Heterogeneity of human fibroblasts isolated from hypertrophic scar.

Pathological wound healing states, such as hypertrophic scarring and keloids, represent a huge clinical and financial burden on healthcare system. The complex biological mechanisms occurring in hypertrophic scarring are still barely understood. To date, there is no satisfactory description of hypertrophic fibroblasts. Therefore, in the present study we focused on the comparatively characterization of the fibroblasts residing in different regions of hypertrophic scars. To achieve this aim, fibroblasts were isolated from normal skin samples (n=4) and hypertrophic scars (n=4). These cell populations were further were used for the evaluation of proliferation and migration capacity, for the gene and protein expression of extracellular matrix protein type I collagen and fibronectin and for the presence of myofibroblasts. Our results demonstrated that perilesional and intralesional fibroblasts isolated from hypertrophic scars could be considered as distinct populations, having different properties. Thus, the intralesional fibroblasts had an increased proliferation capacity and increased gene and protein expression of collagen I and fibronectin. However, the perilesional fibroblasts had augmented mobility as revealed by in vitro scratch test and contained a higher percentage of myofibroblasts [alpha-smooth muscle actin (α-SMA)high cells], in comparison to the intralesional population. In conclusion, our data could provide an explanation regarding the inconsistent efficacy of topic therapies for hypertrophic scars.

Mesenchymal stromal cells derived exosomes as tools for chronic wound healing therapy.

In modern society, the healing of chronic wounds is still a major cause of discomfort for the patients and a financial burden for the care system. Current approaches use either organic tissue-engineered skin substitutes or stem cells based therapy. It has been shown that mesenchymal stem cells (MSCs) are able to improve the wound healing process by secreting factors with anti-inflammatory, anti-fibrotic and pro-angiogenic activities either as soluble molecules (growth factors, cytokines) or encapsulated within membrane vesicles (microparticles, exosomes). It has been shown that exosomes, the small membrane vesicles originating from the endocytic pathway, are the main mediators of MSCs paracrine effect. Their complex cargo (mRNA, microRNA and various anti-apoptotic and pro-angiogenic factors) has been found to induce migration and proliferation of fibroblasts as well as collagen synthesis. Thus, the combination of MSCs derived exosomes and organic biomaterials in order to enhance the healing process represents a novel approach for chronic wounds therapy, involving a cell-free use of MSCs paracrine activity.