Extrarenal Progenitor Cells Do Not Contribute to Renal Endothelial Repair

Abstract

Endothelial progenitor cells (EPCs) may be relevant contributors to endothelial cell (EC) repair in various organ systems. In this study, we investigated the potential role of EPCs in renal EC repair. We analyzed the major EPC subtypes in murine kidneys, blood, and spleens after induction of selective EC injury using the concanavalin A/anti-concanavalin A model and after ischemia/reperfusion (I/R) injury as well as the potential of extrarenal cells to substitute for injured local EC. Bone marrow transplantation (BMTx), kidney transplantation, or a combination of both were performed before EC injury to allow distinction of extrarenal or BM-derived cells from intrinsic renal cells. During endothelial regeneration, cells expressing markers of endothelial colony-forming cells (ECFCs) were the most abundant EPC subtype in kidneys, but were not detected in blood or spleen. Few cells expressing markers of EC colony-forming units (EC-CFUs) were detected. In BM chimeric mice (C57BL/6 with tandem dimer Tomato-positive [tdT+] BM cells), circulating and splenic EC-CFUs were BM-derived (tdT+), whereas cells positive for ECFC markers in kidneys were not. Indeed, most BM-derived tdT+ cells in injured kidneys were inflammatory cells. Kidneys from C57BL/6 donors transplanted into tdT+ recipients with or without prior BMTx from C57BL/6 mice were negative for BM-derived or extrarenal ECFCs. Overall, extrarenal cells did not substitute for any intrinsic ECs. These results demonstrate that endothelial repair in mouse kidneys with acute endothelial lesions depends exclusively on local mechanisms.

Persistent and inducible neogenesis repopulates progenitor renin lineage cells in the kidney

“…The kidney digestion protocol for flow cytometry has been described in detail elsewhere. 26 In brief, kidneys were cut into small pieces; digested in phosphate-buffered saline containing 1% fetal calf serum (ThermoFisher), collagenase type IA (0.25 mg/ml, Sigma-Aldrich), and DNase I (0.25 mg/ml, Sigma-Aldrich); and incubated for 40 minutes at 37°C. The cells were then filtered twice through 40-µm cell strainers (BD Biosciences), and erythrocytes were lysed using BD Pharm Lyse.…”

Hypoxia and hypoxia-inducible factors in chronic kidney disease

“…Second, antiangiogenic factors (e.g., thrombospondin 1 and endostatin) have been reported to be upregulated in several kidney diseases [61][62][63]. Third, the incompetence of endothelial progenitor cells potentially underlies insufficient capillary restoration [64], although recent studies have questioned the direct involvement of bone marrow-derived or circulating progenitor/stem cells in blood vessel regeneration [65,66].…”

Endothelial Progenitor Cells and Kidney Diseases

“…In a mouse model of selective endothelial injury by Hohenstein et al [27, 28], BM-derived cells carrying markers of EPCs were found in injured kidneys and these cells were shown to contribute to subsequent healing of endothelial lesions. However, in another study, Sradnick et al investigated the potential role of EPCs in renal endothelial cell repair [29]. In this study, extrarenal cells were not found to replace any mature endothelial cells suggesting that endothelial repair depends on local mechanisms in acute endothelial injury model.…”