title: Evaluation of skeletal tissue repair, part 2: enhancement of skeletal tissue repair through dual-growth-factor-releasing hydrogels within an ex vivo chick femur defect model.
abstract: There is an unmet need for improved, effective tissue engineering strategies to replace or repair bone damaged through disease or injury. Recent research has focused on developing biomaterial scaffolds capable of spatially and temporally releasing combinations of bioactive growth factors, rather than individual molecules, to recapitulate repair pathways present in vivo. We have developed an ex vivo embryonic chick femur critical size defect model and applied the model in the study of novel extracellular matrix (ECM) hydrogel scaffolds containing spatio-temporal combinatorial growth factor-releasing microparticles and skeletal stem cells for bone regeneration. Alginate/bovine bone ECM (bECM) hydrogels combined with poly(d,l-lactic-co-glycolic acid) (PDLLGA)/triblock copolymer (10-30% PDLLGA-PEG-PLDLGA) microparticles releasing dual combinations of vascular endothelial growth factor (VEGF), chondrogenic transforming growth factor beta 3 (TGF-β3) and the bone morphogenetic protein BMP2, with human adult Stro-1+bone marrow stromal cells (HBMSCs), were placed into 2mm central segmental defects in embryonic day 11 chick femurs and organotypically cultured. Hydrogels loaded with VEGF combinations induced host cell migration and type I collagen deposition. Combinations of TGF-β3/BMP2, particularly with Stro-1+HBMSCs, induced significant formation of structured bone matrix, evidenced by increased Sirius red-stained matrix together with collagen expression demonstrating birefringent alignment within hydrogels. This study demonstrates the successful use of the chick femur organotypic culture system as a high-throughput test model for scaffold/cell/growth factor therapies in regenerative medicine. Temporal release of dual growth factors, combined with enriched Stro-1+HBMSCs, improved the formation of a highly structured bone matrix compared to single release modalities. These studies highlight the potential of a unique alginate/bECM hydrogel dual growth factor release platform for bone repair.
authors.affiliation: Bone & Joint Research Group, Human Development and 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 and 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 and 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 and 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 and 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, Newcastle-under-Lyme, 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 and 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 / Q000166:cytology / Q000378:metabolism*; D001861:Bone Regeneration / Q000187:drug effects*; D002417:Cattle; D002642:Chick Embryo; D002645:Chickens; D016503:Drug Delivery Systems; 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; D019344:Lactic Acid / Q000737:chemistry / Q000494:pharmacology; D008954:Models, Biological; D011100:Polyglycolic Acid / Q000737:chemistry / Q000494:pharmacology; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism* / Q000473:pathology; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D036341:Intercellular Signaling Peptides and Proteins; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D020723:Glucuronic Acid
keywords: Bone repair; Dual growth factor delivery; ECM hydrogel scaffolds; Embryonic femur; Ex vivo model