Identification of Variable Lymphocyte Receptors That Target the Human Blood-Brain Barrier

Area of Science:

• Neuroscience
• Biotechnology
• Drug Delivery

Background:

• Receptor-mediated transcytosis is a key strategy for delivering therapeutics across the blood-brain barrier (BBB).
• Species-specific transporter expression at the BBB poses a challenge for translating preclinical findings to human therapies.
• Identifying human-relevant BBB targets is crucial for effective brain drug delivery.

Purpose of the Study:

• To develop a screening method for identifying human-relevant BBB targeting ligands.
• To generate and screen a library of lamprey variable lymphocyte receptors (VLRs) against human brain microvascular endothelial-like cells (BMEC-like cells).
• To validate the ability of identified VLRs to bind human BBB antigens and cross the BBB.

Main Methods:

• Generated a VLR library by immunizing lamprey with human iPSC-derived BMEC-like cells.
• Screened the VLR library using yeast surface display against human iPSC-derived BMEC-like cells.
• Validated lead VLR candidates using in vitro human models and ex vivo human and mouse brain tissue.

Main Results:

• 14 out of 15 lead VLR candidates bound to human BBB antigens.
• 10 lead VLR candidates showed binding to murine BBB antigens.
• The lead VLR candidate, VLR2G, successfully crossed the mouse BBB and delivered a neurotensin payload, demonstrating a pharmacological effect.

Conclusions:

• A novel screening technique effectively identified human-relevant VLRs targeting the BBB.
• The identified VLRs demonstrate potential for crossing the BBB and delivering therapeutic payloads.
• This approach overcomes species-specific transporter expression challenges in BBB drug delivery research.