A protocol for enrichment of CD34+ stromal cell fraction through human skin disaggregation and magnetic separation

Advances in the Research of Bioinks Based on Natural Collagen, Polysaccharide and Their Derivatives for Skin 3D Bioprinting

The skin plays an important role in protecting the human body, and wound healing must be set in motion immediately following injury or trauma to restore the normal structure and function of skin. The extracellular matrix component of the skin mainly consists of collagen, glycosaminoglycan (GAG), elastin and hyaluronic acid (HA). Recently, natural collagen, polysaccharide and their derivatives such as collagen, gelatin, alginate, chitosan and pectin have been selected as the matrix materials of bioink to construct a functional artificial skin due to their biocompatible and biodegradable properties by 3D bioprinting, which is a revolutionary technology with the potential to transform both research and medical therapeutics. In this review, we outline the current skin bioprinting technologies and the bioink components for skin bioprinting. We also summarize the bioink products practiced in research recently and current challenges to guide future research to develop in a promising direction. While there are challenges regarding currently available skin bioprinting, addressing these issues will facilitate the rapid advancement of 3D skin bioprinting and its ability to mimic the native anatomy and physiology of skin and surrounding tissues in the future.

Skin-derived precursor cells as an in vitro modelling tool for the study of type 1 neurofibromatosis

The most characteristic feature of neurofibromatosis type 1 (NF1) is the development of neurofibromas. It has been suggested that these tumors are caused by somatic inactivation of the wild-type NF1 allele, but the cell that originally suffers this mutation remains controversial. Several lines of evidence support the clonal origin of these tumors, and it has been recently suggested that skin-derived precursor cells (SKPs) could be the cell of origin of dermal neurofibromas. Nullizygous (NF1(-/-)) SKPs do give rise to neurofibromas when transplanted to heterozygous mice. Moreover, a nullizygous population of cells that is S100β negative is present in human neurofibromas, and NF1(+/-) multipotent progenitor cells are seemingly recruited to the tumor. This evidence supports the neurofibroma stem cell hypothesis and a putative involvement of SKPs in the aetiopathogenesis of the disease, suggesting that SKPs could become a valuable tool for the in vitro study of NF1.

Production of human tissue-engineered skin trilayer on a plasma-based hypodermis

Full thickness wounds require a dermal component to achieve functional permanent skin restoration. Currently available tissue-engineered skin substitutes lack a subcutaneous fat layer that would functionally contribute some of the mechanical and thermoregulatory properties of normal skin. To generate a trilayer engineered skin equivalent, we included bone marrow mesenchymal (BM-MSC) or adipose tissue-derived (ASC) stromal cells in a human plasma hydrogel exposed to adipogenic clues for three weeks. Approximately half of the cells differentiated under these conditions into mature adipocytes that survived for two years in culture with minimal medium change. In vitro generation of bona fide fully differentiated adipocytes was assessed by leptin secretion and ultrastructurally demonstrated through semithin to ultrathin sectioning and lipid staining with osmium tetroxide. Furthermore, presence of BM-MSCs or ASCs within the subcutaneous layer contributed to the epidermal differentiation program, with more proliferating basal cells depositing basal membrane proteins and differentiating into mature keratinocytes that were able to generate a pluristratified epithelium. In conclusion, we engineered a fully differentiated human skin trilayer that could present multiple applications such as use for in vitro drug absorption tests and regenerative therapies.