In this study, there was no obvious chromosome elimination, displacement, or chromosomal imbalance as determined from the guidelines of the International System for Human Cytogenetic Nomenclature. Telomerase activity was down-regulated significantly when the culture time was prolonged. Further, no tumors formed in rats injected with human umbilical cord mesenchymal stem cells (hUC-MSCs) cultured in serum-free and in serum containing conditions.

This study concluded that their data showed that hUC-MSCs met the International Society for Cellular Therapy sandards for conditions of long-term in vitro culturing. Since hUC-MSCs can be safely expanded in vitro and are not susceptible to malignant transformation in serum-free medium, these cells are suitable for cell therapy.

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