Immuno-histochemical expression of a1, a2 and a3 integrin subunits during angiogenesis in vitro

Abstract

Aortic explants were obtained from mouse fetuses and cultured in collagen gels. Immuno-fluorescence microscopy, antibodies (anti a1, a2 and a3 integrin subunits) were used. Fibroblastic cells migrated from the aortic explant after one day of cultivation. The migrating cells located in the peripheral part of the aortic explant were positive for a1 and a2 integrin subunit antibodies. Immuno-fluorescence-positive staining for the a3 integrin subunit antibody was clearly seen in the migrating cells located near the aortic explant and surrounding tube-like structures. In an immuno-electron microscope study performed by pre-embedding immuno labeling, gold particles associated with the a3 integrin subunit were found to reside on the membranes of the cells surrounding the capillary-like tubes. Two synthetic peptides, GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro) and KDGEA (Lys-Asp-Gly-Glu-Ala), were added to the growth medium to study their effects on cell migration. KDGEA, a compound containing the recognition sequence for a2ß1 integrin, decreased cell migration, while GRGDSP exhibited no effect.

The migration of fibroblastic cells is an important phenomenon for tube formation. The present study suggested that the a1 and a2 integrin subunits are both involved in the cell migration, and more specifically, that the a2 integrin subunit participates in cell migration through the KDGEA sequence. The a3 integrin subunit played a role in tube formation.