Jinyu Chen

MiR-27a is Essential for the Shift from Osteogenic Differentiation to Adipogenic Differentiation of Mesenchymal Stem Cells in Postmenopausal Osteoporosis.

Background/Aims: Osteoporosis is a progressive bone disease characterized by a decrease in bone mass and density, which results in an increased risk of fractures. Mesenchymal stem cells (MSCs) are progenitor cells that can differentiate into osteoblasts, osteocytes and adipocytes in bone and fat formation. A reduction in the differentiation of MSCs into osteoblasts contributes to the impaired bone formation observed in osteoporosis. MicroRNAs (miRNAs) play a regulatory role in osteogenesis and MSC differentiation. MiR-27a has been reported to be down-regulated in the development of osteoporosis and during adipogenic differentiation. Methods: In this study, a miRNA microarray analysis was used to investigate expression profiles of miRNA in the serum of osteoporotic patients and healthy controls and this data was validated by quantitative real-time PCR (qRT-PCR). MSCs isolated from human and mice with miR-27a inhibition or overexpression were induced to differentiate into osteoblasts or adipocytes. TargetScan and PicTar were used to predict the target gene of miR-27a. The mRNA or protein levels of several specific proteins in MSCs were detected using qRT-PCR or western blot analysis. Ovariectomized mice were used as in vivo model of human postmenopausal osteoporosis for bone mineral density measurement, micro-CT analysis and histomorphometric analysis. Results: Here, we analyzed the role of miR-27a in bone metabolism. Microarray analysis indicated that miR-27a expression was significantly reduced in osteoporotic patients. Analysis on MSCs derived from patients with osteoporosis indicated that osteoblastogenesis was reduced, whereas adipogenesis was increased. MSCs that had undergone osteoblast induction showed a significant increase in miR-27a expression, whereas cells that had undergone adipocyte induction showed a significant decrease in miR-27a expression, indicating that miR-27a was essential for MSC differentiation. We demonstrated that myocyte enhancer factor 2 c (Mef2c), a transcription factor, was the direct target of miR-27a using a dual luciferase assay. An inverse relationship between miR-27a expression and Mef2c expression in osteoporotic patients was shown. Silencing of miR-27a decreased bone formation, confirming the role of miR-27a in bone formation in vivo. Conclusion: In summary, miR-27a was essential for the shift of MSCs from osteogenic differentiation to adipogenic differentiation in osteoporosis by targeting Mef2c.

Suppression of zinc finger protein 467 alleviates osteoporosis through promoting differentiation of adipose derived stem cells to osteoblasts

Osteoblast and adipocyte are derived from common mesenchymal progenitor cells. The bone loss of osteoporosis is associated with altered progenitor differentiation from an osteoblastic to an adipocytic lineage. In this study, a comparative analysis of gene expression profiling using cDNA microarray and realtime-PCR indicated that Zinc finger protein 467 (Zfp467) involved in adipocyte and osteoblast differentiation of cultured adipose derived stem cells (ADSCs). Our results showed that RNA interference for Zfp467 in ADSCs inhibited adipocyte formation and stimulated osteoblast commitment. The mRNA levels of osteogenic and adipogenic markers in ADSCs were regulated by si-Zfp467. Zfp467 RNAi in ADSCs could restore bone function and structure in an ovariectomized (OVX)-induced osteoporotic mouse model. Thus Zfp467 play an important role in ADSCs differentiation to adipocyte and osteoblast. This has relevance to therapeutic interventions in osteoporosis, including si-Zfp467-based therapies currently available, and may be of relevance for the use of adipose-derived stem cells for tissue engineering.

Zinc finger protein 467 regulates Wnt signaling by modulating the expression of sclerostin in adipose derived stem cells

Osteoporosis is a metabolic disease in which a disruption of the balance between bone formation by osteoblasts and bone resorption by osteoclasts leads to the progressive deterioration of bone density and quality. Tissue engineering approaches to the treatment of osteoporosis depend on the identification of factors that promote the differentiation of progenitor cells towards an osteoblastic phenotype. In the present study, we expanded on prior findings on the role of zinc finger protein 467 (Zfp467) in the osteoblastic differentiation of adipose-derived stem cells (ADSCs) and explored the underlying mechanisms. We showed that Zfp467 binds to and regulates the expression of the SOST gene, which encodes a secreted glycoprotein named sclerostin (Sost) that is expressed exclusively by osteocytes and functions as a negative regulator of bone formation through the modulation of Wnt signaling. Overexpression of Zfp467 in ADSCs inhibited Wnt signaling by promoting binding of Sost to the Wnt coreceptors LRP5/6 and disrupting Wnt induced Frizzled-LRP6 complex formation, and siRNA mediated Sost silencing reversed the inhibition of Wnt signaling by Zfp467 in ADSCs. Our results indicate that Zfp467 regulates the differentiation of ADSCs via a mechanism involving Sost-mediated inhibition of Wnt signaling, suggesting potential therapeutic targets for the treatment of osteoporosis.

