title: Sequential growth factor delivery from complexed microspheres for bone tissue engineering.
abstract: Aim of the study was to design a 3D tissue-engineering scaffold capable of sequentially delivering two bone morphogenetic proteins (BMP). The novel delivery system consisted of microspheres of polyelectrolyte complexes of poly(4-vinyl pyridine) (P(4)VN) and alginic acid loaded with the growth factors BMP-2 and BMP-7 which themselves were loaded into the scaffolds constructed of PLGA. Microspheres carrying the growth factors were prepared using polyelectrolyte solutions with different concentrations (4-10%) to control the growth factor release rate. Release kinetics was studied using albumin as the model drug and the populations that release their contents very early and very late in the release study were selected to carry BMP-2 and BMP-7, respectively. Foam porosity changed when the microspheres were loaded. Bone marrow derived stem cells (BMSC) from rats were seeded into these foams. Alkaline phosphatase (ALP) activities were found to be lowest and cell proliferation was highest at all time points with foams carrying both the microsphere populations, regardless of BMP presence. With the present doses used neither BMP-2 nor BMP-7 delivery had any direct effect on proliferation, however, they enhanced osteogenic differentiation. Co-administration of BMP enhanced osteogenic differentiation to a higher degree than with their single administration.
authors.affiliation: Middle East Technical University, BIOMAT, Department of Biological Sciences, Biotechnology Research Unit, 06531 Ankara, Turkey.
authors.forename: F Buket
authors.initials: FB
authors.lastname: Basmanav
authors.forename: Gamze T
authors.initials: GT
authors.lastname: Kose
authors.forename: Vasif
authors.initials: V
authors.lastname: Hasirci
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism*; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D016503:Drug Delivery Systems; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D007700:Kinetics; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D016062:Porosity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D023822:Tissue Engineering
chemical_list: D019485:Bone Morphogenetic Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012710:Serum Albumin, Bovine; D000469:Alkaline Phosphatase