Cryopreservation for tissues seems to be a field in need of disruption. There is no fundamental reason why cryopreservation should be expensive: the fundamental materials are cheap - assuming that the vitrification process (for those not versed in the field: no one freezes anything literally, its vitrification ie. things are cooled down to the point where its almost glass like) depends on some combination of DMSO, liquid nitrogen, and a microwave cavity based chilling solution - and the process itself is inherently repeatable - given an input X, Y, and Z: the process for cryopreservation is going to be exactly the same. There is no rational reason why a provider cant slash the costs and offer cryopreservation as a service to hospitals and individuals alike. The assumption being of course, that the founder rolls her own control rate freezers, uses collective dewars for storage, and aggressively automates all related tasks. Ice formation inside or outside cells has been proposed to be a factor causing cryoinjury to cells/tissues during cryopreservation. How to control, reduce, or eliminate the ice formation has been an important research topic in fundamental cryobiology. The objective of this study was to test a hypothesis that the coupled interaction of microwave radiation and cryoprotectant concentration could significantly influence ice formation and enhance potential vitrification in cryopreservation media at a relative slow cooling rate. Test samples consisted of a series of solutions with ethylene glycol (a cryoprotectant) concentration ranging from 3 to 5.5M.A specific microwave resonant cavity was built and utilized to provide an intense oscillating electric field. Solutions were simultaneously exposed to this electric field and cooled to −196°C by rapid immersion in liquid nitrogen. Control samples were similarly submerged in liquid nitrogen but without the microwave field. The amount of ice formation was determined by analysis of digital images of the samples. The morphology of the solidified samples was observed by cryomicroscopy. It was found that ice formation was greatly influenced by microwave irradiation. For example, ice formation could be reduced by roughly 56% in 3.5Methylene glycol solutions. An average reduction of 66% was observed in 4.5Msolutions. Statistical analysis indicated that the main effects of microwave and ethylene glycol concentration as well as the interaction between these two factors significantly (P< 0.01) influenced ice formation amount, confirming the hypothesis. This preliminary study suggests that a combined use of microwave irradiation and cryoprotectant might be a potential approach to control ice formation in cells/tissues during the cooling process and to enhance vitrification of these biomaterials for long-term cryopreservation.
Posted on: Thu, 11 Sep 2014 16:09:45 +0000
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