X-Message-Number: 7644 From: (Brian Wowk) Newsgroups: sci.cryonics Subject: Re: Freezing cells Date: 4 Feb 97 05:53:36 GMT Message-ID: <> References: <> In <> Jack JWA van Loon <> writes: >Does any of you have any experience in freezing (and storing) single >cells at -20 dgr.C for a prolonged period? I am aware that the best >storage temp. is liquid Nitrogen but I only have -20 degr.C for this >particular experiment. I have to store the cells for at least a few >weeks. >What happens if a cell suspension (with DMSO or any other preservative) >goes trough a temperature profile of -10 to -70 degr.C? Is there a change >in water crystal formation ? A 10% solution of glycerol or DMSO should limit ice formation at -20'C to tolerable amounts (<80%) for single cells. Add solution slowly to avoid osmotic injury, and cool at about 1'C per minute. Faster cooling may result in fatal intracelluar freezing. These suggestions are theoretical and not based on experience. Consult backissues of the journal Cryobiology for more detailed protocols for freezing cell suspensions. Holding at -20'C for long periods of time may be difficult. The cryoprotectant will become highly concentrated in the unfrozen solution, and exposure to such concentrations at -20'C for days will likely be fatal. There definitely will be a change in water crystal formation between -10'C and -70'C. With slow cooling, an increasing percentage of the solution will convert to ice. A greater concentration of cryoprotectant will be required to limit ice to tolerable amounts at ultralow temperatures. *************************************************************************** Brian Wowk CryoCare Foundation 1-800-TOP-CARE President Human Cryopreservation Services http://www.cryocare.org/cryocare/ --------------------------------------------------------------------------- Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=7644