Towards A Serum-Free Medium: Growth Receptors And Signaling Pathways That Regulate Multipotency In Human Mesenchymal Stem Cells

Human mesenchymal stem cells (MSCs) are capable of being used in human therapeutic procedures such as tissue repair and gene therapy due to their multipotency. However, the expansion of MSCs is limited by the restricted use of fetal bovine serum (FBS) as the nutritional supplement. Hence, contamination by pathogens from the xenogenic component can be eliminated if a serum-free media were used. In this paper, we identified the human growth receptors (HGRs) and corresponding signaling pathways expressed in undifferentiated proliferative MSCs by analyzing available microarray data. The microarray datasets were generated by Affymetrix GeneChips and Illumina BeadArrays. The MSC samples used were cultured in both fetal bovine serum (FBS) and autologous serum (AS) at passage one. Results from the different platforms indicated 94 similarly expressed human growth receptors. Affymetrix was also able to detect 129.19% more HGRs than Illumina. We also discovered that HGR expressions across different types of serum were similar, indicating that type of serum had little impact on proliferation mechanisms in early passages. Next, Ingenuity Pathway Analysis identified 11 signaling pathways that were expressed in all four MSC cultures. In particular, the Notch Signaling Pathway and Transforming Growth Factor – Beta Signaling Pathway were consistently expressed in all MSC cultures. These 11 signaling pathways and 94 HGRs are important in understanding the maintenance of MSC undifferentiated proliferative state, and the corresponding growth factors are possibly required minimally in developing a serum-free medium for MSC expansion.