Anti-angiogenic effects and regression of localized murine AML produced by anti-VEGF and anti-Flk-1 antibodies

Reducing the blood supply of tumors is one modality to combat cancer. The objective of this study was to evaluate such an approach in the treatment of localized murine AML (acute myelogenous leukemia). For this purpose we designed an experimental model in which leukemic cells were embedded in 1% agar discs before subcutaneous implantation in C57Bl female mice. The C-1498 AML cell line (Frederick Inst., NCI, MD, USA) was used. Thirty experimental mice received on alternate days injections of 5 x 2.5 microg anti-VEGF (vascular endothelial growth factor) and 5 x 2.5 microg anti-Flk-1 (VEGFR2) antibodies to the site of cell implantation over a period of 10 d. Fifteen control mice received daily PBS injections. All mice were sacrificed 16 d after AML implantation. Of the 30 experimental animals, macroscopic examination showed in 21 animals (70%) small sized, pale tumors (0.5 g); in six mice (20%) the tumors were replaced completely by necrotic tissue, while in three mice (10%), there were large (2.5 g), highly vascularized tumors. In all 15 control mice large highly vascularized tumors were seen. A separate group of mice was studied for total survival following AML implantation. While 12 mice in the control group not treated with antibodies survived for 16 d post-implantation, survival was prolonged in 15 antibody treated mice by approximate 30 d to a total survival time of 48 d. Tumor specimens were processed for histology, immunohistochemistry (IHC) for CD31 endothelial cell antigen, and tube-like formation assay. The small, pale tumors of antibody treated animals consisted of degenerate hyaline material with remnant nests of leukemic cells, whereas large tumors showed sheets of leukemic cells and numerous blood vessels. Specimens processed for CD31 antigen showed scarce or absence of blood vessels in the small, pale tumors in contrast to intensive staining from a rich network of blood vessels in the large, highly vascularized tumors. Tube-like formation assays disclosed rudimentary Grade 1 endothelial cell tubes in the small, pale tumors as opposed to polygonal Grade 4 tube formation in control animals. In conclusion, this murine model of localized AML allows assessment of anti-angiogenic tumor regression. Anti-angiogenic antibodies against VEGF and Flk-1 have therapeutic effects in murine AML.     

High-dose therapy with autologous stem cell transplantation in first response in mantle cell lymphoma

We retrospectively investigated the outcome of 30 newly diagnosed patients with mantle cell lymphoma treated with high-dose therapy and autologous stem cell transplantation in first response. With a median follow-up of 55 months, the 5-year overall-survival is 62%, the 5-year progression-free-survival is 40% and no secondary malignancy has occurred.     

Effects of armagnac or vodka on platelet aggregation in healthy volunteers: a randomized controlled clinical trial

BACKGROUND: Cardiovascular mortality is especially low in southwest France (the French Paradox). In previous experimental studies, we found that alcohol-free extracts of armagnac could inhibit human platelet function in vitro and experimental thrombosis in vivo. To test the possible relevance of these findings, we tested the effects of daily use of small quantities of armagnac against same alcohol strength, polyphenol-free vodka in healthy volunteers. METHOD: Randomized controlled trial comparing 5-year old armagnac (30 ml/day for 2 weeks) to same alcoholic strength vodka, in 20 healthy volunteers, on platelet aggregation induced by ADP, collagen, and thrombin, as well as bleeding time, partial thromboplastin time (pTT), and plasma lipids during and after consumption. Platelet testing was done blind. RESULTS: After 14 days, ADP-induced platelet aggregation was inhibited more in armagnac (-31+/-3.2% compared to pretreatment values, p<.01) than in vodka (-11.0+/-6.8%, NS) users (p<.05, armagnac vs. vodka). A rebound increase of aggregation was found 2 weeks later in vodka but not in armagnac users. The same pattern was found for thrombin-induced aggregation, including post-treatment rebound. No effect was found on collagen-induced aggregation, bleeding time, pTT, or plasma lipids. CONCLUSION: The chronic ingestion of moderate quantities of armagnac modified platelet aggregation to ADP in healthy volunteers. The difference with the effects of same alcohol degree vodka is in favour of an effect of the nonalcoholic fraction in the effects of armagnac, rather than just alcohol. All spirits may not be equal for cardioprotection.     

