Methodological study investigating long term laser Doppler measured cerebral blood flow changes in a permanently occluded rat stroke model

Optical monitoring of cerebral microcirculation in neurointensive care

Continuous optical monitoring of local cerebral microcirculation could benefit neurointensive care patients treated for subarachnoid hemorrhage (SAH). The aim of the study was to evaluate laser Doppler flowmetry (LDF) and diffuse reflectance spectroscopy (DRS) for long-term monitoring of brain microcirculation and oxygen saturation (SO₂) in the neurointensive care unit (NICU). A fiber optic probe was designed for intraparenchymal use and connected to LDF and DRS for assessment of the local blood flow (perfusion and tissue reflectance (TLI)) and SO₂ in the brain. The optically monitored parameters were compared with conventional NICU monitors and Xe-CT. The LDF signals were low with median and 25 to 75% interquartiles of perfusion = 70 (59 to 83) a.u. and TLI = 2.0 (1.0 to 2.4) a.u. and showed correlation with the NICU monitors in terms of heart rate. Median and interquartiles of SO₂ were 17.4 (15.7 to 19.8) %. The lack of correlation between local perfusion and cerebral perfusion pressure indicated intact cerebral autoregulation. The systems were capable of monitoring both local perfusion and SO₂ with stable signals in the NICU over 4 days. Further clinical studies are required to evaluate the optical systems’ potential for assessing the onset of secondary brain injury.

Human Neural Stem Cell Therapy for Chronic Ischemic Stroke: Charting Progress from Laboratory to Patients

Chronic disability after stroke represents a major unmet neurologic need. ReNeuron's development of a human neural stem cell (hNSC) therapy for chronic disability after stroke is progressing through early clinical studies. A Phase I trial has recently been published, showing no safety concerns and some promising signs of efficacy. A single-arm Phase II multicenter trial in patients with stable upper-limb paresis has recently completed recruitment. The hNSCs administrated are from a manufactured, conditionally immortalized hNSC line (ReNeuron's CTX0E03 or CTX), generated with c-mycER^TAM technology. This technology has enabled CTX to be manufactured at large scale under cGMP conditions, ensuring sufficient supply to meets the demands of research, clinical development, and, eventually, the market. CTX has key pro-angiogenic, pro-neurogenic, and immunomodulatory characteristics that are mechanistically important in functional recovery poststroke. This review covers the progress of CTX cell therapy from its laboratory origins to the clinic, concluding with a look into the late stage clinical future.

In vivo and in vitro characterization of the angiogenic effect of CTX0E03 human neural stem cells

CTX0E03 is a human neural stem cell line previously reported to reduce sensory motor deficits in a middle cerebral artery occlusion (MCAo) model of stroke. The objective of this study was to investigate if CTX0E03 treatment promotes angiogenesis. As stroke leads to damage of the vasculature in the brain, angiogenesis may contribute to the functional recovery. To test this hypothesis, the angiogenic activity of CTX0E03 was assessed both in vitro and in vivo. In vitro, CTX0E03 expression of trophic and proangiogenic factors was determined by real-time RT-PCR, Western blot, and ELISA, and its angiogenic activity was investigated in well-established angiogenesis assays. In vivo, angiogenesis was investigated in naive mice and MCAo rat brain and was evaluated by immunohistochemistry (IHC) using Von Willebrand factor (VWF), a marker of blood vessel formation, and BrdU/CD31 double labeling in naive mice only. In vitro results showed that CTX0E03-conditioned medium and coculture significantly increased total tubule formation compared with controls (p=0.002 and p=0.0008, respectively). Furthermore, CTX0E03 cells were found to be in direct association with the tubules by ICC. In vivo CTX0E03-treated brains demonstrated a significant increase in areas occupied by VWF-positive microvessels compared with vehicle-treated naive mice (two-way ANOVA, Interaction p<0.05, Treatment p<0.0001, Time p<0.0) and MCAo rat (p=0.001 unpaired t test, Welch's correction). CTX0E03-treated naive mouse brains showed an increase in BrdU/CD31 colabeling. In conclusion, in vitro CTX0E03 cells express proangiogenic factors and may promote angiogenesis by both release of paracrine factors and direct physical interaction. Furthermore, in vivo CTX0E03-treated rodent brains exhibited a significant increase in microvessels at the site of implantation compared with vehicle-injected groups. Taken together these data suggest that CTX0E03 cell therapy may provide significant benefit to stroke patients through upregulation of angiogenesis in the ischemic brain.

Chronic hyperperfusion and angiogenesis follow subacute hypoperfusion in the thalamus of rats with focal cerebral ischemia

Cerebral blood flow (CBF) is disrupted after focal ischemia in rats. We examined long-term hemodynamic and cerebrovascular changes in the rat thalamus after focal cerebral ischemia. Cerebral blood flow quantified by arterial spin labeling magnetic resonance imaging was decreased in the ipsilateral and contralateral thalamus 2 days after cerebral ischemia. Partial thalamic CBF recovery occurred by day 7, then the ipsilateral thalamus was chronically hyperperfused at 30 days and 3 months compared with its contralateral side. This contrasted with permanent hypoperfusion in the ipsilateral cortex. Angiogenesis was indicated by endothelial cell (RECA-1) immunohistochemistry that showed increased blood vessel branching in the ipsilateral thalamus at the end of the 3-month follow-up. Only transient thalamic IgG extravasation was observed, indicating that the blood-brain barrier was intact after day 2. Angiogenesis was preceded by transiently altered expression levels of cadherin family adhesion molecules, cadherin-7, protocadherin-1, and protocadherin-17. In conclusion, thalamic pathology after focal cerebral ischemia involved long-term hemodynamic changes and angiogenesis preceded by altered expression of vascular adhesion factors. Postischemic angiogenesis in the thalamus represents a novel type of remote plasticity, which may support removal of necrotic brain tissue and aid functional recovery.

Human embryonic neural stem cell transplantation increases subventricular zone cell proliferation and promotes peri-infarct angiogenesis after focal cerebral ischemia

Neurogenesis and angiogenesis are two important processes that may contribute to the repair of brain injury after stroke. This study was designed to investigate whether transplantation of human embryonic neural stem cells (NSCs) into cortical peri-infarction 24h after ischemia effects cell proliferation in the subventricular zone (SVZ) and angiogenesis in the peri-infarct zone. NSCs were prepared from embryonic human brains at 8 weeks gestation. Focal cerebral ischemia was induced by permanent occlusion of the middle cerebral artery of adult rats. Animals were randomly divided into two groups (n=30, each) at 24h after ischemia: NSC-grafted and medium-grafted groups. Toluidine blue staining and 5'-bromo-2'-deoxyuridine (BrdU) or von Willebrand factor (vWF) immunohistochemistry were performed at 7, 14 and 28 days after transplantation. NSC transplantation increased the number of BrdU-positive cells in the ischemic ipsilateral SVZ compared with the medium control at 7 days (P<0.01). This difference in SVZ cell proliferation persisted at 14 days (P<0.01), but was not significant at 28 days (P>0.05). In addition, angiogenesis, as indicated by BrdU and vWF staining in cortical peri-infarct regions, was augmented by 46% and 65% in NSC-grafted rats versus medium-grafted rats at 7 and 14 days, respectively (P<0.05). However, this increase became non-significant at 28 days (P>0.05). Our results indicate that NSC transplantation enhances endogenous cell proliferation in the SVZ and promotes angiogenesis in the peri-infarct zone, even if it is performed in the acute phase of ischemic injury.