Purpose: This study was designed to evaluate the possible nephroprotective and therapeutic role of bone marrow mesenchymal stem cells (BMSCs) in comparison to vitamin C in a rat model of gentamicin (GM) induced nephrotoxicity.
Materials and Methods: Forty adult male Wistar rats (150-200 gm) were used in this study. Five rats were utilized to obtain BMSCs and thirty-five rats were divided into: Group I: control, Group II (GM): received 100mg/kg GM intramuscularly for 8 days, subdivided into: subgroup IIa (GM toxicity): sacrificed after the last dose of GM; and subgroup IIb (GM recovery): sacrificed 8 days after the last injection; Group III (Protection): subdivided into: subgroup IIIa (BMSCs protection): received a single intravenous (IV) injection of BMSCs with the first dose of GM and subgroup IIIb (Vitamin C protection): received 200mg/kg vitamin C intraperitoneal (IP) for 8 days simultaneously with the daily GM doses; and Group IV (Treatment): subdivided into: subgroup IVa (BMSCs treatment): received single IV injection of BMSCs after the last dose of GM and subgroup IVb (Vitamin C treatment): received 200mg/kg vitamin C IP for 8 days after the last dose of GM. Serum creatinine and urea were measured, and kidneys were processed for histological, immunohistochemical and morphometric studies.  Results: GM resulted in vacuolation, desquamation of tubular epithelium, interstitial inflammation, congestion and increased number of PCNA positive cells. Serum creatinine and urea were significantly increased. Vitamin C administration, either as a treatment or protection, significantly ameliorated these changes. Conversely, BMSCs could not prevent the GM toxicity but exerted a therapeutic role.  Conclusion: BMSCs had no role in protection against GM nephrotoxicity, whereas, their administration after kidney injury assisted kidney regeneration. However, vitamin C exhibited a dual significant role in prevention and improvement in kidney structure and biochemical results.