title: Controlled release of IGF-1 and HGF from a biodegradable polyurethane scaffold.
abstract: OBJECTIVE
  Biodegradable elastomers, which can possess favorable mechanical properties and degradation rates for soft tissue engineering applications, are more recently being explored as depots for biomolecule delivery. The objective of this study was to synthesize and process biodegradable, elastomeric poly(ester urethane)urea (PEUU) scaffolds and to characterize their ability to incorporate and release bioactive insulin-like growth factor-1 (IGF-1) and hepatocyte growth factor (HGF).
  
  
  METHODS
  Porous PEUU scaffolds made from either 5 or 8 wt% PEUU were prepared with direct growth-factor incorporation. Long-term in vitro IGF-1 release kinetics were investigated in saline or saline with 100 units/ml lipase to simulate in vivo degradation. Cellular assays were used to confirm released IGF-1 and HGF bioactivity.
  
  
  RESULTS
  IGF-1 release into saline occurred in a complex multi-phasic manner for up to 440 days. Scaffolds generated from 5 wt% PEUU delivered protein faster than 8 wt% scaffolds. Lipase-accelerated scaffold degradation led to delivery of >90% protein over 9 weeks for both polymer concentrations. IGF-1 and HGF bioactivity in the first 3 weeks was confirmed.
  
  
  CONCLUSIONS
  The capacity of a biodegradable elastomeric scaffold to provide long-term growth-factor delivery was demonstrated. Such a system might provide functional benefit in cardiovascular and other soft tissue engineering applications.
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Devin M
authors.initials: DM
authors.lastname: Nelson
authors.forename: Priya R
authors.initials: PR
authors.lastname: Baraniak
authors.forename: Zuwei
authors.initials: Z
authors.lastname: Ma
authors.forename: Jianjun
authors.initials: J
authors.lastname: Guan
authors.forename: N Scott
authors.initials: NS
authors.lastname: Mason
authors.forename: William R
authors.initials: WR
authors.lastname: Wagner
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D041702:BALB 3T3 Cells; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000138:chemical synthesis; D002460:Cell Line; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems / Q000379:methods; D020724:Elastomers / Q000008:administration & dosage / Q000138:chemical synthesis; D017228:Hepatocyte Growth Factor / Q000008:administration & dosage*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage*; D051379:Mice; D011091:Polyesters / Q000008:administration & dosage* / Q000138:chemical synthesis; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D020724:Elastomers; D011091:Polyesters; C497893:poly(ester urethane)urea; D017228:Hepatocyte Growth Factor; D007334:Insulin-Like Growth Factor I