Cell culture and variations in the comet assay do not affect the genomic integrity of adipose-derived stem cells

The application of quality control tests, such as the comet assay, are essential when adipose-derived stem cells are cultured for therapeutic purposes. However, the steps involved in the development of this assay should be investigated, in order to reduce their influence on genomic damage in cells. The study aimed to evaluate if the cell culture process causes DNA damage, and if variations in the lysis time and pH of the electrophoresis buffer interfere in the genotoxicity results. Four different comet assay protocols were evaluated, and the effects of lysis time and pH conditions of the electrophoresis buffer solution were stated as follows: 2 hours and pH 12; 24 hours and pH 12; 2 hours and pH ≥ 13 and 24 hours and pH ≥ 13. The tail moment was analyzed, and results indicated that at the time cells were detached from the flasks, there was little damage to the DNA in the adipose-derived stem cells, which was confirmed by evaluation of the expression of mRNA genes involved in damage and repair processes of genetic material. Also, the tail moment values ​​did not show significant differences among the four evaluated protocols (p < 0.05), with no indication of damage when compared to the positive control (p < 0.05). Thus, any of the tested protocols can be applied in genotoxicity tests with adipose-derived stem cells, without causing damage to them.(AU)

Nerve growth factor with fibrin glue in end-to-side nerve repair in rats / Fator de crescimento nervoso em cola de fibrina no reparo término-lateral de nervos em ratos

PURPOSE: To determine the effects of end-to-side nerve repair performed only with fibrin glue containing nerve growth in rats. METHODS: Seventy two Wistar rats were divided into six equal groups: group A was not submitted to nerve section; group B was submitted to nerve fibular section only. The others groups had the nerve fibular sectioned and then repaired in the lateral surface of an intact tibial nerve, with different procedures: group C: ETS with sutures; group D: ETS with sutures and NGF; group E: ETS with FG only; group F: ETS with FG containing NGF. The motor function was accompanied and the tibial muscle mass, the number and diameter of muscular fibers and regenerated axons were measured. RESULTS: All the analyzed variables did not show any differences among the four operated groups (p>0.05), which were statistically superior to group B (p<0.05), but inferior to group A (p>0.05). CONCLUSION: The end-to-side nerve repair presented the same recovery pattern, independent from the repair used, showing that the addition of nerve growth factor in fibrin glue was not enough for the results potentiating.(AU)

OBJETIVO: Determinar os efeitos do reparo nervoso término-lateral realizado apenas com cola de fibrina contendo fator de crescimento nervoso em ratos. MÉTODOS: Setenta e dois ratos Wistar foram distribuídos em seis grupos: A - não submetido à secção nervosa; B - secção do nervo fibular (sem reparo); Os outros grupos tiveram o nervo fibular seccionado e então reparado na superfície lateral do nervo tibial intacto, com diferentes procedimentos: C - RNTL com suturas; D - RNTL com suturas e FCN; E - RNTL apenas com CF; F - RNTL com CF contendo FCN. A função motora foi acompanhada e a massa do músculo tibial, o número e o diâmetro das fibras musculares e axônios regenerados foram medidos. RESULTADOS: Não houve diferença entre as variáveis avaliadas nos quatro grupos operados (p>0,05), os quais foram superiores ao grupo B (p<0,05), mas inferiores ao grupo A (p>0,05). CONCLUSÕES: O reparo nervoso término-lateral mostrou o mesmo padrão de recuperação, independente do tipo de reparo utilizado, evidenciando que a adição de fator de crescimento nervoso na cola de fibrina não foi suficiente para a potencialização dos resultados.(AU)