Doctor of Philosophy (PhD)
Human adipose tissue provides a uniquely abundant and accessible source of adult stem cells. In response to chemical, hormonal or structural stimuli, these human adipose-derived adult stem (ASCs) cells can differentiate along multiple lineage pathways, including adipocytes, chondrocytes, myocytes, neurons and osteoblasts. Successful cryopreservation of scientifically and commercially important ASCs would revolutionize the tissue engineering and regenerative medicine industry. In this research, we have investigated the water transport phenomenon during freezing of several passages of adipose derived adult stem cells and generated the membrane permeability parameters in the presence and absence of cryoprotective agents. These measured permeability parameters were then used to find the optimal cooling rates for freezing ASCs. We have also analyzed the individual and interaction effects of four important thermal parameters (cooling rate, hold time, thawing rate and end temperature) on the post-thaw viability of all passages (passage 0 to passage 4) of ASCs. We have then studied the effect of nanoparticles on the water transport response and apoptotic behavior of biological systems during a cryopreservation process. Further, we have investigated the maintenance of differentiation potential of post-freeze huASCs through histochemical staining. In an attempt to eliminate the usage of chemical CPAs (DMSO/glycerol) during cryopreservation, studies were conducted to investigate the possibility of using non toxic polymers, such as PVP, as cryoprotective agents. Flow cytometry analysis was employed to assess the post-thaw viability and apoptotic response of P1 ASCs frozen stored for more than two weeks in different concentrations of PVP. The results suggest that PVP in fact posses excellent cryoprotective properties and produced acceptable viability when compared to the most routinely used cryopreservation media involving DMSO and serum. In another study, cell sheet engineering approach has been applied to generate multi-dimensional cell sheets for tissue engineering using ASCs.
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Thirumala, Sreedhar, "Cryopreservation of Adipose Derived Adult Stem Cells and Multidimensional Cell Sheets" (2008). LSU Doctoral Dissertations. 2368.
Ram V. Devireddy