title: TGF-β1 activation in human hamstring cells through growth factor binding peptides on polycaprolactone surfaces.
abstract: The administration of soluble growth factors (GFs) to injured tendons and ligaments (T/L) is known to promote and enhance the healing process. However, the administration of GFs is a complex, expensive and heavily-regulated process and only achieved by employing supraphysiological GF concentrations. In addition, for proper healing, specific and spatial immobilization of the GFs (s) is critical. We hypothesized that biomaterials functionalized with GF-binding peptides can be employed to capture endogenous GFs in a spatially-controlled manner, thus overcoming the need for the exogenous administration of supraphysiological doses of GFs. Here we demonstrate that the modification of films of polycaprolactone (PCL) with transforming growth factor β1 (TGF-β1)-binding peptides allows GFs to be captured and presented to the target cells. Moreover, using a TGF-β reporter cell line and immunocytochemistry, we show that the GFs retained their biological activity. In human primary tendon cells, the immobilized TGF-β1 activated TGF-β target genes ultimately lead to a 2.5-fold increase in total collagen matrix production. In vivo implantation in rats clearly shows an accumulation of TGF-β1 on the polymer films functionalized with the TGF-β1-binding peptide when compared with the native films. This accumulation leads to an increase in the recruitment of inflammatory cells at day 3 and an increase in the fibrogenic response and vascularization around the implant at day 7. The results herein presented will endow current and future medical devices with novel biological properties and by doing so will accelerate T/L healing.
  
  
  
  Our study describes the possibility to deliver hTGF-β1 to human derived hamstring cells using a non-covalent bioactive strategy. The significance of our results in vivo with our functionalized biomaterial with TGF-β1-binding peptides lies in the fact that these materials can now be employed to capture endogenous TGF-β1 in a spatially-controlled manner, overcoming the need for exogenous administration of supra-physiological TGF-β1 doses. Our method is different from current solutions that rely on global TGF-β1 administration, soaking the devices with TGF-β1, etc. Therefore we believe that our method is a significant change from current state-of-the-art in the types of devices that are used for ligament/tendon repair and that following our method can endow current and future medical devices with TGF-β1 binding properties.
authors.affiliation: Department of Developmental Bioengineering, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Drienerlolaan 5, 7500 AE Enschede, The Netherlands; Bioinspired Molecular Engineering Laboratory of the MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Hallenweg 15, 7522 NB Enschede, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Crispim
authors.affiliation: Center for Neuroscience and Cell Biology, Stem Cells and Drug Screening, University of Coimbra, Coimbra, Rua Larga, Faculty of Medicine, Pólo I, 1st floor, 3004-504 Coimbra, Portugal.
authors.forename: H A M
authors.initials: HAM
authors.lastname: Fernandes
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: S C
authors.initials: SC
authors.lastname: Fu
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Y W
authors.initials: YW
authors.lastname: Lee
authors.affiliation: Bioinspired Molecular Engineering Laboratory of the MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Hallenweg 15, 7522 NB Enschede, The Netherlands; Molecular Nanofabrication Group of the MESA+ Institute for Nanotechnology, University of Twente, Hallenweg 15, 7522 NB Enschede, The Netherlands. Electronic address: p.jonkheijm@utwente.nl.
authors.forename: P
authors.initials: P
authors.lastname: Jonkheijm
authors.affiliation: Department of Developmental Bioengineering, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Drienerlolaan 5, 7500 AE Enschede, The Netherlands; Department of Orthopaedics, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. Electronic address: d.b.f.saris@utwente.nl.
authors.forename: D B F
authors.initials: DBF
authors.lastname: Saris
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D016503:Drug Delivery Systems; D004343:Drug Implants; D015870:Gene Expression; D006801:Humans; D055767:Immobilized Proteins / Q000008:administration & dosage / Q000378:metabolism; D008297:Male; D008422:Materials Testing; D008907:Mink; D011091:Polyesters; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000378:metabolism; D051785:Smad Proteins / Q000378:metabolism; D013710:Tendons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000008:administration & dosage* / Q000378:metabolism*; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology
chemical_list: D001672:Biocompatible Materials; D004343:Drug Implants; D055767:Immobilized Proteins; D011091:Polyesters; D011994:Recombinant Proteins; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; C016240:polycaprolactone; D003094:Collagen
keywords: Growth factor binding peptide; Inflammation; TGF-β1; Tendon/Ligament; Vascularization