The Research Of Bone Tissue Engineering Scaffold With Drug Carried Microspheres

Although autogenous and allogeneic bone transplantation for bone repair has their drawbacks separately, they were widely used traditionally. Man-made bone repair materials have gained extensive attention in late years. Scholars paid especially attention to one of the key problems, which is establishing a functional bone repair scaffold with the ability to promote the adhesion, migration, proliferation of cells and seduce them toward specified ones. This study combined tissue engineering and control release of drugs together to establish a functional bone repair scaffold in the hope of providing a 3-D environment as well as controlled releasing certain drug moleculars to stimulate the cells and promote them to grow. This research employed PLGA and PHBV as the matrix, and then fabricated a multilevel structured PLGA scaffold modified by PHBV microspheres. Furthermore, we functionalized the PHBV mcirospheres by loading them with alendronate to make the whole scaffold with the property of sustained releasing drugs. This new scaffold with special structure can provide the 3-D space for the cells to grow on the one hand, on the other, it releases drugs with controlled manner to stimulate the cells to response and proliferate.According to the different solubility in acetone, PLGA and PHBV have been employed to fabricate PLGA/m-PHBV scaffold using particle-leaching method. The PHBV microspheres were used to enhance the PLGA scaffold. By adjusting the amount of PHBV microspheres, NaCl and PLGA concentration, we can control the porosity and pore size distribution of the scaffold. In this study, we made a scaffold with the porosity above 83% and the compressive strength of 1.4MPa. hMSCs were employed to evaluate the cyto-property. The result demonstrated that hMSCs adhered and proliferated well on the PLGA/m-PHBV scaffold. Live/dead experiment showed that most of the visible cells were distributed between PHBV microspheres and PLGA matrix. After induced in the osteogenic medium (OGM) for 21d, hMSCs on the scaffolds were turned into osteoblast according to the positive result of alizarin red dyeing.This study prepared PHBV/HA-AL microspheres with controllable diameter using single emulsion method and investigated the influential factors of microsphere diameter. The results showed that increasing the stirring speed and the concentration of surfactant could reduce the diameter of the microspheres. Owing to the chelation between hydroxyapatite (HA) and AL, this drug delivery system had a high encapsulation efficiency which exceeds 80% and only released 70% of AL within 28 days. During the in vitro degradation experiment, this system did not cause obvious acid environment. Meanwhile, the in vitro cytotoxicity experiment showed that this system did little harm to the hMSCs.The diameter of PHBV/HA-AL microspheres was tailored and they were used to fabricate PLGA/PHBV-HA-AL scaffold by the same method used above. This scaffold possessed a multi-level structure with the porosity of 81% and the compressive strength of 1.1MPa. hMSCs adhered and proliferated well on the scaffolds. The same cells distribution profile was found in the live/dead experiment. After induced in the osteogenesis inducing solution (OS) for 14d and 21d separately, the results of alkaline phosphatase and alizarin red dyeing were positive, which meant that hMSCs had turned into osteoblasts. After been cultured in the L-DMEM for 14d, the result of immunohistochemistry of collagenâ… on the scaffold was positive, which confirmed that this functional scaffold could induce the hMSCs to osteoblasts.