Role of MicroRNA in Mesenchymal Stem Cells Differentiation Into Osteoblasts

T-Box20 inhibits osteogenic differentiation in adipose-derived human mesenchymal stem cells: the role of T-Box20 on osteogenesis

Background

Skeletal development and its cellular function are regulated by various transcription factors. The T-box (Tbx) family of transcription factors have critical roles in cellular differentiation as well as heart and limbs organogenesis. These factors possess activator and/or repressor domains to modify the expression of target genes. Despite the obvious effects of Tbx20 on heart development, its impact on bone development is still unknown.

Methods

To investigate the consequence by forced Tbx20 expression in the osteogenic differentiation of human mesenchymal stem cells derived from adipose tissue (Ad-MSCs), these cells were transduced with a bicistronic lentiviral vector encoding Tbx20 and an enhanced green fluorescent protein.

Results

Tbx20 gene delivery system suppressed the osteogenic differentiation of Ad-MSCs, as indicated by reduction in alkaline phosphatase activity and Alizarin Red S staining. Consistently, reverse transcription-polymerase chain reaction analyses showed that Tbx20 gain-of-function reduced the expression levels of osteoblast marker genes in osteo-inductive Ad-MSCs cultures. Accordingly, Tbx20 negatively affected osteogenesis through modulating expression of key factors involved in this process.

Conclusion

The present study suggests that Tbx20 could inhibit osteogenic differentiation in adipose-derived human mesenchymal stem cells.

Enhanced Transfection of Human Mesenchymal Stem Cells Using a Hyaluronic Acid/Calcium Phosphate Hybrid Gene Delivery System

Human mesenchymal stem cells (hMSCs) show enormous potential in regenerative medicine and tissue engineering. However, current use of hMSCs in clinics is still limited because there is no appropriate way to control their behavior in vivo, such as differentiation to a desired cell type. Genetic modification may provide an opportunity to control the cells in an active manner. One of the major hurdles for genetic manipulation of hMSCs is the lack of an efficient and safe gene delivery system. Herein, biocompatible calcium phosphate (CaP)-based nanoparticles stabilized with a catechol-derivatized hyaluronic acid (dopa-HA) conjugate were used as a carrier for gene transfection to hMSCs for improved differentiation. Owing to the specific interactions between HA and CD44 of bone marrow-derived hMSCs, dopa-HA/CaP showed significantly higher transfection in hMSCs than branched polyethylenimine (bPEI, MW 25 kDa) with no cytotoxicity. The co-delivery of a plasmid DNA encoding bone morphogenetic protein 2 (BMP-2 pDNA) and micro RNA 148b (miRNA-148b) by dopa-HA/CaP achieved significantly improved osteogenic differentiation of hMSCs.

Vitamin K2 promotes mesenchymal stem cell differentiation by inhibiting miR‑133a expression

Vitamin K₂ has been demonstrated to promote the osteogenic differentiation of mesenchymal stem cells; however, the mechanisms underlying this effect remain unclear. As microRNA (miR)-133a has been identified as a negative regulator of osteogenic differentiation, the present study hypothesized that vitamin K₂ promoted osteogenesis by inhibiting miR-133a. Using human bone marrow stromal cells (hBMSCs) overexpressing miR-133a, or a control, the expression levels of osteogenesis-associated proteins, including runt-related transcription factor 2, alkaline phosphatase and osteocalcin, were analyzed. miR-133a significantly suppressed the osteogenic differentiation of hBMSCs. To determine the effect of vitamin K₂ on miR-133a expression and osteogenesis, hBMSCs were treated with vitamin K₂. Vitamin K₂ inhibited miR-133a expression, which was accompanied by enhanced osteogenic differentiation. Furthermore, the expression levels of vitamin K epoxide reductase complex subunit 1, the key protein in γ-carboxylation, were downregulated by miR-133a overexpression and upregulated by vitamin K₂ treatment, indicating a positive feedback on γ-carboxylation. The results of the present study suggested that vitamin K₂ targets miR-133a to regulate osteogenesis.