Role of the nitric oxide system and protein homeostasis in the nephroprotective effect of cell-free cryopreserved biological products in a model of ketorolac-induced nephropathy

Background. Nonsteroidal anti-inflammatory drugs are widely used in clinical practice; however, their use is associated with drug-induced kidney injury, in the pathogenesis of which disturbances of nitric oxide metabolism and protein homeostasis play an important role. The search for multimodal nephroprotective agents capable of correcting nitrosative stress and proteinuria remains relevant. Purpose – to evaluate the role of the NO-ergic system and protein homeostasis in the formation of the nephroprotective effect of cell-free cryopreserved biological agents (placental cryoextract, splenic cryoextract, and conditioned medium of mesenchymal stromal cells) in comparison with the reference drug Canephron in a model of ketorolac- induced nephropathy in rats. Materials and Methods. The study was performed on 42 male rats (200–220 g) randomized into 6 groups of 7 animals each. Nephropathy was induced by intragastric administration of ketorolac at a dose of 15 mg/kg daily for 14 days. Placental cryoextract (2.5 ml/kg), splenic cryoextract (5.0 ml/kg), conditioned medium of mesenchymal stromal cells (0.6 ml/kg, intramuscularly), and Canephron (27 mg/kg) were administered on days 5, 7, 9, 11, and 14, 60 minutes before ketorolac administration. The concentration of nitric oxide metabolites in blood serum, blood albumin levels, and daily proteinuria were determined; parametric or nonparametric statistical tests were applied depending on data distribution. Results. Ketorolac-induced nephropathy was accompanied by marked disturbances of nitric oxide metabolism and protein homeostasis: the level of nitric oxide metabolites almost doubled (+91.1%; p < 0.001), albumin concentration decreased by 68.8% (p < 0.001), and proteinuria increased 5.25-fold (p < 0.001). The reference herbal drug significantly reduced nitric oxide metabolites (−41.9%; p < 0.001) and partially restored albuminemia (+40.0%; p = 0.002), but did not provide a statistically significant reduction in proteinuria. Placental and splenic cryoextracts significantly corrected all parameters, reducing nitric oxide metabolites by 31–33%, increasing albumin levels by 160–170%, and decreasing proteinuria by 33–35% (p ≤ 0.005). The most pronounced nephroprotective effect was demonstrated by the conditioned medium of mesenchymal stromal cells, which normalized albuminemia and reduced nitric oxide metabolites by 41.3% and proteinuria by 49.3% (p < 0.001), exceeding the efficacy of placental cryoextract. Conclusions. Ketorolac-induced nephropathy is accompanied by hyperactivation of nitric oxide metabolism and profound disturbances of protein homeostasis. Cell-free cryopreserved biological agents provide nephroprotection of varying degrees, with the most complete normalization of nitric oxide metabolites, albumin levels, and proteinuria achieved by the conditioned medium of mesenchymal stromal cells.