title: In vivo evaluation of injectable thermosensitive polymer with time-dependent LCST.
abstract: The focus of this study was to examine the biocompatibility, time-dependent LCST, and bioerodable properties of a copolymer system composed of NIPAAm, dimethyl-gamma-butyrolactone (DMBL), and acrylic acid (AAc). Sprague Dawley rats were subcutaneously injected with 25 wt % solutions of poly(NIPAAm-co-DMBL-co-AAc). At predetermined times, animals were sacrificed and polymer implants were recovered for characterization via 1H-NMR. In addition, polymer-contacting tissue sections were harvested and processed for histology. The biocompatibility of the implants was assessed by counting the number of fibroblasts and leukocytes present at the tissue-implant interface. The LCST data obtained from the in vivo implants was shown to agree with that of in vitro findings. Implant mass was shown to decrease after 4 days, indicating accelerated diffusion rates with increased implant swelling, hydrolytic degradation was confirmed with 1H-NMR measurements. The cellular presence at the copolymer implant-tissue interface was shown to return to that of normal tissue 30 days postimplantation, which suggests a normal wound healing response.
authors.affiliation: Harrington Department of Bioengineering, Center for Interventional Biomaterials, Arizona State University, Tempe, Arizona 85287-9709, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Henderson
authors.forename: Bae Hoon
authors.initials: BH
authors.lastname: Lee
authors.forename: Zhanwu
authors.initials: Z
authors.lastname: Cui
authors.forename: Ryan
authors.initials: R
authors.lastname: McLemore
authors.forename: Tedd A
authors.initials: TA
authors.lastname: Brandon
authors.forename: Brent L
authors.initials: BL
authors.lastname: Vernon
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage*; D002452:Cell Count; D004058:Diffusion; D005347:Fibroblasts / Q000166:cytology; D006358:Hot Temperature; D006868:Hydrolysis; D020007:Implants, Experimental / Q000592:standards*; D007267:Injections; D007962:Leukocytes / Q000166:cytology; D008422:Materials Testing; D011108:Polymers / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014945:Wound Healing
chemical_list: D001672:Biocompatible Materials; D011108:Polymers