Published papers

Secondary degeneration after spinal cord injury (SCI) is caused by increased vascular permeability, infiltration of inflammatory cells, and subsequent focal edema. Therapeutic interventions using neurotrophic factors have focused on the prevention of such reactions to reduce cell death and promote tissue regeneration. Vascular endothelial growth factor (VEGF) is a potent angiogenic and vascular permeability factor. However, the effect of VEGF on SCI remains controversial. VEGF signaling is primarily regulated through two primary receptors, VEGF receptor 1 (VEGF-R1) and VEGF receptor 2 (VEGF-R2). The purpose of this study was to examine the effects of intraperitoneal administration of VEGF-R1- and VEGF-R2-neutralizing antibodies on a mouse model of SCI. VEGF-R1 blockade, but not VEGF-R2 blockade, decreased the permeability and infiltration of inflammatory cells, and VEGF-R2 blockade caused a significant increase in neuronal apoptosis in the acute phase of SCI. VEGF-R2 blockade decreased the residual tissue area and the number of neural fibers in the chronic phase of SCI. VEGF-R2 blockade worsened the functional recovery and prolonged the latency of motor evoked potentials. These data suggest that endogenous VEGF-R2 plays a crucial role in neuronal protection after SCI. © 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society.

The present study characterized fetal sulcation patterns and gyrification in the cerebrum of the New World monkey group, common marmosets, using a 3D T2-weighted high-resolution anatomical magnetic resonance imaging (MRI) sequence from the fixed brain at 7-tesla ex vivo. Fetal sulcation in the marmoset cerebrum began to indent the lateral fissure and hippocampal sulcus in gestational week (GW) 12, and then the following sulci emerged: the callosal and calcarine sulci on GW 15; the superior temporal sulcus on GW 17; and the circular and occipitotemporal sulci on GW 18. The degree of cortical convolution was evaluated quantitatively based on 2D MRI slices by the gyrification index (GI) and based on 3D MRI data by sulcation index (SI). Both the mean GI and SI increased from GW 16, and were closely correlated with the cortical volume and the cortical surface area during fetal periods (their correlation coefficients marked more than 0.95). After birth, both the mean GI and SI decreased slightly by 2years of age, whereas the cortical volume and surface area continuously increased. Notably, histological analysis showed that the outer subventricular zone (oSVZ) in non-sulcal regions was thicker than that in the presumptive calcarine sulcal region on GW 13, preceding the infolding of the calcarine sulcus. The present results showed definite sulcal infolding on the cerebral cortical surface of the marmosets, with similar pattern and sequence of their emergences to other higher-order primates such as macaques and humans. Differential expansion of the oSVZ may be involved in gyral convolution and sulcal infolding in the developing cerebrum. © 2013 IBRO.

Somatic mutation of RUNX1 is implicated in various hematological malignancies, including myelodysplastic syndrome and acute myeloid leukemia (AML), and previous studies using mouse models disclosed its critical roles in hematopoiesis. However, the role of RUNX1 in human hematopoiesis has never been tested in experimental settings. Familial platelet disorder (FPD)/AML is an autosomal dominant disorder caused by germline mutation of RUNX1, marked by thrombocytopenia and propensity to acute leukemia. To investigate the physiological function of RUNX1 in human hematopoiesis and pathophysiology of FPD/AML, we derived induced pluripotent stem cells (iPSCs) from three distinct FPD/AML pedigrees (FPD-iPSCs) and examined their defects in hematopoietic differentiation. By in vitro differentiation assays, FPD-iPSCs were clearly defective in the emergence of hematopoietic progenitors and differentiation of megakaryocytes, and overexpression of wild-type (WT)-RUNX1 reversed most of these phenotypes. We further demonstrated that overexpression of mutant-RUNX1 in WT-iPSCs did not recapitulate the phenotype of FPD-iPSCs, showing that the mutations were of loss-of-function type. Taken together, this study demonstrated that haploinsufficient RUNX1 allele imposed cell-intrinsic defects on hematopoietic differentiation in human experimental settings and revealed differential impacts of RUNX1 dosage on human and murine megakaryopoiesis. FPD-iPSCs will be a useful tool to investigate mutant RUNX1-mediated molecular processes in hematopoiesis and leukemogenesis.