrification with agents with much higher glass transition temperatures that permit warmer storage such as at dry ice temperature (b) poly-vitrification, in which high molecular weight polymers are used to stabilize the patient near or at room temperature, and (c) the use of molecular nanobots to induce reversible biostasis (an idea originally proposed by Robert Freitas).

The current position of Alcor is to keep researching and offering conventional cryopreservation without the use of chemical fixatives. The research emphasis of the organization and associated labs this year will be to produce better electron micrographs of cryopreserved brains and the validation of blood brain barrier modifying agents to eliminate the severe dehydration that is currently observed in “good” cryonics cases.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, March-April, 2016

Cryonics is not Mind Uploading

On September 15, 2015, the MIT Technology Review published an article named “The False Science of Cryonics” that revealed how much ignorance about cryonics still exists among those that should know better (scientists, medical professionals, etc.). First of all, cryonics is not a “science” but an experimental medical procedure that is informed by scientific developments in disciplines such as cryobiology and neuroscience.

Semantics aside, a major flaw in the article is that it conflates mind uploading and cryonics. While some of our members may favor the possibility of “substrate-independent minds,” in its most “conservative” incarnation resuscitation will occur through repair of the same biological brain (or whole body) that was preserved. Complicated philosophical issues about whether a copy is “you” do not come into play in this repair scenario at all. So when Alcor was asked by a reporter to comment on the article, we submitted the following response:

The article in the MIT Technology Review rests on several mistaken assumptions. First of all, cryonics does not require or imply mind uploading. While some of our individual members are interested in this topic, the default resuscitation scenario for cryonics patients involves molecular repair of the patient’s biological brain (and body). While we are encouraged by the rise of connectomics, the aim at Alcor is to cryopreserve all the fine details of the brain and even secure viability of the brain as well as we can. In fact, in our stabilization procedures we aim to keep the brain viable by contemporary medical criteria and collect data to evaluate the efficacy of our procedures.

Alcor is a charitable, non-profit, organization and we do not make a profit when we place our patients in biostasis. Also helpful to understanding the ethics and financial feasibility of cryonics for persons of ordinary means is that most people fund cryonics through an affordable, dedicated, life insurance policy, making cryonics an accessible personal choice.

We strongly disagree that without proof of human suspended animation or flawless ultrastructural preservation it is not ethical to practice cryonics. Our organization challenges the mainstream definitions of death, and we believe that perfected cryopreservation is a sufficient but not necessary condition for cryonics to succeed. As long as we have good reasons to believe that the original state of the brain can be inferred from the damaged state, making cryonics arrangements can be a rational choice to make. To our knowledge, there are no rigorous, scientific, studies that demonstrate that today’s cryonics procedures produce irreversible destruction of identity-critical information.

Information about the ultrastructural effects of the vitrification solutions we use to inhibit ice formation can be found here: http://www.alcor.org/Library/html/newtechnology.html

It is disappointing that scientists and professional writers put so little effort into understanding what cryonics entails and what the real technological challenges are. Unfortunately, there is essentially no cost to being factually wrong about cryonics. In fact, when professional cryobiologists comment on cryonics they often make claims about their own field that are factually incorrect, such as that cryonics produces intracellular freezing, or that ice-free cryopreservation of complex organs is not yet possible.

We may not be able to persuade everyone that cryonics is the prudent, conservative choice to make, but we might benefit from giving more thought to how to prevent and counter factually erroneous articles such as the one in the MIT Technology Review.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, November 2015

How to Validate New Cryonics Technologies

Evidence in cryonics is a complicated concept. For starters, it is not possible to “prove” cryonics will work, here and now, because the fundamental idea of cryonics is to stabilize critically ill patients (people considered “dead” by less rigorous criteria) in anticipation of more advanced future medical technologies. What we can do is validate cryonics technologies with reversible cryopreservation (“suspended animation”) as a benchmark. As a general rule, we can state that we make progress in cryonics when stabilization, cryopreservation, and maintenance (“storage”) technologies cause less damage than the technologies that preceded them. But how do we know if this is the case?

The most rigorous form of validation, human clinical trials, is usually not available in cryonics. There are often new (approved) emergency medical technologies, however, that can be modified to be used in cryonics procedures. A major advantage of adopting such technologies is that the validation has already been done by other organizations or companies. Examples of such technologies will often fall under the rubric of emergency medicine. For example, an FDA-approved technology that improves blood flow during cardiopulmonary resuscitation can be added to Alcor’s stabilization equipment to improve stabilization procedures.

One step down from rigorously designed human clinical trials are animal studies. In cryonics we often make a distinction between small animal studies (e.g., mice, rats) and large animal studies (e.g., pigs, dogs) etc. It seems common sense to think that large mammals provide stronger evidence for a technology than smaller animals but the real issue at stake here is not how large an animal is but how closely an animal model tracks what happens in humans. For example, if cat brains have an uncharacteristically high tolerance for cerebral ischemia, the (smaller) rat may actually be a more realistic model for validating neuroprotective strategies in humans.

