| abstract |
An angiogenic material is provided which promotes extensive vascularization when implanted in animal tissue. The angiogenic material contains a biocompatible polymer and a vascularizing polymerizable compound capable of forming anions. The polymer may be a polyacrylate, and the polymerizable compound includes compounds having ionizable groups selected from sulfates, sulfonic acid groups and carboxyl groups. These compounds include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, vinylsulfonic acid and vinylacetic acid. The angiogenic material is preferably used in microcapsule coatings and microspheres for implantation in animals. In microcapsules, the angiogenic material promotes better exchange of nutrients, waste products and cellular products between encapsulated cells and the circulatory system of the host animal. Microspheres containing the angiogenic material may be used to assist in recovery of ischemic heart muscle by injection of the microspheres into the heart muscle or blood vessels serving the ischemic area. Also provided is a method of forming small microcapsules and microspheres by passing cell aggregates or air bubbles through layers of a density gradient to obtain microcapsules or microspheres having a diameter no greater than 500 mum that contain cells or do not contain cells. When cells are present, a semi-permeable coating of the angiogenic material surrounds the cells. |