mTOR Plays an Important Role in the Stemness of Human Fetal Cartilage Progenitor Cells (hFCPCs).

BACKGROUND: Mammalian target of rapamycin (mTOR) is known to regulate self-renewal ability and potency of embryonic stem cells (ESCs) and adult stem cells in opposite manners. However, its effects vary even among adult stem cells and are not reported in fetal stem/progenitor cells. This study investigated the role of mTOR in the function of human fetal cartilage-derived progenitor cells (hFCPCs). METHODS: mTOR activity in hFCPCs was first examined via the level of phosphor-mTOR until passage 19, together with doubling time of cells and senescence-associated b-galactosidase (SA-bGal). Then, the effect of 100 nM rapamycin, the inhibitor of mTOR, was investigated on self-renewal ability, proliferation rate and osteogenic/adipogenic potential of hFCPCs in vitro. Expression of stemness genes (Oct-4, Sox2 and Nanog) and cell cycle regulators (CDK4 and Cyclin D1) was measured at mRNA or protein levels. RESULTS: mTOR activity was maintained constantly at high levels in hFCPCs until passage 19, while their proliferation rate was decreasing from 48 h at passage 13 to 70 h at passage 9 and senescent cells were observed at passage 18 (8.3 ± 1.2%) and 19 (15.6 ± 1.9%). Inhibition of mTOR in hFCPCs impaired their colony forming frequency (CFU-F) by 4 folds, while showing no change in their doubling time and expression of CDK4 and Cyclin D1. Upon mTOR inhibition, Oct4 expression decreased by 2 folds and 4 folds at the mRNA and protein levels, respectively, while that of Sox2 and Nanog did not change significantly. Finally, mTOR inhibition reduced osteogenic and adipogenic differentiation of hFCPCs in vitro. CONCLUSION: This study has shown that mTOR plays an important role in the self-renewal ability of hFCPCS but not in their proliferation, The effect of mTOR appears to be associated with Oct-4 expression and important in the osteogenic and adipogenic differentiation ability of hFCPCs.

Cyanidin 3-O-arabinoside suppresses DHT-induced dermal papilla cell senescence by modulating p38-dependent ER-mitochondria contacts.

BACKGROUND: Androgenetic alopecia (AGA) is a genetic disorder caused by dihydrotestosterone (DHT), accompanied by the senescence of androgen-sensitive dermal papilla cells (DPCs) located in the base of hair follicles. DHT causes DPC senescence in AGA through mitochondrial dysfunction. However, the mechanism of this pathogenesis remains unknown. In this study, we investigated the protective role of cyanidins on DHT-induced mitochondrial dysfunction and DPC senescence and the regulatory mechanism involved. METHODS: DPCs were used to investigate the effect of DHT on mitochondrial dysfunction with MitoSOX and Rhod-2 staining. Senescence-associated ß-galactosidase activity assay was performed to examine the involvement of membrane AR-mediated signaling in DHT-induced DPC senescence. AGA mice model was used to study the cyanidins on DHT-induced hair growth deceleration. RESULTS: Cyanidin 3-O-arabinoside (C3A) effectively decreased DHT-induced mtROS accumulation in DPCs, and C3A reversed the DHT-induced DPC senescence. Excessive mitochondrial calcium accumulation was blocked by C3A. C3A inhibited p38-mediated voltage-dependent anion channel 1 (VDAC1) expression that contributes to mitochondria-associated ER membrane (MAM) formation and transfer of calcium via VDAC1-IP3R1 interactions. DHT-induced MAM formation resulted in increase of DPC senescence. In AGA mice models, C3A restored DHT-induced hair growth deceleration, which activated hair follicle stem cell proliferation. CONCLUSIONS: C3A is a promising natural compound for AGA treatments against DHT-induced DPC senescence through reduction of MAM formation and mitochondrial dysfunction.

Characteristics and Cardiomyogenic Potential of Rat Fetal Cardiac Progenitor Cells at Different Developmental Stage.

In recent years, several kinds of cardiac progenitor cells have been identified and isolated from heart tissue. These cells showed differentiation potential into cardiomyocytes, smooth muscle cells, and endothelial cells in vitro and in vivo. Morphogenetic events are tightly regulated during development to determine cell destiny and reshape the embryonic lineage. In this study, we directly compared the characteristics of rat fetal cardiac progenitor cells (rFCPCs) isolated from the chamber formation stage at embryonic day 12 (E12) and at the septation stage of E15. Both kinds of rFCPCs expressed mesenchymal stem cell markers (CD105, CD73, and CD29) but not CD34 and CD45. The E12 rFCPCs expressed a high level of Oct4 compared to E15 until passage 5 and showed a steep decline of Nkx2.5 expression at passage 5. However, Nkx2.5 expression at E15 was maintained until passage 5 and Oct4 expression slightly increased at passage 5. We also detected an intense staining for Oct4 antibody in E12 heart tissue sections. The average doubling time of the E12 rFCPCs from passage 3 to passage 15 was about 5 hours longer than E15. These cells could also be induced into cardiomyocytes expressing α-MHC, cTnT, cTnC, and Cx43 under cardiomyogenic culture conditions and rFCPCs at E15 showed more intense staining of α-MHC than cells at E12 by immunocytochemistry. Taken together, our results show that developmental differences between E12 and E15 may influence their properties and differentiation. Furthermore those differences should be considered when deciding on the optimal cell source for cell replacement therapy in cardiovascular regeneration.

Erratum to: Characteristics and Cardiomyogenic Potential of Rat Fetal Cardiac Progenitor Cells at Different Developmental Stage.

[This corrects the article DOI: 10.1007/s13770-016-0016-z.].