July 24-27 I attended the 2011 annual Society for Cryobiology conference in Corvallis, Oregon.
A number of the first presentations were concerned with means to *avoid* cryopreservation. Room temperature storage is much less expensive and troublesome, and improves ease of transport, especially in remote areas. One such technology “shrink wrapped” DNA in a glass and another used trehalose to protect lipid membranes in a similar manner. Applied to cells, such technologies are viewed as a form of room-temperature vitrification.
Another researcher had successfully freeze-dried hematopoietic stem cells using trehalose and other additives without losing the ability of the stem cells to differentiate. Stress proteins in combination with trehalose allowed for desiccation of mammalian embryonic kidney cells without loss of viability. Late Embryogenesis Abundant (LEA) proteins also assist trehalose in dehydration tolerance.
Christoph Stoll showed that depleting red blood cell membranes of cholesterol can increase
trehalose uptake, but when I asked him in person about it, he said that the uptake was not enough to make much difference. Depleting cell membranes of cholesterol makes them more vulnerable to chilling injury, so I don’t think cholesterol depletion is a very good idea.
Masakazu Matsumoto spoke about some of the interesting anomalous properties of water.
Andrew Brooks spoke about the largest University cell and DNA repository in the world at Rutgers University. They store DNA by plunging in liquid nitrogen. He told me that 10 freezings and thawings does not impair DNA quality. That is encouraging for CI’s tissue/DNA storage program, because we plunge our samples into liquid nitrogen. Brooks gave data showing that RNA is much less hardy in liquid nitrogen than DNA.
David Denlinger noted that HSP70 RNAi can block cold tolerance in insects. He also mentioned a Czech study which found that insect larva fed proline could survive liquid nitrogen. Perhaps we should be feeding proline to terminal cryonics patients.
In preparation for this conference, I had done a lot of reading on the subject of chilling injury and was hoping to question researchers on the subject. Steve Mullen showed a video of meiotic spindles dissociating at low temperature.
Spindles are a form of microtubules. Microtubules are known to dissociate at low temperature, but can spontaneously re-associate upon rewarming. But that would not be so beneficial when the microtubules are functioning as centrosomes because the reassembly would not be a reconstruction of the original structure. This is probably why cell division often stops at low temperature.
Tiantian Zhang is one of the two candidates to become the new Society for Cryobiology President. Her field of study is cryopreservation of fish embryos and oocytes, which are especially vulnerable to chilling injury.
Fish are useful scientific models because they have a much simpler genome than mammals. 50% of endangered species are fish, but fish don’t get anywhere near the concern that pandas do. In both her lecture, and when I spoke to her in person, Dr. Zhang had apparently not learned any more than what was in her 2009 paper.
Why does reducing yolk content reduce chilling injury? Why is methanol the most non-toxic cryoprotectant for fish embryos, and so protective? If microtubule dissociation were a mechanism of chilling injury, it is indeed ironic that a 2006 Society of Cryobiology meeting presentation found that methanol causes proteolysis.
Kevin Brockbank spoke on the oxygenated hypothermic machine perfusion that he used to preserve pig livers at 4-6deg C for 12 hours. As a somewhat off-the-wall question, I asked him if he had assayed for chilling injury. This was off-the-wall because I have never heard of anyone assaying chilling injury. He responded that he had not, but that there were plans to use gene arrays to assay for chilling injury. This is like gene arrays to assay for aging — it requires deeper analysis, especially if chilling injury — like aging — is due to multiple mechanisms, the mechanisms are controversial, and no one mechanism is dominant. Northern wood frogs, arctic insects, and polar fish don’t have problems with chilling injury, although their adaptations include heat shock proteins and highly unsaturated cell membranes.
Much to my frustration, I have not had a good conversation with Peter Mazur (the uncrowned guru of cryobiology) since he got me to tell him I am a cryonicist several years ago. I have repeatedly asked him questions, and he has repeatedly been rude and dismissive. This year was different, for some reason. When I asked him about frozen water expansion contributing to mechanical damage he noted that cells could tolerate a 9% expansion without lysis even if freezing was intracellular. When I asked him how much dehydration cells could tolerate without damage, he said cells could lose all of the osmotic water (90% of cell water), and could lose more in freeze-drying with proper protectants (like trehalose). I was somewhat stunned by this answer, which takes no account of intracellular electolyte concentration increasing on dehydration. Next year I will be more optimistic about the possibility of talking with him, and I will prepare questions more carefully.
I spoke to Society for Cryobiology President John Crowe about his negative remarks concerning trehalose, in light of the fact that he is very aware of many of its benefits. John told me that a new method of manufacturing trehalose from starch is making trehalose as inexpensive as sucrose. If trehalose is used on bakery sugar, the sugar will not melt and run after a couple of days, as happens with sucrose. I mentioned to John that Robert Ettinger had just died. I had imagined that he might ask me to say a few words about the matter to the cryobiologists at their business meeting, but John treated the matter as a non-event, and I got the distinct impression that he would have preferred that I had not mentioned it.
At the business meeting it was noted that membership has dropped from close to 300 in 2008 and 2009 to just above 200 in 2011. There is concern that web access to the journal
CRYOBIOLOGY is becoming so easy that the incentives for membership have dropped. Or the global financial crisis is taking its toll on Society for Cryobiology membership. CRYOBIOLOGY journal impact factor has fallen to 1.830 from a high of 2.044 in 2002.
I appreciate being able to attend the business meetings, but one of the vehemently anti-cryonics cryobiologists gives me dirty looks. I have not been kicked-out yet, though, and decreasingly worry that I will be. A similar thought goes through my head as when I attend an Alcor meeting: “Spy in the House of Love.” But I really want the Society to prosper and grow, not be harmed, because I appreciate their good work (as with Alcor), even if they view me as a threat.
I had a brief chat with the cryonics-friendly Treasurer, who asked me when I think a cryonics patient will be reanimated. When I told him not less than 50 years, he said that a lot of surprising things can happen in 20 years. He is a more optimistic cryonicist than I am! At least as remarkable is that he is currently working with biotechnologists who are engineering scaffolds that can be used for growing organs from stem cells. That is a very cryonics-relevant project!
Every year I exchange a few words with Arthur Rowe (the cryobiologist who repeatedly compares cryonics to restoring a cow from hamburger — as he did in “Death in the Deep Freeze” – a comparison which probably originated with Peter Mazur). This year Arthur spent a lot of time hanging out with John G. Baust (the man who compared publishing cryonics science research with publishing Nazi hypothermia experiments). At the end of the conference I lost patience trying to catch Arthur alone, so I approached Arthur to say “hi”. Arthur said that he had seen on TV that Robert Ettinger had just died. He asked me about Robert’s educational credentials, and about my taking Robert’s place as CI President. Then he introduced me to John Baust. John was politely quiet, and said very little.
As with the 2010 Cryobiology Conference, I felt decreasingly paranoid as the meeting proceeded, but my level of paranoia was nonetheless very high near the beginning of this meeting. Overall, the amount by which I “came out” as a cryonicist was modest this year, and my softening of the hostility of cryobiologists to cryonics was modest this year compared to the previous one. The 2012 Society for Cryobiology Conference is scheduled to be held in Argentina.