title: Amino-functionalized poly(L-lactide) lamellar single crystals as a valuable substrate for delivery of HPV16-E7 tumor antigen in vaccine development.
abstract: BACKGROUND
  Poly(L-lactide) (PLLA) is a biodegradable polymer currently used in many biomedical applications, including the production of resorbable surgical devices, porous scaffolds for tissue engineering, nanoparticles and microparticles for the controlled release of drugs or antigens. The surfaces of lamellar PLLA single crystals (PLLAsc) were provided with amino groups by reaction with a multifunctional amine and used to adsorb an Escherichia coli-produced human papillomavirus (HPV)16-E7 protein to evaluate its possible use in antigen delivery for vaccine development.
  
  
  METHODS
  PLLA single crystals were made to react with tetraethylenepentamine to obtain amino-functionalized PLLA single crystals (APLLAsc). Pristine and amino-functionalized PLLAsc showed a two-dimensional microsized and one-dimensional nanosized lamellar morphology, with a lateral dimension of about 15-20 μm, a thickness of about 12 nm, and a surface specific area of about 130 m(2)/g. Both particles were characterized and loaded with HPV16-E7 before being administered to C57BL/6 mice for immunogenicity studies. The E7-specific humoral-mediated and cell-mediated immune response as well as tumor protective immunity were analyzed in mice challenged with TC-1 cancer cells.
  
  
  RESULTS
  Pristine and amino-functionalized PLLAsc adsorbed similar amounts of E7 protein, but in protein-release experiments E7-PLLAsc released a higher amount of protein than E7-APLLAsc. When the complexes were dried for observation by scanning electron microscopy, both samples showed a compact layer, but E7-APLLAsc showed greater roughness than E7-PLLAsc. Immunization experiments in mice showed that E7-APLLAsc induced a stronger E7-specific immune response when compared with E7-PLLAsc. Immunoglobulin G isotyping and interferon gamma analysis suggested a mixed Th1/Th2 immune response in both E7-PLLAsc-immunized and E7-APLLAsc-immunized mice. However, only the mice receiving E7-APLLAsc were fully protected from TC-1 tumor growth after three doses of vaccine.
  
  
  CONCLUSIONS
  Our results show that APLLA single crystals improve the immunogenicity of HPV16-E7 and indicate that E7-APLLAsc could be used for development of an HPV16 therapeutic vaccine against HPV16-related tumors.
authors.affiliation: Department of Infectious, Parasitic and Immune-mediated Diseases, Italian National Institute of Health, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Di Bonito
authors.affiliation: Department of Infectious, Parasitic and Immune-mediated Diseases, Italian National Institute of Health, Rome, Italy.
authors.forename: Linda
authors.initials: L
authors.lastname: Petrone
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Rome, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Casini
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Rome, Italy.
authors.forename: Iolanda
authors.initials: I
authors.lastname: Francolini
authors.affiliation: Department of Technology and Health, Italian National Institute of Health, Rome, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Ammendolia
authors.affiliation: Department of Infectious, Parasitic and Immune-mediated Diseases, Italian National Institute of Health, Rome, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Accardi
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Rome, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Piozzi
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Rome, Italy.
authors.forename: Lucio
authors.initials: L
authors.lastname: D'Ilario
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Martinelli
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology; D016503:Drug Delivery Systems / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics; D005029:Ethylenediamines / Q000737:chemistry; D005260:Female; D007111:Immunity, Cellular; D007114:Immunization; D007074:Immunoglobulin G; D051379:Mice; D008810:Mice, Inbred C57BL; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D050725:Papillomavirus E7 Proteins / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D053918:Papillomavirus Vaccines / Q000276:immunology*; D011091:Polyesters / Q000008:administration & dosage / Q000737:chemistry*
chemical_list: D000951:Antigens, Neoplasm; D005029:Ethylenediamines; D007074:Immunoglobulin G; D050725:Papillomavirus E7 Proteins; D053918:Papillomavirus Vaccines; D011091:Polyesters; C059731:oncogene protein E7, Human papillomavirus type 16; C033616:poly(lactide); C034269:tetraethylenepentamine
keywords: HPV16-E7; human papillomavirus; lamellar crystals; poly(l-lactide); therapeutic vaccine