One area where choosing the correct animal model has proven itself to be of crucial importance concerns the effect of cryoprotectants on the brain. Most mammalian species experience dehydration of the brain after equilibration with a vitrification agent. Because it is reasonable to assume that severe dehydration adversely affects brain viability it is tempting to select an animal model that experiences little cryoprotectant-induced dehydration. But one thing that we have learned from burhole measurements and CT scans in human cryonics patients is that under optimal conditions cryoprotective perfusion with both glycerol and the modern vitrification agents produces severe shrinkage of the brain. So if we want to validate strategies to eliminate this dehydration the most important consideration is not how “large” the animal is but how well the animal tracks the effects of cryoprotectants on the human brain.

Most technologies in cryonics need to be evaluated with ultrastructure and/or viability as an endpoint. But there are also new developments in cryonics where such a benchmark would not make a lot of sense. For example, if we build a new patient enclosure to keep the patient cold during cryoprotective perfusion we can just measure the core temperature of the patient to see if we have done a satisfactory engineering job. Another example is the design of new dewars where we can look at variables like the boiloff rate and long-term durability of the design.

In conclusion, there are a number of ways to validate new technologies in cryonics. If a new technology has undergone human clinical trials we often can just adapt that technology for cryonics without designing new experiments. In the case of more cryonics-specific technologies animal studies can be conducted and the choice of animal model will be dictated by how close a model tracks what we know to occur in humans (among other considerations like ethics and cost). Finally, when a new development in cryonics is mostly an engineering challenge, validating its efficacy is often just an issue of doing basic physiological measurements or practical tests.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, August, 2014

Who Decides What We Can Do With Our Body (and Brain)?

Statement on the High Court ruling concerning 14 year-old cancer victim’s right to cryonics

Click here for PDF

Our hearts go out to the young British woman whose battle with cancer ended sadly earlier this month at age 14, as well as to her parents as they cope with this very difficult time. And we commend the British High Court Judge for his important ruling enabling the girl to obtain her wish to be cryogenically preserved. While we have no comment on the specifics of this case, and do not ourselves offer services of this nature, we hope we can shed some light on the project of experimental medical biostasis / cryonics more generally.

Over the past decade, scientists have made significant advances in low-temperature biology, and scientists developing molecular machines will receive this year’s Nobel Prize on December 10. Many, including scientists at places like Cambridge, Oxford, MIT, NASA and Harvard, now openly support cryonics as a legitimate scientific endeavor. Of course there is no guarantee that any cryonics patients will be revived in the future, but as discussed by four tenured professors in this recent MIT Technology Review piece, the best evidence suggests that cryonics deserves open-minded consideration.

Coordinator of the UK Cryonics and Cryopreservation Research Network, Dr João Pedro de Magalhães, when asked for his thoughts, observed that “no matter the probability you assign to the procedure, we think it’s important to give people the choice, just as we give dying patients the opportunity to try other experimental medical therapies to save their lives”.

Cryonics is a similar experimental treatment, albeit one with different legal and ethical implications, and whose probability of success is unknown. Many parts of the world are now taking progressive stances towards the idea of death with dignity. It seems incongruous with these beliefs to stigmatize a procedure for what is at worst an over-optimistic belief about the state of the future.

Despite the many intermediate successes in low-temperature biology over the past few decades, no cryonics organization can currently revive a patient. Nobody has claimed otherwise, and arguments based on this premise are missing the point.

Cryonicists look at how medicine has progressed over the past hundred years, at the millions of people whose lives would have been cut short if not for advances in technology, and it fills them with hope about what might be possible for the future. The goal of cryonics is not to be able to revive someone with contemporary technology, rather the goal is to preserve a person and her brain well enough that future technologies may be able to (repair and) revive the person. One can think of this as transporting the body forward through time or as medical time travel. This depends on technologies that will be developed in the next decades or centuries, not on the world’s capabilities today. All the major cryonics organizations in the western world are non-profits with the goal of surviving for centuries.

As Aschwin de Wolf, President of The Institute for Evidence-Based Cryonics, explained, “Cryonics is based on the premise that the neuro-anatomical basis of identity is more robust than folk wisdom suggests, and we envision future technologies that can infer the healthy state of the brain from the injured state – and even repair any damage that occurs during the cryopreservation process itself. As such, cryonics is not an act of faith, but an act of reason.”

We will cure cancer one day, and it is reasonable for this girl, born too early through no fault of her own, to choose for herself the best chance to make it to that world where more is possible.

Contact / interviews:

Dr João Pedro de Magalhães

Coordinator, UK Cryonics and Cryopreservation Research Network

+44 151 7954517 / aging@liverpool.ac.uk

www.cryonics-research.org.uk

Aschwin de Wolf

President, Institute for Evidence-Based Cryonics

contact@evidencebasedcryonics.org

www.evidencebasedcryonics.org

Appendix of key supporting materials

  • “The patient should participate responsibly in the care, including giving informed consent or refusal to care as the case might be…The patient’s right is based on the philosophical concept of respect for autonomy, the common-law right of self-determinationAmerican College of Physicians Ethics Manual, 2016

The Multi-Headed Hydra

This article explores some of the regulatory challenges facing those who would bring rejuvenation biotechnologies, like those pursued by Dr. Aubrey de Grey and the SENS Foundation, to market. It does not presume familiarity with Dr. de Grey and his work; I’ve tried to make it informative to all alike.

