Background
Because of the heterogeneity of human mesenchymal stem cells (MSCs),
Conclusion
We found differences in the gene expression patterns of MSCs under different culture conditions. MSCs from 10-day cultures seeded at a low density were efficiently expanded, expressed PODXL, α6-integrin, α4-integrin, and LIF, and maintained properties like stemness and immunomodulation. Therefore, ex vivo expansion of MSCs maintained for an adequate culture time after plating at low cell density can provide an effective regenerative medicinal strategy for cell therapies using MSCs.
Methods
Bone marrow-derived MSCs were plated at densities from 200 cells/cm(2) to 5,000 cells/cm(2), and the gene expression patterns were evaluated over time using a reverse-transcription polymerase chain reaction assay.
Results
The mRNA levels of factors that play a critical role in cell migration and tissue regeneration, such as podocalyxin-like protein (PODXL), α4-integrin, α6-integrin, and leukemia inhibitory factor (LIF), were higher in MSCs plated at 200 cells/cm(2) than in MSCs plated at 5,000 cells/cm(2). The mRNA levels of these factors gradually increased for 10 days and then decreased by day 15 in culture. MSCs seeded at 200 cells/cm(2) that were cultured for 10 days expressed high levels of Oct-4 and Nanog. Indoleamine 2,3-dioxygenase, cyclooxygenase-1, and hepatocyte growth factor expression were upregulated in the presence of the proinflammatory cytokine interferon-γ in these cells.