Presentation Authors: Daniel Sun*, Bradley Gill, Paurush Babbar, Mei Kuang, Danli Lin, Margot Damaser, Cleveland, OH
Introduction: Renal artery clamping during partial nephrectomy causes ischemia-reperfusion injury (IRI), which can lead to chronic kidney disease. No therapies for renal IRI exist, and while the anti-inflammatory and trophic properties of mesenchymal stem cells (MSCs) show promise, the use of cellular therapy is limited by concerns about immunogenicity, cost, and malignant potential. We have previously shown that the acellular MSC secretome promotes functional recovery after injury in a rat model of IRI. The mechanisms of its therapeutic benefit are not well understood, but may involve exosomes, membrane-bound extracellular vesicles that carry proteins and genetic material derived from the parent cell. In this study, we investigated the role of MSC-derived exosomes in a rat model of IRI.
Methods: Donor rat bone marrow MSC colonies were used to produce MSC-conditioned culture media (CCM), as previously published. Exosomes were isolated from CCM using serial ultracentrifugation, and the resulting supernatant was collected as exosome-depleted CCM. Thirty-six male Sprague-Dawley rats underwent right nephrectomy. After a 2-week recovery, the left renal hilum was clamped for 45 minutes to produce IRI. Five minutes prior to clamping, rats were administered 300Î¼L of intravenous CCM (n=12), non-conditioned plain media (n=12), MSC exosomes (n=12), or exosome-depleted CCM (n=12). Serum creatinine (SCr) was measured at days 5, 7, 9, and 14 post-ischemia. Quantitative values are presented as mean percent change in SCr from baseline Â± standard error. Statistical comparisons were made using analysis of variance (ANOVA) with a p-value of < 0.05 considered significant.
Results: In all treatment groups, a sharp rise in SCr was observed 5 days following ischemic injury, followed by a gradual recovery towards baseline. By day 14 post-ischemia, rats treated with MSC exosomes compared to plain media had significantly lower SCr (173% Â± 20% v 239% Â± 11%, p=0.008) relative to baseline. When compared to CCM, treatment with exosome-depleted CCM or plain media resulted in significantly higher SCr (130% Â± 12% v 191% Â±17%, p=0.007; 130% Â± 12% v 239% Â± 11%, p=0.0002; respectively) relative to baseline. Renal function at 14 days did not significantly differ between MSC exosome and exosome-depleted CCM groups (173% Â±20% v 190% Â±17%, p>0.05).
Conclusions: When given prior to renal ischemia, MSC-derived exosomes improve renal functional recovery following ischemia reperfusion injury. Exosomes are partially responsible for mediating the therapeutic benefits of the stem cell secretome.