Related Experiment Videos
Effect of human recombinant Endostatin protein on human angiogenesis
Sung P Jung1, Brett Siegrist, Conrad A Hornick
1Department of Surgery, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Abstract:
Tumor growth and metastasis are dependent on the development of new blood vessels. Inhibitors of new vessel growth have been widely investigated as anti-tumor agents. Endostatin, a 20 kDa C-terminal fragment of collagen XVIII inhibits endothelial cell proliferation, induces endothelial cell apoptosis, and can both inhibit and reverse tumor growth in mice. However, human recombinant endostatin has had limited testing against human tissue targets. To investigate the effect of human endostatin on a human vessel target over a broad range of concentrations (10(-l2)-10(-4) M), human placental vein disks were grown for a period of 2 weeks in a 0.3% fibrin clot overlayed with growth medium. Disks from five individual placentas were tested. For each placenta utilized, a control (medium and 20% fetal bovine serum [FBS]) group and a group treated with heparin (300 microg/ml) and hydrocortisone 21-phosphate (350 microg/ml) (heparin-steroid) at a dose known to inhibit angiogenesis were included. Endostatin was tested at concentrations of 10(-12)-10(-4) M in medium containing 20% FBS. The rate of initiation and the angiogenic growth index (on a visually graded semi-quantitative scale of 0-16) were determined for all experimental conditions. Endostatin inhibited angiogenesis in our model only in high concentrations. At 10(-5) M, endostatin did not alter the percent of wells that initiated an angiogenic response, but significantly inhibited subsequent vessel growth. At 10(-4) M, endostatin was able to inhibit both initiation and subsequent new vessel growth. Human endostatin can inhibit the initiation of a human angiogenic response and inhibit the subsequent proliferation of human neovessels when used at high doses in a continuous exposure model.
Insights
Human endostatin inhibits new blood vessel growth in a human model, but only at high concentrations. This finding is crucial for developing novel anti-tumor therapies targeting angiogenesis.
Area of Science:
- Biomedical research
- Cancer biology
- Vascular biology
Background:
- Tumor growth and metastasis rely on angiogenesis (new blood vessel formation).
- Endostatin, a collagen XVIII fragment, inhibits endothelial cells and shows anti-tumor effects in mice.
- Limited data exists on human endostatin's efficacy against human vascular targets.
Purpose of the Study:
- To evaluate the effect of human endostatin on human angiogenesis.
- To determine effective concentrations of human endostatin for inhibiting angiogenesis.
Main Methods:
- Human placental vein disks were cultured in fibrin clots for 2 weeks.
- Disks were exposed to varying concentrations of human endostatin (10⁻¹²–10⁻⁴ M).
- Angiogenesis initiation and growth were assessed, with controls including heparin-steroid treatment.
Main Results:
- Human endostatin demonstrated significant inhibition of angiogenesis only at high concentrations.
- At 10⁻⁵ M, endostatin inhibited subsequent vessel growth but not initiation.
- At 10⁻⁴ M, endostatin inhibited both the initiation and subsequent growth of new blood vessels.
Conclusions:
- High concentrations of human endostatin can inhibit the initiation of human angiogenic responses.
- Human endostatin effectively inhibits the proliferation of human neovessels at high doses in a continuous exposure model.