The Conquest of Aging

Biomedical gerontologist Aubrey de Grey predicts that the first human being to live to 1,000 years old is alive today. Who exactly that person might be – or rather, how old they are today – is a detail that Dr. de Grey has wavered on, but he has remained firm in his commitment to that prediction, and is certainly one of the most prominent figures working towards realization of the technologies required to make his prophecy reality. In his book, Ending Aging, Dr. de Grey describes his proposed approach to the “problem” of aging, and how it differs from those presently in practice.[1]

In Dr. de Grey’s opinion, the current paradigm devotes a vast majority of resources to geriatric care, which attempts to cure or manage age-associated diseases only after they emerge as recognizable groupings of symptoms. To quote an apt metaphor from another longevity advocate:

“[T]he challenge of treating illnesses in the elderly must at times seem like Heracles’ trials of combating the multi-headed Hydra. Each time one head was severed, two more would sprout in its place. Likewise, a patient might survive a serious cardiac episode with help of antihypertensive drugs only to succumb to cancer and dementia.”[2] [emphasis in original]

Meanwhile, the (significantly smaller) remaining portion of research dollars goes towards biogerontology, which studies the upstream causes of aging, any benefit of which is probably unrealizable for several human generations. However, Dr. de Grey argues that without necessarily knowing much more about the upstream causes of aging than is currently understood, it is already possible to categorize the different forms of aging “damage,” and devise therapies that will repair the damage at a sufficient rate to achieve what he terms “longevity escape velocity.”

Dr. de Grey calls his theory “Strategies for Engineered Negligible Senescence” (SENS). There are seven strategies, each related to one of the seven major categories of aging damage thus far discovered. Those categories (and proposed therapies) are: (1) cancer-causing nuclear mutations (removal of telomere-lengthening machinery, aka OncoSENS); (2) mitochondrial mutations (allotopic expression of 13 proteins, aka MitoSENS); (3) intracellular junk (novel lysosomal hydrolases, aka LysoSENS); (4) extracellular junk (immunotherapeutic clearance, aka AmyloSENS); (5) cell loss & tissue atrophy (stem cells and tissue engineering, aka RepleniSENS); (6) cell senescence (targeted ablation, aka ApoptoSENS); and (7) extracellular crosslinks (AGE-breaking molecules and tissue engineering, aka GlycoSENS). The SENS Foundation was established in 2009, helped in part through seed funding provided by Peter Thiel, co-founder of PayPal and a managing partner of The Founders Fund. The SENS Foundation’s stated purpose is “to research, develop and promote comprehensive regenerative medicine solutions for the diseases and disabilities of aging.”[3]

Delving into the details of each of Dr. de Grey’s proposed strategies is beyond the scope of this article, but it is worth taking a closer look at one of the seven. LysoSENS aims at “junk” molecules which cannot be broken down by human lysosomal enzymes. Over time, these molecules accumulate within cells, contributing to conditions like macular degeneration, atherosclerosis, and Alzheimer’s disease (AD)[4]. Dr. de Grey’s proposition is to search for novel lysosomal enzymes (novel to humans, that is) in bacteria, molds, and other microbes that are involved in “recycling” dead animal bodies, since the “junk” inside our cells is — along with the  rest of us — food to them. SENS research being carried out at Rice University has already identified one such enzyme that, when targeted to the lysosome, decreases cytotoxicity of 7-ketocholesterol (7KC), an oxysterol associated with atherosclerosis and Alzheimer’s disease.[5] Enzyme replacement therapy is already used for the treatment of lysosomal storage diseases not associated with aging, like Gaucher’s disease. Insofar as it could be used to treat a condition (or conditions) remedially, a therapy targeting 7KC with a novel lysosomal enzyme might otherwise resemble traditional approaches to disease treatment, but it could also be used preventively. Other SENS pose even greater challenges to the traditional distinctions between cure, prevention and enhancement. The objective of MitoSENS, for instance, is to render the recipient immune to the fallout consequences of mitochondrial DNA mutations by placing backup copies of the thirteen mitochondrial genes — which naturally reside only inside the mitochondria — into the cell nuclei. Significant research progress is being made into this strategy as well.[6]

The problem of normative definitions of aging

Dowsing for fountains of youth is well and good, but won’t get us very far unless they can be tapped and piped to the marketplace, and while there are many scientific obstacles to overcome before rejuvenation biotechnologies are realized, there are also social, political and legal ones. Many of these problems are definitional. For one, what exactly distinguishes age-associated diseases and conditions from “normal” features of aging? In the words of one scholar: “[F]rom the perspective of modern biogerontology, there is little to distinguish biological ageing from a disease state…. To argue that ageing is not a disease by virtue of its universality is as misleading as it is to argue that the Basenji is not a dog because it does not bark.”[7] But to dismiss this debate as purely semantic or philosophical would be to misunderstand the true difficulty the definitional problem poses.

