title: Retention of insulin-like growth factor I bioactivity during the fabrication of sintered polymeric scaffolds.
abstract: The use of growth factors in tissue engineering offers an added benefit to cartilage regeneration. Growth factors, such as insulin-like growth factor I (IGF-I), increase cell proliferation and can therefore decrease the time it takes for cartilage tissue to regrow. In this study, IGF-I was released from poly(lactic-co-glycolic acid) (PLGA) scaffolds that were designed to have a decreased burst release often associated with tissue engineering scaffolds. The scaffolds were fabricated from IGF-I-loaded PLGA microspheres prepared by a double emulsion (W1/O/W2) technique. The microspheres were then compressed, sintered at 49 °C and salt leached. The bioactivity of soluble IGF-I was verified after being heat treated at 37, 43, 45, 49 and 60 °C. Additionally, the bioactivity of IGF-I was confirmed after being released from the sintered scaffolds. The triphasic release lasted 120 days resulting in 20%, 55% and 25% of the IGF-I being released during days 1-3, 4-58 and 59-120, respectively. Seeding bone marrow cells directly onto the IGF-I-loaded scaffolds showed an increase in cell proliferation, based on DNA content, leading to increased glycosaminoglycan production. The present results demonstrated that IGF-I remains active after being incorporated into heat-treated scaffolds, further enhancing tissue regeneration possibilities.
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA.
authors.forename: Amanda
authors.initials: A
authors.lastname: Clark
authors.forename: Todd A
authors.initials: TA
authors.lastname: Milbrandt
authors.forename: J Zach
authors.initials: JZ
authors.lastname: Hilt
authors.forename: David A
authors.initials: DA
authors.lastname: Puleo
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001854:Bone Marrow Cells / Q000166:cytology; D002356:Cartilage / Q000473:pathology; D002460:Cell Line; D049109:Cell Proliferation; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000737:chemistry*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D019344:Lactic Acid / Q000737:chemistry; D008863:Microspheres; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration; D012492:Salts / Q000737:chemistry; D017154:Stromal Cells / Q000166:cytology; D013696:Temperature; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D036341:Intercellular Signaling Peptides and Proteins; D012492:Salts; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D007334:Insulin-Like Growth Factor I