Human Platelet-Derived Factors Regulate Mesenchymal Stem Cell Gene Expression.

The use of animal-derived products during human stem cell processing bears the evident risk of xenogeneic prion, virus, or zoonose contamination. Human platelet lysate (HPL) has recently been recognized as a rich source of cytokines and growth factors with the potential to replace fetal bovine serum (FBS) during ex vivo stem cell manipulation. In this study we compared the gene expression profile of human multipotent mesenchymal stromal/stem cells (MSC) during ex vivo expansion for clinical applications under the aegis of either FBS or HPL.

The Applied Biosystems 1700 Expression Array System was used for full genome expression profiling of MSC after a 12–14 day expansion period in a previously optimized low density expansion system. Data have been obtained from biological as well as technical replicates. A starting amount of 40μg total RNA was directly labeled and DIG-labeled cDNA was hybridized to Human Genome Survey Microarray V2.0. Attribution of regulated genes to biological processes and pathways was done using the PANTHER^® db analysis software.

We identified more than 300 genes that are differentially regulated upon culture of MSC in HPL compared to FBS. Biological processes specifically activated in HPL culture include mesoderm development, cell cycle control, hematopoiesis and angiogenesis which interestingly correspond to a considerable proportion of the regenerative function of MSC. In contrast, processes related to cell adhesion and adhesion-mediated signaling, cell structure, cell motility and cell communication are significantly upregulated in MSC after FBS in comparison to HPL culture.

Replacing FBS with HPL not only avoids bovine prion, viral and zoonose contamination of MSC for clinical use. The tightly regulated gene expression profiles under the aegis of human growth factors and cytokines provided by HPL may even help to develop new stem cell therapy strategies.