TBHQ Regulates the Nrf2/HO-1 Pathway to Enhance Stem Cell Treatment of Diabetic Retinopathy

Abstract

Objective: To investigate the therapeutic effect of human umbilical cord mesenchymal stem cells (hUCMSCs) on diabetic retinopathy (DR) in diabetic rats, and to study the mechanism of hUCMSCs in treating diabetic retinopathy by tert-butylhydroquinone (tBHQ) regulation of the Nrf2/HO-1 pathway.Methods: The diabetic rat model was induced by intraperitoneal injection of streptozotocin (STZ). The experimental animals were divided into six groups: Normal, diabetes mellitus (DM), hUCMSCs, tBHQ, combined tBHQ-hUCMSCs, and all-trans-retinoid acid (ATRA)-hUCMSCs combined group. Visual function experiments and histological analyses were performed eight weeks post intravitreal injection. Biochemical and molecular analyses were used to assess the hUCMSCs composition and its biological effects.Results: Improvements in systemic oxidative stress and inflammation were found in the tBHQ group. Although hUCMSCs had no significant effect on oxidative stress, retinal structure was improved, visual defects reduced and expression of local retinal inflammatory factors were inhibited following its application. The effect of combined therapy was better than that of single therapy. Inhibition of the Nrf2/HO-1 pathway can promote the expression of systemic inflammatory factors and inhibit the therapeutic effect of hUCMSCs in the retina.Conclusions: Intravitreal administration of hUCMSCs triggers an effective cytoprotective microenvironment in the retina of diabetic mice. Alone, however, it may not significantly improve the systemic inflammatory response of diabetes. In combination with tBHQ it may promote Nrf2expression, systemic antioxidant stress and therapeutic effects of hUCMSCs.