Stem cell factor and granulocyte colony-stimulating factor promote brain repair and improve cognitive function through VEGF-A in a mouse model of CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy (CADASIL) is a cerebral small vascular disease caused by NOTCH3 gene mutation in vascular smooth muscle cells (VSMCs), leading to ischemic stroke and vascular dementia. To date, the pathogenesis of CADASIL remains poorly understood, and there is no treatment that can slow the progression of CADASIL. Using a transgenic mouse model of CADASIL (TgNotch3R90C), this study reveals novel findings for understanding CADASIL pathogenesis that decreased cerebral vascular endothelial growth factor (VEGF/VEGF-A) is linked to reduced cerebral blood vessel density. Reduced endothelial cell (EC) proliferation and angiogenesis are seen in TgNotch3R90C mouse brain-isolated ECs. Decreased dendrites, axons, and synapses in the somatosensory and motor cortex layer 2/3 and in the hippocampal CA1, and reduced neurogenesis in both the subventricular zone and subgranular zone occur in 15-month-old TgNotch3R90C mice. These reductions in neuron structures, synapses, and neurogenesis are significantly correlated to decreased cerebral vasculature in the corresponding areas. Impaired spatial learning and memory in TgNotch3R90C mice are significantly correlated with the reduced cerebral vasculature, neuron structures, and synapses. Repeated treatment of stem cell factor and granulocyte colony-stimulating factor (SCF+G-CSF) at 9 and 10 months of age improves cognitive function, increases cerebral VEGF/VEGF-A, restores cerebral vasculature, and enhances regeneration of neuronal structures, synaptogenesis and neurogenesis in TgNotch3R90C mice. Pretreatment with Avastin, an angiogenesis inhibitor by neutralizing VEGF-A, completely eliminates the SCF+G-CSF-enhanced cognitive function, vascular and neuronal structure regeneration, synaptogenesis and neurogenesis in TgNotch3R90C mice. SCF+G-CSF-enhanced EC proliferation and angiogenesis in TgNotch3R90C mouse brain-isolated ECs are also blocked by Avastin pretreatment. These data suggest that SCF+G-CSF treatment may repair Notch3R90C mutation-damaged brain through the VEGF-A-mediated angiogenesis. This study provides novel insight into the involvement of VEGF/VEGF-A in the pathogenesis of CADASIL and sheds light on the mechanism underlying the SCF+G-CSF-enhanced brain repair in CADASIL.

CNS small vessel disease: A clinical review.

CNS small vessel disease (CSVD) causes 25% of strokes and contributes to 45% of dementia cases. Prevalence increases with age, affecting about 5% of people aged 50 years to almost 100% of people older than 90 years. Known causes and risk factors include age, hypertension, branch atheromatous disease, cerebral amyloid angiopathy, radiation exposure, immune-mediated vasculitides, certain infections, and several genetic diseases. CSVD can be asymptomatic; however, depending on location, lesions can cause mild cognitive dysfunction, dementia, mood disorders, motor and gait dysfunction, and urinary incontinence. CSVD is diagnosed on the basis of brain imaging biomarkers, including recent small subcortical infarcts, white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, and cerebral atrophy. Advanced imaging modalities can detect signs of disease even earlier than current standard imaging techniques. Diffusion tensor imaging can identify altered white matter connectivity, and blood oxygenation level-dependent imaging can identify decreased vascular reactivity. Pathogenesis is thought to begin with an etiologically specific insult, with or without genetic predisposition, which results in dysfunction of the neurovascular unit. Uncertainties regarding pathogenesis have delayed development of effective treatment. The most widely accepted approach to treatment is to intensively control well-established vascular risk factors, of which hypertension is the most important. With better understanding of pathogenesis, specific therapies may emerge. Early identification of pathologic characteristics with advanced imaging provides an opportunity to forestall progression before emergence of symptoms.

Stem Cell Factor in Combination with Granulocyte Colony-Stimulating Factor reduces Cerebral Capillary Thrombosis in a Mouse Model of CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a cerebral small vascular disease caused by NOTCH3 mutation-induced vascular smooth muscle cell (VSMC) degeneration, leading to ischemic stroke and vascular dementia. Our previous study has demonstrated that repeated treatment with a combination of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) reduces VSMC degeneration and cerebral endothelial cell (EC) damage and improves cognitive function in a mouse model of CADASIL (TgNotch3R90C). This study aimed to determine whether cerebral thrombosis occurs in TgNotch3R90C mice and whether repeated SCF+G-CSF treatment reduces cerebral thrombosis in TgNotch3R90C mice. Using the approaches of bone marrow transplantation to track bone marrow-derived cells and confocal imaging, we observed bone marrow-derived blood cell occlusion in cerebral small vessels and capillaries (thrombosis). Most thrombosis occurred in the cerebral capillaries (93% of total occluded vessels), and the thrombosis showed an increased frequency in the regions of capillary bifurcation. Degenerated capillary ECs were seen inside and surrounding the thrombosis, and the bone marrow-derived ECs were also found next to the thrombosis. IgG extravasation was seen in and next to the areas of thrombosis. SCF+G-CSF treatment significantly reduced cerebral capillary thrombosis and IgG extravasation. These data suggest that the EC damage is associated with thrombosis and blood-brain barrier leakage in the cerebral capillaries under the CADASIL-like condition, whereas SCF+G-CSF treatment diminishes these pathological alterations. This study provides new insight into the involvement of cerebral capillary thrombosis in the development of CADASIL and potential approaches to reduce the thrombosis, which may restrict the pathological progression of CADASIL.

