Three-dimensional bioprinted GelMA/GO composite hydrogel for stem cell osteogenic differentiation both in vitro and in vivo

In this study, we evaluated the use of graphene oxide (GO) mixed with methyl methacrylate gelatin (GelMA) for the construction of a microenvironmental implant to repair bone defects in orthopedic surgery. A scaffold containing a GelMA/GO composite with mesenchymal stem cells (MSCs) was constructed using three-dimensional bioprinting. The survival and osteogenic capacity of MSCs in the composite bioink were evaluated using cell viability and proliferation assays, osteogenesis-related gene expression analysis, and implantation under the skin of nude mice. The printing process had little effect on cell viability. We found that GO enhanced cell proliferation but had no significant effect on cell viability. In vitro experiments suggested that GO promoted material-cell interactions and the expression of osteogenesis-related genes. In vivo experiments showed that GO decreased the degradation time of the material and increased calcium nodule deposition. In contrast to pure GelMA, the addition of GO created a suitable microenvironment to promote the differentiation of loaded exogenous MSCs in vitro and in vivo, providing a basis for the repair of bone defects.

3D bioprinted GelMA/GO composite induces osteoblastic differentiation

Graft substitute is a mature treatment tool in craniofacial bone repair. However, stress shielding and immutability of structure limit its use in patients with congenital defects. Therefore, a regenerative graft would be best suited for repair. Mesenchymal stem cells (MSCs) have been shown to be feasible in regenerative medicine and the clinical treatment of bone repair. The aim of this study was to propose a strategy that would directly blend graphene oxide (GO) and MSCs with gelatin methacrylate anhydride (GelMA), as bioink, to generate the scaffold for bone regenerative repair. The survival and osteogenic capacity of MSCs in the composite bioink were assessed by cell viability and proliferation assays, along with expression analysis of osteogenesis-related genes and proteins, and targeted immunofluorescence. The introduction of GO to the printing process had no influence on cell printing, viability, or printability of GelMa. However, the GO-involved structure exhibited a positive influence on MSC proliferation, without significantly affecting cell viability. Alkaline phosphatase was expressed more in cells cultured with GO than in those with pure GelMA. In addition, GO promoted the expression of osteogenesis-related genes and proteins, such as osteopontin, osteocalcin, and RUNX2. Collectively, the composite bioink enhanced cell proliferation and adhesion, as well as osteogenic differentiation properties, compared with pure GelMA.