Gene-modified tissue-engineered skin: the next generation of skin substitutes

Simulated microgravity significantly altered metabolism in epidermal stem cells

Simulated microgravity can significantly affect various cell types and multiple systems of the human body, such as cardiovascular system, skeletal muscle system, and immune system, and is known to cause anemia and loss of electrolyte and fluids. Epidermal stem cells (EpSCs) were cultured in a rotary cell culture system (RCCS) bioreactor to simulate microgravity. The metabolites of EpSCs were identified by liquid chromatography-mass spectrometry (LC-MS). Compared with normal gravity (NG) group, a total of 57 different metabolites of EpSCs were identified (P < 0.05, VIP > 1), including lipids and lipid-like molecules (51 molecules), amino acids (5 molecules), nucleosides, nucleotides, and analogues (1 molecule). According to the partial least squares discriminant analysis (PLS-DA) score plot, a VIP > 1 and P < 0.05 were obtained for the 57 different metabolites, of which 23 molecules were significantly downregulated and 34 were significantly upregulated in simulated microgravity (SMG) group. These results showed that SMG has a significant impact on different pathways, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that multiple pathways were involved, mainly the amino acid metabolism pathway, lipid metabolism pathway, membrane transport pathway, and cell growth and death pathways. Thus, the metabolic profile of EpSCs was changed under SMG. Exploring the metabolic profile of EpSCs would be helpful to further understand the growth characteristics of EpSCs under SMG, which will provide a new approach to explore the metabolomics mechanism of stress injury and repair trauma under SMG.

Inhibition of multidrug-resistant Acinetobacter baumannii by nonviral expression of hCAP-18 in a bioengineered human skin tissue

When skin is compromised, a cascade of signals initiates the rapid repair of the epidermis to prevent fluid loss and provide defense against invading microbes. During this response, keratinocytes produce host defense peptides (HDPs) that have antimicrobial activity against a diverse set of pathogens. Using nonviral vectors we have genetically modified the novel, nontumorigenic, pathogen-free human keratinocyte progenitor cell line (NIKS) to express the human cathelicidin HDP in a tissue-specific manner. NIKS skin tissue that expresses elevated levels of cathelicidin possesses key histological features of normal epidermis and displays enhanced antimicrobial activity against bacteria in vitro. Moreover, in an in vivo infected burn wound model, this tissue results in a two log reduction in a clinical isolate of multidrug-resistant Acinetobacter baumannii. Taken together, these results suggest that this genetically engineered human tissue could be applied to burns and ulcers to counteract bacterial contamination and prevent infection.