Characterization of a strain of cerebral endothelial cells derived from goat brain which retain their differentiated traits after long-term passage.

A strain of cerebral endothelial cells was established from isolated cortical microvessels of caprine brain. These cells, which are referred to as EC1 cells, can be routinely subcultured to 32 passages without the loss of differentiated morphologic and immunologic traits. The ability to routinely subculture EC1 cells is an important asset, given that isolated cerebral endothelial cells in mammals generally lose their differentiated traits after only 2 to 3 passages. EC1 cells were shown to contain Factor VIII-related antigen, which is a specific marker for cells of endothelial origin. EC1 cells morphologically demonstrated a scarcity of pinocytotic vesicles on their apical surfaces, a lack of trans-cytoplasmic vesicles, and the ability to form in culture confluent monolayers with tight junctional complexes. Therefore, EC1 cells possess specific antigenic and ultrastructural features which classify them as being small vessel endothelial cells of the blood-brain barrier type. Cytogenetic evaluation of EC1 cells demonstrated a normal female goat 60,XX karyotype and confirmed the apparent non-transformed nature of EC1 cells due to the lack of chromosome abnormalities or rearrangements. Using scanning electron microscopy, EC1 cells were also shown to form confluent monolayers on mixed nitrocellulose filters, a feature that will enable the development of an in vitro system to study trans-endothelial transport. Given that EC1 cells are readily subcultured and grow well on nitrocellulose filters, and that they resemble cerebral endothelium in vivo, it seems evident that EC1 cells can be used as a versatile model for the study of blood-brain barrier function, regulation, and pathology.

Reassessment of a new model of complete cerebral ischemia in rats. Method of induction of clinical death, pathophysiology and cerebrovascular pathology.

The present study was undertaken to ascertain the role of the microcirculation in the phenomenon of hypoperfusion following complete cerebral ischemia. The experiments were performed on rats under superficial ether anesthesia. Cerebral ischemia was induced by cardiac arrest for 3.5 or 10 min, with survival periods that lasted from 3 min to 7 days. A special metal hook-like device was inserted into the chest cavity at the third intercostal spaces for occluding the cardiac vessel bundle. The effect of this procedure was total cessation of systemic circulation, i.e., clinical death. In 52% of animals with 10-min clinical death, resuscitation (external heart massage and artificial ventilation) restored heart activity. When brain circulation was restored, respiratory activity, pain reaction, corneal reflex, bioelectric activity of the cortex, and normal activities of the rats returned. Scanning electron microscopy was applied to study the effect of ischemia on the vessel wall and endothelial cells (EC). Ischemia produced a remarkable increase in the numbers of microvilli and pit-like invaginations on the luminal EC surface. The luminal wall surface of many of the microvessels (MV) formed ridges. Frequently, microthrombi of varying sizes were observed. The most prominent changes were noted from 3 min to 6 h of recirculation, and they correlated with hypoperfusion after ischemia. Seven days later, these changes completely disappeared. The data presented here indicate that progressive hypoperfusion after ischemia occurs with significant alterations in the MV walls. These studies collectively suggest that the focal responses in select MVs may be associated with receptor molecule up-regulation of some, but not all, affected ECs. Our data provide further characterization of a new and unique chronic model of brain ischemia that can be applied to relevant clinical studies.

Therapy of refractory adult acute lymphoblastic leukemia with vincristine and prednisone plus tandem methotrexate and L-asparaginase. Results of a Cancer and Leukemia Group B Study.

Methotrexate (MTX) and L-asparaginase (ASP) are effective agents in the treatment of acute lymphoblastic leukemia (ALL). The effects of combining MTX and ASP are schedule dependent. To investigate this schedule dependency, the Cancer and Leukemia Group B (CALGB) employed vincristine and prednisone with progressive dose escalation of moderate-dose MTX (125 mg/m2) followed 24 h later with ASP (6,000 U/m2) in refractory adult ALL. We treated 38 patients with refractory or first relapse adult ALL. Most patients had received prior ASP (92%) and MTX (72%). A complete remission was achieved in 25% with a median duration of remission of 21 weeks. The median survival for the entire group was 7.4 months. Therapy was well tolerated and toxicity was acceptable. Our response rate was lower than other tandem MTX and ASP adult ALL trials. Therapy was similar with other series, with the exception of the dose of ASP employed. We conclude that tandem MTX and ASP, in the doses and schedule used here, has only modest activity in previously treated adult ALL. This regimen offers little advantage to other salvage regimens.