Kiyohiro Houkin

Moyamoya disease: current concepts and future perspectives

Moyamoya disease is an uncommon cerebrovascular disease that is characterised by progressive stenosis of the terminal portion of the internal carotid artery and its main branches. The disease is associated with the development of dilated, fragile collateral vessels at the base of the brain, which are termed moyamoya vessels. The incidence of moyamoya disease is high in east Asia, and familial forms account for about 15% of patients with this disease. Moyamoya disease has several unique clinical features, which include two peaks of age distribution at 5 years and at about 40 years. Most paediatric patients have ischaemic attacks, whereas adult patients can have ischaemic attacks, intracranial bleeding, or both. Extracranial-intracranial arterial bypass, including anastomosis of the superficial temporal artery to the middle cerebral artery and indirect bypass, can help prevent further ischaemic attacks, although the beneficial effect on haemorrhagic stroke is still not clear. In this Review, we summarise the epidemiology, aetiology, clinical features, diagnosis, surgical treatment, and outcomes of moyamoya disease. Recent updates and future perspectives for moyamoya disease will also be discussed.

Intravenous administration of auto serum-expanded autologous mesenchymal stem cells in stroke

Transplantation of human mesenchymal stem cells has been shown to reduce infarct size and improve functional outcome in animal models of stroke. Here, we report a study designed to assess feasibility and safety of transplantation of autologous human mesenchymal stem cells expanded in autologous human serum in stroke patients. We report an unblinded study on 12 patients with ischaemic grey matter, white matter and mixed lesions, in contrast to a prior study on autologous mesenchymal stem cells expanded in foetal calf serum that focused on grey matter lesions. Cells cultured in human serum expanded more rapidly than in foetal calf serum, reducing cell preparation time and risk of transmissible disorders such as bovine spongiform encephalomyelitis. Autologous mesenchymal stem cells were delivered intravenously 36-133 days post-stroke. All patients had magnetic resonance angiography to identify vascular lesions, and magnetic resonance imaging prior to cell infusion and at intervals up to 1 year after. Magnetic resonance perfusion-imaging and 3D-tractography were carried out in some patients. Neurological status was scored using the National Institutes of Health Stroke Scale and modified Rankin scores. We did not observe any central nervous system tumours, abnormal cell growths or neurological deterioration, and there was no evidence for venous thromboembolism, systemic malignancy or systemic infection in any of the patients following stem cell infusion. The median daily rate of National Institutes of Health Stroke Scale change was 0.36 during the first week post-infusion, compared with a median daily rate of change of 0.04 from the first day of testing to immediately before infusion. Daily rates of change in National Institutes of Health Stroke Scale scores during longer post-infusion intervals that more closely matched the interval between initial scoring and cell infusion also showed an increase following cell infusion. Mean lesion volume as assessed by magnetic resonance imaging was reduced by >20% at 1 week post-cell infusion. While we would emphasize that the current study was unblinded, did not assess overall function or relative functional importance of different types of deficits, and does not exclude placebo effects or a contribution of recovery as a result of the natural history of stroke, our observations provide evidence supporting the feasibility and safety of delivery of a relatively large dose of autologous mesenchymal human stem cells, cultured in autologous human serum, into human subjects with stroke and support the need for additional blinded, placebo-controlled studies on autologous mesenchymal human stem cell infusion in stroke.

I.V. infusion of brain-derived neurotrophic factor gene-modified human mesenchymal stem cells protects against injury in a cerebral ischemia model in adult rat.

I.V. delivery of mesenchymal stem cells prepared from adult bone marrow reduces infarction size and ameliorates functional deficits in rat cerebral ischemia models. Administration of the brain-derived neurotrophic factor to the infarction site has also been demonstrated to be neuroprotective. To test the hypothesis that brain-derived neurotrophic factor contributes to the therapeutic benefits of mesenchymal stem cell delivery, we compared the efficacy of systemic delivery of human mesenchymal stem cells and human mesenchymal stem cells transfected with a fiber-mutant F/RGD adenovirus vector with a brain-derived neurotrophic factor gene (brain-derived neurotrophic factor-human mesenchymal stem cells). A permanent middle cerebral artery occlusion was induced by intraluminal vascular occlusion with a microfilament. Human mesenchymal stem cells and brain-derived neurotrophic factor-human mesenchymal stem cells were i.v. injected into the rats 6 h after middle cerebral artery occlusion. Lesion size was assessed at 6 h, 1, 3 and 7 days using MR imaging, and histological methods. Functional outcome was assessed using the treadmill stress test. Both human mesenchymal stem cells and brain-derived neurotrophic factor-human mesenchymal stem cells reduced lesion volume and elicited functional improvement compared with the control sham group, but the effect was greater in the brain-derived neurotrophic factor-human mesenchymal stem cell group. ELISA analysis of the infarcted hemisphere revealed an increase in brain-derived neurotrophic factor in the human mesenchymal stem cell groups, but a greater increase in the brain-derived neurotrophic factor-human mesenchymal stem cell group. These data support the hypothesis that brain-derived neurotrophic factor contributes to neuroprotection in cerebral ischemia and cellular delivery of brain-derived neurotrophic factor can be achieved by i.v. delivery of human mesenchymal stem cells.

