Abstract
The production of complex inorganic forms, based on naturally occurring scaffolds offers an exciting avenue for the construction of a new generation of ceramic-based bone substitute scaffolds. The following study reports an investigation into the architecture (porosity, pore size distribution, pore interconnectivity and permeability), mechanical properties and cytotoxic response of hydroxyapatite bone substitutes produced using synthetic polymer foam and natural marine sponge performs. Infiltration of polyurethane foam (60 pores/in2) using a high solid content (80wt %), low viscosity (0.126Pas) hydroxyapatite slurry yielded 84-91% porous replica scaffolds with pore sizes ranging from 50?m - 1000?m (average pore size 577?m), 99.99% pore interconnectivity and a permeability value of 46.4 x10-10m2. Infiltration of the natural marine sponge, Spongia agaricina , yielded scaffolds with 56- 61% porosity, with 40% of pores between 0-50?m, 60% of pores between 50-500?m (average pore size 349 ?m), 99.9% pore interconnectivity and a permeability value of 16.8 x10-10m2. The average compressive strengths and compressive moduli of the natural polymer foam and marine sponge replicas were 2.46±1.43MPa/0.099±0.014GPa and 8.4±0.83MPa /0.16±0.016GPa respectively. Cytotoxic response proved encouraging for the HA Spongia agaricina scaffolds; after 7 days in culture medium the scaffolds exhibited endothelial cells (HUVEC and HDMEC) and osteoblast (MG63) attachment, proliferation on the scaffold surface and penetration into the pores. It is proposed that the use of Spongia agaricina as a precursor material allows for the reliable and repeatable production of ceramic-based 3-D tissue engineered scaffolds exhibiting the desired architectural and mechanical characteristics for use as a bone 3 scaffold material. Moreover, the Spongia agaricina scaffolds produced exhibit no adverse cytotoxic response.
Highlights
Given the well documented limitations of traditional bone repair such as limited availability, donor site morbidity and risks of an adverse immune response, biomaterial researchers have a responsibility to develop alternatives that will enhance the functional capabilities of bone graft substitutes and eliminate the need for traditional grafting procedures [1]
The scaffold should (a) be highly porous; while Best et al recommend relatively high levels of 70-4 80%, scaffolds with porosity between 45-90% have successfully induced bone growth [24] (b) have an appropriate pore size distribution; while the majority of pores should lie between 50 - 500μm [21,25,26], according to Yang et al pores of 5 - 50 μm are essential for neovascularisation and fibroblast and osteoblast in growth [27] and (c) have a high degree of interconnectivity between the pores; interconnectivity through openings of approximately 50μm is necessary to promote fluid circulation providing sufficient blood and cellular material to the core of the implant, enhancing bone deposition, nourishment of new bone and removal of waste products [28,29,30]
Scaffold production involves submerging the flexible polyurethane (PU) packaging foam (Ø10mm, 10mm height; 60 pores/in2; density, 30 kg/m3) (Craftworld Ltd, UK) and the marine sponge (10 x 10 x 7-12mm), Spongia agaricina (Pure Sponge UK Ltd, UK), in the optimized 80wt% HA slurry followed by squeezing in a Collin W-100-T Two Roll Mill (LRS Planung and Technologie GMBH, Germany) with the rollers fixed at 3.5mm apart
Summary
Given the well documented limitations of traditional bone repair (auto-, allo- or xeno-grafts) such as limited availability, donor site morbidity and risks of an adverse immune response, biomaterial researchers have a responsibility to develop alternatives that will enhance the functional capabilities of bone graft substitutes and eliminate the need for traditional grafting procedures [1]. With the emergence of new techniques and materials hard tissue replacement has evolved from the use of biomaterials to repair or replace tissue into the development of controlled three-dimensional scaffolds to guide the proliferation and spread of cells in vitro and in vivo [23]. The scaffold should (a) be highly porous; while Best et al recommend relatively high levels of 70-4 80%, scaffolds with porosity between 45-90% have successfully induced bone growth [24] (b) have an appropriate pore size distribution; while the majority of pores should lie between 50 - 500μm [21,25,26], according to Yang et al pores of 5 - 50 μm are essential for neovascularisation and fibroblast and osteoblast in growth [27] and (c) have a high degree of interconnectivity between the pores; interconnectivity through openings of approximately 50μm is necessary to promote fluid circulation providing sufficient blood and cellular material to the core of the implant, enhancing bone deposition, nourishment of new bone and removal of waste products [28,29,30]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
