Realization and characterization of bioactive composite materials for locomotor tissue regeneration

Tissue Enginnering emerges as a potential and alternative therapeutic process to treat severely injured patients with minimally invasive techniques. Cartilage and bone injuries occur due to several reasons and they compromise quality of life. This thesis was focused on development of biomaterials that could mimic cartilage and bone tissue, using only natural substances, gelatin and/or collagen, crosslinked with genipin (GP) and hydroxyapatite (HA) . These materials are cheap and easy to handle, and in particular collagen, represents a chemo- attractor factor, that may help cellular colonization. First of all genipin reaction was studied to establish reaction rate constant and crosslinking degree as function of genipin concetrations. The optimal genipin concentration was decided primarly assuring that it was not cytotoxic, meseauring its release in acqueous enviroment. Then elastic moduli of scaffolds prepared with different GP concentrations, different protocols and different HA concentrations were measured taking into account that scaffolds had to present mechanical properties suited to the implant site. Roughness surface of scaffolds, was also investigated with SEM, to ensure an optimal integration with implant site and to verify the presence of a right porosity to allow its cell colonisation. Bone scaffolds were arranged to reproduce a HA gradient, an important bone feature, and their anisotropy was valueted. Biocompatibility tests, in vitro tests, for cartilage and bone biomaterials were performed using primary and immortalised cells. Finally preliminary in vivo tests using small animal models, rats with a femur lesion, were performed for cartilage and bone substitute, selected on the basis of their mechanical properties. The aim was to follow bone and cartilage regeneration, after injection of biomaterials, and to compare it with the physiological regeneration.