Stem cell grafts enhance endogenous extracellular vesicle expression in the stroke brain.

Endogenous brain repair occurs following an ischemic stroke but is transient, thus unable to fully mount a neuroprotective response against the evolving secondary cell death. Finding a treatment strategy that may render robust and long-lasting therapeutic effects stands as a clinically relevant therapy for stroke. Extracellular vesicles appear to be upregulated after stroke, which may represent a candidate target for neuroprotection. In this study, we probed whether transplanted stem cells could enhance the expression of extracellular vesicles to afford stable tissue remodeling in the ischemic stroke brain. Aged rats were initially exposed to the established ischemic stroke model of middle cerebral artery occlusion then received intravenous delivery of either bone marrow-derived mesenchymal stem cell transplantation or vehicle. A year later, the animals were assayed for brain damage, inflammation, and extracellular vesicle expression. Our findings revealed that while core infarction was not reduced, the stroke animals transplanted with stem cells displayed a significant reduction in peri-infarct cell loss that coincided with downregulated Iba1-labeled inflammatory cells and upregulated CD63-positive extracellular vesicles that appeared to be co-localized with GFAP-positive astrocytes. Interestingly, grafted stem cells were not detected at one year post-transplantation period, suggesting that the extracellular vesicles likely originated within the host brain. That long-lasting functional benefits persisted in the absence of surviving transplanted stem cells, but with upregulation of endogenous extracellular vesicles, advances the concept that transplantation of stem cells acutely after stroke propels host extracellular vesicles to the ischemic brain, altogether promoting chronic brain remodeling.

Probing Multiple Transplant Delivery Routes of CD+34 Stem Cells for Promoting Behavioral and Histological Benefits in Experimental Ischemic Stroke.

Stroke is a leading cause of death in the US and around the world but with limited treatment options. Survivors often present with long-term cognitive and neurological deficits. Stem cell-based therapy has emerged as a potential treatment for stroke. While stem cell transplantation in stroke has reached clinical trials, mostly safety outcomes have been reported with efficacy readouts warranting more studies. In an effort to optimize the stem cell regimen for stroke, here we conducted vis-a-vis comparison of different routes of transplantation, namely, intracerebral, intraarterial, and intranasal delivery of expanded human CD34 + stem cells, called ProtheraCytes, in the established stroke model of transient middle cerebral artery occlusion (MCAO) using adult Sprague-Dawley rats. After adjusting for the dose and subacute timing of cell delivery, animals were randomly assigned to receive either ProtheraCytes or vehicle. Motor and neurological assays from days 7 to 28 post-stroke revealed significant functional recovery across all 3 delivery routes of ProtheraCytes compared to vehicle-treated stroke rats. Additionally, ProtheraCytes-transplanted stroke rats displayed significantly reduced infarct size and cell loss in the peri-infarct area coupled with enhanced neurogenesis and angiogenesis compared to vehicle-treated stroke rats. These results highlight the safety and efficacy of transplanting ProtheraCytes, including via the minimally invasive intranasal route, in conferring robust and stable behavioral and histological positive outcomes in experimental stroke.

Paclitaxel binds and activates C5aR1: A new potential therapeutic target for the prevention of chemotherapy-induced peripheral neuropathy and hypersensitivity reactions.

Chemotherapy-induced peripheral neuropathy (CIPN) and hypersensitivity reactions (HSRs) are among the most frequent and impairing side effects of the antineoplastic agent paclitaxel. Here, we demonstrated that paclitaxel can bind and activate complement component 5a receptor 1 (C5aR1) and that this binding is crucial in the etiology of paclitaxel-induced CIPN and anaphylaxis. Starting from our previous data demonstrating the role of interleukin (IL)-8 in paclitaxel-induced neuronal toxicity, we searched for proteins that activate IL-8 expression and, by using the Exscalate platform for molecular docking simulations, we predicted the high affinity of C5aR1 with paclitaxel. By in vitro studies, we confirmed the specific and competitive nature of the C5aR1-paclitaxel binding and found that it triggers intracellularly the NFkB/P38 pathway and c-Fos. In F11 neuronal cells and rat dorsal root ganglia, C5aR1 inhibition protected from paclitaxel-induced neuropathological effects, while in paclitaxel-treated mice, the absence (knock-out mice) or the inhibition of C5aR1 significantly ameliorated CIPN symptoms-in terms of cold and mechanical allodynia-and reduced the chronic pathological state in the paw. Finally, we found that C5aR1 inhibition can counteract paclitaxel-induced anaphylactic cytokine release in macrophages in vitro, as well as the onset of HSRs in mice. Altogether these data identified C5aR1 as a key mediator and a new potential pharmacological target for the prevention and treatment of CIPN and HSRs induced by paclitaxel.