title: Optimization of encapsulation of a synthetic long peptide in PLGA nanoparticles: low-burst release is crucial for efficient CD8(+) T cell activation.
abstract: Overlapping synthetic long peptides (SLPs) hold great promise for immunotherapy of cancer. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) are being developed as delivery systems to improve the potency of peptide-based therapeutic cancer vaccines. Our aim was to optimize PLGA NP for SLP delivery with respect to encapsulation and release, using OVA24, a 24-residue long synthetic antigenic peptide covering a CTL epitope of ovalbumin (SIINFEKL), as a model antigen. Peptide-loaded PLGA NPs were prepared by a double emulsion/solvent evaporation technique. Using standard conditions (acidic inner aqueous phase), we observed that either encapsulation was very low (1-30%), or burst release extremely high (>70%) upon resuspension of NP in physiological buffers. By adjusting formulation and process parameters, we uncovered that the pH of the first emulsion was critical to efficient encapsulation and controlled release. In particular, an alkaline inner aqueous phase resulted in circa 330 nm sized NP with approximately 40% encapsulation efficiency and low (<10%) burst release. These NP showed enhanced MHC class I restricted T cell activation in vitro when compared to high-burst releasing NP and soluble OVA24, proving that efficient entrapment of the antigen is crucial to induce a potent cellular immune response.
authors.affiliation: Division of Drug Delivery Technology, Leiden/Amsterdam Center for Drug Research, Leiden, The Netherlands.
authors.forename: A L
authors.initials: AL
authors.lastname: Silva
authors.forename: R A
authors.initials: RA
authors.lastname: Rosalia
authors.forename: A
authors.initials: A
authors.lastname: Sazak
authors.forename: M G
authors.initials: MG
authors.lastname: Carstens
authors.forename: F
authors.initials: F
authors.lastname: Ossendorp
authors.forename: J
authors.initials: J
authors.lastname: Oostendorp
authors.forename: W
authors.initials: W
authors.lastname: Jiskoot
mesh_terms: D000595:Amino Acid Sequence; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019344:Lactic Acid / Q000737:chemistry*; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D053758:Nanoparticles; D010455:Peptides / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer
chemical_list: D010455:Peptides; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid