Avaliação in vivo de toxicidade, biocompatibilidade, biodegradação e efeito sistêmico de membranas híbridas de celulose bacteriana e alginato de algas marrons para regeneração óssea

Abstract

The synergy of benefits of different polymers, ceramics and bioactives for the constitution of guided bone regeneration barrier membranes motivates the development of hybrid biomaterials of bacterial cellulose (BC), which exhibit biological safety and efficacy. This preclinical study evaluated hybrid membranes of BC/strontium apatite (G1) and oxidized BC/strontium apatite (G2) for toxicity, biocompatibility, biodegradation and metabolism. Incubation with Artemia salina for 24h determined mortality and LC50 compared to potassium dichromate (C+) by Probit analysis. Subcutaneous implants in Swiss mice were compared to sham (C-) and collagen membrane (C+) at 1, 3 and 9 weeks. The histopathology of local tissue irritation according to ISO 10993-6 and the integrity of biomaterials were evaluated by non-parametric multiple comparisons using Kruskal-Wallis test and Durbin-Conover post-hoc test, considering p<0.05. In parallel, liver, kidneys and tibias had anatomopathological analysis of relative weight by ANOVA and Tukey post-hoc test and biochemical analysis of iodine, nitrite and catalase scores by Kruskal-Wallis test and Durbin-Conover post-hoc test, considering p<0.05. The mortality of microcrustaceans was low and inversely proportional to LC50 well above 1,000 μm/mL with similarity between G1 and G2. For rodents, absence of irritation was noted in 1 week and mild irritation after 3 weeks (G1, G2 and C+). The density of neutrophils, lymphocytes and giant cells was lower for G1 and higher for G2 up to 9 weeks. Macrophages were reduced for G1 and increased for G2. Neovascularization was higher for C+ at 1 week and for G1, G2 and C+ after 3 weeks. Fibrosis was lower for G2 and higher for G1 up to 9 weeks. Biodegradation showed intragroup differences, with loss of biomaterial integrity in G1 and G2 after 3 weeks and in C+ after 9 weeks. The relative weight at 9 weeks was higher in the kidneys for G1. The reaction to iodine in the kidneys showed higher scores at 3 weeks for G1 and 9 weeks for G1. Nitrite was absent. The reaction of endogenous catalase was higher in the liver with no difference between groups, in the kidneys at 1 week for G2, 3 weeks for G1 and 9 weeks in G1. Tibias showed no differences in any biochemical parameter. All BC hydrogels were biocompatible and did not evoke acute toxicity or nitrosative stress, with safer and more resorbable associations with strontium apatite, with the non-oxidized form having persistent renal kinetics. Future studies in bone defects are needed to elucidate the osteopromoting efficacy of the hydrogels.