The U.S. Food, Drug and Cosmetic Act defines “drug” as, inter alia, “articles intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals” and “articles (other than food) intended to affect the structure or any function of the body of man or other animals.” [8] So far so good, because even if the U.S. Food and Drug Administration (“FDA”) did not agree that a particular undesired physical state was a “disease” for the purposes of the first definition, it would be difficult to deny that a proposed therapeutic (whether a chemical entity or a biological product[9]) was not intended to affect the structure or functioning of the body, at some level. However, present regulatory approval pathways indirectly require that a drug be “indicated for the treatment, prevention, mitigation, cure, or diagnosis of a recognized disease or condition or of a manifestation of a recognized disease or condition, or for the relief of symptoms associated with a recognized disease or condition.”[10] [emphasis mine]. The phrase “recognized disease or condition” is not defined in this context[11], and the FDA is not itself the recognizer, but rather looks for consensus within the clinical and/or scientific communities regarding the existence of a particular disease or condition, and of clear criteria for clinical diagnosis thereof.[12] To quote one author: “To the extent that many problems of ageing have not been formally recognized by any of these processes, the FDA has no clear guidance on how to determine if a proposed indication would be acceptable.” [13]

For many age-associated conditions, the question of “recognition” is a valueladen debate. While some commentators will no doubt accuse longevity advocates of “disease-mongering”[14], Dr. de Grey would probably argue that that sort of reaction is a symptom of what he terms the “pro-aging trance”[15] — a terror management strategy that accepts and embraces the apparently unavoidable progressive wasting of one’s body (and mind), instead of rejecting and resisting it. But the cognitively dissonant distinction between normal, “healthy” aging on the one hand, and “diseases” of aging on the other is not impermeable. For some historical perspective, it is worth considering the example of Alzheimer’s disease. When it was first described in 1910, AD only included what is now referred to as “earlyonset Alzheimer’s disease,” i.e., when the symptoms of “senile dementia” appeared in someone under 65.[16] Due to its vastly less frequent incidence, this “presenile dementia” was assumed to be distinct from the normal variety. However this normal/ abnormal categorization broke down in 1977, due to professional recognition of their near identical symptomologies, making the early-onset subtype by far the minority of AD incidence.[17]

A present-day example of this process of recognizing “normal” features of aging as diseases or conditions of aging, is the case of sarcopenia. Sarcopenia (literally “poverty of the flesh”) describes the degeneration of skeletal muscle mass and strength that occurs with aging that contributes (in part) to disability, frailty, and morbidity in older persons.[18] Until fairly recently, sarcopenia and related conditions like sarcopenic obesity were considered “normal” aspects of aging, much like senile dementia prior to 1977. To be fair, both sarcopenia and senile dementia are normal, insofar as they are common conditions in older persons — but that does not mean they are untreatable, nor that they should be left untreated. A number of potential drug targets have been identified that may be of use in treating sarcopenia[19], but if consensus recognition of the condition is lacking there may not yet be a regulatory pathway for licensing therapeutics to treat it.[20]

Thus, as it stands, forging a regulatory pathway for treatments of a common, disabling (and in some cases indirectly lethal) feature of aging involves two distinct steps: first, persuade the scientific and clinical communities that a particular symptomology of aging can and should be treated, and second, persuade the FDA that everyone else is persuaded. But this is not insurmountable. The European Working Group on Sarcopenia in Older People published a “practical clinical definition and consensus diagnostic criteria for agerelated sarcopenia” in 2010[21], which was followed by a consensus definition from The International Working Group on Sarcopenia in 2011[22]. In the U.S., the Foundation for the National Institutes of Health, the National Institute on Aging, and the FDA held a Sarcopenia Consensus Summit on May 8-11, 2012.[23] A number of clinically meaningful end points have been proposed for assessing treatment efficacy[24], including patient-reported outcomes.[25] Under appropriate regulatory supervision, medicalization of sarcopenia would help older persons maintain or even regain functional independence and quality of life — and perhaps boost lifespan, via a reduction in comorbidity with diseases like osteoporosis.

The problem of causally interrelated disease states

There is another definitional problem: What distinguishes one age-associated disease from another? This may seem like a facetious question, given the obvious symptomatic differences between atherosclerosis and AD. However, as mentioned above, the oxysterol 7KC has been implicated in the pathogenesis of both those disease states. If 7KC is indeed a metabolic byproduct that is causally related to both atherosclerosis and AD then, in addition to being a promising drug target itself, it could conceivably qualify as a surrogate endpoint for clinical trials of new drugs indicated for those diseases. FDA has issued a draft guidance regarding qualification of biomarkers as drug development tools[26], but surrogate endpoints may only be used in lieu of direct measures of clinical benefit under the FDA’s “Fast-Track Program,” which is only available for new drugs intended for the treatment of a serious or lifethreatening condition and that demonstrate the potential to address unmet medical needs for such a condition.[27] However, it would not be necessary to qualify 7KC reduction as a surrogate endpoint for both AD and atherosclerosis. Doing so for one or the other based on which is thought to be the more serious condition and/or the greater unmet need would allow its use in a fast-tracked New Drug Application for the one indication, and then if safety and efficacy in humans is established and the therapeutic is approved, data from (likely compulsory) post-marketing studies could be used in a new indication claim for the other condition.

