In Vitro Degradation of Electrospun Poly(Lactic-Co-Glycolic Acid) (PLGA) for Oral Mucosa Regeneration.

Poly(lactic-co-glycolic acid) (PLGA) has been used in the field of tissue engineering as a scaffold due to its good biocompatibility, biodegradability and mechanical strength. With the aim to explore the degradability of PLGA electrospun nonwoven structures for oral mucosa tissue engineering applications, non-irradiated and gamma irradiated nonwovens were immersed in three different solutions, in which simulated body fluid (SBF) and artificial saliva are important for future oral mucosa tissue engineering. The nonwovens were immersed for 7, 15 and 30 days in SBF, culture media (DMEM) and artificial saliva at 37 °C. Before immersion in the solutions, the dosage of 15 kGy was applied for sterilization in one assay and compared with non-irradiated samples at the same timepoints. Samples were characterized using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and gel permeation chromatography (GPC) to evaluate the nonwoven degradation and Fourier-transform infrared spectroscopy (FTIR) to evaluate the chain scissions. Our results showed that PLGA nonwovens were constituted by semicrystalline fibers with moderate degradation properties up to thirty days. The non-irradiated samples exhibited slower kinetics of degradation than irradiated nonwovens. For immersion times longer than 7 days in the three different solutions, the mean diameter of irradiated fibers stayed in the same range, but significantly different from the control sample. On non-irradiated samples, the degradation kinetics was slower and the plateau in the diameter value was only attained after 30 days of immersion in the fluids. Plasticization (fluid absorption into the fiber structure) occurred in the bulk material, as confirmed by a decrease in Tg observed by DSC analyses of non-irradiated and irradiated nonwovens, in comparison with the respective controls. In addition, artificial saliva showed a higher capacity of influencing PLGA crystallization than SBF and DMEM. FTIR analyses showed typical PLGA chemical functional groups changes. These results will be important for future application of those PLGA electrospun nonwovens for oral mucosa regeneration.

Trypanosoma cruzi trypomastigotes induce cytoskeleton modifications during HeLa cell invasion

It has been recently shown that Trypanosoma cruzi trypomastigotes subvert a constitutive membrane repair mechanism to invade HeLa cells. Using a membrane extraction protocol and high-resolution microscopy, the HeLa cytoskeleton and T. cruzi parasites were imaged during the invasion process after 15 min and 45 min. Parasites were initially found under cells and were later observed in the cytoplasm. At later stages, parasite-driven protrusions with parallel filaments were observed, with trypomastigotes at their tips. We conclude that T. cruzi trypomastigotes induce deformations of the cortical actin cytoskeleton shortly after invasion, leading to the formation of pseudopod-like structures.

Trypanosoma cruzi trypomastigotes induce cytoskeleton modifications during HeLa cell invasion.

It has been recently shown that Trypanosoma cruzi trypomastigotes subvert a constitutive membrane repair mechanism to invade HeLa cells. Using a membrane extraction protocol and high-resolution microscopy, the HeLa cytoskeleton and T. cruzi parasites were imaged during the invasion process after 15 min and 45 min. Parasites were initially found under cells and were later observed in the cytoplasm. At later stages, parasite-driven protrusions with parallel filaments were observed, with trypomastigotes at their tips. We conclude that T. cruzi trypomastigotes induce deformations of the cortical actin cytoskeleton shortly after invasion, leading to the formation of pseudopod-like structures.

Alterações histológicas e de conteúdo mineral na área de correção de fenda alveolar por distração osteogênica - in vivo / Mineral contents and histological changes of the wound healing in the bone defect area corrected with distraction osteogenesis - in vivo

O objetivo deste estudo piloto foi de avaliar as alterações de características histológicas e no conteúdo mineral na área de regeneração entre superfícies ósseas aproximadas por distração osteogênica. Foi criado cirurgicamente defeito alveolar, com 4 mm de largura, 6 mm em comprimento e 10 mm em profundidade, em três suínos jovens Sus scropha. Os distratores foram fixados no palato com a finalidade de transportar o segmento ósseo, delimitado por corticotomia, no sentido do fechamento do defeito criado. A área do defeito foi recoberta subperiostamente com membrana absorvível de colágeno e a ativação do parafuso foi iniciada com 1 mm/dia. Os animais testados foram sacrificados no 27° e 48° de cicatrização e o animal controle, que não passou por procedimento cirúrgico algum, foi sacrificado aos três meses de idade. Análise histológica e de energia dispersiva por raios-X (EDXA) revelaram diferenças das características do reparo em relação ao crescimento, observando-se a formação de pontes ósseas entre as superfícies ósseas e deposição gradativa de elementos minerais até os 48 dias de reparo. Ainda, menor densidade mineral foi observada na área de reparo.