Chronic treatment with progesterone but not medroxyprogesterone acetate restores the endothelial control of vascular tone in the mesenteric artery of ovariectomized rats

OBJECTIVE: To examine whether chronic administration of the natural hormone progesterone or a synthetic progestogen, medroxyprogesterone acetate, to ovariectomized rats affects the endothelial control of arterial tone in the isolated mesenteric artery. DESIGN: Sham-operated rats received a daily subcutaneous injection of solvent (sesame oil), whereas ovariectomized rats received either sesame oil, progesterone (22 mg kg/day), or medroxyprogesterone acetate (22 mg kg/day) for 4 weeks, according to their respective group. RESULTS: Phenylephrine-induced contractions were significantly increased (about 200% at 10 microM) by N-nitro-L-arginine, a nitric oxide synthase inhibitor, in intact mesenteric arterial rings from the sham-operated but not from the ovariectomized group. The progesterone but not the medroxyprogesterone treatment restored the potentiating effect of N-nitro-L-arginine on phenylephrine-induced contraction (about 180% at 10 microM). Contractions to phenylephrine were not affected by the combination of charybdotoxin plus apamin, two inhibitors of endothelium-derived hyperpolarizing factor-mediated responses, in all groups. Acetylcholine induced endothelium-dependent relaxations, which were partially inhibited by N-nitro-L-arginine and abolished by the combination of N-nitro-L-arginine plus charybdotoxin and apamin, in all groups. Acetylcholine induced similar charybdotoxin and apamin-sensitive hyperpolarizations in intact mesenteric artery segments from all groups. CONCLUSIONS: Chronic administration of progesterone, but not medroxyprogesterone, to ovarictomized rats restores the endothelium-dependent attenuation of contractile responses to phenylephrine in mesenteric arterial rings through the endothelial formation of nitric oxide. Thus, an enhancement of the protective effect of endothelial cells on the arterial wall might contribute to the beneficial effect of certain progestogen-containing preparations during hormonal treatment.     

How can transforming growth factor beta be targeted usefully to combat liver fibrosis?

Transforming growth factor beta-1 (TGF-beta 1) plays a pivotal role in tissue fibrogenesis. Understanding the factors that control resolution of fibrosis is critical to devising means to combat clinical fibrosis. Future challenges would include designing ways to block the fibrosis-specific actions of TGF-beta.Blockade of transforming growth factor beta (TGF-beta) activity in vivo in animal models has proven to be an effective means of inhibiting the fibrotic response to injury in various organs. Similarly, transgenic animals in which TGF-beta 1 expression is artificially enhanced show marked spontaneous fibrosis or increased fibrotic response to injury. TGF-beta is known to effect fibroplasias, not only by its well known action of increasing extracellular matrix synthesis but also by coordinately regulating key proteins which mediate connective tissue homeostasis. This includes down-regulation of interstitial collagenase and other matrix metalloproteinases and up-regulation of antiproteases such as tissue inhibitor of metalloproteinase I and plasminogen activator inhibitor. Whilst inhibition of TGF-beta activity appears to be well tolerated in rodents over several weeks, the ultimately lethal phenotype of TGF-beta 1 knockout mice warns us that this pluripotent cytokine is essential for normal health. Therefore, downstream pathways activated by TGF-beta, which might be specific for its fibrotic effects, might be more useful targets for human fibrotic disease therapy. For example, the TGF-beta response protein connective tissue growth factor may be a good target for antifibrotics but definitive evidence awaits development of suitable genetically modified animal models and specific inhibitors.