Effect of Autologous Bone Marrow Stromal Cell Seeding and Bone Morphogenetic Protein-2 Delivery on Ectopic Bone Formation in a Microsphere/Poly(Propylene Fumarate) Composite

Abstract

A biodegradable microsphere=scaffold composite based on the synthetic polymer poly(propylene fumarate) (PPF) holds promise as a scaffold for cell growth and sustained delivery vehicle for growth factors for bone regeneration. The objective of the current work was to investigate the in vitro release and in vivo bone forming capacity of this microsphere=scaffold composite containing bone morphogenetic protein-2 (BMP-2) in combination with autologous bone marrow stromal cells (BMSCs) in a goat ectopic implantation model. Three composites consisting of 0, 0.08, or 8 mg BMP-2 per mg of poly(lactic-co-glycolic acid) microspheres, embedded in a porous PPF scaffold, were combined with either plasma (no cells) or culture-expanded BMSCs. PPF scaffolds impregnated with a BMP-2 solution and combined with BMSCs as well as empty PPF scaffolds were also tested. The eight different composites were implanted subcutaneously in the dorsal thoracolumbar area of goats. Incorporation of BMP-2-loaded microspheres in the PPF scaffold resulted in a more sustained in vitro release with a lower burst phase, as compared to BMP-2-impregnated scaffolds. Histological analysis after 9 weeks of implantation showed bone formation in the pores of 11=16 composites containing 8 mg=mg BMP-2-loaded microspheres with no significant difference between composites with or without BMSCs (6=8 and 5=8, respectively). Bone formation was also observed in 1=8 of the BMP-2-impregnated scaffolds. No bone formation was observed in the other conditions. Overall, this study shows the feasibility of bone induction by BMP-2 release from microspheres=scaffold composites.

Retention of in vitro and in vivo BMP-2 bioactivities in sustained delivery vehicles for bone tissue engineering

“…The intermediate dimer was polymerized to PPF via condensation under vacuum at 130 °C for another 4 h. The microsphere/PPF composites (Implant 3) were fabricated by photocrosslinking PPF with N-vinylpyrrolidinone (NVP, Acros, Pittsburgh, PA) using bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide (BAPO, Ciba Specialty Chemicals, Tarrytown, NY). [27,31] Briefly, 1.0 g of PPF and 50 µl of a 100 mg/ml BAPO/dichloromethane solution were dissolved in 0.5 ml of NVP. The PPF/NVP/BAPO paste (45 wt%) was mixed with PLGA microspheres (55 wt%) and mixed using a spatula.…”

Ligament Tissue Engineering Using a Novel Porous Polycaprolactone Fumarate Scaffold and Adipose Tissue-Derived Mesenchymal Stem Cells Grown in Platelet Lysate

“…In a previous investigation, we were able to embed PLGA microspheres containing bone morphogenetic protein-2 (BMP-2) into PPF scaffolds and seeded with bone marrow stromal cells (BMSCs). 33 However, this cytocompatibility was not limited to PPF and PLGA, as PCLF is also very compatible with many different cell types. Given the ability to modify the mechanical properties and geometric properties of PCLF, it is an appealing biomaterial for use in connective tissue engineering applications.…”

Evaluation of Osteoconductive Scaffolds in the Canine Femoral Multi-Defect Model

“…The bulk polymer materials that were evaluated included 70:30 Poly(L-lactide-co-e-caprolactone) (PLCL; Boehringer [30][31][32][33] Supplementary data describing more details on the PPF material synthesis and fabrication is available online at www.liebertpub.com/tea. All scaffolds were manufactured using previously defined methods into cylinders with dimensions of 0.99 cm diameter and 1.5 cm height.…”