The use of digital image processing to quantitate angiogenesis induced by basic fibroblast growth factor and transplanted pancreatic islets.

We have used digital image processing as a technique to quantify the formation of blood vessels in situ in response to the application of either an angiogenic peptide, basic fibroblast growth factor, or isolated pancreatic islets. The peptide or the islets were placed under the rat kidney capsule. For in vivo microscopy fluorescein-labeled dextran was injected intravenously and video images were made as deemed appropriate. Images to be analyzed were selected manually, digitized, and stored in a computer for processing. The calculation of the total vessel length per area was called the microvascular index. Three weeks after the transplantation of 200 islets, the microvascular index was fairly constant and did not change significantly when the same measurements were performed 1 week later. In another experiment, pellets containing 0.5 micrograms of basic fibroblast growth factor produced an angiogenic response no different from that of a control pellet. At a dose of 1 microgram, however, the response was statistically significant after 1 week. These data indicate that digital image processing may be a useful method to quantitate the angiogenesis induced by local administration of angiogenic stimulants.