Collagen-hydroxyapatite tubular scaffold with radially oriented porosity for osteochondral defect replacement

When the cartilage damages, sometimes the subchondral bone is involved becoming pathologically altered. An alternative therapeutic approach to surgery for osteochondral defect replacement may consist in the use of innovative scaffolds able to be colonized by cells in vivo. A key role in the scaffold colonization by cells is played by its vasculariza- tion. Aim of the present study is to develop a hydroxyapatite-collagen (HA-Coll) tubular scaffold with a radially oriented porosity in order to enhance the angiogenesis within the scaffold structure. HA crystals in collagen matrix composites 70wt% Coll - 30wt% HA were prepared by direct nucleation of HA using Ca(OH)2 and H3PO4 as calcium and phosphorus precursors; tubular scaffolds were produced by a spin-casting technique followed by a standard freeze-drying and dehydrothermal crosslinking. XRD and EDS spectrum revealed the for- mation of HA crystals on the collagen matrix. SEM analysis of tubular scaffold confirmed the formation of nano-sized apatite crystals on the fibrous collagen with radial oriented pores. FTIR diagram evidenced the chemical interaction between HA crystals and collagen. In vitro/in vivo tests have been used to evaluate the ability of the scaffolds to be colonized by cells, enhance angiogenesis, and sustain the osteo- chondral matrix formation