Study of Antimicrobial Peptide Dendrimers on Wound healing in SKin Tissue Engineering
Infections are one of the most common complications in burn injuries. In severe burns, the wound surface is optimal for microbial proliferation as the exudate is a protein rich environment. Autograft and cultured grafts are the main treatments used nowadays. However, they require a two-step surgical procedure, a collecting step and a grafting step, which slows down the treatment. In order to circumvent this two-step procedure, the CHUV has developed biological bandages made of collagen sheets seeded with fetal skin fibroblasts. The specific gene regulation and growth factor production of fetal cells allows a better healing. The goal of this project was to study the combination of antimicrobial peptide dendrimers with the existing biological bandages, for an improved tissue engineering skin construct having antimicrobial properties. To begin, the cytotoxic effect of two antimicrobial peptides, G3KL and G3RL, was tested on fetal and adult skin fibroblasts. The results showed that fetal cells were more sensitive to the peptides than adult cells. A high peptide concentration induced a higher death rate but in some cases also a higher amount of live cells. In parallel a scratch assay was performed and showed that peptides did not influence cell migration. Then, the efficacy of the antimicrobial peptides was tested against P.aeruginosa by a time kill and zone of inhibition assay. The results showed that both peptides were able to slow down the bacterial growth and that G3KL could even reduce the amount of bacteria. Finally, the biocompatibility of the peptides was tested with a chorioallantoic membrane assay (CAM). The results showed no adverse effect on the membrane or its vascularization and suggested a potential angiogenic effect of G3KL. The gene expression of fetal cells cultured with peptides was measured with a quantitative PCR and showed a small up-regulation of VEGFC, suggesting an explanation for the results obtained with the CAM.