Surrogate endpoints need only be “reasonably likely to predict clinical benefit”[28], and some commentators have pointed out that applying this lower standard to the screening of surrogate endpoints may result in drugs approved on the basis of evidence of an effect on a biomarker which, while related to the disease, is not actually causally related to any clinical benefit.[29] Of course, given its ambitious objective, the SENS Foundation has a strong vested interest in tying 7KC to clinical benefit, and the fact that FDA-qualified biomarkers are released into the public domain also fits within the Foundation’s public interest mandate, and could enhance perceptions of the legitimacy of its research goals. But more importantly, it could shorten clinical trials, an oft-criticized source of delay and drug costs. While its work to date has primarily been proof-of-concept research, in the future the SENS Foundation might devote some of its resources to running forms of aging damage like 7KC through the biomarker qualification process. Although publishing both the proof-of-concept and such valuable drug development tools might cut out some of the traditional patenting opportunities[30], it also offsets costs ordinarily borne by pharmaceutical companies. A little low-hanging fruit might stir up some productive competition in an industry sometimes criticized for chasing after minor therapeutic improvements and patent trolling.

Another option that is very in line with the social agenda of longevity advocates would be to promote the rebranding of multiple disease states with significantly overlapping low-level chemistry as single unified conditions that present varied symptom groupings based on exposure to particular environmental factors (including the endogenous “environment,” like certain genes or epigenetic variations, along with more traditional exogenous contributors like diet, exercise, etc). Admittedly, this would be the more difficult path, because it relies on the two-step process of disease recognition, discussed above, and considering how long it took AD and senile dementia to be folded into AD with an early-onset subtype, trying to replicate this process with diseases that present as differently as atherosclerosis and AD may be a Sisyphean task. On the other hand, academic pressure of this kind could have trickle-out effects on the public, re-situating the discourse of age-associated diseases further upstream, pressing on towards greater recognition of aging as disease.

Finally, slight augmentations to the SENS branding could be in order. Dr. de Grey gave unique names to his proposed strategies (LysoSENS, MitoSENS, etc.), but not to the categories of damage which are the targets of those strategies. Devising and promoting novel medical names for these categories of damage, like idiocytotoxicosis[31] for the “intracellular junk” targeted by LysoSENS, might prompt frame-shifting in the academic and clinical communities that could consequently (albeit indirectly, and thus probably slowly) broaden the scope of “recognized disease or condition”. Sadly for the planet, ‘junk’ doesn’t seem to be something humans take terribly seriously — idiocytotoxicosis, on the other hand, well that’s clearly a monster. Perhaps this suggestion borders on “disease-mongering” — but isn’t that term itself equally agenda-driven, given the not-so-subtle association with war-mongering? Dr. de Grey and other longevity advocates consider themselves to be on moral high ground, so these kinds of accusations are only of consequence if they provoke counter-productive public response, and reframing well-recognized diseases like AD and atherosclerosis as symptoms of underlying “metabolic pathology” can hardly be characterized as “questionable new diagnoses — like [premenstrual dysphoric dysfunction] and social anxiety disorder — which are hard to distinguish from normal life,” the likes of which give at least one critic concern. [32] And perhaps it is the very idea that “normal” is the ultimate objective — as opposed to simply “better” — that is the problem.

What’s the alternative?

If the perceived burden is too high, and the cost of doing nothing too great, stakeholders may look to circumvent the FDA. The SENS Foundation characterizes the assault on aging as the next space race.If the U.S. doesn’t take action to foster local development of what will assuredly be highly sought-after therapies, the movement may simply move underground (i.e. further in the vein of DIYbio), and overseas (medical tourism, and seasteads), which will only hamper the FDA’s mandate to protect Americans from harm.

Endnotes

[1]: Aubrey de Grey & Michael Rae, Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime, (New York: St Martin’s Press, 2007).

[2]: David Gems, “Tragedy and delight: the ethics of decelerated aging” (2011) 366 Philosophical Transactions of the Royal Society B [Phil Trans R Soc B] 108 at 110.

[3]: SENS Foundation, SENS Foundation, online: <http://www.sens.org/about-thefoundation>.

[4]: Jacques M Mathieu et al, “7-Ketocholesterol Catabolism by Rhodococcus jostii RHA1” (2010) 76:1 Applied and Environmental Microbiology 352.

5]: Jacques M Mathieu et al, “Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase” (2012) Biotechnology and Bioengineering, online:
<http://www.wileyonlinelibrary.com> DOI 10.1002/bit.24506.

[6]: SENS Foundation, Research Report 2011, online: <http://images.sens.org/reports/ SENS%20Research%20Report%202011.pdf>.

[7]: Supra note 2 at 109.

[8]: 21 USC § 321(g)(1).

[9]: 42 USC § 262(i). The phrase “analogous product” has been used to justify the extension of the FDA’s regulatory authority to human cells, tissues, and cellular and tissue-based products (HCT/Ps). See also Areta L Kupchyk, “Approval of Products for Human Use” in HB Wellons et al, Biotechnology and the Law (ABA, 2007) 591 at 617, note 41

[10]: 21 CFR § 201.57(c)(2) Specifically, this is a labeling requirement, but if a drug cannot be labeled according to the regulation, the New Drug Application cannot be approved. See also 21 CFR § 201.56.

[11]: The term disease is defined in 21 CFR §101.93(g) for the purposes of disease claims relating to dietary supplements, but that is only applicable in that context. See also 21 USC 343(r)(6).

[12]: William J Evans, “Drug discovery and development for ageing: opportunities and challenges” (2011) 366 Phil Trans R Soc B 113 at 114.

[13]: Ibid at 114.

[14]: Barbara Mintzes, “Disease Mongering in Drug Promotion: Do Governments Have a Regulatory Role?” (2006) 3:4 PLoS Medicine e198.

