PINK1 siRNA‐loaded poly(lactic‐co‐glycolic acid) nanoparticles provide neuroprotection in a mouse model of photothrombosis‐induced ischemic stroke

PTEN‐induced kinase 1 (PINK1) is a well‐known critical marker in the pathway for mitophagy regulation as well as mitochondrial dysfunction. Evidence suggests that mitochondrial dynamics and mitophagy flux play an important role in the development of brain damage from stroke pathogenesis. In this study, we propose a treatment strategy using nanoparticles that can control PINK1. We used a murine photothrombotic ischemic stroke (PTS) model in which clogging of blood vessels is induced with Rose Bengal (RB) to cause brain damage. We targeted PINK1 with poly(lactic‐co‐glycolic acid) (PLGA)‐based nanoparticles loaded with PINK1 siRNA (PINK1 NPs). After characterizing siRNA loading in the nanoparticles, we assessed the efficacy of PINK1 NPs in mice with PTS using immunohistochemistry, 1% 2,3,5‐triphenyltetrazolium chloride staining, measurement of motor dysfunction, and Western blot. PINK1 was highly expressed in microglia 24 h after PTS induction. PINK1 siRNA treatment increased phagocytic activity, migration, and expression of an anti‐inflammatory state in microglia. In addition, the PLGA nanoparticles were selectively taken up by microglia and specifically regulated PINK1 expression in those cells. Treatment with PINK1 NPs prior to stroke induction reduced expression of mitophagy‐inducing factors, infarct volume, and motor dysfunction in mice with photothrombotic ischemia. Experiments with PINK1‐knockout mice and microglia depletion with PLX3397 confirmed a decrease in stroke‐induced infarct volume and behavioral dysfunction. Application of nanoparticles for PINK1 inhibition attenuates RB‐induced photothrombotic ischemic injury by inhibiting microglia responses, suggesting that a nanomedical approach targeting the PINK1 pathway may provide a therapeutic avenue for stroke treatment. Main Points PTEN‐induced kinase 1 (PINK1) was highly expressed in microglia 24 h after photothrombotic ischemic stroke (PTS) induction. Poly(lactic‐co‐glycolic acid) nanoparticles were selectively taken up by microglia and specifically regulated PINK1 expression. Treatment with PINK1 siRNA nanoparticles reduced mitophagy, infarct volume, and motor dysfunction with photothrombotic ischemia.