Cholestasis is a severe clinical complication that severely damages the liver. Kidneys are also the most affected extrahepatic organs in cholestasis. The pivotal role of oxidative stress has been mentioned in the pathogenesis of cholestasis-induced organ injury. The activation of the nuclear factor-E2-related factor 2 (Nrf2) pathway is involved in response to oxidative stress. The current study was designed to evaluate the potential role of Nrf2 signaling activation in preventing bile acids-induced toxicity in the liver and kidney. Dimethyl fumarate was used as a robust activator of Nrf2 signaling. Rats underwent bile duct ligation surgery and were treated with dimethyl fumarate (10 and 40 mg/kg). Severe oxidative stress was evident in the liver and kidney of cholestatic animals (P < 0.05). On the other hand, the expression and activity of Nrf2 and downstream genes were time-dependently decreased (P < 0.05). Moreover, significant mitochondrial depolarization, decreased ATP levels, and mitochondrial permeabilization were detected in bile duct-ligated rats (P < 0.05). Histopathological alterations included liver necrosis, fibrosis, inflammation and kidney interstitial inflammation, and cast formation. It was found that dimethyl fumarate significantly decreased hepatic and renal injury in cholestatic animals (P < 0.05). Based on these data, the activation of the cellular antioxidant response could serve as an efficient therapeutic option for managing cholestasis-induced organ injury. Oxidative stress and mitochondrial impairment play a primary role in cholestasis-induced hepatic and renal injury. BDL, Bile duct-ligated; ROS, reactive oxygen species; Nrf2, nuclear factor-2-related factor; sMAF, small musculo-aponeurotic fibrosarcoma; ARE, antioxidant response element; RER, rough endoplasmic reticulum; CAT, catalase; SOD, superoxide dismutase; GST, glutathione-S-transferase; HO, heme oxygenase; NQO1, NADH quinone dehydrogenase 1.

Graphene and its derivatives have gained popularity due to their numerous applications in various fields, such as biomedicine. Recent reports have revealed the severe toxic effects of these nanomaterials on cells and organs. In general, the chemical composition and surface chemistry of nanomaterials affect their biocompatibility. Therefore, the purpose of the present study was to evaluate the cytotoxicity and genotoxicity of graphene oxide (GO) synthesized by Hummer's method and functionalized by different amino acids such as lysine, methionine, aspartate, and tyrosine. The obtained nanosheets were identified by FT-IR, EDX, RAMAN, FE-SEM, and DLS techniques. In addition, trypan blue and Alamar blue methods were used to assess the cytotoxicity of mesenchymal stem cells extracted from human embryonic umbilical cord Wharton jelly (WJ-MSCs). The annexin V staining procedure was used to determine apoptotic and necrotic death. In addition, COMET and karyotyping techniques were used to assess the extent of DNA and chromosome damage. The results of the cytotoxicity assay showed that amino acid modifications significantly reduced the concentration-dependent cytotoxicity of GO to varying degrees. The GO modified with aspartic acid had the lowest cytotoxicity. There was no evidence of chromosomal damage in the karyotyping method, but in the comet assay, the samples modified with tyrosine and lysine showed the greatest DNA damage and rate of apoptosis. Overall, the aspartic acid-modified GO caused the least cellular and genetic damage to WJ-MSCs, implying its superior biomedical applications such as cell therapy and tissue engineering over GO.