title: Continuous delivery of endogenous inhibitors from poly(lactic-co-glycolic acid) polymeric microspheres inhibits glioma tumor growth.
abstract: OBJECTIVE
  There is an urgent need for modalities that can localize and prolong the administration of the antitumor agents, particularly antiangiogenic, to achieve long-term tumor inhibition. However, one of the major obstacles is designing a device in which the biological activity of sensitive endogenous inhibitors is retained. We have designed a biodegradable polymeric device, which provides a unique and practical means of localizing and continuously delivering hemopexin (PEX) or platelet factor 4 fragment (PF-4/CTF) at the tumor site while maintaining their biological activity. The potential and efficacy of this system is shown in vitro and in vivo in a human glioma mouse model.
  
  
  METHODS
  Polymeric microspheres made of poly(lactic-co-glycolic acid) (PLGA) were loaded with very low amounts of PEX and PF-4/CTF. The release profiles of these factors from PLGA and their biological activity were confirmed in vitro using proliferation assays done on endothelial and tumor cells. Tumor inhibition using this system was studied in nude mice bearing a human s.c. glioma.
  
  
  RESULTS
  PEX and PF-4/CTF released in vitro from PLGA microspheres were biologically active and significantly inhibited the proliferation of human umbilical vein endothelial cells, bovine capillary endothelial cells, and U87-MG cells. A single local s.c. injection of PLGA microspheres loaded with low amounts of PEX or PF-4/CTF resulted in an 88% and 95% reduction in glioma tumor volume 30 days post-treatment. Immunohistochemical analysis of the treated tumors showed a marked decrease in tumor vessel density compared with untreated tumors.
  
  
  CONCLUSIONS
  Our findings show that polymeric microspheres are a very promising approach to locally and efficiently deliver endogenous inhibitors to the tumor site leading to a significant inhibition of the tumor.
authors.affiliation: Laboratory of Cancer Drug Therapeutics and Mammalian Cell Technology, Faculty of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ofra
authors.initials: O
authors.lastname: Benny
authors.forename: Maayan
authors.initials: M
authors.lastname: Duvshani-Eshet
authors.forename: Theresa
authors.initials: T
authors.lastname: Cargioli
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bello
authors.forename: Andreas
authors.initials: A
authors.lastname: Bikfalvi
authors.forename: Rona S
authors.initials: RS
authors.lastname: Carroll
authors.forename: Marcelle
authors.initials: M
authors.lastname: Machluf
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002417:Cattle; D003029:Coagulants / Q000627:therapeutic use; D016503:Drug Delivery Systems; D042783:Endothelial Cells / Q000187:drug effects; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006466:Hemopexin / Q000627:therapeutic use*; D006801:Humans; D007124:Immunoenzyme Techniques; D066298:In Vitro Techniques; D019344:Lactic Acid; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008863:Microspheres; D010446:Peptide Fragments / Q000627:therapeutic use; D010978:Platelet Factor 4 / Q000627:therapeutic use*; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D014471:Umbilical Veins
chemical_list: D001672:Biocompatible Materials; D003029:Coagulants; D010446:Peptide Fragments; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D010978:Platelet Factor 4; D006466:Hemopexin