title: Biodegradable PELA block copolymers: in vitro degradation and tissue reaction.
abstract: Degradation of, and tissue reaction elicited by a series of polyethylene oxide (PEO)/polylactic acid (PLA) PELA block copolymers were studied in vitro and in vivo. In particular, the effect of pH, temperature and enzymatic activity was addressed. The mass loss was faster, the more basic the media, while, expectedly, PELA copolymers degraded faster with the higher temperature. The addition of an enzyme (carboxylic ester hydrolase) had no effect. The degradation process strongly affected the mechanical properties of the materials under investigation, the elongation at break dropping drastically after two days of degradation. After seven days, only gross observation of the extensively degraded samples was possible. The in vivo studies compared the tissue reaction elicited by various PELA copolymers to that evoked by PLA. Evaluation of tissue reaction observed with a PELA sample after sterilization with gamma radiation showed acute inflammation with considerable dispersion of the material, 12 days after implantation. The granulomatous reaction observed with PELA copolymers after ethylene oxide sterilization was identical to the reaction observed with PLA.
authors.affiliation: Casali Institute of Applied Chemistry, Hebrew University of Jerusalem, Israel.
authors.forename: H
authors.initials: H
authors.lastname: Younes
authors.forename: P R
authors.initials: PR
authors.lastname: Nataf
authors.forename: D
authors.initials: D
authors.lastname: Cohn
authors.forename: Y J
authors.initials: YJ
authors.lastname: Appelbaum
authors.forename: G
authors.initials: G
authors.lastname: Pizov
authors.forename: G
authors.initials: G
authors.lastname: Uretzky
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism* / Q000633:toxicity; D001673:Biodegradation, Environmental; D001696:Biomechanical Phenomena; D005260:Female; D005549:Foreign-Body Reaction / Q000473:pathology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism* / Q000633:toxicity; D019344:Lactic Acid; D008297:Male; D008422:Materials Testing; D011091:Polyesters; D011092:Polyethylene Glycols / Q000378:metabolism* / Q000633:toxicity; D011108:Polymers / Q000378:metabolism* / Q000633:toxicity; D011817:Rabbits; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D007773:Lactates; D011091:Polyesters; D011108:Polymers; C058523:polyethylene oxide-polylactic acid block copolymer; D019344:Lactic Acid; D011092:Polyethylene Glycols; C033616:poly(lactide)