Mesenchymal stem cells and cell-free preparations for treating atopic dermatitis

Atopic dermatitis(AD)is a chronic cutaneous inflammatory disease caused by an interaction between genetic,immune and epidermal barrier factors.Several treatments can be used to treat this disease but there are patients that do not respond to actual drugs.So,there is a need to develop effective therapies for AD.Mesenchymal stem cells(MSCs)are non-hematopoietic multipotent adult progenitor cells with immunomodulatory power and self-regenerating capacity to repair tissue damage,so they could be a potential effective treatment for AD.MSCs-Conditioned Medium(CM)and MSCs-exosomes are cell-free preparation with molecules secreted by stem cells that could be also beneficial for AD.This viewpoint reviews the actual development of MSCs,MSCs-CM and MSCs-exosomes for treating patients with AD.

In vitro comparison of human plasma-based and self-assembled tissue-engineered skin substitutes:two different manufacturing processes for the treatment of deep and difficult to heal injuries

Background:The aim of this in vitro study was to compare side-by-side two models of human bilayered tissue-engineered skin substitutes(hbTESSs)designed for the treatment of severely burned patients.These are the scaffold-free self-assembled skin substitute(SASS)and the human plasma-based skin substitute(HPSS).Methods:Fibroblasts and keratinocytes from three humans were extracted from skin biopsies(N=3)and cells from the same donor were used to produce both hbTESS models.For SASS manu-facture,keratinocytes were seeded over three self-assembled dermal sheets comprising fibroblasts and the extracellular matrix they produced(n=12),while for HPSS production,keratinocytes were cultured over hydrogels composed of fibroblasts embedded in either plasma as unique biomaterial(Fibrin),plasma combined with hyaluronic acid(Fibrin-HA)or plasma combined with collagen(Fibrin-Col)(n/biomaterial=9).The production time was 46-55 days for SASSs and 32-39 days for HPSSs.Substitutes were characterized by histology,mechanical testing,PrestoBlue™-assay,immunofluorescence(Ki67,Keratin(K)10,K15,K19,Loricrin,type IV collagen)and Western blot(type I and IV collagens).Results:The SASSs were more resistant to tensile forces(p-value<0.01)but less elastic(p-value<0.001)compared to HPSSs.A higher number of proliferative Ki67+cells were found in SASSs although their metabolic activity was lower.After epidermal differentiation,no significant difference was observed in the expression of K10,K15,K19 and Loricrin.Overall,the production of type I and type IV collagens and the adhesive strength of the dermal-epidermal junction was higher in SASSs.Conclusions:This study demonstrates,for the first time,that both hbTESS models present similar in vitro biological characteristics.However,mechanical properties differ and future in vivo experiments will aim to compare their wound healing potential.