Gelatin- and hydroxyapatite-based cryogels for bone tissue engineering: synthesis, characterization, in vitro and in vivo biocompatibility.

The aim of this study was the synthesis and characterization of gelatin- and hydroxyapatite (osteoconductive component of bone)-based cryogels for tissue-engineering applications. Preliminary in vitro and in vivo biocompatibility tests were conducted. Gelatin- and hydroxyapatite-based cryogels of varying concentrations were synthesized using glutaraldehyde as the crosslinking agent. Chemical structure, pore morphology, pore size distribution, mechanical properties, swelling characteristics and degradation profiles of the synthesized cryogels were demonstrated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mercury porosimetry, a mechanical test device, swelling ratio tests and weight loss measurements, respectively. In vitro cell viability and in vivo biocompatility tests were performed in order to show the performance of the cryogels in the biological environment. Changing the concentrations of gelatin, hydroxyapatite and crosslinker changed the chemical structure, pore size and pore size distribution of the cryogels, which in turn resulted in the ultimate behaviour (mechanical properties, swelling ratio, degradation profile). In vitro cell culture tests showed the viability of the cells. The cryogels did not show any cytotoxic effects on the cells. Clinical outcomes and the gross pathological results demonstrated that there was no necrosis noted in the abdominal and thoracic regions at the end of implantation and the implanted cryogel was found to be non-irritant and non-toxic at 12 weeks of implantation.