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Background: Moyamoya disease (MMD) is a very specific disorder in terms of spontaneous development of extracranial-to-intracranial collateral circulation through the dura mater, but the underlying mechanisms are unclear. This study aimed to investigate the role of the arachnoid membrane in this unique angiogenesis in MMD., Methods: A piece of arachnoid membrane and 1- to 2-mL cerebrospinal fluid were simultaneously harvested during surgery from 26 patients with MMD. The specimens were also collected during surgery as the controls from 6 patients with atherosclerotic carotid artery diseases. The arachnoid membrane was subjected to immunohistochemistry and the cerebrospinal fluid was used to measure the concentration of cytokines using ELISA., Results: The number of cells positive for PDGFR (platelet-derived growth factor receptor) α was significantly higher in MMD than in the controls (5.4±3.1 versus 2.3±2.1 cells/field; P =0.02). The results were same in PDGFRβ-positive cells (10.1±4.6 versus 4.8±2.8; P=0.01) and α-SMA (alpha-smooth muscle actin)-positive cells (8.8±3.1 versus 2.0±2.5; P<0.01). On multicolor immunofluorescence, 80.5±15.6% of cells positive for PDGFRα in MMD also expressed α-SMA, being significantly higher than 14.6±7.2% in the controls ( P <0.01). The density of collagen in the arachnoid membrane was significantly higher in MMD than in the controls (60.3±15.0% versus 40.1±15.3%; P <0.01). In MMD, advanced disease stage was significantly associated with a larger number of α-SMA-positive cells in the arachnoid membrane ( P =0.04). On ELISA, the cerebrospinal fluid concentrations of bFGF (basic fibroblast growth factor), HGF (hepatocyte growth factor), and TGF (transforming growth factor)-β1 were significantly higher in MMD than in the controls., Conclusions: Based on these findings, MMD may elevate the concentrations of angiogenic factors in the cerebrospinal fluid and then promote the proliferation of fibroblasts in the arachnoid membrane and their differentiation into myofibroblasts, which may, in turn, enhance the production of collagen essential for spontaneous collateral formation across the arachnoid membrane.

Background and Purpose- Moyamoya disease (MMD) is a unique cerebrovascular occlusive disease characterized by progressive stenosis and negative remodeling of the distal internal carotid artery (ICA). We hypothesized that cav-1 (caveolin-1)-a protein that controls the regulation of endothelial vesicular trafficking and signal transduction-is associated with negative remodeling in MMD. Methods- We prospectively recruited 77 consecutive patients with MMD diagnosed via conventional angiography. Seventeen patients with intracranial atherosclerotic stroke and no RNF213 mutation served as controls. The outer distal ICA diameters were examined using high-resolution magnetic resonance imaging. We evaluated whether the degree of negative remodeling in the patients with MMD was associated with RNF213 polymorphism, cav-1 levels, or various clinical and vascular risk factors. We also investigated whether the derived factor was associated with negative remodeling at the cellular level using the tube formation and apoptosis assays. Results- The serum cav-1 level was lower in the patients with MMD than in the controls (0.47±0.29 versus 0.86±0.68 ng/mL; P=0.034). The mean ICA diameter was 2.48±0.98 mm for the 126 affected distal ICAs in patients with MMD and 3.84±0.42 mm for the asymptomatic ICAs in the controls ( P<0.001). After adjusting for confounders, cav-1 levels (coefficient, 1.018; P<0.001) were independently associated with the distal ICA diameter in patients with MMD. In vitro analysis showed that cav-1 downregulation suppressed angiogenesis in the endothelial cells and induced apoptosis in the smooth muscle cells. Conclusions- Our findings suggest that cav-1 may play a major role in negative arterial remodeling in MMD.

