Daniele Pressato

Design of graded biomimetic osteochondral composite scaffolds

With the ultimate goal to generate suitable materials for the repair of osteochondral defects, in this work we aimed at developing composite osteochondral scaffolds organized in different integrated layers, with features which are biomimetic for articular cartilage and subchondral bone and can differentially support formation of such tissues. A biologically inspired mineralization process was first developed to nucleate Mg-doped hydroxyapatite crystals on type I collagen fibers during their self-assembling. The resulting mineral phase was non-stoichiometric and amorphous, resembling chemico-physical features of newly deposited, natural bone matrix. A graded material was then generated, consisting of (i) a lower layer of the developed biomineralized collagen, corresponding to the subchondral bone, (ii) an upper layer of hyaluronic acid-charged collagen, mimicking the cartilaginous region, and (iii) an intermediate layer of the same nature as the biomineralized collagen, but with a lower extent of mineral, resembling the tidemark. The layers were stacked and freeze-dried to obtain an integrated monolithic composite. Culture of the material for 2 weeks after loading with articular chondrocytes yielded cartilaginous tissue formation selectively in the upper layer. Conversely, ectopic implantation in nude mice of the material after loading with bone marrow stromal cells resulted in bone formation which remained confined within the lower layer. In conclusion, we developed a composite material with cues which are biomimetic of an osteochondral tissue and with the capacity to differentially support cartilage and bone tissue generation. The results warrant testing of the material as a substitute for the repair of osteochondral lesions in orthotopic animal models.

A novel hyaluronan-based gel in laparoscopic adhesion prevention: preclinical evaluation in an animal model

OBJECTIVE To evaluate the effectiveness of a crosslinked hyaluronan solution (ACP gel) in the prevention of postsurgical adhesions in laparoscopic surgery. DESIGN A randomized blinded study using a rabbit model in laparoscopic surgery. SETTING A standardized surgical trauma in the rabbit uterine horn to induce adhesion formation. ANIMALS Sixty-four sexually matured female New Zealand white rabbits weighing 2.5 to 3.0 kg and aged 3-4 months. INTERVENTION(S) After trauma, group 1 (n = 22) received no treatment, group 2 animals (n = 20) received oxidized-regenerated cellulose (Interceed [TC7]) in group 3 (n = 22) 5 mL of ACP gel were applied on the lesion. MAIN OUTCOME MEASURE(S) Six weeks after laparoscopy, a laparotomy was performed and the adhesions were scored according to Blauers scoring system. RESULT(S) 66% of the untreated animals and 85% of the animals treated with Interceed presented with severe adhesions, whereas only 35% of the ACP gel treatment group had significant adhesions. The mean ( +/- SEM) increased adhesion score was 2.24 +/- 0.26 in the untreated group, 2.45 +/- 0.22 in the Interceed group, and was 1.25 +/- 0.28 in the ACP gel group. CONCLUSION(S) This study revealed that ACP gel holds promise as a novel resorbable biomaterial for the reduction of postoperative adhesions after laparoscopic surgery.