Targeted Thrombospondin-1 Expression in Ocular Vascular Development and Neovascularization

Area of Science:

• Ophthalmology
• Vascular Biology
• Cell Biology

Background:

• Angiogenesis regulation is critical for ocular health; dysregulation causes vision loss.
• Thrombospondin-1 (TSP1) is a key negative regulator of ocular angiogenesis and inflammation.
• Loss of TSP1 leads to increased retinal vascular density and pathological neovascularization.

Purpose of the Study:

• To investigate the specific roles of TSP1 in different ocular cell types (endothelial cells, pericytes, astrocytes) on vascular homeostasis.
• To determine how cell-type-specific TSP1 deficiency impacts retinal and choroidal neovascularization.
• To compare the effects of global TSP1 loss versus cell-type-specific TSP1 loss on ocular vascular responses.

Main Methods:

• Generated genetically modified mice with TSP1 selectively deleted in endothelial cells, pericytes, or astrocytes.
• Assessed choroidal neovascularization (CNV) and retinal vascular density in these models.
• Evaluated retinal vascular responses to hyperoxia-induced stress.

Main Results:

• Selective TSP1 deletion in endothelial cells significantly increased choroidal neovascularization.
• TSP1 loss in pericytes or astrocytes did not significantly impact choroidal neovascularization.
• Global TSP1 knockout mice showed increased retinal vascular density, but cell-specific TSP1 loss led to decreased endothelial cell numbers.
• None of the cell-type-specific TSP1 knockout models were protected from hyperoxia-induced retinal vessel regression.

Conclusions:

• TSP1 exerts distinct functions depending on its expression in specific ocular cell types.
• Endothelial cell TSP1 is crucial for preventing pathological choroidal neovascularization.
• The coordinated action of TSP1 across different ocular cell types is essential for maintaining vascular homeostasis and vision.