title: Biodegradation and in vivo biocompatibility of a degradable, polar/hydrophobic/ionic polyurethane for tissue engineering applications.
abstract: A degradable, polar/hydrophobic/ionic polyurethane (D-PHI) scaffold was optimized in in vitro studies to yield mechanical properties appropriate to replicate vascular graft tissue while eliciting a more wound-healing phenotype macrophage when compared to established materials. The objectives of this study were to characterize the biodegradation (in vitro and in vivo) and assess the in vivo biocompatibility of D-PHI, comparing it to a well-established, commercially-available scaffold biomaterial, polylactic glycolic acid (PLGA), recognized as being degradable, non-cytotoxic, and showing good biocompatibility. PLGA and D-PHI were formed into 6 mm diameter disk-shaped scaffolds (2 mm thick) of similar porosity (∼82%) and implanted subcutaneously in rats. Both PLGA and D-PHI scaffolds were well-tolerated at the 7 d time point in vivo. In vitro D-PHI scaffolds degraded slowly (only 12 wt% in PBS in vitro after 120 d at 37 °C). In vivo, D-PHI scaffolds degraded at a more controlled rate (7 wt% loss over the acute 7 d implant phase and subsequently a linear profile of degradation leading to a 21 wt% mass loss by 100 d (chronic period)) than PLGA scaffolds which showed an initial more rapid degradation (14 wt% over 7 d), followed by minimal change between 7 and 30 d, and then a very rapid breakdown of the scaffold over the next 60 d. Histological examination of D-PHI scaffolds showed tissue ingrowth into the pores increased with time whereas PLGA scaffolds excluded cells/tissue from its porous structure as it degraded. The results of this study suggest that D-PHI has promising qualities for use as an elastomeric scaffold material for soft TE applications yielding well integrated tissue within the scaffold and a controlled rate of degradation stabilizing the form and shape of the implant.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5G1G6, Canada.
authors.forename: Joanne E
authors.initials: JE
authors.lastname: McBane
authors.forename: Soroor
authors.initials: S
authors.lastname: Sharifpoor
authors.forename: Kuihua
authors.initials: K
authors.lastname: Cai
authors.forename: Rosalind S
authors.initials: RS
authors.lastname: Labow
authors.forename: J Paul
authors.initials: JP
authors.lastname: Santerre
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects* / Q000378:metabolism*; D008297:Male; D008855:Microscopy, Electron, Scanning; D011140:Polyurethanes / Q000009:adverse effects / Q000378:metabolism*; D016062:Porosity; D051381:Rats; D017208:Rats, Wistar; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D011140:Polyurethanes