Aging modulates the effects of ischemic injury upon mesenchymal cells within the renal interstitium and microvasculature

• Published in: Stem cells translational medicine 2021-08, Vol.10 (8), p.1232-1248
• Main Authors: Shaw, Isaac W., O'Sullivan, Eoin D., Pisco, Angela O., Borthwick, Gary, Gallagher, Kevin M., Péault, Bruno, Hughes, Jeremy, Ferenbach, David A.
• Format: Article
• Language: English
• Subjects: Age; Aging; Analysis; Animals; Fibroblasts; fibrosis; Gene expression; Histopathology; Ischemia; kidney; Kidney diseases; Kidneys; Labeling; Localization; Mesenchyme; Microvasculature; pericyte; Pericytes; Phenotypes; Reperfusion; Software; Stem cells; Surgery; Tissue‐specific Progenitor and Stem cells; Transcriptomes; Wound healing
• ISSN: 2157-6564; 2157-6580; 2157-6580
• DOI: 10.1002/sctm.20-0392

The renal mesenchyme contains heterogeneous cells, including interstitial fibroblasts and pericytes, with key roles in wound healing. Although healing is impaired in aged kidneys, the effect of age and injury on the mesenchyme remains poorly understood. We characterized renal mesenchymal cell heterogeneity in young vs old animals and after ischemia‐reperfusion‐injury (IRI) using multiplex immunolabeling and single cell transcriptomics. Expression patterns of perivascular cell markers (α‐SMA, CD146, NG2, PDGFR‐α, and PDGFR‐β) correlated with their interstitial location. PDGFR‐α and PDGFR‐β co‐expression labeled renal myofibroblasts more efficiently than the current standard marker α‐SMA, and CD146 was a superior murine renal pericyte marker. Three renal mesenchymal subtypes; pericytes, fibroblasts, and myofibroblasts, were recapitulated with data from two independently performed single cell transcriptomic analyzes of murine kidneys, the first dataset an aging cohort and the second dataset injured kidneys following IRI. Mesenchymal cells segregated into subtypes with distinct patterns of expression with aging and following injury. Baseline uninjured old kidneys resembled post‐ischemic young kidneys, with this phenotype further exaggerated following IRI. These studies demonstrate that age modulates renal perivascular/interstitial cell marker expression and transcriptome at baseline and in response to injury and provide tools for the histological and transcriptomic analysis of renal mesenchymal cells, paving the way for more accurate classification of renal mesenchymal cell heterogeneity and identification of age‐specific pathways and targets. Kidney mesenchyme contains progenitor cells important in disease aetiology yet is poorly characterized with age and lacks research tools. Healthy and ischemia reperfusion injured (IRI) kidneys from old and young mice, analyzed using immunohistochemistry (IHC) and single cell RNA sequencing (scRNAseq), uncovered differences in aged injury response and provided more detailed characterization of kidney mesenchyme. BV = blood vessel.