Objective: Cell-based therapies are being investigated as an adjunct to IV thrombolysis or mechanical thrombectomy in ischemic stroke. This review summarizes the potential applications as well as challenges of intravascular cell delivery in ischemic stroke. Method:We conducted a search of Medline as well as the clinicaltrials.gov Web site for all ongoing human clinical studies using stem cells in ischemic stroke patients. Result:The pros and cons of the various donor cell types and routes of cell delivery, including intravascular delivery, in ischemic stroke are discussed. In addition, the potential challenges in translation from bench to bedside, the optimal techniques for intravascular cell delivery, and an updated comprehensive list of ongoing clinical trials in ischemic stroke are highlighted. Conclusions:Stem cells have shown a promising role in ischemic stroke, in preclinical studies as well as initial pilot studies. Further studies are needed to assess intravascular cell therapy as a potential adjunct to thrombolysis or mechanical thrombectomy in ischemic stroke. Neurology Cell therapy is emerging as a promising new modality for enhancing neurologic recovery in ischemic stroke.1 Numerous basic science studies have demonstrated positive results in animal models of ischemic stroke following implantation of progenitor cells derived from various sources, including adipose, human fetal/embryonic tissue, bone marrow, peripheral, and umbilical cord blood (figure).2 These animal studies have utilized various methods of cell delivery or implantation (table 1), including direct intracerebral (IC) injection, intracisternal/cerebroventricular (ICV), or intravascular routes of delivery such as IV or intra-arterial (IA) infusion.Methods of cellular delivery and implantation. Intracerebral. Direct injection is invasive, and despite being a precise method of cellular delivery and implantation, it results in a poor distribution of cells in the target lesion.3 Initial pilot human studies investigating stereotactic IC cell implantation in patients with chronic stroke also reported adverse events, including seizures, syncope, asymptomatic subdural hematoma, transient motor worsening, and enhancing lesions on MRI. 4,5Intracisternal/cerebroventricular. The ICV route of cell delivery is less invasive than direct IC implantation but is also associated with variable cell migration to the ischemic site.6,7 In a pilot human study investigating ICV delivery in 10 chronic stroke patients (7 ischemic and 3 hemorrhagic), some patients developed fever and meningeal signs 48 hours after cellular delivery via ICV route. IV.Infusion is the least invasive method, allowing wide distribution of cells with exposure to chemotactic signals that potentially guide them toward the target ischemic lesion. This method, however, results in cells being trapped by peripheral organs, including the lungs, liver, and spleen, thereby limiting potential engraftment in the ischemic lesion in the brain.2 Since patients with ischemic stroke commonly ha...

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Type I mucopolysaccharidosis (MPS I) is an autosomal recessive lysosomal storage disorder with neurological features. Humans and laboratory animals with MPS I exhibit various white matter abnormalities involving the corpus callosum and other regions. In this study, we first validated a novel MRI technique, entitled Relaxation Along a Fictitious Field in the rotating frame of rank n (RAFFn), as a measure of myelination and dysmyelination in mice. We then examined differences between MPS I mice and heterozygotes using RAFF5 and histology. RAFF5 (i.e., RAFFn with n = 5) relaxation time constants were highly correlated with histological myelin density (R2 = 0.68, P<0.001), and RAFF5 clearly distinguished between the hypomyelinated and dysmyelinated shiverer mouse and the wild-type mouse. Bloch-McConnell theoretical analysis revealed slower exchange correlation times and smaller exchange-induced relaxation rate constants for RAFF4 and RAFF5 compared to RAFF1-3, T 1ρ, and T 2ρ. These data suggest that RAFF5 may assess methylene protons in myelin lipids and proteins, though other mechanisms (e.g. detection of myelin-bound water) may also explain the sensitivity of RAFF5 to myelin. In MPS I mice, mean RAFF5 relaxation time constants were significantly larger for the striatum (P = 0.004) and internal capsule (P = 0.039), and marginally larger for the fornix (P = 0.15). Histological assessment revealed no differences between MPS I mice and heterozygotes in myelin density or corpus callosum thickness. Taken together, these findings support subtle dysmyelination in the brains of mice with MPS I. Dysmyelination may result from myelin lipid abnormalities caused by the absence of α-L-iduronidase. Our findings may help to explain locomotor and cognitive deficits seen in mice with MPS I.