Notch -- a goldilocks signaling pathway in disease and cancer therapy.

The Notch signaling pathway is a fundamental signaling mechanism operating in most, if not all, multicellular organisms and in most cell types in the body. Like other "ivy league" pathways such as Wnt, PI3K, Sonic Hedgehog, Receptor Tyrosine Kinases (RTKs), and JAK/STAT signaling, the Notch pathway is a linear signaling mechanism, i.e., an extracellular ligand activates a receptor, which ultimately leads to transcriptional alterations in the cell nucleus, but Notch signaling is a strict cell-cell communication mechanism and lacks built-in amplification steps in the signaling pathway. Dysregulated Notch signaling, either by direct mutations in the pathway or by altered signaling output, is increasingly linked to disease, and Notch can act as an oncogene or tumor suppressor depending on the cellular context. This underscores that appropriate level of Notch signaling is important for differentiation and tissue homeostasis, a notion supported also by genetic data indicating that Notch signaling is very gene dosage-sensitive. Thus, too much or too little signaling can lead to disease and Notch can therefore be considered a Goldilocks signaling pathway. Given the emerging role of dysregulated Notch signaling in disease, there is increasing interest in developing therapeutic approaches to modulate Notch signaling. In this review we discuss recent findings on how signal transduction is tuned in the Notch pathway and how Notch signaling is dysregulated in disease. We also discuss different strategies to modulate Notch signaling for clinical use, for example by novel antibody-based tools and by taking advantage of the cross-talk between Notch and other signaling mechanisms.

Stem cell factor and granulocyte colony-stimulating factor exhibit therapeutic effects in a mouse model of CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a Notch3 dominant mutation-induced cerebral small vascular disease, is characterized by progressive degeneration of vascular smooth muscle cells (vSMCs) of small arteries in the brain, leading to recurrent ischemic stroke, vascular dementia and death. To date, no treatment can stop or delay the progression of this disease. Herein, we determined the therapeutic effects of stem cell factor (SCF) in combination with granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) in a mouse model of CADASIL carrying the human mutant Notch3 gene. SCF+G-CSF was subcutaneously administered for 5 days and repeated 4 times with 1-4 month intervals. We found through water maze testing that SCF+G-CSF treatment improved cognitive function. SCF+G-CSF also attenuated vSMC degeneration in small arteries, increased cerebral blood vascular density, and inhibited apoptosis in CADASIL mice. We also discovered that loss of cerebral capillary endothelial cells and neural stem cells/neural progenitor cells (NSCs/NPCs) occurred in CADASIL mice. SCF+G-CSF treatment inhibited the CADASIL-induced cell loss in the endothelia and NSCs/NPCs and promoted neurogenesis. In an in vitro model of apoptosis, SCF+G-CSF prevented apoptotic cell death in vSMCs through AKT signaling and by inhibiting caspase-3 activity. These data suggest that SCF+G-CSF restricts the pathological progression of CADASIL. This study offers new insights into developing therapeutic strategies for CADASIL.

Therapeutic modulation of Notch signalling--are we there yet?

The Notch signalling pathway is evolutionarily conserved and is crucial for the development and homeostasis of most tissues. Deregulated Notch signalling leads to various diseases, such as T cell leukaemia, Alagille syndrome and a stroke and dementia syndrome known as CADASIL, and so strategies to therapeutically modulate Notch signalling are of interest. Clinical trials of Notch pathway inhibitors in patients with solid tumours have been reported, and several approaches are under preclinical evaluation. In this Review, we focus on aspects of the pathway that are amenable to therapeutic intervention, diseases that could be targeted and the various Notch pathway modulation strategies that are currently being explored.

[A case of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in which lomerizine hydrochloride was suggested to prevent recurrent stroke].

A 60-year-old man visited our hospital because of left hemiparesis in September 2006. Magnetic resonance imaging (MRI) revealed a high-intensity lesions in the right corona radiata on diffusion-weighted images and a high-intensity lesions in the basal ganglia and deep white matter on T2-weighted images. He recovered with no sequelae. Antithrombotic agents such as aspirin were given to prevent stroke, but stroke recurred three times over the course of 3 years. In February 2009, neurological examination revealed right hemiparalysis and dysarthria. Dysphagia and cognitive decline had been progressing gradually. We suspected cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) on the basis of the clinical and family history. An Arg75Pro mutation in the Notch3 gene was found, but did not involve a cysteine residue. Antithrombotic agents were ineffective. We tried lomerizine hydrochloride, which was reported to prevent stroke in a patient with CADASIL. In Japan, lomerizine hydrochloride is used to prevent migraine and to selectively inhibit cerebral artery contraction. During treatment with lomerizine hydrochloride (5 mg/day) for more than 3 years, there was no recurrence of cerebral infarction and no further deterioration of cognitive function or MRI findings. There is no evidence supporting the efficacy of antithrombotic agents in CADASIL patients. Moreover, antithrombotic agents have been reported to increase the frequency of clinically silent microbleeds on MRI in CADASIL. Lomerizine hydrochloride might therefore be one option for the treatment of CADASIL.