Kiyonobu Ikezaki

BACKGROUND AND PURPOSE: Vascular endothelial growth/vascular permeability factor (VEGF) is a candidate for an angiogenic and hyperpermeability inducing factor in an infarct because it is a secretable mitogen specific for endothelial cells and is upregulated by hypoxia. Our study attempts to clarify the chronological expression of VEGF and its receptor (flt) system in experimental cerebral infarction. METHODS: With the use of a reproducible middle cerebral artery occlusion model in rats, VEGF expression was identified by Western blotting with anti-VEGF antibody. The chronological expression of the VEGF/flt system was analyzed semiquantitatively by immunohistochemical means in infarcts with different time courses from 3 hours to 3 weeks. RESULTS: VEGF and flt were expressed exclusively in the ischemic brain. The bands obtained on the immunoblot at 38 and 45 kD are related to those of VEGF121 and VEGF165 isoforms. Macrophages, neurons, and glial cells chronologically expressed VEGF immunoreactivity in a different fashion. Both VEGF (bound) and flt were detected in endothelial cells along with the development of angiogenesis. CONCLUSIONS: In the ischemic brain the macrophages, neurons, and glial cells appear to contain VEGF. The VEGF receptor flt was induced in endothelial cells along with the progression of angiogenesis in infarct. The VEGF/flt system is thus considered to be involved in the healing process of brain infarct.

Moyamoya disease is a specific chronic cerebrovascular occlusive disease first reported by Japanese surgeons in 1957. The disease is characterized by stenosis or occlusion of the terminal portions of the bilateral internal carotid arteries and abnormal vascular network in the vicinity of the arterial occlusion. It may cause ischemic attacks or cerebral infarction, which is more frequent in children than in adults. In adults, cerebral hemorrhage may occur. The disease is distributed in all age groups, but the highest peak is in childhood at less than 10 years of age. The characteristic histopathologic features of the steno-occlusive arteries are fibrocellular thickening of the intima containing proliferated smooth muscle cells and prominently tortuous and often duplicated internal elastic lamina. There is usually no atheromatous plaque in the arterial wall. Etiology of the disease is still unknown; however, multifactorial inheritance is considered possible because of a higher incidence of the disease in Japanese and Koreans and approximately 10% of familial occurrence among the Japanese. Recent genetic studies suggest some responsible genetic foci in chromosomes 3, 6 and 17.

Genetic factors have been suggested to contribute to the etiology of moyamoya disease. The authors have previously reported an association between moyamoya disease and several alleles for human leukocyte antigens (HLA). To further specify the genetic component of moyamoya disease, a linkage study of moyamoya disease using markers on chromosome 6, where the HLA gene is located, was performed. The 15 microsatellite markers of chromosome 6 were studied in 20 affected sibling pairs. From an identical-by-descent analysis of these markers, an allele with possible linkage to moyamoya disease was identified. Sharing of the allele among affected members in 19 families was investigated, considering the haplotype. The marker, D6S441, might be linked to moyamoya disease. Considering the haplotype, the allele was shared among the affected members in 16 (82%) of the 19 families, but not in two others. In one family, sharing of the allele could not be determined because of low heterozygosity. Further studies are necessary to clarify multiple genetic factors that are definitely linked with moyamoya disease.