Correlation of TCF4, GSK, TERT and TERC Expressions with Proliferation Potential of Early and Late Culture of Human Peripheral Blood Mesenchymal Stem Cells

β-Catenin promotes long-term survival and angiogenesis of peripheral blood mesenchymal stem cells via the Oct4 signaling pathway

Stem cell therapy has been extensively studied to improve heart function following myocardial infarction; however, its therapeutic potency is limited by low rates of engraftment, survival, and differentiation. Here, we aimed to determine the roles of the β-catenin/Oct4 signaling axis in the regulation of long-term survival and angiogenesis of peripheral blood mesenchymal stem cells (PBMSCs). These cells were obtained from rat abdominal aortic blood. We showed that β-catenin promotes the self-renewal, antiapoptotic effects, and long-term survival of PBMSCs by activating the Oct4 pathway through upregulation of the expression of the antiapoptotic factors Bcl2 and survivin and the proangiogenic cytokine bFGF and suppression of the levels of the proapoptotic factors Bax and cleaved caspase-3. β-Catenin overexpression increased Oct4 expression. β-Catenin knockdown suppressed Oct4 expression in PBMSCs. However, β-catenin levels were not affected by Oct4 overexpression or knockdown. Chromatin immunoprecipitation assays proved that β-catenin directly regulates Oct4 transcription in PBMSCs. In vivo, PBMSCs overexpressing β-catenin showed high survival in infarcted hearts and resulted in better myocardial repair. Further functional analysis identified Oct4 as the direct upstream regulator of Ang1, bFGF, HGF, VEGF, Bcl2, and survivin, which cooperatively drive antiapoptosis and angiogenesis of engrafted PBMSCs. These findings revealed the regulation of β-catenin in PBMSCs by the Oct4-mediated antiapoptotic/proangiogenic signaling axis and provide a breakthrough point for improving the long-term survival and therapeutic effects of PBMSCs.

Boosting expression of a specific gene has allowed researchers to generate stem cells with increased capacity for tissue repair after a heart attack. Several studies have shown that treatment with a population of circulating cells known as ‘peripheral blood mesenchymal stem cells’ (PBMSCs) can regenerate cardiac tissue. These cells generally have a short lifespan when used therapeutically, but researchers led by Shaoheng Zhang at Jinan University in Guangzhou China have increased long-term survival and performance by boosting expression of the gene encoding β-catenin, a protein that promotes cell survival and proliferation. PBMSCs expressing increased levels of β-catenin preserved heart function in a rat model of heart attack, stimulating blood vessel growth and improving animal survival. This study also reveals proteins regulated by β-catenin, which could potentially be exploited for finer control of PBMSC function.