Coexpression of EGFRvIII and PTEN by glioblastoma cells is associated with responsiveness to EGFR kinase inhibitors.

Purpose: We previously reported that autologous dendritic cells pulsed with acid-eluted tumor peptides can stimulateTcell^mediated antitumor immune responses against brain tumors in animal models. As a next step in vaccine development, a phase I clinical trial was established to evaluate this strategy for its feasibility, safety, and induction of systemic and intracranial

Background and Purpose-Information regarding the histological structure of thromboemboli that cause acute stroke provides insight into pathogenesis and clinical management. Methods-This report describes the histological analysis of thromboemboli retrieved by endovascular mechanical extraction from the middle cerebral artery (MCA) and intracranial carotid artery (ICA) of 25 patients with acute ischemic stroke. Results-The large majority (75%) of thromboemboli shared architectural features of random fibrin:platelet deposits interspersed with linear collections of nucleated cells (monocytes and neutrophils) and confined erythrocyte-rich regions. This histology was prevalent with both cardioembolic and atherosclerotic sources of embolism. "Red" clots composed uniquely of erythrocytes were uncommon and observed only with incomplete extractions, and cholesterol crystals were notably absent. The histology of thromboemboli that could not be retrieved from 29 concurrent patients may be different. No thrombus Ͼ3 mm wide caused stroke limited to the MCA, and no thrombus Ͼ5 mm wide was removed from the ICA. A mycotic embolus was successfully removed in 1 case, and a small atheroma and attached intima were removed without clinical consequence from another. Conclusions-Thromboemboli retrieved from the MCA or intracranial ICA of patients with acute ischemic stroke have similar histological components, whether derived from cardiac or arterial sources. Embolus size determines ultimate destination, those Ͼ5 mm wide likely bypassing the cerebral vessels entirely. The fibrin:platelet pattern that dominates thromboembolic structure provides a foundation for both antiplatelet and anticoagulant treatment strategies in stroke prevention.

To obtain insights into the pathogenesis of ischemic stroke, we analyzed thromboemboli and other occlusive material retrieved acutely from the cerebral arteries of patients. The experimental design was an observational study in 25 consecutive patients with acute ischemic stroke treated by endovascular mechanical thromboembolectomy. Patients with acute occlusion of a proximal cerebral artery, a disabling neurologic deficit, and either initiation of therapy within 8 hours of onset or initiation of therapy beyond 8 hours if imaging demonstrated substantial residual penumbral tissue at risk were treated at a tertiary Comprehensive Stroke Center (the UCLA Stroke Center). Thrombus was removed by an endovascular mechanical embolectomy device (Merci® Retriever System, Concentric Medical, Mountain View, CA) after placement by angiographic catheter into the occluded intracranial carotid artery, middle cerebral artery or vertebral-basilar artery under fluoroscopic guidance. Our results show that the large majority (20 of 25) of extracted thrombi have similar histologic architecture, a complex of layered, sometimes serpentine, lengths of fibrin:platelet deposits interspersed with linear streaks of nucleated cells. This histology was prevalent with both cardioembolic and atherosclerotic etiologies, indicating the same pathogenetic influences of blood flow and shear in thrombus formation. This histologic pattern among thrombi was present in both the internal carotid artery (ICA) and the middle cerebral artery (MCA). Clots composed uniformly of erythrocytes were uncommon (3 of 25) and were observed only with incomplete extractions, suggesting that sampling was of the proximal thrombus tail where post-occlusion thrombosis had occurred under conditions of stagnant flow. Calcifications or cholesterol were not present. Thrombus size, not histology, predicted the site of arterial occlusion, with no thrombus larger than 3 mm width causing stroke limited to the MCA and no thrombus larger than 5 mm width removed from the ICA. Fungus-containing thrombus was extracted from one patient who had mycotic valvular disease, and an unusual complication occurred in another case, namely, scraping of a small atheroma and attached intima from the MCA, albeit without clinical consequence. We conclude that thromboemboli that cause acute ischemic stroke are of similar, complex structure, regardless of macroscopic dimensions, and are similarly influenced by blood flow, whether the primary etiology is cardioembolic or atherosclerotic. Embolus size is the critical aspect that determines its ultimate destination, those of more than 5 mm width appearing to bypass the cerebral vessels entirely. The mixed fibrin:platelet pattern present in the preponderance of thromboemboli provides foundation for the success of both antiplatelet and anticoagulant treatment strategies in stroke prevention.

Adult human bone marrow (ABM) is an important source of hematopoietic stem cells for transplantation in the treatment of malignant and nonmalignant diseases. However, in contrast to the recent progress that has been achieved with umbilical cord blood, methods to expand ABM stem cells for therapeutic applications have been disappointing. In this study, we describe a novel culture method that uses human brain endothelial cells (HUBECs) and that supports the quantitative expansion of the most primitive measurable cell within the adult bone marrow compartment, the nonobese diabetic/ severe combined immunodeficient (NOD/ SCID) repopulating cell (SRC). Coculture of human ABM CD34 ؉ cells with brain endothelial cells for 7 days supported a 5.4-fold increase in CD34 ؉ cells, induced more than 95% of the CD34 ؉ CD38 ؊ subset to enter cell division, and produced progeny that engrafted NOD/SCID mice at significantly higher rates than fresh ABM CD34 ؉ cells. Using a limiting dilution analysis, we found the frequency of SRCs within fresh ABM CD34 ؉ cells to be 1 in 9.9 ؋ 10 5 cells. Following HUBEC culture, the estimated frequency of SRCs increased to 1 in 2.4 ؋ 10 5 cells. All mice that received transplants of HUBECcultured cells showed B-lymphoid and myeloid differentiation, indicating that a primitive hematopoietic cell was preserved during culture. Noncontact HUBEC cultures also maintained SRCs at a level comparable to contact HUBEC cultures, suggesting that cell-to-cell contact was not required. These data demonstrate that human brain endothelial cells possess a unique hematopoietic activity that increases the repopulating capacity of adult human bone marrow. IntroductionThe development of ex vivo culture methods that promote the expansion of adult human bone marrow (ABM) stem cells would have direct application in clinical gene therapy and stem cell transplantation. However, results obtained from stroma-based 1 and stroma-free ex vivo culture systems [2][3][4][5] have been disappointing, owing to insufficient activation of primitive CD34 ϩ CD38 Ϫ cells, cell differentiation, and a loss of repopulating capacity following short-term culture. 6 Moreover, increased CD34 ϩ cell numbers, colony-forming cells (CFCs), and long-term culture initiating cells (LTC-ICs) are not quantitative indicators of in vivo repopulating potential. [7][8][9][10] Therefore, the importance of evaluating ex vivo cultured cells in an in vivo repopulation model has been emphasized. 8 The nonobese diabetic/severe combined immunodeficient (NOD/ SCID) model system has been used to measure the long-term reconstitution potential of ex vivo-expanded human lymphohematopoietic stem cells. 7-10 SCID-repopulating cells (SRCs) are enriched in human cord blood (CB) as compared with adult ABM and mobilized peripheral blood 11,12 and are most highly concentrated within the CD34 ϩ CD38 Ϫ population. 8 SRCs are considered to be biologically more primitive than assayable LTC-IC and CFC progenitors, 1,9,10,13 which are found in both the CD34 ϩ CD38 ϩ and the CD34 ϩ...