Michiyuki Miyamoto

Bone Marrow Stromal Cell Transplantation Enhances Recovery of Local Glucose Metabolism After Cerebral Infarction in Rats: A Serial 18F-FDG PET Study

This study aimed to assess whether 18F-FDG PET could serially monitor the beneficial effects of bone marrow stromal cells (BMSC) on cerebral glucose metabolism when transplanted into the infarct brain of rats. Methods: The BMSC from green fluorescent protein transgenic rats or vehicle was stereotactically transplanted into the ipsilateral striatum at 7 d after permanent middle cerebral artery occlusion of rats. Local glucose metabolism was semiquantitatively measured at 6 and 35 d after ischemia using 18F-FDG PET. Motor function was serially evaluated throughout the experiments. At 35 d after ischemia, immunohistochemistry was performed to evaluate the phenotype of BMSC and their effects on the expression of brain-type glucose transporters. Results: BMSC transplantation not only enhanced functional recovery but also promoted the recovery of glucose utilization in the periinfarct area when stereotactically transplanted at 1 wk after ischemia. The engrafted cells were widely distributed, and most expressed a neuron-specific protein, NeuN. BMSC transplantation also prevented the pathologic upregulation of glucose transporters in the periinfarct neocortex. Conclusion: The present findings strongly suggest that the BMSC may enhance functional recovery by promoting the recovery of local glucose metabolism in the periinfarct area when directly transplanted into the infarct brain at clinically relevant timing. The BMSC also inhibit the pathologic upregulation of brain-isoform glucose transporters type 1 and 3. 18F-FDG PET may be a valuable modality to scientifically prove the beneficial effects of BMSC transplantation on the host brain in clinical situations.

Bone Marrow Stromal Cells Rescue Ischemic Brain by Trophic Effects and Phenotypic Change Toward Neural Cells

Background. Transplantation of bone marrow stromal cells (BMSCs) may contribute to functional recovery after stroke. This study was designed to clarify their mechanisms, trophic effects of neurotrophic factors, and neural differentiation. Methods. Mouse neurons exposed to glutamate were cocultured with mouse BMSCs. Either neutralizing antibodies against brain-derived neurotrophic factor (BDNF) or nerve growth factor (NGF) or Trk inhibitor K252a was added to explore the mechanism of their protective effects. Fluorescence in situ hybridization (FISH) was used to assess BDNF or NGF mRNA expression in BMSCs. The mice were subjected to permanent focal ischemia, and 7 days later, either BMSCs or the vehicle was stereotactically transplanted into the ipsilateral striatum. The mouse brains were processed for FISH and immunostaining 2 or 4 weeks after transplantation. Results. BMSCs significantly ameliorated glutamate-induced neuronal death. Treatment with anti-BDNF antibody significantly reduced their protective effects. FISH analysis showed that the majority of BMSCs expressed BDNF and NGF mRNA in vitro. BMSC transplantation significantly improved the survival of neurons in peri-infarct areas. FISH analysis revealed that approximately half of BMSCs expressed BDNF and NGF mRNA 2 weeks after transplantation; however, the percentage of BDNF and NGF mRNA-positive cells decreased thereafter. Instead, the percentage of microtubule-associated protein 2–positive BMSCs gradually increased during 4 weeks after transplantation. Conclusions. These findings strongly suggest that BDNF may be a key factor underlying the trophic effects of BMSCs. BMSCs might exhibit the trophic effect in the early stage of cell therapy and the phenotypic change toward neural cells thereafter.

Human Recombinant Peptide Sponge Enables Novel, Less Invasive Cell Therapy for Ischemic Stroke

Bone marrow stromal cell (BMSC) transplantation has the therapeutic potential for ischemic stroke. However, it is unclear which delivery routes would yield both safety and maximal therapeutic benefits. We assessed whether a novel recombinant peptide (RCP) sponge, that resembles human collagen, could act as a less invasive and beneficial scaffold in cell therapy for ischemic stroke. BMSCs from green fluorescent protein-transgenic rats were cultured and Sprague–Dawley rats were subjected to permanent middle cerebral artery occlusion (MCAo). A BMSC-RCP sponge construct was transplanted onto the ipsilateral intact neocortex 7 days after MCAo. A BMSC suspension or vehicle was transplanted into the ipsilateral striatum. Rat motor function was serially evaluated and histological analysis was performed 5 weeks after transplantation. The results showed that BMSCs could proliferate well in the RCP sponge and the BMSC-RCP sponge significantly promoted functional recovery, compared with the vehicle group. Histological analysis revealed that the RCP sponge provoked few inflammatory reactions in the host brain. Moreover, some BMSCs migrated to the peri-infarct area and differentiated into neurons in the BMSC-RCP sponge group. These findings suggest that the RCP sponge may be a promising candidate for animal protein-free scaffolds in cell therapy for ischemic stroke in humans.

