Transforming growth factor beta (TGF-B) stimulation of angiogenesis: an electron microscopic study

Area of Science:

• Ophthalmology
• Vascular Biology
• Cell Biology

Background:

• Corneal neovascularization is a significant cause of vision impairment.
• Understanding the molecular mechanisms driving angiogenesis is crucial for developing therapeutic strategies.
• Transforming growth factor beta (TGF-B) is implicated in angiogenesis, but its precise role in corneal neovascularization requires detailed investigation.

Purpose of the Study:

• To investigate the initiation and pattern of corneal angiogenesis induced by TGF-B.
• To elucidate the cellular and vascular changes during TGF-B-stimulated corneal neovascularization.

Main Methods:

• Utilized transforming growth factor beta (TGF-B) loaded onto a slow-release polymer (Hydron) implanted in rabbit corneas.
• Employed transmission electron microscopy (TEM) to examine cellular infiltration at 2 and 7 days post-implantation.
• Applied scanning electron microscopy (SEM) on vascular corrosion casts to visualize the neovascularization pattern.

Main Results:

• TEM revealed significant inflammatory cell infiltration, primarily neutrophils, at 2 days post-implantation.
• By 7 days, inflammation subsided, and new capillaries were observed within the corneal stroma.
• SEM demonstrated leukocyte margination/diapedesis from limbal venules at 2 days and showed new vessels originating solely from limbal venules at 7 days.

Conclusions:

• TGF-B induces corneal angiogenesis through an inflammatory cell-mediated process.
• Neovascularization originates from existing limbal vasculature.
• The findings provide insights into the dynamics of corneal neovascularization and potential therapeutic targets.