X-Message-Number: 14879 Date: Wed, 08 Nov 2000 13:43:22 -0800 From: Jeff Davis <> Subject: Re: Frogs and fish Marta Sandberg wrote, referring to natural, antarctic-fish cryoprotectant: >The last point is moot. The molecules are too large to be absorbed into >cells. Unless they can be slimmed down they can't be used as a perfusate >anyway. "Can't be used.." is pretty strong language. Always be aware--or try to occasionally remind yourself--of the natural human tendency to think 'habitually': to mistake the way things are with the way things will always be, mistake the way things are done now, with the way they will always be done. Compared to the seeming 'magicalness' of future technologies, the current suspension techniques will shortly be sources of derision and embarrassment. Laughable in their first generation crudeness. Consider. As mentioned above, cellular penetration of a given cryoprotectent candidate, is consider AT PRESENT an absolutely crucial consideration. The large molecules mentioned in the above quote, and trehelose, and a long list of other and otherwise-promising cryoprotectant candidates don't penetrate the cell membrane worth a hoot. So they're of no use, right? Not at all. We're simply in need of a method of efficient transmembrane transport. Now this could be something as yet undreamed of, or it could be dreamed of but not perfected--like a buckyball nanobot transport vesicle such as can be found in Frietas's Nanomedicine (available full text on the web--sorry, I don't have a link), or it could be something already in early use, a hijacked viral-shell vector or a customized liposome. (Check the web to see the extent to which liposome technology is already developed, and how strikingly cheap it is. The liposome 'bubbles' are created by blowing phospholipid 'soap' through a perforated plastic sieve.) Consider this last item. (Vesicles=liposomes) A cryoprotectant phospholipid vesicle iv solution would contain a mix of vesicles appropriate for the full range cell types. Each individual vesicle type would contain the cryoprotectant (or cryoprotectant mix) of choice FOR ONE SPECIFIC CELL TYPE, and would have have the complementary transmembrane docking protein/cellular identifier for THAT SPECIFIC CELL TYPE. It would dock to that cell, and that cell only, the phospholipid membrane of the vesicle would fuse with that of the cell, and the contents of the vesicle would then 'be inside' the cell. Job done. Next problem. Specific cellular targeting is here today or just around the corner, because it is one of the several state-of-the-art approaches to cancer and other therapies. The only 'real' question is "How long?" I'll be fifty-two in December. If I can hold out for another twenty years--my health is good but my family has a history of cancer--I expect to have available to me a vastly improved suspension capability. Perhaps even 'routine' reversible suspension. Perhaps even socially-mandated, universal, legally-guaranteed access to suspension as medical entitlement. It is, after all, a life-saving procedure. Like my boy, Ray, says. Best, Jeff Davis "Everything's hard till you know how to do it." Ray Charles Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=14879