Feasibility of Ex Vivo Ligandomics

Area of Science:

• Biochemistry
• Molecular Biology
• Ophthalmology

Background:

• In vivo ligandomics profiles vascular ligands but is limited to endothelial cells (ECs) due to perfusion requirements.
• Secretogranin III (Scg3) was previously identified as an angiogenic factor selectively binding to diabetic retinal vessels.
• Ocular vasculopathies, such as those in diabetic retinopathy, represent a significant unmet medical need.

Purpose of the Study:

• To develop and validate an ex vivo ligandomics approach for profiling ligands on non-vascular cells.
• To assess the feasibility of ex vivo ligandomics for cell-specific ligand discovery.
• To confirm the selective binding of Scg3 to diabetic retinal cells using the ex vivo method.

Main Methods:

• Developed ex vivo ligandomics by isolating retinal ganglion cells (RGCs) and ECs from diabetic and healthy mouse retinas via immunopanning.
• Quantified phage clone binding displaying Scg3 and vascular endothelial growth factor (VEGF) to isolated cells.
• Performed ligandomics on immunopanned cells to map ligand-target interactions.

Main Results:

• Ex vivo binding patterns of Scg3 and VEGF to isolated ECs mirrored in vivo observations.
• Scg3 and VEGF binding to isolated RGCs reflected their in vivo activities.
• Ligandomics confirmed Scg3 enrichment and selective binding to diabetic ECs, but not to healthy ECs or RGCs.

Conclusions:

• Ex vivo ligandomics is a feasible and broadly applicable method for cell-specific ligand discovery.
• This technique extends ligand profiling beyond vascular cells to various cell types, tissues, and diseases.
• Ex vivo ligandomics holds promise for identifying novel therapeutic targets in diverse pathological conditions.