Intra-arterial Stem Cell Therapy Diminishes Inflammasome Activation After Ischemic Stroke: a Possible Role of Acid Sensing Ion Channel 1a

Abstract

Studies from our lab demonstrated that 1 × 10⁵ intra-arterial mesenchymal stem cells (IA MSCs) at 6 h following ischemic stroke are efficacious owing to its maximum homing due to elevated stromal derived factor 1 (SDF1) in the tissue. Further, IA MSCs could abate the infarct progression, improve functional outcome, and decrease expression of calcineurin by modifying neuronal Ca²⁺ channels following ischemic stroke. Since stroke pathology also encompasses acidosis that worsens the condition; hence, the role of acid sensing ion channels (ASICs) in this context could not be overlooked. ASIC1a being the major contributor towards acidosis triggers Ca²⁺ ions overload which progressively contributes towards exacerbation of neuronal injury following ischemic insult. Inflammasome involvement in ischemic stroke is well reported as activated ASIC1a increases the expression of inflammasome in a pH-dependent manner to trigger inflammatory cascade. Hence, the current study aimed to identify if IA MSCs can decrease the production of inflammasome by attenuating ASIC1a expression to render neuroprotection. Ovariectomized Sprague Dawley (SD) rats exposed to middle cerebral artery occlusion (MCAo) for 90 min were treated with phosphate-buffered saline (PBS) or 1 × 10⁵ MSCs IA at 6 h to check for the expression of ASIC1a and inflammasome in different groups. Inhibition studies were carried out to explore the underlying mechanism. Our results demonstrate that IA MSCs improves functional outcome and oxidative stress parameters, and decreases the expression of ASIC1a and inflammasomes in the cortical brain region after ischemic stroke. This study offers a preliminary evidence of the role of IA MSCs in regulating inflammasome by modulating ASIC1a.

Keywords: Inflammasome proteins; Interleukin-1β; Ischemic stroke; Mesenchymal stem cells; Peri-infarct area.