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Distinct effects of RGD-glycoproteins on Integrin-mediated adhesion and osteogenic differentiation of human mesenchymal stem cells.

ABSTRACT: The detailed interactions of mesenchymal stem cells (MSCs) with their extracellular matrix (ECM) and the resulting effects on MSC differentiation are still largely unknown. Integrins are the main mediators of cell-ECM interaction. In this study, we investigated the adhesion of human MSCs to fibronectin, vitronectin and osteopontin, three ECM glycoproteins which contain an integrin-binding sequence, the RGD motif. We then assayed MSCs for their osteogenic commitment in the presence of the different ECM proteins. As early as 2 hours after seeding, human MSCs displayed increased adhesion when plated on fibronectin, whereas no significant difference was observed when adhering either to vitronectin or osteopontin. Over a 10-day observation period, cell proliferation was increased when cells were cultured on fibronectin and osteopontin, albeit after 5 days in culture. The adhesive role of fibronectin was further confirmed by measurements of cell area, which was significantly increased on this type of substrate. However, integrin-mediated clusters, namely focal adhesions, were larger and more mature in MSCs adhering to vitronectin and osteopontin. Adhesion to fibronectin induced elevated expression of ??-integrin, which was further upregulated under osteogenic conditions also for vitronectin and osteopontin. In contrast, during osteogenic differentiation the expression level of ??-integrin was decreased in MSCs adhering to the different ECM proteins. When MSCs were cultured under osteogenic conditions, their commitment to the osteoblast lineage and their ability to form a mineralized matrix in vitro was increased in presence of fibronectin and osteopontin. Taken together these results indicate a distinct role of ECM proteins in regulating cell adhesion, lineage commitment and phenotype of MSCs, which is due to the modulation of the expression of specific integrin subunits during growth or osteogenic differentiation.

SUBMITTER: Schwab EH

PROVIDER: S-EPMC3856375 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Distinct effects of RGD-glycoproteins on Integrin-mediated adhesion and osteogenic differentiation of human mesenchymal stem cells.

Schwab Elisabeth H EH Halbig Maria M Glenske Kristina K Wagner Alena-Svenja AS Wenisch Sabine S Cavalcanti-Adam Elisabetta A EA

International journal of medical sciences 20131109 13

The detailed interactions of mesenchymal stem cells (MSCs) with their extracellular matrix (ECM) and the resulting effects on MSC differentiation are still largely unknown. Integrins are the main mediators of cell-ECM interaction. In this study, we investigated the adhesion of human MSCs to fibronectin, vitronectin and osteopontin, three ECM glycoproteins which contain an integrin-binding sequence, the RGD motif. We then assayed MSCs for their osteogenic commitment in the presence of the differe ...[more]

PMID: 24324361

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Project description:BACKGROUND:Human mesenchymal stem cell (hMSC) differentiation into osteoblasts has important clinical significance in treating bone injury, and the stiffness of the extracellular matrix (ECM) has been shown to be an important regulatory factor for hMSC differentiation. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through integrin α5/β1, FAK, and Wnt signaling, subsequently regulating the osteogenic phenotype of hMSCs. METHODS:hMSCs were cultured on tunable polyacrylamide hydrogels coated with fibronectin with stiffness corresponding to a Young's modulus of 13-16 kPa and 62-68 kPa. After hMSCs were cultured on gels for 1 week, gene expression of alpha-1 type I collagen, BGLAP, and RUNX2 were evaluated by real-time PCR. After hMSCs were cultured on gels for 24 h, signaling molecules relating to integrin α5 (FAK, ERK, p-ERK, Akt, p-Akt, GSK-3β, p-GSK-3β, and β-catenin) were evaluated by western blot analysis. RESULTS:Osteogenic differentiation was increased on 62-68 kPa ECM, as evidenced by alpha-1 type I collagen, BGLAP, and RUNX2 gene expression, calcium deposition, and ALP staining. In the process of differentiation, gene and protein expression of integrin α5/β1 increased, together with protein expression of the downstream signaling molecules FAK, p-ERK, p-Akt, GSK-3β, p-GSK-3β, and β-catenin, indicating that these molecules can affect the osteogenic differentiation of hMSCs. An antibody blocking integrin α5 suppressed the stiffness-induced expression of all osteoblast markers examined. In particular, alpha-1 type I collagen, RUNX2, and BGLAP were significantly downregulated, indicating that integrin α5 regulates hMSC osteogenic differentiation. Downstream expression of FAK, ERK, p-ERK, and β-catenin protein was unchanged, whereas Akt, p-Akt, GSK-3β, and p-GSK-3β were upregulated. Moreover, expression of Akt and p-Akt was upregulated with anti-integrin α5 antibody, but no difference was observed for FAK, ERK, and p-ERK between the with or without anti-integrin α5 antibody groups. At the same time, expression of GSK-3β and p-GSK-3β was upregulated and β-catenin levels showed no difference between the groups with or without anti-integrin α5 antibody. Since Akt, p-Akt, GSK-3β, and p-GSK-3β displayed the same changes between the groups with or without anti-integrin α5 antibody, we then detected the links among them. Expression of p-Akt and p-GSK-3β was reduced effectively in the presence of the Akt inhibitor Triciribine. However, Akt, GSK-3β, and β-catenin were unchanged. These results suggested that expression of p-GSK-3β was regulated by p-Akt on 62-68 kPa ECM. CONCLUSIONS:Taken together, our results provide evidence that matrix stiffness (62-68 kPa) affects the osteogenic outcome of hMSCs through mechanotransduction events that are mediated by integrin α5.

