Correlation between telomere maintenance and stemness of mesenchymal stem/stromal cells

Tissue regeneration and repair is strongly dependent on resident stem cells behavior and functionality. Telomeres and telomerase are known to be regulators of self-renewal capacity of stem cells, controlling their cell cycle and thus determining their replication capacity. Also, telomeres and telomerase are involved in regulation of differentiation progress of stem cells, although these effects are poorly understood. In previously published study, we compared relative telomere length (RTL) and hTERT mRNA expression in mesenchymal stem/stromal cells (MSCs) isolated from: peripheral blood (PB-MSCs), umbilical cord (UC-MSCs), exfoliated deciduous teeth (SHEDs), periodontal ligament (PDL-MSCs) and adipose tissue (AT-MSCs), in context of their proliferation and differentiation. We found that PB-MSCs and UC-MSCs demonstrated the highest RTL and hTERT mRNA expression, accompanied with their higher proliferation capacity and adipogenic differentiation in comparison with other MSCs. On the other hand, SHEDs, PDL-MSCs and AT-MSCs demonstrated lower RTL value and hTERT mRNA expression accompanied with  higher osteogenic differentiation capacity and higher expression of pluripotency markers (Nanog, Oct-4A, Oct-4B and SOX-2) mRNA, when compared to PB-MSCs and UC-MSCs. These results highlighted the difference between MSCs isolated from various tissues with indications that telomere status might be one of the predictable factors for their stemness and functionality, prior to their potential application in cell-based therapy.