Human liver stem cells and derived extracellular vesicles improve recovery in a murine model of acute kidney injury

Introduction: Several cellular sources of stem cells have been tested in the attempt to yield innovative interventions in acute kidney injury (AKI). Human liver stem cells (HLSCs) are cells isolated from the normal adult human liver which are gaining attention for their therapeutic potential. In the present study, we investigated whether HLSCs and the derived extracellular vesicles may promote tubular regeneration after AKI induced by glycerol injection in severe-combined immune-deficient mice. Methods: HLSCs were expanded and conditioned medium (CM) and extracellular vesicles (EVs) were purified. HLSCs and their bioproducts were tested in a model of AKI induced by intra-muscle glycerol injection. Renal function and morphology were evaluated five days after induction of damage. The effect of EVs on proliferation and apoptosis of murine renal tubular cells was tested in vitro. Results: We found that intravenous injection of 3.5×10⁵ HLSCs into mice three days after induction of AKI significantly improved functional and morphological recovery. The injection of HLSCs decreased creatinine and urea, as well as hyaline cast formation, tubular necrosis and enhanced in vivo tubular cell proliferation. The effect of soluble factors release by HLSCs in the regenerative processes was also studied. CM produced by HLSCs, mimicked the effect of the cells. However, depletion of EVs significantly reduced the functional and morphological recovery of CM. Moreover, we found that purified HLSC-derived EVs ameliorated renal function and morphology in a manner comparable to the cells. In vitro HLSC-derived EVs were shown to stimulate proliferation and inhibit apoptosis of murine renal tubular cells. Conclusions: These results indicate that HLSCs increase recovery after AKI. EVs are the main component of HLSC-derived CM capable of promoting regeneration in experimental AKI.