Avaliação

Patrícia da Luz Moreira

Collagen has been extensively described as an important material in bone tissue engineering due to its biocompatibility, biodegradability, low antigenicity, and high tensile strength. However, collagen scaffolds in their pure form have some drawbacks and improvements in its physical, chemical and biological properties are necessary to overcome those inadequacies. Recently, the selective hydrolysis of carboxyamides groups of asparagine and glutamine residues of collagen has been employed to increase the number of negative sites and enhance the piezoelectric properties. Anionic collagen scaffolds were prepared by hydrolysis of bovine pericardium for both 24 h (BP24), and 48 h (BP48). Bovine osteoblasts were cultured on them and on native matrices to understand the cellular interactions responsible for the good osteoconductivity and biocompatibility reported with in vivo tests. Cellular adhesion and morphology, mineralization process, chondroitin sulfate, alkaline phosphatase (ALP) and osteocalcin were the parameters evaluated. Cellular adhesion was considered satisfactory in all matrices, while cellular proliferation (through histological analysis) in BP48 matrices kept in common medium has shown to be higher than the one found for BP24 and native collagen matrices. When BP48 was stimulated to mineralize, they showed a decrease at the proliferation, which may be related to the beginning of the differentiation process of these cells. All matrices allowed multilayered cellular proliferation, presenting several similar characteristics, but when they were stimulated to mineralize, they presented a higher amount of surface?s vesicles. Mineralization process was observed at all matrices kept in mineralization medium and, mainly at their surfaces. EDS analysis showed that these deposits were composed of calcium phosphates. ALP production was observed in all matrices, despite the fact that matrices kept in common medium showed a higher production of ALP, due to the lack of nutritional supplement for mineral deposition. BP48 matrix favored ALP production, which may be related to its degree of mineralization. Osteocalcin detection in all matrices kept in the mineralization medium should be due to the fact of a higher differentiation of those osteoblasts. Based on these results, BP48 matrix has shown to be more adequate to the bone regeneration process because of its good influence on osteoblastic differentiation and bone matrix production compared to the results obtained for native matrices, which present reduced piezoelectric properties

Avaliação "in vitro" dos processos de proliferação e diferenciação de celulas osteoblasticas e a mineralização sobre matrizes anionicas de colageno para reparo osseo

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