[15]: Aubrey de Grey, “Combating the Tihtonus Error: What Works?” (2008), 11:4 Rejuvenation Research 713.

[16]: GE Berrios, “Alzheimer’s disease: a conceptual history” (1990) 5:6 International Journal of Geriatric Psychiatry 355.

[17]: Robert Katzman et al, Alzheimer’s disease: senile dementia and related disorders (NY: Raven Press, 1978) at 595.

[18]: Eric P Brass & Kathy E Sietsema, “Considerations in the Development of Drugs to Treat Sarcopenia” (2011) 59:3 Journal of the American Geriatrics Society 530.

[19]: Ibid at 531.

[20]: Supra note 12 at 116.

[21]: Alfonso J Cruz-Jentoft et al, “Sarcopenia: European consensus on definition and diagnosis” (2010) 39:4 Age and Ageing 412 (Abstract).

[22]: Roger A Fielding et al, “Sarcopenia: An Undiagnosed Condition in Older Adults. Current Consensus Definition: Prevalence, Etiology, and Consequences” (2011)12:4 Journal of the American Medical Doctors Association [JAMDA] 249 (Abstract).

[23]: See Marco Brotto, “Lessons from the FNIH-NIA-FDA sarcopenia consensus summit” (2012) 9 IBMS BoneKEy 210.

[24]: Supra note 18 at 531-533.

[25]: Ibid at 533. See also Christopher J Evans et al, “Development of a New Patient-Reported Outcome Measure in Sarcopenia” (2011) 12:3 JAMDA 226.

[26]: Center for Drug Evaluation and Research, “Guidance for Industry – Qualification Process for Drug Development Tools,” FDA (October 2010) online: <http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM230597.pdf>.

[27]: 21 USC § 356(a)(1).

[28]: 21 CFR § 314.510.

[29]: Thomas R Fleming, “Surrogate Endpoints And FDA’s Accelerated Approval Process” (2005) 24:1 Health Affairs 67. See also Thomas R Fleming and David L DeMets, “Surrogate end points in clinical trials: are we being misled?” (1996) 125:7 Annals of Internal Medicine 605.

[30]: There may be other intellectual property issues implicated in this shift of paradigm in drug development and regulation, but they are beyond the scope of this article.

[31]: Meaning “self, one’s own” + “cell” + “toxin” + “condition of increase”.

[32]: Supra note 14 at 0463.

[33]: SENS Foundation, Annual Report 2011, online: <http://www.sens.org/sites/ srf.org/files/SENS%20Foundation%20 Annual%20Report%202011.pdf>.

First published as a regular column called In Perpetuity in Cryonics Magazine, March 2013

Advances in Cryoprotectant Toxicity Research

There is little disagreement among cryobiologists that the biggest limiting factor to reversible organ cryopreservation is cryoprotectant toxicity. It is actually not that hard to create vitrification solutions that completely inhibit ice formation at even the slowest cooling rates. The problem is that such highly concentrated vitrification solutions are too toxic to permit recovery of complex tissues. The least toxic vitrification solution for complex mammalian organs as of writing is M22. M22 is the culmination of many years of experimental and theoretical work by cryobiologist Greg Fahy and colleagues using rabbit kidney slices. Studying selected cryoprotectant mixtures on rabbit kidney slices, Fahy and colleagues came to the following conclusions:

1. High concentrations of a cryoprotective agent (or a mixture of different cryoprotective agents) can prevent ice formation during cooldown and warming.

2. The toxicity of some cryoprotectants can be neutralized by combining them with other cryoprotective agents.

3. The non-specific toxicity of a  cryoprotectant solution can be predicted by calculating a quantity (“qv*”) which is intended to measure the average hydrogen-bonding strength of the cryoprotectant polar groups with the water molecules in the solution.

4. Within limits, non-penetrating agents can reduce the exposure of cells to toxic amounts of cryoprotectants without reducing vitrification ability.

5. Synthetic “ice blockers” can be included in a vitrification mixture to reduce the concentration of toxic cryoprotective agents necessary to achieve vitrification.

While M22 is a low toxicity solution, its toxicity profile still necessitates minimizing exposure time and introduction and removal at low (subzero) temperatures. If we had a better understanding of the mechanisms of cryoprotectant toxicity, vitrification solutions with no toxicity at all could be introduced at higher temperatures and exposure times could be increased to optimize complete equilibration of the tissue with the cryoprotectant. It would also allow safer storage at intermediate temperature temperatures (around -130 degrees Celsius) because ultra-stable vitrification solutions could be used that are less prone to de-vitrification upon re-warming. This would be of particular interest for the cryopreservation of large organs or even whole organisms (with applications such as suspended animation and cryonics).

Two major reviews of cryoprotectant toxicity were published in the last 5 years; Gregory Fahy’s “Cryoprotectant Toxicity Neutralization” (Cryobiology, 2010) and Benjamin Best’s “Cryoprotective Toxicity: Facts, Issues, and Questions” (Rejuvenation Research, 2015).