Novel epidemiological features of moyamoya disease

Background: Many clinical features that are specific to moyamoya disease have been reported and cited in textbooks based on previous data. The purpose of this study is to investigate the present epidemiological features of moyamoya disease based on recently obtained regional all-inclusive data. Methods: The authors performed an all-inclusive survey of moyamoya disease in Hokkaido, one of the major islands in Japan that has a population of 5.63 million. The epidemiological features were analysed based on the data from 267 newly registered patients with moyamoya disease in Hokkaido from 2002 to 2006. These analysed data were adjusted to the whole Japanese population at 2005. Results: The detection rate of the disease per year was 0.94 patients per 100 000 people, and prevalence was 10.5 patients per 100 000 people. The incidence of ischaemia concerned with the disease was 0.53 patients per 100 000 people-years and haemorrhage was 0.2 patients per 100 000 people-years. The ratio of female to male patients was 2.18. The ratio of patients aged 10 years and above to under 10 years of age at onset was 6.18. Two peaks for age of onset were seen: the highest was observed between 45 and 49 years, and the second between 5 and 9 years. Asymptomatic patients comprised 17.8% of the total number of patients. Conclusion: The epidemiological features of moyamoya disease determined by this survey varied considerably from previous data. The detection rate and prevalence of the disease were higher than those reported previously. The highest peak of onset age was older than those reported previously. In addition, it was revealed that asymptomatic moyamoya patients are not always rare in Japan.

A therapeutic window for intravenous administration of autologous bone marrow after cerebral ischemia in adult rats.

The primary objective of this study was to test the hypothesis that intravenous administration of autologous bone marrow cells could improve functional recovery after middle cerebral artery occlusion (MCAO) for 45 min in the rat and to determine specific time windows for efficacy. Mononuclear cells from autologous bone marrow were transfected with the LacZ reporter gene, and injected intravenously into rats at 3-72 h after induction of MCAO. Histological analysis of the ischemic lesion at 14 days after transplantation revealed reduced ischemic lesion volume. Lesion volume was 250+/-45 mm(3) (n=6) after MCAO without cell transplantation. Lesions were minimally detected by absence of 2,3,5-triphenyltetrazolium chloride (TTC) staining when bone marrow cells were infused 3 h after lesion induction. Lesions were clearly detected beginning with the 6-h postlesion group and became progressively larger at 12, 24 and 72 h (80+/-25, 140+/-18, and 180+/-22 mm(3), respectively; n=6 for each group). Transplanted LacZ(+) bone marrow cells accumulated extensively in and around the ischemic lesions, and immunohistochemistry suggests some neuronal and glial lineage differentiation. Behavioral testing (Morris water maze and Treadmill stress test) indicated greater functional recovery in the treated group. These findings suggest that early intervention with intravenous administration of autologous mononuclear cells from bone marrow can reduce lesion size in the MCAO model in the rat, and improve functional outcome.

Intravenous infusion of immortalized human mesenchymal stem cells protects against injury in a cerebral ischemia model in adult rat

Intravenous infusion of bone marrow cells has demonstrated therapeutic efficacy in animal models of cerebral ischemia and spinal cord injury. We intravenously delivered human mesenchymal stem cells (SH2+, SH3+, CD34-, and CD45-) immortalized with a human-telomerase gene (hTERT-MSCs) and transfected with eGFP or LacZ into rats 12 h after induction of transient middle cerebral artery occlusion (MCAO), to study their potential therapeutic benefit. hTERT-MSCs were delivered at 12 h after lesion induction. Lesion size was assessed using MR imaging and spectroscopy, and histological methods. Functional outcome was assessed using the Morris water maze and a treadmill test. Intravenous delivery of hTERT-MSCs reduced lesion volume and the magnitude of the reduction and functional improvement was positively correlated with the number of cells injected. The reduction of lesion size could be assessed in vivo with MRI and MRS and was correlated with subsequent histological examination of the brain. This work demonstrates that highly purified hTERT-MSCs reduce cerebral infarction volume and improve functional outcome.

BDNF- hypersecreting human mesenchymal stem cells promote functional recovery, axonal sprouting and protection of corticospinal neurons after spinal cord injury

Transplantation of mesenchymal stem cells (MSCs) derived from bone marrow has been shown to improve functional outcome in spinal cord injury (SCI). We transplanted MSCs derived from human bone marrow (hMSCs) to study their potential therapeutic effect in SCI in the rat. In addition to hMSCs, we used gene-modified hMSCs to secrete brain-derived neurotrophic factor (BDNF-hMSCs). After a dorsal transection lesion was induced at T9, cells were microinjected on each side of the transection site. Fluorogold (FG) was injected into the epicenter of the lesion cavity to identify transected corticospinal tract (CST) neurons. At 5 weeks after transplantation, the animals were perfused. Locomotor recovery improvement was observed for the BDNF-hMSC group, but not in the hMSC group. Structurally there was increased sprouting of injured corticospinal tract and serotonergic projections after hMSC and BDNF-hMSC transplantation. Moreover, an increased number of serotonergic fibers was observed in spinal gray matter including the ventral horn at and below the level of the lesion, indicating increased innervation in the terminal regions of a descending projection important for locomotion. Stereological quantification was performed on the brains to determine neuronal density in primary motor (M1) cortex. The number of FG backfilled cells demonstrated an increased cell survival of CST neurons in M1 cortex in both the hMSC and BDNF-hMSC groups at 5 weeks, but the increase for the BDNF-hMSC group was greater. These results indicate that transplantation of hMSCs hypersecreting BDNF results in structural changes in brain and spinal cord, which are associated with improved functional outcome in acute SCI.

