title: Evaluation of skeletal tissue repair, part 1: assessment of novel growth-factor-releasing hydrogels in an ex vivo chick femur defect model.
abstract: Current clinical treatments for skeletal conditions resulting in large-scale bone loss include autograft or allograft, both of which have limited effectiveness. In seeking to address bone regeneration, several tissue engineering strategies have come to the fore, including the development of growth factor releasing technologies and appropriate animal models to evaluate repair. Ex vivo models represent a promising alternative to simple in vitro systems or complex, ethically challenging in vivo models. We have developed an ex vivo culture system of whole embryonic chick femora, adapted in this study as a critical size defect model to investigate the effects of novel bone extracellular matrix (bECM) hydrogel scaffolds containing spatio-temporal growth factor-releasing microparticles and skeletal stem cells on bone regeneration, to develop a viable alternative treatment for skeletal degeneration. Alginate/bECM hydrogels combined with poly (d,l-lactic-co-glycolic acid) (PDLLGA)/triblock copolymer (10-30% PDLLGA-PEG-PDLLGA) microparticles releasing VEGF, TGF-β3 or BMP-2 were placed, with human adult Stro-1+ bone marrow stromal cells, into 2mm central segmental defects in embryonic chick femurs. Alginate/bECM hydrogels loaded with HSA/VEGF or HSA/TGF-β3 demonstrated a cartilage-like phenotype, with minimal collagen I deposition, comparable to HSA-only control hydrogels. The addition of BMP-2 releasing microparticles resulted in enhanced structured bone matrix formation, evidenced by increased Sirius red-stained matrix and collagen expression within hydrogels. This study demonstrates delivery of bioactive growth factors from a novel alginate/bECM hydrogel to augment skeletal tissue formation and the use of an organotypic chick femur defect culture system as a high-throughput test model for scaffold/cell/growth factor therapies for regenerative medicine.
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK. Electronic address: E.L.Smith@soton.ac.uk.
authors.forename: E L
authors.initials: EL
authors.lastname: Smith
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Kanczler
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK.
authors.forename: D
authors.initials: D
authors.lastname: Gothard
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Roberts
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Wells
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: L J
authors.initials: LJ
authors.lastname: White
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: O
authors.initials: O
authors.lastname: Qutachi
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Sawkins
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: H
authors.initials: H
authors.lastname: Peto
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: H
authors.initials: H
authors.lastname: Rashidi
authors.affiliation: Department of Materials, Imperial College London, London, UK; Institute for Biomedical Engineering, Imperial College London, London, UK; Institute of Polymer Science & Technology, CSIC and CIBER-BBN, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Rojo
authors.affiliation: Department of Materials, Imperial College London, London, UK; Institute for Biomedical Engineering, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, London, UK.
authors.forename: M M
authors.initials: MM
authors.lastname: Stevens
authors.affiliation: Institute for Science and Technology in Medicine, School of Medicine, Keele University, Keele, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: El Haj
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK.
authors.forename: F R A J
authors.initials: FR
authors.lastname: Rose
authors.affiliation: The Wolfson Centre for Stem Cells, Tissue Engineering & Modelling (STEM), School of Pharmacy, University of Nottingham, Nottingham, UK. Electronic address: kevin.shakesheff@nottingham.ac.uk.
authors.forename: K M
authors.initials: KM
authors.lastname: Shakesheff
authors.affiliation: Bone & Joint Research Group, Human Development & Health, Institute of Developmental Sciences, University of Southampton, Southampton, UK. Electronic address: roco@soton.ac.uk.
authors.forename: R O C
authors.initials: RO
authors.lastname: Oreffo
mesh_terms: D000328:Adult; D000464:Alginates / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000473:pathology; D001861:Bone Regeneration; D002417:Cattle; D002645:Chickens; D005109:Extracellular Matrix / Q000737:chemistry; D005269:Femur / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D020723:Glucuronic Acid / Q000737:chemistry / Q000494:pharmacology; D006603:Hexuronic Acids / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D020100:Hydrogels / Q000737:chemistry / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000494:pharmacology; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism* / Q000473:pathology; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D036341:Intercellular Signaling Peptides and Proteins; D020723:Glucuronic Acid
keywords: Bioactive growth factor delivery; Bone repair; ECM hydrogel scaffolds; Embryonic femur; Ex vivo model