Characterization and evaluation of titanium substrates coated with gelatin/hydroxyapatite composite for culturing rat bone marrow derived mesenchymal stromal cells

摘要

Titanium (Ti) is widely used for making tissue engineering implants, due to its good corrosion resistance, biocompatibility and mechanical properties. However, bare Ti does not integrate well with natural bone tissue and releases ions and particles that are harmful to the extracellular matrix. To overcome these problems, the Ti substrate could be coated with various biocompatible materials including a composite of gelatin and hydroxyapatite (HA). However, few have characterized and evaluated the coating of gelatin/HA on Ti substrate and its effect on bone related cells. In this study, samples of Ti substrate coated with gelatin/HA composite were fabricated with gelatin concentration ranging from 0 to 200 mg/L. The porous surface structure of gelatin/HA composite formed on the Ti substrate was then examined and characterized for its composition and topography by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and image processing and analysis software (ImageJ), respectively. Subsequently, rat bone marrow-derived mesenchymal stromal cells (BMMSC) were cultured on the surface of gelatin/HA composite on Ti substrate, and evaluated for cell morphology, proliferation, and osteo-differentiation using SEM, MTT assay, and alkaline phosphatase (ALP) assay, respectively. It is shown that gelatin enhanced binding of HA onto Ti substrate, and the topography of the porous surface structures was influenced by gelatin concentration only for the large pore sizes. Furthermore, the results indicate that the porous surface structures of gelatin/HA on Ti substrate promoted proliferation and osteodifferentiation as compared to the naked pure Ti substrate, particularly on that with concentration of gelatin at 100 mg/L. These findings, taken together, suggest that Ti substrate can be coated with different porous surface structures of gelatin/HA composite with gelatin solution of different concentrations. Such coated Ti substrates can promote cytocompitibility and osteo-differentiation of BMMSC, and thus may be of potential in development of implants and devices for bone tissue engineering.