RESUMO
Autologous stem cell therapy has not been as effective as forecasted from preclinical studies. Patient age was reported as an important contributing factor. The goal of this study was to uncover age-dependent mechanisms of stem cell dysfunction and to investigate possible means to restore the cellular function. Bone marrow mesenchymal stem cells (MSCs) were isolated from cardiovascular patients. Cell proliferation and number of colonies were inversely correlated with patient age. Myogenic differentiation of MSCs in culture was induced with 5-azacytidine. Differentiation correlated with age, with less differentiation in MSCs from aged patients. We performed real-time PCR to identify genes in the WNT/ß-catenin signaling network and found that transcript levels of CTNNB1, LEF1, FZD8, WNT3A, and SFRP4 were negatively correlated with age, whereas FOSL1, LRP6, and FZD6 were positively correlated with age. Protein evaluation showed that ß-catenin nuclear translocation correlated with age and was lower in aged MSCs. Aged MSCs treated with lithium chloride-to increase the bioavailability of ß-catenin-recovered their capacity for myogenic differentiation through myocyte enhancer factor 2C but not with the knockdown of ß-catenin using small-interfering RNA. This study may be the first to relate reduced nuclear ß-catenin bioavailability in MSCs from aged patients. Most important, this abnormality was potentially recoverable, providing a target for improving the function of bone marrow stem cells and their clinical utility in aged patients.
