Bony engineering using time-release porous scaffolds to provide sustained growth factor delivery

• Published in: The Journal of craniofacial surgery Vol. 23; no. 3; p. 638
• Main Authors: Szpalski, Caroline, Nguyen, Phuong D, Cretiu Vasiliu, Cornelia E, Chesnoiu-Matei, Ioana, Ricci, John L, Clark, Elizabeth, Smay, James E, Warren, Stephen M
• Format: Journal Article
• Language: English
• Published: United States 01.05.2012
• Subjects: Adipose Tissue - cytology; Alkaline Phosphatase - metabolism; Analysis of Variance; Bone Morphogenetic Protein 2 - pharmacology; Bone Regeneration - physiology; Calcium Phosphates - pharmacology; Calcium Sulfate - pharmacology; Cell Culture Techniques; Cell Differentiation; Durapatite - pharmacology; Enzyme-Linked Immunosorbent Assay; Humans; Mesenchymal Stem Cells - metabolism; Porosity; Recombinant Proteins - pharmacology; Reverse Transcriptase Polymerase Chain Reaction; Sp7 Transcription Factor; Staining and Labeling; Tissue Engineering - instrumentation; Tissue Scaffolds; Transcription Factors - metabolism; Transforming Growth Factor beta - pharmacology
• ISSN: 1536-3732
• DOI: 10.1097/SCS.0b013e31824db8d4

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.