title: Biologic activity of nerve growth factor slowly released from microspheres.
abstract: Efficient and sustained delivery of neurotrophic factors to the regenerating nerve in biologically active form presents a challenge. Protein delivery in biodegradable microsphere vehicles has been difficult, based on destabilization and breakdown during both the loading and release phases. This study examines the extravasation and stability of Nerve Growth Factor (NGF) in polylactic-co-glycolic acid (PLGA) microspheres, via both ELISA and PC-12 bioassays. PLGA microspheres co-loaded with bovine serum albumin (BSA) and NGF were prepared by a water-in-oil-in-water (W/O/W) technique, using chloroform for the organic phase and 1 percent polyvinyl alcohol (PVA) for the emulsion step. Aliquots of lyophilized microspheres were incubated in double distilled water (dd H2O) at 37 degrees C, and the supernatants assayed over time for NGF activity. ELISA was utilized for quantitative determination of NGF concentration, and a PC-12 cell neurite outgrowth assay assessed biologic activity. Both ELISA and PC-12 assays demonstrated the extravasation of NGF from microspheres. Over time, the predicted concentration of NGF via the two assays differed, suggesting possible preservation of recognizable epitopes for ELISA, but loss of biologic activity. NGF can be stored and released from microspheres. Extravasation studies should include biologically relevant assays for activity.
authors.affiliation: Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology/Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
authors.forename: Tessa A
authors.initials: TA
authors.lastname: Hadlock
authors.forename: Timothy
authors.initials: T
authors.lastname: Sheahan
authors.forename: Mack L
authors.initials: ML
authors.lastname: Cheney
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Vacanti
authors.forename: Cathryn A
authors.initials: CA
authors.lastname: Sundback
mesh_terms: D000818:Animals; D002417:Cattle; D003692:Delayed-Action Preparations / Q000493:pharmacokinetics; D004337:Drug Carriers; D016503:Drug Delivery Systems; D004797:Enzyme-Linked Immunosorbent Assay; D019344:Lactic Acid; D008863:Microspheres; D020932:Nerve Growth Factor / Q000493:pharmacokinetics*; D009416:Nerve Regeneration / Q000187:drug effects; D016716:PC12 Cells; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D051381:Rats; D012709:Serum Albumin
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011108:Polymers; D012709:Serum Albumin; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D020932:Nerve Growth Factor