In vivo validation of biological responses of bFGF released from microspheres formulated by blending poly-lactide-co-glycolide and poly(ethylene glycol)-grafted-chitosan in hamster cheek pouch microcirculatory models.
Microspheres formulated from blending poly(lactide-co-glycolide) (PLGA) and poly(ethylene glycol)-grafted-chitosan (PEG-g-CHN), using a modified in-emulsion-solvent-evaporation method, were investigated for the delivery of protein. A model protein, bovine serum albumin (BSA), was incorporated into the PLGA/PEG-g-CHN microspheres and both initial burst and release kinetics could be modulated by varying the PEG-g-CHN content. Basic fibroblast growth factor (bFGF) was formulated into the microspheres containing 5% PEG-g-CHN and the bFGF contents in the releasates were determined by a receptor-based ELISA with their in vitro bioactivities validated by fibroblast cell culture. The in vivo effect of the bFGF microspheres formulation was evaluated in a hamster cheek pouch model using a 7 day exposure (e.g., before significant vascular remodeling was expected). Using intravital microscopy, the tissue showed no evidence of inflammation with any formulation; deliberate activation of a preconditioning response linked to inflammation was attenuated by BSA microspheres alone. Vasoactive responses (receptor-dependant and independent constriction and dilation) linked to nitric oxide were attenuated, and constriction to endothelin was enhanced in bFGF and not BSA containing microspheres. PLGA/PEG-g-CHN blended microspheres were also demonstrated to be non-inflammatory and non-thrombogenic in vivo by observing the vascular changes in the cheek pouch. In conclusion, the addition of PEG-g-CHN to PLGA microspheres can serve as a sustained delivery vehicle for bFGF and the released protein provides vasoactive changes consistent with chronic bFGF exposure.
Falabella
Christine A
CA
Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, NY, USA.
Jiang
Hongliang
H
Frame
Mary D
MD
Chen
Weiliam
W
D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects; D001672:Biocompatible Materials / Q000737:chemistry / Q000633:toxicity; D002417:Cattle; D002460:Cell Line; D002610:Cheek / Q000098:blood supply; D048271:Chitosan / Q000737:chemistry*; D006224:Cricetinae; D004337:Drug Carriers / Q000737:chemistry* / Q000633:toxicity; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008833:Microcirculation / Q000187:drug effects*; D008863:Microspheres; D023421:Models, Animal; D008954:Models, Biological; D011092:Polyethylene Glycols / Q000737:chemistry*; D011098:Polyglactin 910 / Q000737:chemistry*; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000378:metabolism / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D001672:Biocompatible Materials; D004337:Drug Carriers; D016222:Fibroblast Growth Factor 2; D012710:Serum Albumin, Bovine; D011098:Polyglactin 910; D011092:Polyethylene Glycols; D048271:Chitosan