Mesenchymal stem cells (MSC) as therapeutic cytoreagents for gene therapy

We developed human mesenchymal stem cell (MSC) lines that could differentiate into various tissue cells including bone, neural cells, bone marrow (BM) stromal cells supporting the growth of hematopoietic stem cell (HSC), and so‐called ‘tumor stromal cells’ mixing with tumor cells. We investigated the applicability of MSC as therapeutic cell transplanting reagents (cytoreagents). Telomerized human BM derived stromal cells exhibited a prolonged lifespan and supported the growth of hematopoietic clonogenic cells. The gene transfer of Indian hedgehog (Ihh) remarkably enhanced the HSC expansion supported by the human BM stromal cells. Gene‐modified MSC are useful as therapeutic tools for brain tissue damage (e.g. brain infarction) and malignant brain neoplasms. MSC transplantation protected the brain tissue from acute ischemic damage in the midcerebral artery occlusion (MCAO) animal model. Brain‐derived neurotrophic factor (BDNF)‐gene transduction further enhanced the protective efficacy against the ischemic damage. MSC possessed excellent migratory ability and exerted inhibitory effects on the proliferation of glioma cells. Gene‐modification of MSC with therapeutic cytokines clearly augmented the antitumor effect and prolonged the survival of tumor‐bearing animals. Gene therapy employing MSC as a tissue‐protecting and targeting cytoreagent would be a promising approach. (Cancer Sci 2005; 96: 149–156)

Therapeutic benefits by human mesenchymal stem cells (hMSCs) and Ang-1 gene-modified hMSCs after cerebral ischemia

Transplantation of human mesenchymal stem cells (hMSCs) prepared from adult bone marrow has been reported to ameliorate functional deficits after cerebral artery occlusion in rats. Although several hypotheses to account for these therapeutic effects have been suggested, current thinking is that both neuroprotection and angiogenesis are primarily responsible. In this study, we compared the effects of hMSCs and angiopoietin-1 gene-modified hMSCs (Ang-hMSCs) intravenously infused into rats 6 h after permanent middle cerebral artery occlusion. Magnetic resonance imaging and histologic analyses revealed that rats receiving hMSCs or Ang-hMSCs exhibited comparable reduction in gross lesion volume as compared with the control group. Although both cell types indeed improved angiogenesis near the border of the ischemic lesions, neovascularization and regional cerebral blood flow were greater in some border areas in Ang-hMSC group. Both hMSC- and Ang-hMSC-treated rats showed greater improved functional recovery in the treadmill stress test than did control rats, but the Ang-hMSC group was greater. These results indicate the intravenous administration of genetically modified hMSCs to express angiopoietin has a similar effect on reducing lesion volume as hMSCs, but the Ang-hMSC group showed enhanced regions of increased angiogenesis at the lesion border, and modest additional improvement in functional outcome.

Surgical Therapy for Adult Moyamoya Disease Can Surgical Revascularization Prevent the Recurrence of Intracerebral Hemorrhage

BACKGROUND AND PURPOSE It is well recognized that revascularization surgery using direct and/or indirect bypass provides effective surgical management for pediatric moyamoya disease. However, surgical treatment of the adult hemorrhagic type remains controversial. In this study, the effect of surgery for adult moyamoya disease was investigated. METHODS We analyzed 35 patients with adult moyamoya disease (patient age, over 20 years), 24 patients with initial onset of intracerebral hemorrhage, and 11 patients with initial onset of cerebral ischemia who underwent both direct bypass surgery of the superficial temporal artery to the middle cerebral artery anastomosis and indirect revascularization of encephalo-duro-arteriomyo-synangiosis. RESULTS Of 24 patients with hemorrhagic-type disease, 3 showed rebleeding: of 11 patients with the ischemic type, 2 showed intracerebral hemorrhage after surgery. Overall, 5 of 35 patients (14.3%) had hemorrhage after revascularization surgery (mean follow-up period, 6.4 years). Postoperative angiography revealed that direct anastomosis is effective whereas indirect revascularization is not always effective for adult moyamoya disease. Moyamoya vessels, which are supposed to be responsible for hemorrhage, decreased in 25% of patients. CONCLUSIONS Revascularization surgery cannot always prevent rebleeding. However, a decrease in moyamoya vessels was induced by surgery, which may reduce the risk of hemorrhage more effectively than conservative treatment. In cases of adult moyamoya disease, direct bypass is particularly important, since the indirect revascularization is not as useful in adult cases as in pediatric cases.