Bone morphogenetic protein 9 enhances osteogenic and angiogenic responses of human amniotic mesenchymal stem cells cocultured with umbilical vein endothelial cells through the PI3K/AKT/m-TOR signaling pathway

Abstract

Background: Neovascularization plays an essential part in bone fracture and defect healing, constructing tissue engineered bone that targets bone regeneration. Bone morphogenetic protein 9 (BMP9) is a regular indicator that potentiates osteogenic and angiogenic differentiation of MSCs. Objectives: To investigate the effects of BMP9 on osteogenesis and angiogenesis of human amniotic mesenchymal stem cells (hAMSCs) cocultured with human umbilical vein endothelial cells (HUVECs) and determine the possible underlying molecular mechanism. Results: The isolated hAMSCs expressed surface markers of MSCs. hAMSCs cocultured with HUVECs enhance osteogenic differentiation and upregulate the expression of angiogenic factors. BMP9 not only potentiates angiogenic signaling of hAMSCs cocultured with HUVECs also increases ectopic bone formation and subcutaneous vessel invasion. Mechanically, the coupling effect between osteogenesis and angiogenesis induced by BMP9 was activated by the BMP/Smad and PI3K/AKT/m-TOR signaling pathways. Conclusions: BMP9-enhanced osteoblastic and angiogenic differentiation in cocultivation with hAMSCs and HUVECs in vitro and in vivo also provide a chance to harness the BMP9-regulated coordinated effect between osteogenic and angiogenic pathways through BMP/Smad and PI3K/AKT/m-TOR signalings. Materials and Methods: The ALP and Alizarin Red S staining assay to determine the effects of osteoblastic differentiation. RT-qPCR and western blot was measured the expression of angiogenesis-related factors. Ectopic bone formation was established and retrieved bony masses were subjected to histochemical staining. The angiogenesis ability and vessel invasion were subsequently determined by immunofluorescence staining. Molecular mechanisms such as the BMP/Smad and PI3K/AKT/m-TOR signaling pathways were detected by ELISA and western blot analysis.

Histological evaluation of the effects of bone morphogenetic protein 9 and angiopoietin 1 on bone healing

“…Neovascularization is crucial for the repair of bone defects and fractures. 38 It was clear from the results that the TN was significantly decreased in all treated groups, which enclosed newly formed bone marrow compared with the control group. Our results are in accordance with those of Toru et al, 23 who found that osteogenesis and angiogenesis were stimulated by Ang1, which is expressed by osteoblasts.…”

BMP9 induces osteogenic differentiation through up-regulating LGR4 via the mTORC1/Stat3 pathway in mesenchymal stem cells

“…PI3K/Akt/mTOR pathway plays an important role in regulating the osteoblastic differentiation spurred by BMP9. 30 However, the precise regulatory roles of mTORC1 and mTORC2 in this process remain unclear. PCR results revealed that Raptor and Rictor were both up-regulated by BMP9 ( Fig.…”

“… 52 , 53 Activation of this pathway promoted the pre-osteoblasts and BMSCs differentiate into osteoblasts, whereas targeted inhibition suppressed the bone formation in vivo and in vitro . 54 BMP9 osteogenic potency can be promoted by activating PI3K/AKT signal, 30 , 55 although the detailed molecular mechanism required further analysis. As downstream targets of PI3K/AKT, both mTOR and GSK-3β contribute to cell growth regulation and protein synthesis.…”

Micropattern Silk Fibroin Film Facilitates Tendon Repair In Vivo and Promotes Tenogenic Differentiation of Tendon Stem/Progenitor Cells through the α2β1/FAK/PI3K/AKT Signaling Pathway In Vitro

“…The PI3K/AKT signaling pathway plays a key role in regulating cells under physical stimulation [51]. The signaling [52][53][54][55] found that modulating the cytoskeleton using perturbing drugs changes signal transduction and the differentiation tendency of mesenchymal stem cells. Gu et al [56] found that the surface-modified titanium matrix can promote the secretion of bone calcium matrix by mesenchymal stem cells through the PI3K/AKT signaling pathway.…”