Greg Fahy’s paper is a rigorous exposition of experimental results concerning the phenomenon of cryoprotectant toxicity neutralization. The paper is mostly limited to the discovery that DMSO can block the toxic effects of amides such as formamide. The combination of DMSO and formamide (or other amides such as urea and acetamide) is indeed one of the building blocks of M22 but this combination cannot be used without limit and the paper includes data that indicate the maximum molar concentrations (and ratios) that still permit full viability. In theory, if two (or more) cryoprotectants would completely neutralize each other’s toxicity they could be the sole components of a vitrification solution. But as the formulation of M22 shows, it is still necessary to add weak glass formers such as ethylene glycol, extracellular CPA’s, and “ice blockers” to supplement the toxicity neutralization obtained with formamide and DMSO. An important finding in Fahy’s paper is that n-methylation abolishes toxicity neutralization for amides and combining methylated amides also does not lead to toxicity neutralization between them. In fact, Fahy found that the presence of n-methylated compounds renders even small amounts of DMSO toxic. The remainder of the paper discusses the mechanisms of cryoprotectant toxicity and Fahy now favors protein denaturation as a plausible mechanism of (non-specific) toxicity. While other cases of toxicity neutralization have been reported in the literature, no rigorous studies have been done to produce a body of knowledge that is comparible to what we know about amide-DMSO interactions.

Benjamin Best’s paper is more general in scope but presents a lot of experimental data and also critically discusses Fahy’s work on cryoprotectant toxicity. As Ben Best points out, different (and seemingly contradictory) results do not necessarily mean that cryoprotectant toxicity is a species or cell-type dependent phenomenon. One could imagine a meta-analysis of cryobiology data in which variables such as concentration, loading- and unloading protocols, exposure temperature, exposure time, and the type of viability assay are matched to ensure methodological consistency. It is also important to compare cryoprotectants at their minimum concentration to vitrify to make meaningful toxicity comparisons. If the work at 21st Century Medicine is an indication, universal low-toxicity cryoprotective solutions should be feasible. Perhaps the most interesting part of the paper is where Best offers a critique of Grag Fahy’s “qv* hypothesis of cryoprotectant toxicity”, which aims to show that non-specfic toxicity concerns the degree to which cryoprotectants leave water available to hydrate macromolecules. This discovery allowed for the substitution of ethylene glycol for propylene glycol in Fahy’s lower toxicity vitrification solutions, despite the resulting higher CPA concentrations. Best observes, “it seems contradictory that water remains available for hydration, but not available for ice formation.” A potential rejoinder to this observation is that so called “bound water” does not participate in ice formation but can be disturbed by strong glass formers. Best also suggests a potential refinement of qv* that allows for more precise calculation of the hydrogen bonding strength of the polar groups that are used to calculate qv*. It is conceivable that such a refinement would eliminate the few remaining outliers in the data that support the qv* hypothesis. The paper also draws attention to the possibility of kosmotropic co-solvents and changes of pH and microenvironment polarity to mitigate cryoprotectant toxicity.

Neither of the papers discusses cryopreservation of the mammalian brain, but there is good reason to believe that in the case of this organ modification of low-toxicity vitrification solutions is required. Conventional cryoprotective agents such as PG, EG, and DMSO have poor blood brain barrier (BBB) penetration and the brain may not tolerate the CPA exposure times that other organs do. For example, while M22 can be used for cryopreservation of the brain, many of its component have poor BBB penetration and PVP and the ice blockers (X-1000 and Z-1000) are assumed not to cross the (non-ischemic) BBB at all. One potential solution is to (reversibly) open the BBB with so- called BBB modifying agents like detergents or perhaps to search for cryoprotective agents that can cross the BBB.

The most fundamental question in the design of vitrification solutions remains whether it is possible at all to introduce high concentrations of cryoprotectants without creating any kind of irreversible molecular and ultrastructural adverse effects. Understanding what specific and non-specific cryoprotectant toxicity exactly is should enable us to answer this question.

Originally published as a column (Quod incepimus conficiemus) in Cryonics magazine, September-October, 2016

An End to the Virus

Breakthroughs in medicine have increased substantially over the last hundred years, and most would agree that the introduction of antibiotics in 1942 has been one of the largest milestones in the history of medicine thus far. The success in treating bacterial infection has only accentuated the glaring lack of progress in developing effective therapeutics for those other enemies of the immune system, viruses. But Dr. Todd Rider and his team at MIT have dropped a bombshell with their announcement of a new broad spectrum antiviral therapeutic, DRACO, which appears not only to cure the common cold, but to halt or prevent infections by all known viruses.

Before talking specifically about this exciting news, let us first review viral biology and why viral infections have been so difficult to treat.

As you may recall from your early education, a virus particle, or virion, consists of DNA or RNA surrounded only by a protein coat (i.e., naked virus) or, occasionally, a protein coat and a lipid membrane (i.e., enveloped virus). Viruses have no organelles or metabolism and do not reproduce on their own, so they cannot function without using the cellular machinery of a host (bacteria, plant, or animal).

Viruses can be found all throughout our environment and are easily picked up and transferred to areas where they may enter our bodies, usually through the nose, mouth, or breaks in the skin. Once inside the host, the virus particle finds a host cell to infect so it can reproduce.

There are two ways that viruses reproduce. The first way is by attaching to the host cell and entering it or injecting viral DNA/RNA into the cell. This causes the host cell to make copies of the viral DNA and translate that DNA to make viral proteins. The host cell assembles new viruses and releases them when the cells break apart and die, or it buds the new viruses off, which preserves the host cell. This approach is called the lytic cycle.

