Human stem cells expressing novel TSP-1 variant have anti-angiogenic effect on brain tumors.

Novel therapeutic agents combined with innovative modes of delivery and non-invasive imaging of drug delivery, pharmacokinetics and efficacy are crucial in developing effective clinical anticancer therapies. In this study, we have created and characterized multiple novel variants of anti-angiogenic protein thrombospondin (aaTSP-1) that comprises unique regions of three type-I-repeats of TSP-1 and used engineered human neural stem cells (hNSC) to provide sustained on-site delivery of secretable aaTSP-1 to tumor-vasculature. We show that hNSC-aaTSP-1 has anti-angiogenic effect on human brain and dermal microvascular endothelial cells co-cultured with established glioma cells and CD133+ glioma-initiating cells. Using human glioma cells and hNSC engineered with different combinations of fluorescent and bioluminescent marker proteins and employing multi-modality imaging techniques, we show that aaTSP-1 targets the vascular-component of gliomas and a single administration of hNSC-aaTSP-1 markedly reduces tumor vessel-density that results in inhibition of tumor-progression and increased survival in mice bearing highly malignant human gliomas. We also show that therapeutic hNSC do not proliferate and remain in an un-differentiated state in the brains of glioma-bearing mice. This study provides a platform for accelerated development of future cell-based therapies for cancer.

Plasma angiotensin II levels at moment of drinking during angiotensin II intravenous infusion.

Angiotensin II (ANG II) was infused intravenously within an apparent physiological dose range of 10-200 ng.kg-1.min-1 to induce a drinking response in rats. To determine the plasma ANG II level at the moment of drinking, blood samples were collected from the femoral artery at the onset of the drinking response. Control blood samples were obtained in a similar way before infusion. The lowest dose of ANG II did not evoke drinking. Variable water intake in response to 25, 50, and 75 ng ANG II.kg-1.min-1 after a relatively long latency to drink (40-65 min) was observed. All animals showed a drinking response when 100 ng ANG II.kg-1.min-1 or higher doses of ANG II were infused. The latencies to drink were inversely correlated to the dose of ANG II and were as short as 8 min with 200 ng ANG II.kg-1.min-1. Measurement of ANG II in the plasma of drinking rats showed that all concentrations were similar with an average of 458 +/- 58.1 pg/ml. This dipsogenic plasma ANG II level is equivalent to plasma ANG II after 48 h of dehydration. The results show that drinking in response to exogenous intravenous ANG II requires a threshold level to be reached that is equivalent to levels produced by the endogenous renin-angiotensin system when dehydration is prolonged. This suggests that intravenous ANG II is not involved in moment-to-moment fluid homeostasis but operates only when dehydration is severe.