Conditioned media from hypoxic-cultured human dental pulp cells promotes bone healing during distraction osteogenesis

Distraction osteogenesis (DO) is a surgical procedure used to correct various skeletal disorders. Improving the technique by reducing the healing time would be of clinical relevance. The aim of this study was to determine the angiogenic and regenerative potential of conditioned media (CMs) collected from human dental pulp cells (hDPCs) grown under different culture conditions. CM collected from cells under hypoxia was used to improve bone healing and the DO procedure in vivo. The angiogenic potentials of CMs collected from hDPCs grown under normoxic (−Nor) and hypoxic (−Hyp) conditions were evaluated by quantitative PCR (VEGF-A, angiopoietin-1, angiopoietin-2, interleukin-6 (IL-6) and CXCL12), ELISA assays (VEGF-A, Ang-2), tube-formation and wound-healing assays, using human umbilical vein endothelial cells. The results demonstrated that hypoxic CM had significantly higher angiogenic potential than normoxic CM. Human fetal osteoblasts (hFOBs) were exposed to CM, followed by alizarin red staining, to assess the osteogenic potential. It was found that CM did not enhance the mineralization capacity of hFOBs. DO was performed in the tibiae of 30 mice, followed by a local injection of 20 µl CM (CM–Nor and CM–Hyp groups) or serum-free DMEM (control group) into the distraction zone every second day. The mice were sacrificed at days 13 and 27. The CM–Hyp treatment revealed a higher X-ray density than the control group (p < 0.05). Our study suggests that the angiogenic effect promoted by hypoxic culture conditions is dependent on VEGF-A and Ang-2 released from hDPCs. Furthermore, CM–Hyp treatment may thus improve the DO procedure, accelerating bone healing. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.publishedVersio

Selective Synthesis of Compound Semiconductor/Oxide Composite Nanowires

Semiconductor/oxide composite nanowires (NWs) were synthesized by molecular beam epitaxial growth and subsequent wet oxidation. Nonselective and selective oxidation conditions applied to the GaAs/AlGaAs core–shell NWs grown on silicon substrates produced GaOx/AlGaOx and GaAs/AlGaOx NWs, respectively. The oxidized amorphous AlGaOx shell produced cathodoluminescence over a wide spectral range encompassing ultraviolet and visible wavelengths, possibly sourced from molecular species related to oxygen. The wire core was buried in the oxides when the diameter of the oxide shell increased, forming a planar structure. These composites are expected to pave the way to future electrical and optical functions for NWs

Npas4 Regulates Mdm2 and thus Dcx in Experience-Dependent Dendritic Spine Development of Newborn Olfactory Bulb Interneurons

Sensory experience regulates the development of various brain structures, including the cortex, hippocampus, and olfactory bulb (OB). Little is known about how sensory experience regulates the dendritic spine development of OB interneurons, such as granule cells (GCs), although it is well studied in mitral/tufted cells. Here, we identify a transcription factor, Npas4, which is expressed in OB GCs immediately after sensory input and is required for dendritic spine formation. Npas4 overexpression in OB GCs increases dendritic spine density, even under sensory deprivation, and rescues reduction of dendrite spine density in the Npas4 knockout OB. Furthermore, loss of Npas4 upregulates expression of the E3-ubiquitin ligase Mdm2, which ubiquitinates a microtubule-associated protein Dcx. This leads to reduction in the dendritic spine density of OB GCs. Together, these findings suggest that Npas4 regulates Mdm2 expression to ubiquitinate and degrade Dcx during dendritic spine development in newborn OB GCs after sensory experience