Dilmar Francisco Leonardi

Mesenchymal stem cells combined with an artificial dermal substitute improve repair in full-thickness skin wounds

Autografts represent the gold standard for the treatment of full thickness burns. Factors such as lack of suitable donor sites and poor skin quality, however, have led to the development of artificial dermal substitutes. The investigation of mechanisms leading to enhanced functionality of these skin substitutes has been attracting great attention. This study aimed to investigate the effect of autologous stem cells on the integration and vascularization of a dermal substitute in full-thickness skin wounds, in a murine model. Two cell populations were compared, whole bone marrow cells and cultivated mesenchymal stem cells, isolated from mice transgenic for the enhanced green fluorescent protein, which allowed tracking of the transplanted cells. The number of cells colonizing the dermal substitute, as well as vascular density, were higher in mice receiving total bone marrow and particularly mesenchymal stem cells, than in control animals. The effect was more pronounced in animals treated with mesenchymal stem cells, which located primarily in the wound bed, suggesting a paracrine therapeutic mechanism. These results indicate that combining mesenchymal stem cells with artificial dermal substitutes may represent an important potential modality for treating full thickness burns, even in allogeneic combinations due to the immunoregulatory property of these cells.

Development of a new nanofiber scaffold for use with stem cells in a third degree burn animal model.

The combination of mesenchymal stem cells (MSCs) and nanotechnology to promote tissue engineering presents a strategy for the creation of new substitutes for tissues. Aiming at the utilization of the scaffolds of poly-d,l-lactic acid (PDLLA) associated or not with Spirulina biomass (PDLLA/Sp) in skin wounds, MSCs were seeded onto nanofibers produced by electrospinning. These matrices were evaluated for morphology and fiber diameter by scanning electron microscopy and their interaction with the MSCs by confocal microscopy analysis. The biomaterials were implanted in mice with burn imitating skin defects for up to 7 days and five groups were studied for healing characteristics. The scaffolds demonstrated fibrous and porous structures and, when implanted in the animals, they tolerated mechanical stress for up to two weeks. Seven days after the induction of lesions, a similar presence of ulceration, inflammation and fibrosis among all the treatments was observed. No group showed signs of re-epithelization, keratinization or presence of hair follicles on the lesion site. In conclusion, although there was no microscopical difference among all the groups, it is possible that more prolonged analysis would show different results. Moreover, the macroscopic analysis of the groups with the scaffolds showed better cicatrization in comparison with the control group.