Novel bioactive collagen-polyurethane-pectin scaffolds for potential application in bone regenerative medicine

Recently, the development of bioactive scaffolds that allow improved bone repair is of interest for hard tissue regenerative medicine strategies. The use of biopolymers with synthetic polymer represents an innovative alternative for this purpose due to its excellent capacity to mimic the bone extracellular matrix. In this work, scaffolds based on bovine tendon collagen and pectin derived from orange (Citrus sinensis) peels were designed. The surfaces were prepared by a polymeric semi-interpenetration process where linear pectin chains were interpenetrated in a polyurethane-crosslinked collagen matrix. The effect of pectin content (10-40 wt.%) on the structural, physicochemical and biological properties of this type of scaffolds was evaluated. The increment in pectin content generates amorphous, granular surfaces with interconnected porosity, improving crosslinking, decreasing swelling and accelerating its rate of degradation in physiological and proteolytic media, also pro-moting antibacterial capacity showing inhibition of growth of pathogens such as E. coli. Specifically, the scaffold with 20 wt.% pectin (CPc20) shows a mechanical improvement of 342 +/- 12% (with respect to crosslinked collagen), allowing the mineralization of 15 +/- 1.5% of carbonated apatite on its surface, showing no cytotoxic effects on fibroblasts and allowing their proliferation; in addition, it was determined that immune system cells such as human monocytes can secrete high levels of transforming growth factor beta (TGF-beta) and low levels of tumor necrosis factor alpha (TNF-alpha), conditions required in the process of bone formation. These results demonstrate that these bioactive scaffolds could be applied in bone tissue regenerative medicine strategies.