Although many bone substitutes have been designed and produced, the development of bone tissue engineering products that mimic the microstructural characteristics of native bone remains challenging. It has been shown that pore orientation within collagen scaffolds influences bone matrix formation by the endochondral route. In addition, that the unidirectional orientation of the scaffolds can limit the growth of blood vessels. However, a comparison between the amount of bone that can be formed in scaffolds with different pore orientations in addition to analyzing the effect of loading osteogenic and proangiogenic factors is still required. In this work we fabricated uni- and multidirectional collagen sponges and evaluated their microstructural, physicochemical, mechanical and biological characteristics. Although the porosity and average pore size of the uni- and multidirectional scaffolds was similar (94.5% vs. 97.1% and 260 µm vs. 269 µm, respectively) the unidirectional sponges had a higher tensile strength, Young’s modulus and capacity to uptake liquids than the multidirectional ones (0.271 MPa vs. 0.478 MPa, 9.623 MPa vs. 3.426 MPa and 8000% mass gain vs. 4000%, respectively). Culturing of rat bone marrow mesenchymal stem cells demonstrated that these scaffolds support cell growth and osteoblastic differentiation in the presence of BMP-2 in vitro, although the pore orientation somehow affected cell attachment and differentiation. The evaluation of the ability of the scaffolds to support bone growth when loaded with BMP-2 or BMP-2 + VEGF in an ectopic rat model showed that they both supported bone formation. Histological analysis and quantification of mineralized matrix revealed that the pore orientation of the collagen scaffolds influenced the osteogenic process.

This work assessed wound healing response in rabbit oral lesions grafted with autologous artificial connective tissue or acellular collagen scaffolds. Autologous artificial oral connective tissue (AACT) was produced using rabbit fibroblasts and collagen I scaffolds. Before implantation, AACT grafts were assayed to demonstrate the presence of fibroblasts and extracellular matrix components, as well as the expression of characteristic genes and secretion of chemokines, cytokines, and growth factors. AACT grafts were tested in the rabbits from which the fibroblasts were obtained, whereas acellular collagen type I scaffolds (CS) were evaluated in a separate group of rabbits. In both cases, contralateral wounds closed by secondary intention were used as controls. In a separate experiment, AACT-grafted wounds were directly compared with contralateral CS-grafted wounds in the same animals. Wound contraction and histological parameters were examined to evaluate closure differences between the treatments in the three animal experiments performed. Contraction of wounds grafted with AACT and CS was significantly lower than in their controls ( p < 0.05). Additionally, AACT significantly lowered wound contraction when compared with CS ( p < 0.05). Intriguingly, it was observed that AACT-grafted wounds initially displayed a significantly higher ( p < 0.05)—albeit transient—inflammatory response than seen in CS-grafted wounds and secondary healed wounds. This suggests that an early inflammatory component may contribute to tissue regeneration. Altogether, the results suggest that AACT- and CS-grafted wounds favor regeneration of oral mucosa.