title: Fibrin hydrogels functionalized with cartilage extracellular matrix and incorporating freshly isolated stromal cells as an injectable for cartilage regeneration.
abstract: Freshly isolated stromal cells can potentially be used as an alternative to in vitro expanded cells in regenerative medicine. Their use requires the development of bioactive hydrogels or scaffolds which provide an environment to enhance their proliferation and tissue-specific differentiation in vivo. The goal of the current study was to develop an injectable fibrin hydrogel functionalized with cartilage ECM microparticles and transforming growth factor (TGF)-β3 as a putative therapeutic for articular cartilage regeneration. ECM microparticles were produced by cryomilling and freeze-drying porcine articular cartilage. Up to 2% (w/v) ECM could be incorporated into fibrin without detrimentally affecting its capacity to form stable hydrogels. To access the chondroinductivity of cartilage ECM, we compared chondrogenesis of infrapatellar fat pad-derived stem cells in fibrin hydrogels functionalized with either particulated ECM or control gelatin microspheres. Cartilage ECM particles could be used to control the delivery of TGF-β3 to IFP-derived stem cells within fibrin hydrogels in vitro, and furthermore, led to higher levels of sulphated glycosaminoglycan (sGAG) and collagen accumulation compared to control constructs loaded with gelatin microspheres. In vivo, freshly isolated stromal cells generated a more cartilage-like tissue within fibrin hydrogels functionalized with cartilage ECM particles compared to the control gelatin loaded constructs. These tissues stained strongly for type II collagen and contained higher levels of sGAGs. These results support the use of fibrin hydrogels functionalized with cartilage ECM components in single-stage, cell-based therapies for joint regeneration.
  
  
  
  An alternative to the use of in vitro expanded cells in regenerative medicine is the use of freshly isolated stromal cells, where a bioactive scaffold or hydrogel is used to provide an environment that enhances their proliferation and tissue-specific differentiation in vivo. The objective of this study was to develop an injectable fibrin hydrogel functionalized with cartilage ECM micro-particles and the growth factor TGF-β3 as a therapeutic for articular cartilage regeneration. This study demonstrates that freshly isolated stromal cells generate cartilage tissue in vivo when incorporated into such a fibrin hydrogels functionalized with cartilage ECM particles. These findings open up new possibilities for in-theatre, single-stage, cell-based therapies for joint regeneration.
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: H V
authors.initials: HV
authors.lastname: Almeida
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland; Department of Biomedical Sciences, Sri Ramachandra University, Porur, Chennai, India.
authors.forename: R
authors.initials: R
authors.lastname: Eswaramoorthy
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: G M
authors.initials: GM
authors.lastname: Cunniffe
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: C T
authors.initials: CT
authors.lastname: Buckley
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin & Royal College of Surgeons in Ireland, Dublin 2, Ireland; Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland.
authors.forename: F J
authors.initials: FJ
authors.lastname: O'Brien
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin & Royal College of Surgeons in Ireland, Dublin 2, Ireland; Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland. Electronic address: kellyd9@tcd.ie.
authors.forename: D J
authors.initials: DJ
authors.lastname: Kelly
mesh_terms: D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000502:physiology*; D020219:Chondrogenesis; D005109:Extracellular Matrix / Q000737:chemistry*; D005260:Female; D005337:Fibrin / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D008297:Male; D012038:Regeneration; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism; D013552:Swine
chemical_list: D020100:Hydrogels; D005337:Fibrin
keywords: Articular cartilage; Extracellular matrix; Fibrin hydrogel; Growth factor; Single-stage therapy