X-Message-Number: 15227 From: Date: Mon, 1 Jan 2001 11:58:47 EST Subject: Vitrification Instalment 3 KIDNEYS VIABLE AFTER PERFUSION This is Instalment 3 of my sometime background series on vitrification, and refers to the paper "Permanent Life Support by Kidneys Perfused with a Vitrifiable (7.5 Molar) Cryoprotectant Solution" by Bijan S. Kheirabadi and Gregory M. Fahy, TRANSPLANTATION vol. 70, 51-57, No. 1, July 15, 2000. Except where quotation marks are used, the statements and comments are my impressions and not directly from the paper. The last paragraph of the abstract reads: "Conclusions. The results described provide the strongest evidence to date that it may be possible to bank kidneys for unlimited periods in the absence of ice for later transplantation." Again, part of my purpose here is to put in perspective some of the claims made for current ability to vitrify human brains. The paper discussed today is only about six months old, based on work probably only about a year old. It does not concern human brains, but rabbit kidneys. It does not concern vitrification, except indirectly-there was no vitrification, only perfusion with a "vitrifiable" solution, followed by washout and autografting to show viability. In other words, the only purpose--achieved substantially, but not completely--was to show that the perfusate solution in and of itself would be harmless. The solution used is called VS4, consisting of a mixture of DMSO and formamide in a 1:1 mole ratio, plus 15% weight per volume of 1,2 propanediol (propylene glycol), total concentration 7.5 molar, these solutes included in an undiluted EC (EuroCollins) vehicle solution. This solution is reported to vitrify when "cooled at about 10 deg C per minute in a non-damaging pressure range for cryoprotected rabbit renal cortical tissue." In other words, apparently, the vitrification had only been confirmed for kidney cortical tissue, not whole rabbit kidneys, and higher than normal atmospheric pressure is contemplated. (One of Dr. Fahy's earlier patents used very high pressures, probably completely impractical for human brains. The present paper says that "The next step required before kidneys can be vitrified with VS4 is to show that they, like kidney slices, can be subjected to elevated pressure in the presence of VS4 without serious injury.") Survival was demonstrated by observing the rabbits left with only the treated kidney. Survival rate for the control group was 7 of 10, and for the three experimental groups respectively 5 of 13, 6 of 10, and 10 of 10. The fact that 30% of the control group failed suggests considerable individual variation. There was "acute sublethal injury even in the most successful experimental group." The most successful group was that with the lowest temperature of perfusion, 2 or 3 deg below zero C. Success also required use of certain drugs, such as pretreatment with iloprost. The mechanism of protection here is not well understood, although the actions of the drug include dilation of the blood vessels, protection from ischemic (lack of blood) injury, and antiplatelet activity (prevention of clotting). The 21CM workers now have gone beyond VS4 to alkoxylated compounds, and for all I know beyond those, so all of the above is somewhat moot. Still, as far as I know, nothing more recent is in the public record, except the glycol ethers on which I have previously commented. Once again, then, as far as I know, not a single mammalian organ of any kind has been vitrified to long term storage temperature and then rewarmed and examined. The difficulties with rabbit kidneys, stretching over many years, suggest that problems with human brains may well take decades to resolve. Of course, this is a reason for more research effort, not less--but it is also a reason to take with a very large grain of salt any claims about current capabilities. Robert Ettinger Cryonics Institute Immortalist Society http://www.cryonics.org Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15227