The Safety and Efficacy of Early-Stage Bi-Weekly Alendronate to Improve Bone Mineral Density and Bone Turnover in Chinese Post-Menopausal Women at Risk of Osteoporosis

The efficacy and safety of early, low frequency antiresorptive drug intervention for osteopaenia on bone mineral density (BMD) and bone turnover in Chinese post-menopausal women at risk of developing osteoporosis were investigated. A total of 180 women aged 40 − 70 years were enrolled and equally randomized to receive either 70 mg alendronate once every 2 weeks plus 0.5 μg alfacalcidol daily (treatment group) or alfacalcidol 0.5 μg daily alone (control group) for 12 months. In the treatment group, lumbar spine and total hip BMD at 12 months had increased significantly from baseline and compared with the control group. There were also significant reductions in serum levels of the bone turnover biomarkers, bone-specific alkaline phosphatase and C-terminal telopeptide of type I collagen, compared with the control. No serious adverse events were observed in either group and safety profiles were similar. It was concluded that early intervention with 70 mg alendronate once every 2 weeks was safe, well tolerated and more effective than alfacalcidol alone (control) in increasing BMD and reducing bone turnover, and might prevent serious outcomes, such as fragility fractures, reduce rates of adverse effects and improve patient compliance.

Clinicopathological Characteristics and Computed Tomography Features of Mucinous Gastric Carcinoma

This study investigated the clinicopathological characteristics of mucinous gastric carcinoma (MGC) and assessed whether multidetector-row computed tomography (MDCT) could differentiate MGC from non-mucinous gastric carcinoma (NGC). Clinicopathological data from 542 patients with gastric carcinoma (23 MGC, 519 NGC), who underwent pre-operative MDCT examination and curative or palliative gastrectomy, were analysed. Only seven of the 23 patients with MGC were correctly diagnosed pre-operatively by endoscopic biopsy. The MGC patients had larger tumours, a higher frequency of lymph node metastases, were more likely to have tumours of tumour, node, metastasis stages III and IV, and were less likely to have a curative resection than NGC patients. In addition, five MGC patients had calcifications in the thickened gastric wall. In conclusion, MGC is rare and is detected mostly at an advanced stage. The diagnostic sensitivity of MGC by endoscopic biopsy was relatively low, whereas MDCT was helpful in distinguishing MGC from NGC.

SOST Gene Inhibits Osteogenesis from Adipose-Derived Mesenchymal Stem Cells by Inducing Th17 Cell Differentiation

Background/Aims: Postmenopausal osteoporosis is considered to be an autoimmune and inflammatory process, and IL-17 plays important roles in the loss of bone mass. Sclerostin (SOST) acts as a negative regulator of bone formation by inhibiting the Wnt signaling pathway. It also is a mediator of the crosstalk between the skeletal and immune systems. However, few studies have examined the role of SOST gene in the differentiation of T helper 17 (Th17) cells. Methods: Adipose-derived stem cells (ADSCs) were isolated and transfected with pcDNA3-SOST or shSOST, and then co-cultured with CD4+ T cells isolated from peripheral blood mononuclear cells. The differentiation, adipogenesis, and osteogenesis of Th17 and regulatory T (Treg) cells were examined by western blot, intracellular and intranuclear staining, ELISA, and real-time quantitative PCR in this co-culture model. Results: The SOST gene promoted the secretion of IL-6 and TGF-β in ADSCs. After co-culture of ADSCs with CD4+ T cells, the SOST gene increased the number of CD4+IL-17+ cells and the levels of IL-17 and RORγ. However, the number of CD4+CD25+Foxp3+ cells was decreased, which was accompanied with a reduction of IL-10 and Foxp3 expression. In the meantime, the SOST gene inhibited the expression of COL1, OCN, and OPN, reduced the activity of alkaline phosphatase, and increased the expression of LPL and PPARγ. Furthermore, IL-17 promoted SOST gene-induced adipogenesis and increased the inhibition of osteogenesis. Conclusions: SOST promoted the differentiation of Th17 cells and reduced the differentiation of Treg cells, which exacerbated the SOST gene-induced inhibition of osteogenesis from ADSCs.