Accumulating experimental evidence demonstrates that tumor growth and lethality are dependent on angiogenesis. Based on this concept, there is growing interest in the use of antiangiogenesis agents to inhibit tumor expansion. Compelling data implicate vascular endothelium (VE)-cadherin (an endothelium specific protein) as a key factor in the last step of angiogenesis, where the endothelial cells join one to each other and form microtubules (future blood vessels). We propose a novel approach to the inhibition of angiogenesis by immobilizing VE-cadherin-secreting hybridoma cells in alginate-agarose microcapsules. Hybridoma cells can be protected with biocompatible and semipermeable membranes that permit exit of anti-VE-cadherin monoclonal antibodies but not entry of cellular immune mediators. Stability studies were performed to select the suitable microcapsule for cell immobilization. Alginate and agarose solid beads coated with poly-L-lysine and alginate were chosen according to their stability and diusional properties. 1B5 hybridoma cells were grown within the microcapsules and secreted anti-VE-cadherin antibodies during the 9 days of culture, reaching a cumulative concentration of 1.7 mug/mL. This antibody concentration inhibited microtubule formation (87%) in the in vitro angiogenesis Matrigel assay. Moreover, the antiangiogenic effect observed was antibody concentration related. These findings open a new alternative for the inhibition or prevention of angiogenesis and demonstrates the feasibility of using microencapsulated cells as a control-drug delivery system.