Intercellular Calcium Dynamics in Adipose Derived Stem Cell (ASCs) Sheets in Response to Stimulation: Cells coordinate their activities by transmitting rises in intracellular calcium from cell to cell. Information embedded in calcium dynamics can provide molecular cues for cell behavior such as cell differentiation. Although calcium dynamics are versatile and likely to depend on cell type, the calcium dynamics in human adipose stem cells (ASCs) and its role in differentiation have not been clearly established. In this study we are characterizing the calcium dynamic profiles in ASCs, in response to external stimulation, in a multidimensional cell sheet environment.

Multi-Dimensional Adipose Derived Stem Cell (ASCs) Sheets for in-vivo Tissue Engineering Applications: Working in collaboration with the stem cell laboratory at Pennington Biomedical Research Center (www.pbrc.edu) to develop multi-dimensional stem cell sheets using thermo-responsive polymer hydrogel films. One of the primary objectives is to develop a cell sheet engineering technique for off-the-shelf supply of thermo-responsive TCPS dishes without resorting to complex irradiation procedures. The cell sheets will be evaluated for immunophenotype and differentiation capacity. The multilayered cell sheets will be used as a new platform to spatially pattern different cell types for the in vitro and in vivo analysis of complex physiology and for several tissue engineering applications.

Serum Free and DMSO Free Stem Cell Banking: The objective of this study is to test the effect of non-permeating, non-toxic polymers on the low temperature response of biological systems. Flow cytometry analysis is employed to evaluate proliferation, apoptosis, necrosis, immunophenotype and differentiation ability of post-thaw Adipose Derived Stem Cells (ASCs). Successful freezing of ASCs with no serum and no DMSO provides a convenient and improved alternative for adult stem cell culture and preservation techniques.

Cryobiological Investigations of Human Adipose Tissue-Derived Adult Stem (ASCs) Cells. Working with 'Pennington Biomedical Research Center (PBRC)', Louisiana State University, to develop optimized cryopreservation protocols for Adipose Tissue Derived Adult Stem Cells (ASCs). At the end of this work we will have a mechanistic understanding of how the several different ASCs behave during a freezing protocol. In addition, we will also know how the ASCs respond to a prescribed osmotic (CPA) and thermal cooling history as well obtaining for the first time the effect of freezing/long term storage techniques on the genetic integrity of ASCs.

Methylcellulose Based Thermally Reversible Hydrogel System for Tissue Engineering Applications. S. Thirumala and R.V. Devireddy. In Preparation.

Evaluation of Methylcellulose and Dimethylsulfoxide as the Cryoprotectants in a Serum Free Freezing Media for Cryopreservation of Adipose Derived Adult Stem Cells. S. Thirumala, J.M. Gimble and R.V. Devireddy. Stem Cells and Development, In Press. doi:10.1089/scd.2009.0173

Cryopreservation of Stromal Vascular Fraction of Adipose Tissue in a Serum Free Freezing Media. S. Thirumala, J.M. Gimble and R.V. Devireddy. Journal of Tissue Engineering and Regenerative Medicine, In Press. doi:10.1002/term.232

Evaluation of Polyvinylpyrollidone (PVP) as a Cryoprotectant for Adipose Derived Adult Stem Cells. S. Thirumala, X. Wu, J.M. Gimble and R.V. Devireddy. Tissue Engineering Part C: Methods, In Press. doi:10.1089/ten.tec.2009.0552

 B.C. Goh, S. Thirumala, G Kilroy R.V. Devireddy and J.M. Gimble. "Cryopreservation Characteristics of Adipose-Derived Stem Cells: Maintenance of Differentiation Potential and Viability",  Journal of Tissue Engineering and Regenerative Medicine. Vol. 1(4), 2007, pp:322-324.

S. Thirumala, J.M Forman, T. Monore, and R.V. Devireddy. "Freezing and Post-Thaw Apoptotic Behavior of Cells in The Presence of Palmitoyl Nanogold Particles", . Nanotechnology. Vol. 18, 2007, pp: 195104-19515.

G. Li, S. Thirumala, S.P. Leibo and R.V. Devireddy. "Subzero Water Transport Characteristics and Optimal Rates of Freezing Macaca mulatta (Rhesus Monkey) Ovarian Tissue",  Molecular Reproduction & Development. Vol. 73, 2006, pp: 1600-1611.

S. Thirumala, W.T. Campbell, M.R. Vicknair, T.R. Tiersch and R. V. Devireddy. "Freezing Response and Optimal Cooling Rates for Cryopreserving Sperm Cells of Striped Bass, Morone Saxatilis", Theriogenology. Vol. 66, 2006, pp: 964-973.

R.V. Devireddy, S. Thirumala, J.M. Gimble. "Cellular Response of Adipose Derived Passage-4 Adult Stem Cells to Freezing Stress". ASME Journal of Biomechanical Engineering, Vol. 127, 2005, pp: 1081-1086.

S. Thirumala, S. Zvonic, E. Floyd, J. Gimble and R.V. Devireddy. “The Effect of Various Freezing Parameters on the Immediate Post-Thaw Membrane Integrity of Adipose Tissue Derived Adult Stem Cells”, Biotechnology Progress, Vol. 21, 2005, pp: 1511-1524.

S. Thirumala, J. Gimble and R.V. Devireddy. "Transport Phenomena During Freezing of Adipose Tissue Derived Adult Stem Cells". Biotechnology & Bioengineering,  Vol.92, 2005, pp:372-383.

 S. Thirumala, Changjiang Huang, Qiaoxiang Dong, Terrence R. Tiersch, Ram V Devireddy. “A Theoretically Estimated Cooling Rate for the Cryopreservation of Sperm Cells from a Live Bearing Fish, the Green Swordtail Xiphophorus Helleri”, Theriogenology, Vol.63:2005, pp:2395-2415