Functional Bio-imaging

Cell transplantation therapy has been expected to promote functional recovery in various kinds of central nervous system (CNS) disorders, including cerebral stroke. However, there are several concerns to be resolved before clinical application of cell therapy for CNS disorders. The issues include the development of imaging techniques to monitor the response of the host CNS. It would be essential to establish functional bio-imaging technique serially and noninvasively validating the effects of cell therapy on the host CNS in order to achieve clinical application of cell therapy for cerebral stroke. Nuclear imaging technique is one of the most useful methods to assess the functional change in various kinds of CNS disorders, including cerebral stroke. Very recently, using a small-animal SPECT/CT apparatus, we could serially visualize the effects of BMSC transplantation on the distribution of 123I-IMZ in the infarct brain of the living rodents longitudinally and noninvasively. Furthermore, we serially assessed local glucose metabolism in the rats subjected to permanent MCA occlusion and found that BMSC transplantation significantly enhances the recovery in the peri-infarct area, using small-animal 18F-FDG PET/CT system. The BMSCs may enhance the recovery of local glucose metabolism by improving neuronal integrity in the peri-infarct area, when directly transplanted into the infarct brain. Although there are few studies that indicate the utility of imaging techniques to monitor the response of the host CNS after cell therapy and further investigation is needed, 123I-IMZ SPECT and 18F-FDG PET may be promising modalities to assess the therapeutic benefits of cell therapy for ischemic stroke without subjective bias in clinical situation.

[Successful acute endovascular therapy of cerebral embolism for a patient with ventricular assist device: a case report].

The number of patients with a ventricular assist device(VAD)will increase with the spread of heart transplantation in Japan. On the other hand, it is likely that VADs could cause cerebral embolism. However, there are few reports about endovascular therapy for intracranial embolic infarction from VAD. The authors report successful acute endovascular therapy for cerebral embolism. A 19-year-old woman with a VAD who received anti-coagulant treatment by warfarin sodium presented disturbance of consciousness and right hemiparesis. CT scan showed early CT sign in the left middle cerebral artery (MCA) area. 3D-CTA demonstrated occlusion of the left MCA and basilar artery (BA). We first performed endovascular recanalization in the left MCA, because IV tPA was ineligible. The left MCA was recanalized with TICI 2b perfusion and her symptoms were significantly improved. The treatment of the VAD patient reveals important issues. First, the femoral puncture requires ultrasound due to pulseless femoral artery. Second, the access route is an intact artery because of the anatomy of the VAD. Third, even if the patient has a hemorrhagic complication by intervention, the patient must be kept on anti-coagulant treatment because the VAD requires it. Careful consideration should be given to recanalization of occlusive vessels.

Pathological Considerations for Unruptured Dissecting Aneurysm in the Posterior Inferior Cerebellar Artery: Case Report

Because of the wide spread of magnetic resonance image (MRI), it may be increasing to find a dissecting aneurysm (DA) of the posterior inferior cerebellar artery (PICA) that causes headache without associated hemorrhage or infarction. Generally, surgical treatment might be considered in cases of DA with hemorrhage. However, the treatment of an unruptured DA with headache or infarction has not been well established. This is the first report regarding the pathology of an intact DA of the PICA that presents with headache only, and the pathological findings showed interesting figures. A 44-year-old man with an unruptured DA of the left PICA presented with sudden left occipital headache. MRI revealed no hemorrhage or infarction. Magnetic resonance angiography (MRA) showed growth of the DA 12 days after the onset of headache. Therefore, surgery was performed to prevent aneurysmal rupture. This DA aneurysm was trapped and removed after an occipital artery (OA)-PICA anastomosis was performed. The surgery was performed without complication. Pathological findings showed folding of the internal elastic lamina, and the true lumen was torn by the false lumen. The dissection reached the adventitia and the wall had numerous macrophages. Pathological findings might help understanding the etiology of DAs and inflammation might play an important role in DAs.