Hideomi Kitajima

Staged angioplasty for carotid artery stenosis to prevent postoperative hyperperfusion.

OBJECTIVE Hyperperfusion (HP) is a rare but potentially devastating complication after carotid revascularization. This report describes the clinical efficacy of staged angioplasty (SAP) for carotid artery stenosis to prevent HP after carotid revascularization. METHODS Eighteen of 143 patients with high-grade internal carotid artery stenosis scheduled for angioplasty were considered at high risk of postprocedure HP based on their severely impaired cerebral blood flow (CBF) and cerebral vasoreactivity, which were determined using single-photon emission computed tomography with acetazolamide. Nine of the high-risk patients were treated with carotid artery stenting and the other 9 were treated with SAP, which consisted of balloon angioplasty with undersized balloon catheters (Stage 1) followed by carotid artery stenting 1 to 2 months later (Stage 2). RESULTS In the regular carotid artery stenting group, 5 of 9 patients (56%) showed HP phenomenon on single-photon emission computed tomography just after stenting, and 1 patient (11%) developed status epilepticus owing to HP. In the SAP group, none of the 8 patients treated by SAP or the 1 patient who required stent placement during the first stage owing to a wall dissection developed postprocedure HP phenomenon or HP syndrome. CONCLUSION SAP decreased the HP phenomenon on single-photon emission computed tomography after performing these procedures in selected patients. Although additional intervention is needed, SAP is considered a relatively simple and effective method to avoid HP in patients at high risk of HP after carotid revascularization.

Hepatocyte growth factor promotes proliferation and neuronal differentiation of neural stem cells from mouse embryos

Hepatocyte growth factor (HGF), originally cloned as a hepatocyte mitogen, has recently been reported to exhibit neurotrophic activity in addition to being expressed in different parts of the nervous system. At present, the effects of HGF on neural stem cells (NSCs) are not known. In this study, we first report the promoting effect of HGF on the proliferation of neurospheres and neuronal differentiation of NSCs. Medium containing only HGF was capable of inducing neurosphere formation. Addition of HGF to medium containing fibroblast growth factor 2 or epidermal growth factor increased both the size and number of newly formed neurospheres. More neurons were also obtained when HGF was added in differentiation medium. In contrast, neurosphere numbers were reduced after repeated subculture by mechanical dissociation, suggesting that HGF-formed neurospheres comprised predominantly progenitor cells committed to neuronal or glial lines. Together, these results suggest that HGF promotes proliferation of neurospheres and neuronal differentiation of NSCs derived from mouse embyos.

Culture method for the induction of neurospheres from mouse embryonic stem cells by coculture with PA6 stromal cells

Embryonic stem (ES) cells proliferate and maintain their pluripotency for over 1 year in vitro and may therefore provide a sufficient source for cell therapies. However, most of the previously reported methods for obtaining a source for cell therapies have not been simple. We describe here a novel method for induction of neurospheres from mouse ES cells by coculturing on PA6 cells instead of the formation of embryoid bodies. The ES cells cocultured with the PA6 stromal cell line for at least 3 days were capable of differentiating into spheres. The cells in the spheres were all green fluorescent protein (GFP) positive, showing that they were derived from GFP‐expressing D3‐ES cells. The spheres contained nestin‐positive cells. The number of spheres increased when they were cocultured with PA6 for a longer period. Sphere formation was observed even after 10 mechanical dissociations and subculturings, showing its self‐renewal ability. The cells differentiated into microtubule‐associated protein‐2 (MAP2)‐positive neuronal cells and glial fibrillary acidic protein (GFAP)‐positive glial cells. γ‐Aminobutyric acid‐positive cells and tyrosine hydroxylase‐positive cells were also observed in the spheres. The percentages of the MAP2‐ or GFAP‐positive cells in the sphere changed according to the period of coculture on PA6 cells. At an early stage of coculture, more neurons were generated and, at a later period, more glial cells were generated. These results suggested that neurosphere could be generated from ES cells by coculturing with PA6, and that these cells resembled neural stem cells derived from mouse fetal brain tissue.

Hepatocyte growth factor promotes neuronal differentiation of neural stem cells derived from embryonic stem cells.

We previously reported that hepatocyte growth factor (HGF) promoted proliferation of neurospheres and neuronal differentiation of neural stem cells (NSCs) derived from mouse embryonic brain. In this study, spheres from mouse embryonic stem (ES) cells were generated by floating culture following co-culture on PA6 stromal cells. In contrast to the behavior of the neurospheres derived from embryonic brain, addition of HGF to the growth medium of the floating cultures decreased the number of spheres derived from ES cells. When spheres were stained using a MAP-2 antibody, more MAP-2-positive cells were observed in spheres cultured with HGF. When HGF was added to the growth and/or differentiation medium, more MAP-2-positive cells were also obtained. These results suggest that HGF promotes neuronal differentiation of NSCs derived from ES cells.