Biological function evaluation and effects of laser micro-pore burn-denatured acellular dermal matrix

Frozen bean curd-inspired Xenogeneic acellular dermal matrix with triple pretreatment approach of freeze-thaw, laser drilling and ADSCs pre-culture for promoting early vascularization and integration

Xenogeneic acellular dermal matrix (ADM) is widely used in clinical practice given its good biocompatibility and biomechanical properties. Yet, its dense structure remains a hindrance. Incorporation of laser drilling and pre-culture with Adipose-derived stem cells (ADSCs) have been attempted to promote early vascularization and integration, but the results were not ideal. Inspired by the manufacturing procedure of frozen bean curd, we proposed a freeze-thaw treatment to enhance the porosity of ADM. We found that the ADM treated with -80°C3R+-30°C3R had the largest disorder of stratified plane arrangement (deviation angle 28.6%) and the largest porosity (96%), making it an optimal approach. Human umbilical vein endothelial cells on freeze-thaw treated ADM demonstrated increased expression in Tie-2 and CD105 genes, proliferation, and tube formation in vitro compared with those on ADM. Combining freeze-thaw with laser drilling and pre-culture with ADSCs, such tri-treatment improved the gene expression of pro-angiogenic factors including IGF-1, EGF, and VEGF, promoted tube formation, increased cell infiltration, and accelerated vascularization soon after implantation. Overall, freeze-thaw is an effective method for optimizing the internal structure of ADM, and tri-treatments may yield clinical significance by promoting early cell infiltration, vascularization, and integration with surrounding tissues.

Advances on the modification and biomedical applications of acellular dermal matrices

Acellular dermal matrix (ADM) is derived from natural skin by removing the entire epidermis and the cell components of dermis, but retaining the collagen components of dermis. It can be used as a therapeutic alternative to “gold standard” tissue grafts and has been widely used in many surgical fields, since it possesses affluent predominant physicochemical and biological characteristics that have attracted the attention of researchers. Herein, the basic science of biologics with a focus on ADMs is comprehensively described, the modification principles and technologies of ADM are discussed, and the characteristics of ADMs and the evidence behind their use for a variety of reconstructive and prosthetic purposes are reviewed. In addition, the advances in biomedical applications of ADMs and the common indications for use in reconstructing and repairing wounds, maintaining homeostasis in the filling of a tissue defect, guiding tissue regeneration, and delivering cells via grafts in surgical applications are thoroughly analyzed. This review expectedly promotes and inspires the emergence of natural raw collagen-based materials as an advanced substitute biomaterial to autologous tissue transplantation.

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Denatured Collagen Could Increase the Autophagy Level and Inhibit Apoptosis of Fibroblasts to Help Cell Survival and Influence Wound Healing

When exposed to thermal factors, collagen in the dermis denatures, which could affect the biological behavior of cells. Previous studies have demonstrated that denatured collagen could influence the activity of fibroblasts and induce fibroblasts differentiate into myofibroblasts. However, information on the regulation of fibroblasts by denatured collagen-modulated autophagy and apoptosis during the wound healing process is limited. In this article, we researched the effect of denatured collagen-modulated autophagy and apoptosis on fibroblasts. An in vitro model comprising fibroblasts and denatured collagen was established to identify the potential ability of denatured collagen to modulate autophagy and apoptosis. Western blotting, quantitative polymerase chain reaction, transmission electron microscopy, TUNEL assay, and immunofluorescence staining were used to examine the changes induced by denatured collage. Protein and mRNA levels of LC3 and beclin-1 were significantly increased after stimulated by denatured collagen, while those of caspase-3 were reduced. Unlike stimulation with normal collagen, denatured collagen enhanced autophagy and inhibited apoptosis of fibroblasts. After blocking autophagy using 3-methyladenine, the apoptotic function was increased. Denatured collagen could increase autophagy and inhibit apoptosis of the fibroblasts to promote cell survival and influence wound healing.