No abstract

We recently demonstrated that blood–brain barrier permeabilization using mannitol enhances the therapeutic efficacy of systemically administered human umbilical cord blood (HUCB) by facilitating the entry of neurotrophic factors from the periphery into the adult stroke brain. Here, we examined whether the same blood–brain barrier manipulation approach increases the therapeutic effects of intravenously delivered HUCB in a neonatal hypoxic-ischaemic (HI) injury model. Seven-day-old Sprague–Dawley rats were subjected to unilateral HI injury and then at day 7 after the insult, animals intravenously received vehicle alone, mannitol alone, HUCB cells (15k mononuclear fraction) alone or a combination of mannitol and HUCB cells. Behavioural tests at post-transplantation days 7 and 14 showed that HI animals that received HUCB cells alone or when combined with mannitol were significantly less impaired in motor asymmetry and motor coordination compared with those that received vehicle alone or mannitol alone. Brain tissues from a separate animal cohort from the four treatment conditions were processed for enzyme-linked immunosorbent assay at day 3 post-transplantation, and revealed elevated levels of GDNF, NGF and BDNF in those that received HUCB cells alone or when combined with mannitol compared with those that received vehicle or mannitol alone, with the combined HUCB cells and mannitol exhibiting the most robust neurotropic factor up-regulation. Histological assays revealed only sporadic detection of HUCB cells, suggesting that the trophic factor–mediated mechanism, rather than cell replacement per se, principally contributed to the behavioural improvement. These findings extend the utility of blood–brain barrier permeabilization in facilitating cell therapy for treating neonatal HI injury.

Once hypoxic-ischemic (HI) injury ensues in the human neonate at birth, the resulting brain damage lasts throughout the individual's lifetime, as no ameliorative treatments are currently available. We have recently shown that intracerebral transplantation of multipotent adult progenitor cells (MAPCs) results in behavioral improvement and reduction in ischemic cell loss in neonatal rat HI-injury model. In an attempt to advance this cellular therapy to the clinic, we explored the more practical and less invasive intravenous administration of MAPCs. Seven-day-old Sprague-Dawley rats were initially subjected to unilateral HI injury, then 7 days later received intracerebral or intravenous injections of allogeneic rat MAPCs. On post-transplantation days 7 and 14, the animals that received MAPCs via the intracerebral or intravenous route exhibited improved motor and neurologic scores compared with those that received vehicle infusion alone. Immunohistochemical evaluations at day 14 after transplantation revealed that both intracerebrally and intravenously transplanted MAPCs were detected in the ischemic hippocampal area. The degree of hippocampal cell preservation was almost the same in the two treatment groups and greater than that in the vehicle group. These results show that intravenous delivery of MAPCs is a feasible and efficacious cell therapy with potential for clinical use.

Gene transfection with Notch 1 intracellular domain and subsequent growth factor treatment stimulate neuron-like differentiation of bone marrow stromal cells (BMSCs). Here, we examined the potential of transplanting Notch-induced BMSCs to exert therapeutic effects in a rat model of chronic ischemic stroke. In experiment 1, Notch-induced rat BMSCs were intrastriatally transplanted in rats at 1 month after being subjected to transient occlusion of middle cerebral artery (MCAo). Compared to post-stroke/pretransplantation level, significant improvements in locomotor and neurological function were detected in stroke rats that received 100 k and 200 k BMSCs, but not in those that received 40 k BMSCs. Histological results revealed 9%-15% graft survival, which dose-dependently correlated with behavioral recovery. At 5 weeks post-transplantation, some grafted BMSCs were positive for the glial marker GFAP (about 5%), but only a few cells (2-5 cells per brain) were positive for the neuronal marker NeuN. However, at 12 weeks post-transplantation, where the number of GFAP-positive BMSCs was maintained (5%), there was a dramatic increase in NeuN-positive BMSCs (23%). In experiment 2, Notch-induced human BMSCs were intrastriatally transplanted in rats at 1 month following the same MCAo model. Improvements in both locomotor and neurological function were observed from day 7 to day 28 post-transplantation, with the high dose (180 k) displaying significantly better behavioral recovery than the low dose (90 k) or vehicle. There were no observable adverse behavioral effects during this study period that also involved chronic immunosuppression of all animals. Histological analyses revealed a modest 5%-7% graft survival, with few (<1%) cells expressing an intermediate MAP2 neuronal marker, but not glial or oligodendroglial markers. In addition, striatal peri-infarct cell loss was significantly reduced in transplanted stroke animals compared to vehicle-treated stroke animals. The present study demonstrates the potential of Notch-induced BMSC cell therapy for patients presenting with fixed ischemic stroke.

Background: Minocycline, a second-generation tetracycline with anti-inflammatory and antiapoptotic properties, has been shown to promote therapeutic benefits in experimental stroke. However, equally compelling evidence demonstrates that the drug exerts variable and even detrimental effects in many neurological disease models. Assessment of the mechanism underlying minocycline neuroprotection should clarify the drug's clinical value in acute stroke setting.