Evaluation of collagen type I scaffolds including gelatin-collagen microparticles and Aloe vera in a model of full-thickness skin wound.

Research on collagen type I scaffolds with Aloe vera is sparse. The aim of this work was to develop collagen type I scaffolds with gelatin-collagen microparticles and loaded with a dispersion of A. vera, to assess their performance as grafting material for healing of skin wounds. Scaffolds were evaluated in a Cavia porcellus model with full-thickness skin wound and compared with wounds healed by secondary intention (controls). Animals grafted with scaffolds without A. vera and their control wounds were also included in the study. Evaluation of enzymatic degradation and percentage of the scaffolds' free amino groups-as an indirect assessment of their cross-linking-were also carried out because A. vera contains compounds which affect their stability. We found that dispersions of lyophilized A. vera extract loaded on scaffolds do not have cytotoxic potential, and they decrease collagenase degradation of scaffolds in the range of 0.1 to 0.3% w/v in a dose-dependent manner. Only the A. vera dispersion with the highest concentration (0.3% w/v) decreased the percentage of free amino groups, which are the ones involved in the cross-link of collagen fibers. This finding suggests that cross-linking is not the mechanism by which the tested dispersions stabilize the scaffolds. Preclinical, histochemical, and histomorphometric analyses of repaired wound tissue indicate that loading collagen type I scaffolds, including microparticles of gelatin-collagen, with A. vera in the concentrations tested does not improve wound healing. Low biodegradability of the tested scaffolds caused by the inhibition of collagenase activity might account for these results.

Controlled release of an extract of Calendula officinalis flowers from a system based on the incorporation of gelatin-collagen microparticles into collagen I scaffolds: design and in vitro performance.

Aiming to develop biological skin dresses with improved performance in the treatment of skin wounds, acellular collagen I scaffolds were modified with polymeric microparticles and the subsequent loading of a hydroglycolic extract of Calendula officinalis flowers. Microparticles made of gelatin-collagen were produced by a water-in-oil emulsion/cross-linking method. Thereafter, these microparticles were mixed with collagen suspensions at three increasing concentrations and the resulting mixtures lyophilized to make microparticle-loaded porous collagen scaffolds. Resistance to enzymatic degradation, ability to associate with the C. officinalis extract, and the extract release profile of the three gelatin-collagen microparticle-scaffold prototypes were assessed in vitro and compared to collagen scaffolds without microparticles used as control. Data indicated that the incorporation of gelatin-collagen microparticles increased the resistance of the scaffolds to in vitro enzymatic degradation, as well as their association with the C. officinalis flower extract. In addition, a sharp decrease in cytotoxicity, as well as more prolonged release of the extract, was attained. Overall results support the potential of these systems to develop innovative dermal substitutes with improved features. Furthermore, the gelatin-collagen mixture represents a low-cost and scalable alternative with high clinical transferability, especially appealing in developing countries.