Effects Of Gelatin/Hydroxyapatite Composite Titanium On Rat Bone Marrow Mesenchymal Stem Cells Proliferation And Differentiation

Titanium and its alloys have been widely used in the biomedical fields and tissue engineering implants, due to their good corrosion resistance, biocompatibility and mechanical properties. However, when a titanium implant was implanted into a human being, it could not tightly bind to surrounding natural bone tissue, the osteointegration is not sufficient, osteoblasts could not grow well on it; moreover, ions released from the implant affect the extracellular matrix. All of these factors lead to the failure of implantation. It has been demonstrated that coating treatment on titanium and its alloys could improve the implants'abrasion resistance and biological performance. In fact hydroxyapatite (HA,Ca10(PO4)6(OH)2) has attracted a great deal of attention over the last few decades as its high bioaffinity to cells and excellent osteoconductivity,Moreover,The combination of the HA coatings with some bioresorbable polymers to form biocomposites that improve the stablity of implants-bone interface and adhesion with cells has been considered as an efficient approach to tackle its own brittleness and low mechanical strengthIn this study, we fabricated gradient concerntrations(50 mg/L,100 mg/L, 150mg/L和200 mg/L) of gelatin/apatite coatings onto pure titanium substrates via a biomemitic approach. Substrates were characterized by Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD) techniques, scanning electron microscopy (SEM) and atomic force microscopy (AFM). And the interrelationship between gelatin and hydroxyapatite has been generally described. The differences of gelatin/apatite coatings were quantitatively evaluated by ImageJ method. The proliferation and AKP express level of BMMSC on the coatings were assessed in vitro as well.As revealed by SEM, gelatin/apatite titanium substrates display stable interconnected and porous structures only with the gelatin concentration of 100mg/L and 150mg/L. And both of the substrates pore size and roundness are significant. As shown in FTIR, there is a significant absorption peak of amido bond in the wavelength range of 1640～1655 cm-1. XRD spectrum shows that the characteristic adsorption of hydroxyapatite was improved with addition of gelatin. It suggests that the deposition of hydroxyapatite was accelerated by adding of gelatin. AFM shows the height of these two concentrations of gelatin/apatite titanium substrates were 4.286μm,4.633μm, respectively.The proliferation of BMMSC cultured on the gelatin/apatite titanium substrates was assessed via MTT. The results indicate that the composite substrates showed higher proliferation and osteoblast differentiation tendency than that of naked titanium substrates (control). And the level of proliferation and differentiation of BMMSC on 100mg/L gelatin/apatite titanium are both higher than the other one. The results suggest that different substrates surfaces have different influences of stem cells and the gelatin/apatite coating treated titanium substrates show high potential application in biomedical implants.