Effects of vascular endothelial growth factor and basic fibroblast growth factor: application with corneal grafts on the chorioallantoic membrane.

The corneae of 17- to 19-day-old chick embryos were dissected and grafted on the chorioallantoic membrane (CAM) of 10- to 14-day-old embryos with reincubation periods of 3-9 days. After fixation, serial semithin or paraffin sections were made. Furthermore, two growth factors were applied together with the corneae. The 165-amino-acid vascular endothelial growth factor (VEGF165) or basic fibroblast growth factor (bFGF) was either pipetted onto the corneae, or pieces of shell membrane were soaked in a factor solution, dried and inserted into an incision in the corneae. After a reincubation of 4-6 days, serial paraffin sections were made. The controls show that the viability of the grafts decreases with increasing age of the host CAM. Furthermore, with prolonged reincubation, the viable corneae become more and more spherical. Due to this movement, necrotic tissue of the CAM is shifted into the center of the sphere. After 9 days, blood vessels can be seen growing in the direction of the necrosis. bFGF pipetted onto the grafts induces marked proliferation of the stroma of the CAM beneath the corneae. Additionally, bFGF carriers inserted into the corneae induce fibrocyte ingrowth in the grafts together with a few blood vessels. VEGF165 specifically induces vascular growth in the CAM beneath the cornea but did not induce blood vessel growth into the grafts. The pros and cons of the method are discussed.