title: Bony engineering using time-release porous scaffolds to provide sustained growth factor delivery.
abstract: Microporous scaffolds designed to improve bony repair have had limited success; therefore, we sought to evaluate whether time-released porous scaffolds with or without recombinant bone morphogenetic protein 2 (rhBMP-2) could enhance stem cell osteoinduction. Custom-made 15/85 hydroxyapatite/β-tricalcium phosphate scaffolds were left empty (E) or filled with rhBMP-2 (E+), calcium sulfate (CS), or CS and rhBMP-2 (CS+). All scaffolds were placed in media and weighed daily. Conditioned supernatant was analyzed for rhBMP-2 and then used to feed human adipose-derived mesenchymal stem cells (ASCs). Adipose-derived mesenchymal stem cell ALP activity, OSTERIX expression, and bone nodule formation were determined. E scaffolds retained 97% (SD, 2%) of the initial weight, whereas CS scaffolds had a near-linear 30% (SD, 3%) decrease over 60 days. E+ scaffolds released 155 (SD, 5) ng of rhBMP-2 (77%) by day 2. In contrast, CS+ scaffolds released only 30 (SD, 2) ng (10%) by day 2, and the remaining rhBMP-2 was released over 20 days. Conditioned media from E+ scaffolds stimulated the highest ALP activity and OSTERIX expression in ACSs on day 2. However, after day 6, media from CS+ scaffolds stimulated the highest ALP activity and OSTERIX expression in ASCs. Adipose-derived mesenchymal stem cells exposed to day 8 CS+-conditioned media produced significantly more bone nodules (10.1 [SD, 1.7] nodules per high-power field) than all other scaffolds. Interestingly, day 8 conditioned media from CS scaffolds simulated significantly more bone nodules than either E or E+ scaffold (P < 0.05 for both). Time-released hydroxyapatite/β-tricalcium phosphate porosity provides sustained growth factor release, enhances ASC osteoinduction, and may result in better in vivo bone formation.
authors.affiliation: Department of Plastic Surgery, New York University Langone Medical Center, New York, NY, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Szpalski
authors.forename: Phuong D
authors.initials: PD
authors.lastname: Nguyen
authors.forename: Cornelia E
authors.initials: CE
authors.lastname: Cretiu Vasiliu
authors.forename: Ioana
authors.initials: I
authors.lastname: Chesnoiu-Matei
authors.forename: John L
authors.initials: JL
authors.lastname: Ricci
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Clark
authors.forename: James E
authors.initials: JE
authors.lastname: Smay
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Warren
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000469:Alkaline Phosphatase / Q000378:metabolism; D000704:Analysis of Variance; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D001861:Bone Regeneration / Q000502:physiology*; D002130:Calcium Phosphates / Q000494:pharmacology*; D002133:Calcium Sulfate / Q000494:pharmacology; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D017886:Durapatite / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D016062:Porosity; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000076182:Sp7 Transcription Factor; D013194:Staining and Labeling; D023822:Tissue Engineering / Q000295:instrumentation*; D054457:Tissue Scaffolds; D014157:Transcription Factors / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D055396:Bone Morphogenetic Protein 2; D002130:Calcium Phosphates; D011994:Recombinant Proteins; D000076182:Sp7 Transcription Factor; C478163:SP7 protein, human; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C485817:beta-tricalcium phosphate; C499469:recombinant human bone morphogenetic protein-2; D017886:Durapatite; D000469:Alkaline Phosphatase; D002133:Calcium Sulfate