Background and Purpose: The etiology of moyamoya disease still remains unknown. This study was aimed to explore the role of hepatocyte growth factor (HGF), a strong inducer of angiogenesis, in development of moyamoya disease., Methods: We studied cerebrospinal fluid (CSF) from 39 patients with moyamoya disease (24 children and 15 adults), 6 control patients with cervical spondylosis, and 7 control patients with internal carotid artery occlusion. CSF level of HGF was determined by enzyme-linked immunosorbent assay technique. We also evaluated the distribution of HGF and its cellular receptor c-Met in the carotid fork obtained from 2 patients with moyamoya disease and 2 control patients., Results: CSF level of HGF was 408.2+/-201.6 pg/mL and 443.2+/-193.5 pg/mL in patients with cervical spondylosis and internal carotid artery occlusion, respectively (mean+/-SD). On the other hand, CSF level of HGF was 820.3+/-319.0 pg/mL in patients with moyamoya disease, being significantly higher than those in 2 control groups (P<0.01). Both HGF and c-Met were widely distributed in the media and thickened intima of the carotid fork in patients with moyamoya disease but not in control patients., Conclusions: This study revealed that HGF is densely found in the carotid fork, and its CSF level is markedly elevated in moyamoya disease, suggesting that HGF may be a key protein for pathogenesis of moyamoya disease.

Perioperative ischemic complications not directly related to surgery require special attention in patients with moyamoya disease; positron emission tomography (H(2) 15O-PET) and single-photon emission computed tomography have been considered indispensable for evaluating pre- and postsurgical cerebral hemodynamics. The clinical records of 14 patients with moyamoya disease who underwent 26 extracranial-intracranial bypass operations were reviewed with special reference to perisurgical complications. One patient developed multiple postoperative ischemic infarctions and died of ischemic brain edema. The history of this patient with prolonged acidosis is analyzed, and the role of metabolic changes induced by H(2) 15O-PET with acetazolamide challenge is reviewed. Seven (77.8%) of nine patients operated on within 48 hours after H(2) 15O-PET with acetazolamide (group 1) developed metabolic acidosis, whereas only three (17.6%) of 17 patients operated on >48 hours (group 2) after the examination had intraoperative pH of <7.35. In group 1, the mean intraoperative pH was 7.328, which was significantly lower than the mean pH of 7.393 (P <.0001) in group 2. After H(2) 15O-PET with acetazolamide challenge, patients must be carefully observed concerning acidosis and volume state. We recommend at least 48 hours between examination and surgery for patients with moyamoya disease so that their conditions can stabilize. Furthermore, special care should be taken to avoid additional perioperative risk factors such as hypotension, hypocapnia, hypercapnia, and hypovolemia.

Moyamoya disease is a progressive cerebrovascular occlusive disease that primarily affects children. The cause is unknown. We examined the production of prostanoids and the expression of cyclooxygenase-2 (COX-2) in cultured arterial smooth muscle cells (SMCs) derived from patients with moyamoya disease. Twelve moyamoya and 8 control cell strains were examined. The steady-state levels of prostanoids in the culture medium did not differ between moyamoya and control SMCs. When the cells were stimulated with interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)) release into the medium was significantly greater from moyamoya SMCs than from control SMCs, whereas the amounts of prostacyclin and thromboxane B(2) did not differ. IL-1beta-induced PGE(2) production by moyamoya SMCs was completely blocked by the addition of indomethacin or NS-398. IL-1beta significantly stimulated cell migration and DNA synthesis in control SMCs but had an inhibitory effect on moyamoya SMCs. The inhibitory effects on the growth and migration of moyamoya SMCs were caused by excessive secretion of PGE(2) and was reversed with indomethacin treatment. Immunofluorescence studies and Western blot analysis showed greater amounts of COX-2 protein expression in IL-1beta-stimulated moyamoya SMCs. These findings suggest that moyamoya SMCs respond to inflammatory stimuli to produce excess amounts of PGE(2) through the activation of COX-2, which increases vascular permeability and decreases vascular tone. This facilitates the exposure of vessels to blood constituents and promotes the development of intimal thickening in moyamoya disease.