Project description:BACKGROUND:The differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts (OBs) is a prerequisite for bone formation. However, little is known about the definitive surface markers for OBs during osteogenesis. METHODS:To study the surface markers on OBs, we generated and used monoclonal antibodies (MAbs) against surface molecules on transforming growth factor-?1 (TGF-?1)-treated cancer cells. The generated MAbs were further selected toward expression changes on hMSCs cultured with TGF-?1/bone morphogenetic protein-2 (BMP-2) or osteogenic differentiation medium (ODM) by flow cytometry. Immunoprecipitation and mass spectrometry were performed to identify target antigens of selected MAbs. Expression changes of the target antigens were evaluated in hMSCs, human periodontal ligament cells (hPDLCs), and human dental pulp cells (hDPCs) during osteogenic and adipogenic differentiation by quantitative polymerase chain reaction (qPCR) and flow cytometry. hMSCs were also sorted by the MAbs using magnetic-activated cell sorting system, and osteogenic potential of sorted cells was evaluated via Alizarin Red S (ARS) staining and qPCR. RESULTS:The binding reactivity of MR14-E5, one of the MAbs, was downregulated in hMSCs with ODM while the binding reactivity of ER7-A7, ER7-A8, and MR1-B1 MAbs was upregulated. Mass spectrometry and overexpression identified that MR14-E5, ER7-A7/ER7-A8, and MR1-B1 recognized integrin ?2, ?3, and ?V, respectively. Upon osteogenic differentiation of hMSCs, the expression of integrin ?2 was drastically downregulated, but the expression of integrin ?3 and ?V was upregulated in accordance with upregulation of osteogenic markers. Expression of integrin ?3 and ?V was also upregulated in hPDLCs and hDPCs during osteogenic differentiation. Cell sorting showed that integrin ?V-high hMSCs have a greater osteogenic potential than integrin ?V-low hMSCs upon the osteogenic differentiation of hMSCs. Cell sorting further revealed that the surface expression of integrin ?V is more dramatically induced even in integrin ?V-low hMSCs. CONCLUSION:These findings suggest that integrin ?3 and ?V induction is a good indicator of OB differentiation. These findings also shed insight into the expression dynamics of integrins upon osteogenic differentiation of hMSCs and provide the reason why different integrin ligands are required for OB differentiation of hMSCs.

Project description:Type 2 diabetes mellitus (T2DM) is a clinically important risk factor for dental implant treatment failure. An imbalance in the microenvironment of the jawbone of diabetic patients can impair the functions of bone marrow mesenchymal stem cells (BMSCs), thereby interfering with implant osseointegration during the healing phase. This study aims to investigate potential molecular factors associated with abnormal BMSC biological functions in diabetic patients with dental implant failure and identify intervention targets to improve implant osseointegration. The results of cell adhesion, cell scratch migration, alkaline phosphatase (ALP) activity, alizarin red staining, and real-time PCR assays showed that the adhesion, migration, and osteogenic differentiation abilities were significantly lower in alveolar BMSCs isolated from diabetic patients with implant failure (DM-F group) than in those isolated from diabetic patients with implant success (DM-S group) and normal patients (Nor group). Also, bioinformatics analysis and verification of whole-cell proteomics results revealed that integrin subunit alpha10 (ITGA10) expression in BMSCs was significantly lower in the DM-F group than in the DM-S group and much lower than that in the Nor group. In addition, lentiviral mediated short hairpin RNA (shRNA) or complementary DNA (cDNA) was used to knockdown or overexpress ITGA10 in BMSCs from diabetic patients, and the results revealed that ITGA10 knockdown significantly reduced the adhesion and migration abilities of BMSCs and inhibited their osteogenic differentiation potential by disturbing the FAK/PI3K/AKT/GSK3β/β-catenin pathway. ITGA10 overexpression produced the opposite results. In summary, this study revealed that low ITGA10 expression in BMSCs from the DM-F group is a major cause of cell dysfunction, including reduction in the adhesion, migration, and osteogenic differentiation abilities of BMSCs, and provided insight into the underlying mechanism. Additionally, ITGA10 was identified as a potential target protein for improving the biological functions of BMSCs and dental implant osseointegration in T2DM patients.

Dataset Information

Distinct effects of RGD-glycoproteins on Integrin-mediated adhesion and osteogenic differentiation of human mesenchymal stem cells.

Publications

Distinct effects of RGD-glycoproteins on Integrin-mediated adhesion and osteogenic differentiation of human mesenchymal stem cells.

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