Biological Effects Of Skin Stem Cells Under Simulated Microgravity

Purpose: During long-term space flight,the injury with the highest incidence in astronauts is skin injury.As the most basic unit of the structure and function of organisms,cells are the basis for studying the occurrence of skin injury-related diseases in microgravity environments.Therefore,studying and exploring the biological effects of skin stem cells in skin wounds under space microgravity environment is one of the primary problems to be solved in space maintenance support,and it is also one of the basic bases to develop the experimental tasks of space station cells.Methods: In this study,primary skin stem cells in SD rat wounds were used,and a 3D culture protocol was established to form typical monoclonal stem cell 3D spheroids 1 week after cell culture.The isolated and purified 3D cultured skin stem cells were divided into microgravity stimulated 1g gravity control group and cultured for 14 days under two different gravity conditions.CCK-8 method was used to detect the proliferation ability of skin stem cells under microgravity and 1 g gravity,immunofluorescence staining was used to detect the expression of stem cell stemness markers Ki67,nestin and Lgr6 after culture under microgravity,and transcriptomic analysis was used to detect the differential gene expression of skin stem cells under microgravity and 1 g gravity.Results: Compared with 1 g gravity,simulated microgravity made rat skin stem cells more inclined to suspend 3D spheroids to grow and maintain their stemness gene expression.The cell proliferation rate was 11.93% higher after 7 days of microgravity stimulation compared with 7 days of 1 g gravity culture.Transcriptomic analysis showed that there were 1673 up-regulated genes and 1409 down-regulated genes.GO enrichment analysis showed that it was related to multicellular organism development,sodium ion transport system;extracellular components,cell membrane;and transporter activity of skin stem cells stimulated by microgravity.The pathways with significant KEGG enrichment were mutant diseases as well as wound healing inflammation-related PPAR pathways.Conclusion: The results of this experimental study show that spatial microgravity can promote the 3D growth of skin stem cells and maintain the pluripotency of stem cells.And spatial microgravity also has a certain promoting effect on skin stem cell proliferation.Spatial microgravity stimulation significantly affects cutaneous stem cell transcriptomics expression.This study provides some evidence for understanding the proliferation ability and stemness characteristics of skin-derived stem cells under spatial microgravity,and also provides a new idea for the in vitro expansion of stem cells using a microgravity environment.