Novel Highly Regenerative and Scalable Progenitor Cell Exosomes for Treating Stroke

ABSTRACT Stroke is a leading cause of disability worldwideGloballythere aremillion stroke survivors each year who have significant neurological deficits including sensory and motor disabilityleading to excessive socioeconomic burdenCell therapy using primary MSCs has been actively explored by us and others as a therapeutic solution to this unmet medical needHoweversince the therapeutic efficacy of MSCs has been shown to be dependent on intercellular communication between administered cells and brain parenchymawe reasoned that the exosomesnanoscale extracellular vesiclesthat cells secrete to transmit this information could be used instead of and perhaps more efficiently than the cells themselvesIndeedwe were the first to report that systemic delivery of exosomes released by mesenchymal stromal cellsMSCsto rats subjected to stroke or traumatic brain injuryTBIsubstantially improves recovery of neurological functionA key rationale for using exosomes is that they obviate many of the risks associated with cell therapy because their use concentrates the active component of stem cells in a simpler compact non replicative formImportantlythey can cross the BBB allowing systemic delivery for treating the injured brainMoreoverexosomes have low risk of immune rejection and are likely to be more cost effective to produce and convenient to use and store and thus have potential for anoffthe shelftreatmentHoweverthere are significant roadblocks to translation of our preclinical results using MSC exosomes because of inherent limitations of MSCs for industrial scale productionMSCs are a poorly defined heterogeneous cell population with low proliferative capacity which can hinder batch consistency and limit scaleup for exosome productionThus to overcome these roadblockswe propose here to use exosomes derived from BioTime s clonally pure PureStemprogenitor cell lineswhich have a high degree of homogeneity and are highly proliferative and regenerative because of their early embryonic originThe goal of this phase I proposal is to conduct a feasibility study that would demonstrate neurological recovery in our rat stroke model using PureStem exosomesWe propose to identifyPureStem derived candidate exosomes based on angiogenic activity and micro RNA and protein content because increasing angiogenesis in the ischemic brain facilitates improvement of neurological function after strokeThelead candidates will be tested for efficacy measured by neurological function in our rat middle cerebral artery occlusionMCAOmodelEvidence of feasibility using our well established model to mimic human stroke and using exosomes from a scalable PureStem cell line will pave the way for further preclinical development and IND enabling studies in phase II NARRATIVE Stroke is a leading cause of disability worldwidestroke induced angiogenesis and associated neurogenesis are limitedthus limiting the functional recoveryExosomes cross the blood brain barrierBBBand enhance angiogenesis by delivering functional cargo to trigger gene expression in specific recipient cell types in the brainThus we propose to employ exosomes to improve neurological function after strokeWe are developing exosomes derived from BioTime s clonally pure Purestemprogenitor stem cell lineswhich have a high degree of homogeneity and are highly proliferative and regenerativeThe goal of this phase I proposal is to demonstrate feasibility by selecting candidate exosome production cell lines from our library and demonstrating efficacy of candidate exosomes on improvement of neurological outcomes in a clinically relevant animal model of embolic strokemiddle cerebral artery occlusionMACO