Abstract: Normal cells, such as fibroblasts or other tissue or organ cell types, are genetically engineered to express biologically active, anti-angiogenic compounds, in particular, thrombospondin-2. These cells are seeded into a matrix for implantation into the patient to be treated. Cells may also be engineered to include a lethal gene, so that implanted cells can be destroyed once treatment is completed. Cells can be implanted in a variety of different matrices. In a preferred embodiment, these matrices are implantable and biodegradable over a period of time equal to or less than the expected period of treatment, during which the engrafted cells form a functional tissue producing the desired biologically active agent for longer periods of time.