Stem cells from foreign body granulation tissue accelerate recovery from acute kidney injury.

Background: In previous studies, we obtained mesenchymal stem cells called granulation tissue stem cells (GTSC) from a regenerating granulation tissue created by placing a foreign body in the subcutaneous tissue of rats. Here, we used GTSC to ameliorate ischemia/reperfusion-induced acute kidney injury (AKI) in rats.

Methods: In two groups of Fischer rats, we induced ischemia/reperfusion injury. Group 1 (treated rats) received one intravenous injection of GTSC 3 h after injury; Group 2 (control rats) received vehicle. Both groups were subsequently studied by renal function tests, kidney histology and immunohistochemistry.

Results: At 24 and 48 h after injury, plasma creatinine and blood urea nitrogen were significantly lower in the treated rats as compared to control rats. The levels remained low and declined to near baseline levels by Day 4 in the treated group. At the cortico-medullary region, the treated rats showed significantly higher renal tubular cell proliferation and less tubular cell apoptosis. Histological analysis of the kidney for tubular dilatation, necrosis, congestion and casts was not significantly different in the two groups. To understand the mechanism of the GTSC effect, messenger RNA levels of several growth and immune modulatory factors were quantified in cultured GTSC and compared with those in cultured glomerular epithelial cell (GEC; a non-stem cell line). GTSC had 2- to 8-fold higher expression of FGF2, HGF, IGF-1, vascular endothelial growth factor (growth factors) and IL-4, IL-6 (anti-inflammatory factors) than GEC.

Conclusions: Administration of GTSC accelerates recovery in rats with ischemia/reperfusion-induced AKI. This effect may be mediated by the paracrine action of growth and immune-suppressive factors secreted by these cells.