Background and Purpose: Moyamoya disease is a progressive cerebrovascular occlusive disease affecting primarily children. The etiology remains unknown. We examined the chemotactic and proliferative activities of inflammatory cell products from arterial smooth muscle cells (SMCs) derived from moyamoya patients and compared them with those from control subjects., Methods: We used 12 SMC strains from moyamoya patients and eight from control subjects. SMC migration was examined in a micro chemotaxis chamber. DNA synthesis was measured by an immunoperoxidase technique., Results: Platelet-derived growth factor (PDGF)-BB markedly stimulated cell migration and DNA synthesis in control SMCs. PDGF-AA stimulated only DNA synthesis in control SMCs. In moyamoya SMCs, PDGF-AA and PDGF-BB stimulated cell migration but not DNA synthesis. Basic fibroblast growth factor had little migratory activity but stimulated DNA synthesis in moyamoya SMCs and control SMCs. Conversely, hepatocyte growth factor stimulated cell migration but not DNA synthesis in moyamoya SMCs and control SMCs. In contrast, interleukin-1 beta (IL-1 beta) significantly stimulated the migration and DNA synthesis of control SMCs, while it inhibited moyamoya SMC migration. The levels of IL-1 beta-induced nitric oxide production did not differ between moyamoya SMCs and control SMCs, suggesting that IL-1 beta inhibits the migration of moyamoya SMCs through a nitric oxide-independent pathway., Conclusions: The differences in responses to PDGF and IL-1 in moyamoya SMCs are involved in the mechanism by which intimal thickening develops in moyamoya disease.

Background and Purpose: Moyamoya disease is a progressive cerebrovascular occlusive disease that is rare in all ages but frequently presents in children. The etiology of the disease is unknown. We examined elastin gene transcripts and elastin synthesis in cultured arterial smooth muscle cells (SMCs) derived from moyamoya patients and compared them with those in SMCs from age-matched control subjects., Methods: We used six cell strains from moyamoya patients and four from controls. The expression of elastin protein was observed by Western blot analysis and metabolic labeling with 3H-valine. Elastin gene transcripts were identified by Northern blot analysis., Results: Elastin mRNA and protein levels were elevated in all SMCs from moyamoya patients compared with control SMCs. Although transforming growth factor-beta 1 (TGF-beta 1), a potent enhancer of the expression of elastin in arterial SMCs, upregulated elastin mRNA and protein levels in SMCs from both moyamoya patients and control subjects, the maximum levels of elastin synthesis and elastin gene transcripts in response to exogenous TGF-beta 1 were significantly greater in moyamoya SMCs than control SMCs. In addition, quiescent moyamoya SMCs secreted significantly more TGF-beta 1 into the culture medium than quiescent control SMCs (P < .01)., Conclusions: Our findings suggest that moyamoya disease may result, at least in part, from an abnormal regulation of extracellular matrix metabolism that leads to increased steady state levels of elastin mRNA and elastin accumulation in the intimal thickening and that increased elastin accumulation is a stable marker of SMCs from patients with moyamoya disease.

To clarify the differences in cerebral hemodynamics and metabolism between children and adults with bilateral moyamoya disease, we measured regional cerebral blood flow, regional oxygen extraction fraction, regional metabolic rate for oxygen, regional cerebral blood volume, and regional transit time using positron emission tomography in nine patients (five children and four adults) and compared the values with those in controls (four children with unilateral moyamoya disease and six normal adults). The major differences between pediatric and adult patients were in regional cerebral blood volume and regional oxygen extraction fraction. Regional cerebral blood volume was more markedly increased relative to the control value in the children than in the adults. Also, regional oxygen extraction fraction was greater than control in areas with low blood flow in the children but was never increased in the adults. However, in the adults, only regional transit time was significantly prolonged relative to the control values. The increased regional oxygen extraction fraction relative to the control value observed in children with moyamoya disease may explain why transient ischemic attacks are a common symptom in this group.