Renal and Bone Marrow Cells Fuse after Renal Ischemic Injury

Abstract

After acute kidney injury, bone marrow cells contribute to renal repair by converting into renal cells, but the mechanism of this conversion is not well understood. To determine whether cell fusion between bone marrow cells and injured renal cells plays a role, we subjected female mice expressing Cre recombinase in tubular epithelial cells to unilateral renal ischemia-reperfusion injury, and subsequently transplanted male bone marrow cells containing a loxP-flanked reporter gene. After 28 days, cell fusion was detected by polysomy for the sex chromosomes and Cre-mediated activation of the reporter gene. After injury, 1.8% of tubular cells were bone marrow-derived, but Cre/loxP recombination demonstrated a frequency of fusion between tubular epithelial and bone marrow cells of only 0.066% (approximately 7 per 10,000 tubular cells). The second strategy, chromosome fluorescence in situ hybridization (FISH), detected cell fusion in 3.8% of bone marrow-derived tubular epithelial cells. No cell fusion was observed in nonischemic kidneys, suggesting that injury was required for cell fusion. This finding was substantiated in co-culture experiments, because cell fusion was only observed between bone marrow cells and renal tubular cells when the latter were depleted of ATP. In conclusion, bone marrow cells can fuse with renal epithelial cells after ischemic injury, but the low frequency of fusion does not account for the majority of the observed conversion of bone marrow cells into kidney cells.

Collecting Duct-Derived Cells Display Mesenchymal Stem Cell Properties and Retain Selective In Vitro and In Vivo Epithelial Capacity

“…Indeed, there has been no evidence of an in vitro or in vivo epithelial potential for BMMSCs. 11,40,41 Collecting duct cells can undergo EMT in response to urinary obstruction, resulting in the formation of after neonatal injection is presented. PKH26 signal was excited at 551 nm and detected at emission at 567 nm, and Aqp2 staining was detected with anti-rabbit 647, excited at 645 nm, and detected at emission at 660 nm using upright laser-scanning confocal microscope for bright field and epifluorescence (LSM 710 up).…”

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“…35 Briefly, kidneys were collected from 3-weekold female CAG-RFP-GFP-LC3 mice after perfusion with 30 ml of sterile PBS followed by 3 ml of 0.2% collagenase (Sigma-Aldrich). Kidneys were cut into 1-to 2-mm 3 pieces and digested with collagenase for 10 minutes at 37°C with gentle shaking.…”

Autophagy Is a Component of Epithelial Cell Fate in Obstructive Uropathy

“…19 The primary antibodies were directed against enhanced green fluorescent protein (EGFP) that cross reacted with EYFP . Tissue sections were incubated with the primary antibodies at 4°C overnight or at room temperature for 2 hours after permeabilization with 0.1% Triton X100 in PBS and blocking with 10% goat serum and 0.5% bovine serum albumin.…”

“…16,17 Furthermore, Cre is not expressed in extra-renal tissues including bone marrow cells. 19 Cre ksp mice were crossed with R26R-EYFP reporter mice, 18 which carry an EYFP reporter gene that is activated only in the presence of Cre recombinase. 19 Once the EYFP gene is activated, it is expressed under the control of the ubiquitous Rosa26 promoter.…”

“…19 Cre ksp mice were crossed with R26R-EYFP reporter mice, 18 which carry an EYFP reporter gene that is activated only in the presence of Cre recombinase. 19 Once the EYFP gene is activated, it is expressed under the control of the ubiquitous Rosa26 promoter. Consequently, EYFP will continue to be expressed in the labeled cells and all their progeny, irrespective of whether they continue to express Cre.…”