Evaluation of dose-dependent hematotoxic effects of celastrol on human blood cells in vitro

Over the past two decades, celastrol has gained significant scientific interest due to its ability to inhibit NF-κB, STAT3, and NLRP3 signaling pathways, resulting in antiinflammatory, antioxidant, and anticancer effects in various rodent disease models. Despite these findings, celastrol has not progressed beyond Phase I clinical evaluation due to its low bioavailability, limited stability, short half-life, and several off-target effects. Although studies have described the protective effects of celastrol on neutrophils, endothelial cells, and platelets, information regarding its cytotoxic effects on blood cells remains poorly understood. Since blood cells are the first cellular components exposed to the compound after intravenous or oral absorption, understanding its impact on these cells is essential. In this study, we examined the effects of celastrol on RBCs, platelets, neutrophils, and PBMCs. In RBCs, celastrol induced an elevated intracellular ROS and Ca²⁺ levels and loss of membrane integrity, leading to eryptosis and hemolysis. Inhibition of NOX activity mitigated these effects, indicating that celastrol-induced eryptosis and hemolysis is NOX-dependent manner. Celastrol also induced cell death in platelets, neutrophils, and PBMCs. At lower doses, celastrol exhibits protective role in RBCs and platelets. In contrast, higher concentrations exerted cytotoxic effects, suggesting concentration-dependent dual effect in its biological action. These findings underline the importance of establishing precise dosing regimens and optimized formulations to ensure safety in clinical translation.