Comparative protein interactomics of neuroglobin and myoglobin.

Neuroglobin is a hypoxia-inducible O(2)-binding protein with neuroprotective effects in cell and animal models of stroke and Alzheimer's disease. The mechanism underlying neuroglobin's cytoprotective action is unknown, although several possibilities have been proposed, including anti-oxidative and anti-apoptotic effects. We used affinity purification-mass spectrometry methods to identify neuroglobin-interacting proteins in normoxic and hypoxic murine neuronal (HN33) cell lysates, and to compare these interactions with those of a structurally and functionally related protein, myoglobin. We report that the protein interactomes of neuroglobin and myoglobin overlap substantially and are modified by hypoxia. In addition, neuroglobin-interacting proteins include partners consistent with both anti-oxidative and anti-apoptotic functions, as well as with a relationship to several neurodegenerative diseases.

Flow-induced regulation of brain endothelial cells in vitro.

Endothelial cell (EC) function and susceptibility to vascular disease are regulated by flow; this relationship has been modeled in systemic, but not cerebrovascular, EC culture. We studied the effects of unidirectional flow of medium, produced by orbital rotation of cultures, on morphology and protein expression in bEnd.3 mouse brain ECs. Flow altered the expression of key transcription factors and gasotransmitter-synthesizing enzymes, and increased NO production. Statins and angiotensin receptor blockers reproduced the effect of flow on endothelial nitric oxide synthase expression. Thus, flow modified brain EC properties and function in vitro, with similarities and possible differences compared to previous studies on systemic ECs. Thus, the effect of flow on brain ECs can be modeled in vitro and may assist the investigation of mechanisms of cerebrovascular disease.

Effect of human neural precursor cell transplantation on endogenous neurogenesis after focal cerebral ischemia in the rat.

Little is known about the relationship between neuronal cell transplantation and endogenous neurogenesis after experimental stroke. We found previously that transplantation of neuronal precursors derived from BG01 human embryonic stem cells reduced infarct volume and improved behavioral outcome after distal middle cerebral artery occlusion (MCAO) in rats. In this study, transplantation was performed 14 days after distal MCAO and doublecortin (Dcx)-expressing cells in the subventricular zone (SVZ) and subgranular zone of dentate gyrus (SGZ) were counted 60 days post-transplant. Transplantation increased neurogenesis (Dcx expression) in ipsilateral SVZ, but not in contralateral SVZ or either SGZ, in both young adult (3-month-old) and aged (24-month-old) rats. These findings suggest that cell-based therapy for stroke may be associated with changes in endogenous adaptive processes, including neurogenesis.

Delayed transplantation of human neural precursor cells improves outcome from focal cerebral ischemia in aged rats.

Neural precursor cell (NPC) transplantation may have a role in restoring brain function after stroke, but how aging might affect the brain's receptivity to such transplants is unknown. We reported previously that transplantation of human embryonic stem cell (hESC)-derived NPCs together with biomaterial (Matrigel) scaffolding into the brains of young adult Sprague-Dawley rats 3 weeks after distal middle cerebral artery occlusion (MCAO) reduced infarct volume and improved neurobehavioral performance. In this study, we compared the effect of NPC and Matrigel transplants in young adult (3-month-old) and aged (24-month-old) Fisher 344 rats from the National Institute on Aging's aged rodent colony. Distal MCAO was induced by electrocoagulation, and hESC-derived NPCs were transplanted into the infarct cavity 3 weeks later. Aged rats developed larger infarcts, but infarct volume and performance on the cylinder and elevated body swing tests, measured 6-8 weeks post-transplant, were improved by transplantation. We conclude that advanced age does not preclude a beneficial response to NPC transplantation following experimental stroke.