title: Release and bioactivity of bone morphogenetic protein-2 are affected by scaffold binding techniques in vitro and in vivo.
abstract: A low dose of 1μg rhBMP-2 was immobilised by four different functionalising techniques on recently developed poly(l-lactide)-co-(ε-caprolactone) [(poly(LLA-co-CL)] scaffolds. It was either (i) physisorbed on unmodified scaffolds [PHY], (ii) physisorbed onto scaffolds modified with nanodiamond particles [nDP-PHY], (iii) covalently linked onto nDPs that were used to modify the scaffolds [nDP-COV] or (iv) encapsulated in microspheres distributed on the scaffolds [MICS]. Release kinetics of BMP-2 from the different scaffolds was quantified using targeted mass spectrometry for up to 70days. PHY scaffolds had an initial burst of release while MICS showed a gradual and sustained increase in release. In contrast, NDP-PHY and nDP-COV scaffolds showed no significant release, although nDP-PHY scaffolds maintained bioactivity of BMP-2. Human mesenchymal stem cells cultured in vitro showed upregulated BMP-2 and osteocalcin gene expression at both week 1 and week 3 in the MICS and nDP-PHY scaffold groups. These groups also demonstrated the highest BMP-2 extracellular protein levels as assessed by ELISA, and mineralization confirmed by Alizarin red. Cells grown on the PHY scaffolds in vitro expressed collagen type 1 alpha 2 early but the scaffold could not sustain rhBMP-2 release to express mineralization. After 4weeks post-implantation using a rat mandible critical-sized defect model, micro-CT and Masson trichrome results showed accelerated bone regeneration in the PHY, nDP-PHY and MICS groups. The results demonstrate that PHY scaffolds may not be desirable for clinical use, since similar osteogenic potential was not seen under both in vitro and in vivo conditions, in contrast to nDP-PHY and MICS groups, where continuous low doses of BMP-2 induced satisfactory bone regeneration in both conditions. The nDP-PHY scaffolds used here in critical-sized bone defects for the first time appear to have promise compared to growth factors adsorbed onto a polymer alone and the short distance effect prevents adverse systemic side effects.
authors.affiliation: Department of Clinical Dentistry, Center for Clinical Dental Research, University of Bergen, Norway. Electronic address: salwa.suliman@iko.uib.no.
authors.forename: Salwa
authors.initials: S
authors.lastname: Suliman
authors.affiliation: Department of Clinical Dentistry, Center for Clinical Dental Research, University of Bergen, Norway.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Xing
authors.affiliation: Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Xujun
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Clinical Dentistry, Center for Clinical Dental Research, University of Bergen, Norway.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Department of Clinical Dentistry, Center for Clinical Dental Research, University of Bergen, Norway.
authors.forename: Torbjorn O
authors.initials: TO
authors.lastname: Pedersen
authors.affiliation: Department of Fibre and Polymer Technology, Royal Institute of Technology, KTH, Stockholm, Sweden.
authors.forename: Yang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Biomedicine, University of Bergen, Norway.
authors.forename: Anne P
authors.initials: AP
authors.lastname: Døskeland
authors.affiliation: Chair Tissue Engineering and Regenerative Medicine, University Hospital of Würzburg, Germany; Fraunhofer Project Group Regenerative Technologies in Oncology, Würzburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Nickel
authors.affiliation: Institute of Organic Chemistry, University of Würzburg, Würzburg, Germany.
authors.forename: Thilo
authors.initials: T
authors.lastname: Waag
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Henning
authors.initials: H
authors.lastname: Lygre
authors.affiliation: Department of Fibre and Polymer Technology, Royal Institute of Technology, KTH, Stockholm, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Finne-Wistrand
authors.affiliation: DiaCoating GmbH, Innsbruck, Austria.
authors.forename: Doris
authors.initials: D
authors.lastname: Steinmüller-Nethl
authors.affiliation: Institute of Organic Chemistry, University of Würzburg, Würzburg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Krueger
authors.affiliation: Department of Clinical Dentistry, Center for Clinical Dental Research, University of Bergen, Norway. Electronic address: kamal.mustafa@iko.uib.no.
authors.forename: Kamal
authors.initials: K
authors.lastname: Mustafa
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001861:Bone Regeneration / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D008863:Microspheres; D011091:Polyesters / Q000737:chemistry; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D054457:Tissue Scaffolds
chemical_list: D055396:Bone Morphogenetic Protein 2; D011091:Polyesters; C062968:lactide-caprolactone copolymer
keywords: Benzoquinone (PubChem CID: 4650); Caprolactone (PubChem CID 10401); Copolymer scaffold; Drug delivery; Functionalization; Growth factor; Nanodiamond; Tissue engineering; l-lactide (PubChem CID: 107983)