Background: The Notch signaling pathway is implicated in a broad range of developmental processes, including cell fate decisions. This study was designed to determine the role of Notch signaling in adipogenic differentiation of human bone marrow derived MSCs (BM-MSCs). Methods: The Notch signaling was inhibited by the γ-secretase inhibitor N-[N-(3,5-difluor- ophenacetyl-L-alanyl)]-S-phenylglycine t-butylester (DAPT). The markers involving adipogenic differentiation of MSCs, the relative pathway PTEN-PI3K/Akt/mTOR and autophagy activation were then analyzed. Furthermore, the autophagy inhibitor chloroquine (CQ) and 3-methyladenine (3-MA) were used to study the role of autophagy in the DAPT-induced the adipogenic differentiation of MSCs. Results: We first confirmed the down -regulation of Notch gene expression during MSCs adipocyte differentiation, and showed that the inhibition of Notch signaling significantly enhanced adipogenic differentiation of MSCs. Furthermore, Notch inhibitor DAPT induced early autophagy by acting on PTEN-PI3K/Akt/mTOR pathway. The autophagy inhibitor CQ and 3-MA dramatically abolished the effects of DAPT-induced autophagy and adipogenic differentiation of MSCs. Conclusion: Our results indicate that inhibition of Notch signaling could promote MSCs adipogenesis mediated by autophagy involving PTEN-PI3K/Akt/mTOR pathway. Notch signaling could be a novel target for regulating the adipogenic differentiation of MSCs.

IntroductionMesenchymal stem cells (MSCs) represent a heterogeneous cell population that is promising for regenerative medicine. The present study was designed to assess whether VCAM-1 can be used as a marker of MSC subpopulation with superior angiogenic potential.MethodsMSCs were isolated from placenta chorionic villi (CV). The VCAM-1+/− CV-MSCs population were separated by Flow Cytometry and subjected to a comparative analysis for their angiogenic properties including angiogenic genes expression, vasculo-angiogenic abilities on Matrigel in vitro and in vivo, angiogenic paracrine activities, cytokine array, and therapeutic angiogenesis in vascular ischemic diseases.ResultsAngiogenic genes, including HGF, ANG, IL8, IL6, VEGF-A, TGFβ, MMP2 and bFGF, were up-regulated in VCAM-1+CV-MSCs. Consistently, angiogenic cytokines especially HGF, IL8, angiogenin, angiopoitin-2, μPAR, CXCL1, IL-1β, IL-1α, CSF2, CSF3, MCP-3, CTACK, and OPG were found to be significantly increased in VCAM-1+ CV-MSCs. Moreover, VCAM-1+CV-MSCs showed remarkable vasculo-angiogenic abilities by angiogenesis analysis with Matrigel in vitro and in vivo and the conditioned medium of VCAM-1+ CV-MSCs exerted markedly pro-proliferative and pro-migratory effects on endothelial cells compared to VCAM-1−CV-MSCs. Finally, transplantation of VCAM-1+CV-MSCs into the ischemic hind limb of BALB/c nude mice resulted in a significantly functional improvement in comparison with VCAM-1−CV-MSCs transplantation.ConclusionsVCAM-1+CV-MSCs possessed a favorable angiogenic paracrine activity and displayed therapeutic efficacy on hindlimb ischemia. Our results suggested that VCAM-1+CV-MSCs may represent an important subpopulation of MSC for efficient therapeutic angiogenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0297-0) contains supplementary material, which is available to authorized users.

IntroductionAcquired aplastic anemia (AA), characterized by pancytopenia in peripheral blood (PB) and bone marrow (BM) hypoplasia, is a bone marrow failure syndrome attacked by autologous T cells, such as CD8 ϩ cytotoxic T cells, CD4 ϩ Th1 cells, and Th17 cells, on BM hematopoietic progenitors. [1][2][3][4] Hematopoiesis recovery after successful immunosuppressive treatment provided powerful evidence for the core role of the immune-mediated destruction of hematopoietic progenitor/stem cells. Mechanisms of immunemediated destruction of hematopoiesis include Th1 polarization response conferring immoderate production of inhibitory cytokines such as interferon-␥ (IFN-␥), tumor necrosis factor-␣ (TNF-␣), and interleukin-2 (IL-2), direct toxicity to autologous CD34 ϩ cells by T-cell populations, and Th17 immune response. [4][5][6][7] In that sense, AA is a specific autoimmune disease because of aberrant T-cell immune homeostasis and BM is the main target organ.It is now well established that CD4 ϩ T-cell subpopulations constitutively expressing the surface protein CD25 and the transcription factor FoxP3 are indispensable for the maintenance of immunologic self-tolerance and immunosuppression. [8][9][10][11] There is also accumulating evidence that impaired function of CD4 ϩ CD25 ϩ regulatory T cells (Tregs) has been implicated in the development of several common autoimmune diseases, 8,10 myelodysplastic syndromes, 12 and AA. 13 Until now, the only report of Treg abnormality in AA has shown that the numbers of circulating Tregs decreased in most patients. Meanwhile, almost all patients had low levels of nuclear factor of activated T cells, cytoplasmic 2 (NFAT1/ NFATc2) which could explain decreased FoxP3 expression in Tregs from AA patients. 13 But little is known regarding the function of Tregs in AA.Physiologically, induction of immune tolerance and suppression of autoreactive effector T-cell proliferation were the critical function of CD4 ϩ CD25 ϩ Tregs through cell contact-inhibition mechanisms and/or production of inhibitory cytokine. Furthermore, BM is a reservoir for CD4 ϩ CD25 ϩ Tregs that home to and are retained in BM through the stromal-derived factor-1␣ (SDF-1␣)/ CXCR4 signal. 14 Previous data demonstrated that the only way for Tregs homing to BM was via the SDF-1␣/CXCR4 signal. 14,15 It was believed that CXCR4 was the only receptor of SDF-1␣ for years. However, several reports recently provided evidence that SDF-1␣ also bound to another 7 transmembrane span receptor CXCR7. 16,17 Thus, the role of the SDF-1␣/CXCR4 axis in regulating Treg trafficking between BM and PB becomes more complex. Combined with the fact that BM is the target organ attacked by autoreactive effector T cells leading to hematopoiesis destruction, we hypothesized that Tregs in AA might have impaired homing potential to BM so as to be less efficient to suppress the effector T-cell proliferation and Th1-type cytokine production. We also hypothesized that Tregs in AA had intrinsic deficiencies of immunosuppression for autologous effector T...