Biocompatibility and Bone Formation of Flexible, Cotton Wool-like PLGA/Calcium Phosphate Nanocomposites in Sheep

Oliver D Schneider 1, Dirk Mohn 1, Roland Fuhrer 1, Karina Klein 2, Käthi Kämpf 2, Katja M.R Nuss 2, Michèle Sidler 2, Katalin Zlinszky 2, Brigitte von Rechenberg 2, 3, Wendelin J Stark*, 1, 3
1 Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
2 Musculoskeletal Research Unit (MSRU), Equine Hospital, University of Zurich, 8057 Zurich, Switzerland
3 Center of Applied Biotechnology and Molecular Medicine (CABMM), Equine Hospital, Vetsuisse Faculty, 8057 Zurich, Switzerland

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© Schneider et al.; Licensee Bentham Open.

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* Address correspondence to this author at the ETH Zurich, Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, Wolfgang-Pauli-Str. 10, HCI E 107, 8093 Zurich, Switzerland; Tel: +41 44 632 09 80; Fax: +41 44 633 10 83; E-mail:



The purpose of this preliminary study was to assess the in vivo performance of synthetic, cotton wool-like nanocomposites consisting of a biodegradable poly(lactide-co-glycolide) fibrous matrix and containing either calcium phosphate nanoparticles (PLGA/CaP 60:40) or silver doped CaP nanoparticles (PLGA/Ag-CaP 60:40). Besides its extraordinary in vitro bioactivity the latter biomaterial (0.4 wt% total silver concentration) provides additional antimicrobial properties for treating bone defects exposed to microorganisms.

Materials and Methods:

Both flexible artificial bone substitutes were implanted into totally 16 epiphyseal and metaphyseal drill hole defects of long bone in sheep and followed for 8 weeks. Histological and histomorphological analyses were conducted to evaluate the biocompatibility and bone formation applying a score system. The influence of silver on the in vivo performance was further investigated.


Semi-quantitative evaluation of histology sections showed for both implant materials an excellent biocompatibility and bone healing with no resorption in the adjacent bone. No signs of inflammation were detectable, either macroscopically or microscopically, as was evident in 5 µm plastic sections by the minimal amount of inflammatory cells. The fibrous biomaterials enabled bone formation directly in the centre of the former defect. The area fraction of new bone formation as determined histomorphometrically after 8 weeks implantation was very similar with 20.5 ± 11.2 % and 22.5 ± 9.2 % for PLGA/CaP and PLGA/Ag-CaP, respectively.


The cotton wool-like bone substitute material is easily applicable, biocompatible and might be beneficial in minimal invasive surgery for treating bone defects.

Keywords: In vivo, bone regeneration, flexible, scaffold, silver.