Metabolite-Based Microparticles Enhance the Metabolic Fitness of T cells

Abstract

Abstract Adoptive Cell Transfer (ACT) therapies have recently fostered excitement for the treatment of hematogenous cancers. However, efficacy has largely been stunted in the treatment of solid tumors, especially for ovarian cancer, in part due to nutrient restriction within the tumor microenvironment. We recently demonstrated that intracellular delivery of biodegradable microparticles (MPs) made from polymers of alpha-ketoglutarate modulated dendritic cell energy metabolism and immunophenotype, altering regulatory and helper T cell frequencies. To determine if continuous metabolite release from MPs would rescue T cell dysfunction in nutrient-poor, immunosuppressive conditions, we generated MPs of polymerized glycolytic and tricarboxylic acid cycle central-carbon metabolites. Flow cytometric analysis and confocal microscopy indicated that FITC-conjugated MPs were efficiently loaded into the cytoplasm of activated primary murine T cells via membrane adsorption or electroporation. The MPs were retained intracellularly and sustained proliferation of mouse T cells for over five days in vitro. Glycolysis and mitochondrial respiration stress tests using an Agilent Seahorse XFe96 Analyzer demonstrated that primary mouse CD8 T cells utilized the MPs as a metabolic substrate. In particular, MPs increased metabolic function, as indicated by increased spare respiratory capacity, glycolysis, and glycolytic capacity. The results of this study provide preliminary evidence in support of utilizing sustained-releasing particles of metabolic substrates for the metabolic reprogramming of immune cells used in ACT therapies. This strategy has potential to improve or expand the efficacy of existing ACT therapies for solid tumors.