Nanobody-based gene therapy targeting complement component C3 reduces choroidal neovascularization in mice

Area of Science:

• Ophthalmology
• Immunology
• Gene Therapy

Background:

• Wet age-related macular degeneration (wAMD) is a primary cause of vision impairment, characterized by choroidal neovascularization (CNV).
• Current treatments for CNV are insufficient, necessitating novel therapeutic strategies.
• The complement system's overactivation plays a key role in wAMD pathogenesis and retinal damage.

Purpose of the Study:

• To develop and evaluate a gene therapy approach using a nanobody targeting the alternative complement pathway for wAMD treatment.
• To assess the safety and efficacy of expressing the nanobody hC3Nb1 within the eye.

Main Methods:

• Generation of a lentiviral vector for co-expression of hC3Nb1 and eGFP.
• In vitro assessment of hC3Nb1's complement inhibition activity.
• Subretinal injection of the vector in mice to confirm expression, secretion, and safety.
• In vitro and in vivo evaluation of therapeutic effects on retinal pigment epithelium (RPE) and laser-induced CNV.

Main Results:

• The hC3Nb1 nanobody was efficiently expressed and secreted by mammalian cells, inhibiting both alternative and classical complement pathways in vitro.
• Subretinal delivery of the vector resulted in safe and sustained hC3Nb1 expression and secretion from RPE cells in mice.
• Vector-encoded hC3Nb1 protected RPE cells from complement-mediated damage in vitro and reduced CNV size in vivo.

Conclusions:

• Nanobody-based gene therapy represents a novel therapeutic strategy for wAMD.
• This approach demonstrates potential for safe, long-acting treatment of wAMD and other complement-mediated chorioretinal diseases.