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Brad P. Barnett, Katayoon B. Ebrahimi, Sonny E. Dike, James T. Handa; Intraocular Cell-Based Production Of Anti-VEGF In The Vitreous. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4361.
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The introduction of anti-VEGF therapy has revolutionized the treatment of exudative age-related macular degeneration. Current therapeutic regimens involve intravitreal injections on a monthly or quarterly basis. One potential strategy to minimize injection frequency would be to implant microencapsulated hybridoma cells that secrete anti-VEGF monoclonal antibody (MAb). We present here such a formulation and examine the viability of encapsulated hybridoma cells and rate of release of MAb.
Microcapsules were formed using a solution of .6% w/v ultrapurified sodium alginate with murine Anti-VEGF2 hybridoma cells adjusted to 1, 5 and 10 million cells/ml in normal saline. This solution was passed through an electrostatic droplet generator and gelled in a 100mM calcium chloride bath. Encapsulated cells were cultured in RPMI media supplemented with FBS, L-glut, G1-P and Pen/Strep. Viability of hybridoma cells was determined with a live/dead cell assay (Fig. A). Encapsulated hybridomas (n=3) or non-cell containing spheres (n=3) were injected intravitreally in rats. Antibody release during in vitro culture and one week following in vivo injection was monitored using a mouse IgG ELISA.
Encapsulated hybridomas demonstrated an average viability of 86-94% over a 14 day period in culture without a significant difference in viability for all three cell concentrations (Fig. B). Rat eyes receiving hybridoma loaded microspheres had an average MAb concentration of 73.1 ng/ml, approximately 1/3 of the current dose of 250ng/ml used in humans. Controls had negligible levels (Fig. C). Microspheres initially seeded at 10 million cells/ml showed a gradual production and release of MAb over 18 days in culture (Fig. D).
The present study demonstrated that anti-VEGF secreting hybridoma cells microencapsulated in calcium alginate survived well in culture and provided sustained MAb release. In vivo experiments demonstrated MAb release with no noted inflammation arising from intravitreal injection. Future efforts will explore the release potential over a longer time period and the associated anti-angiogenic effects.
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