ABSTRACT
Tissue engineering is limited by the time of culture expansion of cells needed for scaffold seeding. Thus, a simple means of accelerated stem cell proliferation could represent a significant advance. Here, Nebivolol was investigated for its effect on the replicative capacity of adipose-derived stem cells (ASCs). This study indicates that the number of ASCs with Nebivolol treatment showed a significant population increase of 51.5% compared to untreated cells (p<0.01). Cell cycle analysis showed a significant decrease in the percentage of ASCs in G1 phase with Nebivolol treatment compared to untreated cells (p<0.01), suggesting that Nebivolol shortens the G1 phase of ASCs, resulting in a faster proliferative rate. Furthermore, our results showed that Nebivolol significantly increased colony-forming units of ASCs (p<0.01). Despite increasing ASC proliferative potential, we showed that Nebivolol has an inhibitory effect on adipogenic and osteogenic differentiation potential as indicated by significantly reduced expression of CCAAT Enhancer Binding Protein alpha (P<0.01) and lipoprotein lipase (P<0.01) and inhibited activity of alkaline phosphatase (P<0.01), respectively. Taken together, these results showed that Nebivolol accelerated ASC proliferation through shortening G1 phase, while inhibiting both adipogenic and osteogenic potentials of ASCs. These data identify a novel and simple approach to accelerate stem cell expansion in vitro before cell differentiation.
ABSTRACT
Statins reduce atherosclerotic events and cardiovascular mortality. Their side effects include memory loss, myopathy, cataract formation, and increased risk of diabetes. As cardiovascular mortality relates to plaque instability, which depends on the integrity of the fibrous cap, we hypothesize that the inhibition of the potential of mesenchymal stem cells (MSCs) to differentiate into macrophages would help to explain the long known, but less understood "non-lipid-associated" or pleiotropic benefit of statins on cardiovascular mortality. In the present investigation, MSCs were treated with atorvastatin or pravastatin at clinically relevant concentrations and their proliferation, differentiation potential, and gene expression profile were assessed. Both types of statins reduced the overall growth rate of MSCs. Especially, statins reduced the potential of MSCs to differentiate into macrophages while they exhibited no direct effect on macrophage function. These findings suggest that the limited capacity of MSCs to differentiate into macrophages could possibly result in decreased macrophage density within the arterial plaque, reduced inflammation, and subsequently enhance plaque stability. This would explain the non-lipid-associated reduction in cardiovascular events. On a negative side, statins impaired the osteogenic and chondrogenic differentiation potential of MSCs and increased cell senescence and apoptosis, as indicated by upregulation of p16, p53 and Caspase 3, 8, and 9. Statins also impaired the expression of DNA repair genes, including XRCC4, XRCC6, and Apex1. While the effect on macrophage differentiation explains the beneficial side of statins, their impact on other biologic properties of stem cells provides a novel explanation for their adverse clinical effects.
