Whole-transcriptome analysis illustrates evolving transcriptional human response to injury in acute wounds and scars

The goal of this study was to use RNA sequencing to identify novel genes involved in wound healing and scar formation in human burn wounds and scars. RNA was isolated from 108 human samples comprising of uninjured skin (n=26), acute burn wounds (n=54), and hypertrophic scars (HTS) (n=30). Genes with at least 1.5-fold change and a p-value less than 0.05 with a false discovery rate of 0.05 were considered differentially expressed. Samples were sequenced using Illumina Hi-Seq sequencers, and pathway/Gene Ontology (GO) Enrichment analysis was conducted using iPathwayGuide. Comparing wounds to uninjured skin, we found 9,311 differentially expressed genes, accounting for 1,017 GO terms. Comparing HTS to uninjured skin, we found 7,299 differentially expressed genes, accounting for 1,022 GO terms. By analyzing the whole transcriptome, we characterized dominant genes expressed temporally in wounds and scars. This study reveals the complexity of these processes and helps to bring novel genes to light. Overall design: For this study, RNA was isolated from 108 human samples comprising of uninjured skin (n=26), acute burn wounds (n=54), and hypertrophic scars (HTS) (n=30). Samples were collected from patients admitted to the UW Medicine Regional Burn Center and undergoing an operation for burn injury from 2002 to 2018. Samples consisted of discarded burn wounds, scars, and donor skin that were stored as part of an IRB exempt human tissue repository. All samples were de-identified upon collection. Specific to the wound samples, when able, samples were collected at periphery of the burn wound to include the epithelial edge where the transition from wound to normal tissue exists as previously described.[8] Tissue samples were minced and placed in cryogenic vials for either snap freezing in liquid nitrogen within 20 minutes of collection or placement in RNALater (Invitrogen, Carlsbad, CA) and stored in 4°C overnight to allow the solution to penetrate the tissue. All samples were transferred to -80°C for long term storage.