No abstract

Human dermal papilla (DP) cells have been studied extensively when grown in the conventional monolayer. However, because of great deviation from the real in vivo three-dimensional (3D) environment, these two-dimensional (2D) grown cells tend to lose the hair-inducible capability during passaging. Hence, these 2D caused concerns have motivated the development of novel 3D culture techniques to produce cellular microtissues with suitable mimics. The hanging-drop approach is based on surface tension-based technique and the interaction between surface tension and gravity field that makes a convergence of liquid drops. This study used this technique in a converged drop to form cellular spheroids of dermal papilla cells. It leads to a controllable 3Dspheroid model for scalable fabrication of inductive DP microtissues. The optimal conditions for culturing high-passaged (P8) DP spheroids were determined first. Then, the morphological, histological and functional studies were performed. In addition, expressions of hair-inductive markers including alkaline phosphatase, α-smooth muscle actin and neural cell adhesion molecule were also analyzed by quantitative RT-PCR, immunostaining and immunoblotting. Finally, P8-DP microtissues were coimplanted with newborn mouse epidermal cells (EPCs) into nude mice. Our results indicated that the formation of 3D microtissues not only endowed P8-DP microtissues many similarities to primary DP, but also confer these microtissues an enhanced ability to induce hair-follicle (HF) neogenesis in vivo. This model provides a potential to elucidate the native biology of human DP, and also shows the promising for the controllable and scalable production of inductive DP cells applied in future follicle regeneration.

Background Diabetic wounds threaten the health and quality of life of patients and their treatment remains challenging. ADSC-derived exosomes have shown encouraging results in enhancing diabetic wound healing. However, how to use exosomes in wound treatment effectively is a problem that needs to be addressed at present. Methods A diabetic mouse skin wound model was established. ADSC-derived exosomes (ADSC-Exos) were isolated, and in vitro application of exosomes was evaluated using human umbilical vein endothelial cells (HUVECs) and human dermal fibroblasts (HDFs). After preparation and characterization of a scaffold of human acellular amniotic membrane (hAAM) loaded with ADSC-Exos in vitro, they were transplanted into wounds in vivo and wound healing phenomena were observed by histological and immunohistochemical analyses to identify the wound healing mechanism of the exosome-hAAM composites. Results The hAAM scaffold dressing was very suitable for the delivery of exosomes. ADSC-Exos enhanced the proliferation and migration of HDFs and promoted proliferation and tube formation of HUVECs in vitro. In vivo results from a diabetic skin wound model showed that the hAAM-Exos dressing accelerated wound healing by regulating inflammation, stimulating vascularization, and promoting the production of extracellular matrix. Conclusion Exosome-incorporated hAAM scaffolds showed great potential in promoting diabetic skin wound healing, while also providing strong evidence for the future clinical applications of ADSC-derived exosomes.

Morphogenesis of hair follicles during development and in hair reconstitution assays involves complex interactions between epithelial cells and dermal papilla cells (DPCs). DPCs may be a source of cells for hair regeneration in alopecia patients. Reconstitution of engineered hair follicles requires in vitro culture of trichogenic cells, a three-dimensional scaffolds, and biomolecular signals. However, DPCs tend to lose their biological activity when cultured as trichogenic cells, and scaffolds currently used for hair follicle regeneration lack biological efficiency and biocompatibility. Platelet-rich plasma (PRP) gel forms a three-dimensional scaffold that can release endogenous growth factors, is mitogenic for a variety of cell types and is used in model tissue repair and regeneration systems. We found that 5% activated PRP significantly enhanced cell proliferation and hair-inductive capability of mouse and human DPCs in vitro and promoted mouse hair follicle formation in vivo. PRP also formed a three-dimensional gel after activation. We used PRP gel as a scaffold to form many de novo hair follicles on a plane surface, showing it to be candidate bioactive scaffold capable of releasing endogenous growth factors for cell-based hair follicle regeneration.