The effect of extended passaging on the phenotype and osteogenic potential of human umbilical cord mesenchymal stem cells.

Retaining biological characteristics in the extended passaging is crucial for human umbilical cord mesenchymal stem cells (hUCMSCs) in tissue engineering. We aimed to assess morphology, viability, MSC marker expression, and osteogenic activity of hUCSMCs after extended passaging. Passages 4 (P4) and 16 (P16) hUCMSCs displayed similar morphology and viability. The flow cytometry results showed that CD73, CD90, and CD105 were highly expressed at P1-P16. CD166 expression decreased progressively from 90 % at P2 to 61.5 % at P5 (p < 0.05), followed by stable expression through P16. Results from calcium deposition alkaline phosphatase activity and RT-PCR assay showed that both P4 and P16 hUCMSCs differentiated down an osteogenic lineage, with no significant difference in osteogenic capacity (p < 0.05). High-passage UMCSCs maintained stable expression of MSC CD markers as well as stable osteogenic activity. hUCMSCs may thus be suitable for tissue engineering and regenerative medicine applications.