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The Effects of Microgravity on Stem Cell Differentiation.  S.E. Kelly, P.P. Claudio, and J.V. Valluri. Division of Biological Sciences, Marshall Univ., Huntington, WV.

   Cell replacement therapy is of great interest as a long-term treatment of degenerative diseases. Stem cells are capable of differentiating into functional cells. But there are no reliable methods to induce the stem cells to form specific cells or to gain enough cells for transplantation, which limits their application in clinical therapy. SAOS-2 is a human sarcoma cell line, which has been used as model for osteoblastic cells. The SAOS-2 cell line has been found to have about 10 percent CD133+ stem cells.   The purpose of this experiment is two fold. This first objective of this study is the optimization of conditions for stem cell growth and to prevent premature differentiation. The second objective is to determine optimal condition for differentiation of stem cells into osteocytes. These objectives will be accomplished by growing stem cells in the Hydrodynamic Focusing Bioreactor (HFB) developed by NASA at the Johnson Space Center. The HFB provides a method to proliferate mesenchymal stem cells (MSCs) and CD133+ SAOS-2 cells by using the rotating three-dimensional (3-D) culture system, which can provide low shear, 3-D environment with simulated microgravity.   The stem cells in the SAOS-2 line were isolated by using an antibody attached to the CD133 protein. The stem cells from the SAOS-2 line were cultured in the HFB immediately following separation.  The yield of stem cells was measured by use of a fluorescent antibody in conjunction with flow cytometry. A Bone Morphogenetic Protein (BMP) was introduced into the cell culture to promote differentiation of MSCs into osteocytes.   A larger quantity of cancer stem cells were the result after being grown in the HFB compared to traditional 2-D methods. The stem cells had a lower rate of premature differentiation then the cells that were grown in 2-D. When the stem cells were introduced to BMP they showed a clean transformation into osteocytes.

(Supported by a grant from the WV Space Grant Consortium.)