title: Unitary bioresorbable cage/core bone graft substitutes for spinal arthrodesis coextruded from polycaprolactone biocomposites.
abstract: A unitary bioresorbable cage/core bone graft substitute consisting of a stiff cage and a softer core with interconnected porosity is offered for spinal arthrodesis. Polycaprolactone, PCL, was used as the matrix and hydroxyapatite, HA, and β-tricalcium phosphate, TCP, were used in the formulation of the cage layer to impart modulus increase and osteoconductivity while the core consisted solely of PCL. The crystallinity, biodegradation rate (under accelerated conditions) and mechanical properties, i.e., the uniaxial compression, relaxation modulus upon step compression and cyclic compressive fatigue properties, of the co-extruded cage/core bone graft substitutes could be manipulated by changes in the concentration of HA/TCP in the cage layer. The cyclic fatigue behavior of the cage/core bone graft substitutes were also compared to the behavior of bovine vertebral cancellous bone characterized under similar testing conditions. The biocompatibility of the cage/core bone graft substitutes were assessed via                         in vitro culturing of human bone marrow derived stromal cells, BMSCs. The cell proliferation rates, time dependencies of the alkaline phosphates (ALP) activity and the expressions of bone markers, i.e., Runx2, ALP, collagen type I, osteopontin and osteocalcin, and the collected μ-CT images demonstrated the differentiation of BMSCs via osteogenic lineage and formation of mineralized bone tissue to indicate the biocompatibility of the cage/core bone graft substitutes.
authors.affiliation: Department of Chemical Engineering & Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
authors.forename: Asli
authors.initials: A
authors.lastname: Ergun
authors.forename: Rebecca
authors.initials: R
authors.lastname: Chung
authors.forename: Daniel
authors.initials: D
authors.lastname: Ward
authors.forename: Antonio
authors.initials: A
authors.lastname: Valdevit
authors.forename: Arthur
authors.initials: A
authors.lastname: Ritter
authors.forename: Dilhan M
authors.initials: DM
authors.lastname: Kalyon
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D018786:Bone Substitutes / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002417:Cattle; D002478:Cells, Cultured; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D013123:Spinal Fusion; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D000943:Antigens, Differentiation; D018786:Bone Substitutes; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; D017886:Durapatite