The second way that viruses reproduce is to use the host cell’s own materials. A viral enzyme called reverse transcriptase makes a segment of DNA from its RNA using host materials. The DNA segment gets incorporated into the host cell’s DNA. There, the viral DNA lies dormant and gets reproduced with the host cell. When some environmental cue happens, the viral DNA takes over, makes viral RNA and proteins, and uses the host cell machinery to assemble new viruses. The new viruses bud off. This approach is called the lysogenic cycle; these viruses are called retroviruses and include herpes viruses and HIV.

Once free from the host cell the new viruses can attack other cells and produce thousands more virus particles, spreading quickly throughout the body. The immune system responds quickly by producing proteins to interfere with viral replication, pyrogenic chemicals to raise body temperature, and the induction of cell death (apoptosis). In some cases simply continuing the natural immune response is enough to eventually halt viral infection. But the virus kills many host cells in the meantime, leading to symptoms ranging from the characteristic runny nose and sore throat of a cold (rhinovirus) to the muscle aches and coughing associated with the flu (influenza virus).

Any virus can be deadly, especially to hosts with a weakened immune system, such as the elderly, small children, and persons with AIDS (though death is actually often due to a secondary bacterial infection). And any viral infection will cause pain and suffering, making treatment a very worthwhile goal. So far, the most successful approach to stopping viral infections has been prevention through the ubiquitous use of vaccines. The vaccine— either a weakened form of a particular virus or a mimic of one—stimulates the immune system to produce antibodies specific to that virus, thereby preventing infection when the virus is encountered in the environment. In another approach, antiviral medications are administered post-infection and work by targeting some of the specific ways that viruses reproduce.

However, viruses are very difficult to defeat. They vary enormously in genetic composition and physical conformation, making it difficult to develop a treatment that works for more than one specific virus. The immense number of viral types in nature makes even their classification a monumental job as there is more enormous structural diversity among viruses. Viruses have been evolving much longer than any cells have even existed and they have evolved methods to avoid detection and to overcome attempts to block replication. So, while we have made some progress in individual battles, those pesky viruses have definitely been winning the war.

Which is why the announcement of a broad spectrum antiviral therapeutic agent is such huge news. In their paper, Rider et al. describe a drug that is able to identify cells infected by any type of virus and which is then able to specifically kill only the infected cells to terminate the infection. The drug, named DRACO (which stands for Double-stranded RNA (dsRNA) Activated Caspase Oligomerizer), was tested against 15 viruses including rhinoviruses, H1N1 influenza, polio virus, and several types of hemorrhagic fever. And it was effective against every virus it was pitted against.

Dr. Rider looked closely at living cells’ own defense mechanisms in order to design DRACO. First, he observed that all known viruses make long strings of doublestranded RNA (dsRNA) during replication inside of a host cell, and that dsRNA is not found in human or other cells. As part of the natural immune response, human cells have proteins that latch onto dsRNA and start a biochemical cascade that prevents viral replication. But many viruses have evolved to overcome this response quite easily. So Rider combined dsRNA detection with a more potent weapon: apoptosis, or cell suicide.

Basically, the DRACO consists of two ends. One end identifies dsRNA and the other end induces cells to undergo apoptosis. When the DRACO binds to dsRNA it signals the other end of the DRACO to initiate cell suicide, thus killing the infected cell and terminating the infection. Beautifully, the DRACO also carries a protein that allows it to cross cell membranes and enter any human or animal cell. But if no dsRNA is present, it simply does nothing, leaving the cell unharmed.

An interesting question is whether any viruses are actually beneficial and whether wiping all viruses out of an organismal system may have negative consequences (as happens when antibiotic treatment eradicates both invading pathogenic bacteria and non-pathogenic flora, often leading to symptoms such as digestive upset). After his recent presentation at the 6th Strategies for Engineered Negligible Senescence (SENS) conference in September 2013, Dr. Rider fielded this question and stated quite adamantly that there are no known beneficial, symbiotic, or non-harmful viruses. This point is further emphasized in a recently published interview in which he is asked whether DRACO-triggered cell death could lead to a lesion in a tissue or organ. Rider responds that “Virtually all viruses will kill the host cell on the way out. Of the hand-full that don’t, your own immune system will try to kill those infected cells. So we’re not really killing any more cells with our approach than we already have been. It’s just that we’re killing them at an early enough stage before they infect and ultimately kill more cells. So, if anything, this limits the amount of cell death.”

So far, DRACO has been tested in cellular culture and in mouse models against a variety of very different virus types. Rider hopes to license DRACO to a pharmaceutical company so that it can be assessed in larger animal trials and, ultimately, human trials. Unfortunately, it may take a decade or more to complete this process and make the drug available for human therapeutic purposes, and that’s only if there is enough interest to do so. Amazingly, the DRACO project was started over 11 years ago and has barely survived during that period due to lack of interest and funding. Even now, after the DRACOs have been successfully engineered, produced, and tested, no one has yet reached out to Rider about taking them beyond the basic research stage. Let us hope that those of us who do find this work unbelievably exciting can make enough noise that Rider’s work continues to the benefit of all mankind.

Originally published as an article (in the Cooler Minds Prevail series) in Cryonics magazine, November, 2013