Three dimensional (3D) porous scaffolds with favourable osteogenic ability and mechanical properties are promising candidates for bone repair and regeneration. Scaffolds geometry, porosity and topography in combination with chemical composition and surface coating are known to influence cell attachment, proliferation, differentiation and subsequently osteointegration of biomaterials. Taken this evidence base into account, the aim of our study is to evaluate the bioactivity of a novel 3D printed polycaprolactone (PCL) scaffold with nanometer thick polymer coating designed for use as a bone implants to heal the mind blast injury. Here we used an inductively coupled plasma system to modify 3D scaffold with thin coatings of poly (ethyl acrylate) (PEA). Our lab has previously shown the outstanding functional properties of PEA, that induce a fibrillar conformation of fibronectin (FN) adsorbed on its surface, biomimetically exposing its integrin and growth factor-binding domains, and in turn allowing an efficient and synergistic presentation of growth factors in vitro and in vivo ^{(1, 2)}. The efficiency of plasma polymerisation as well as FN adsorption and interaction with bone morphogenetic protein-2 (BMP-2) on PEA coated PCL scaffolds were evaluated. We have then studied the in vitro ability of PEA coated PCL scaffolds to facilitate cell proliferation and osteoblast differentiation when the scaffolds were subjected to varying scaffolds pore geometry accomplished by manipulating the advancing angle between printed layers. Alkaline phosphatase assays, PCR analysis, immunofluorescence and calcium mineralisation studies revealed that the PCL scaffolds coated with PEA, FN and BMP-2 enhanced the osteogenic differentiation of hMSCs. Thereafter, the chorioallantoic membrane (CAM) assay confirmed biocompatibility of the PCL material, PEA coating and growth factor coating, and the ability of the coatings to support blood vessel formation in a dynamic biological environment. In addition, the coated scaffolds were subcutaneously implanted into rats to assess early-stage osteogenesis and vascularization. We propose that our functionalised 3D scaffolds exhibit potential technique for bone regenerative therapies.

References  

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2. Z.A. Cheng, A. Alba-Perez, C. Gonzalez-Garcia, H. Donnelly, V. Llopis-Hernandez, V. Jayawarna, P. Childs, D.W. Shields, M. Cantini, L. Ruiz-Cantu, A. Reid, J.F.C. Windmill, E.S. Addison, S. Corr, W.G. Marshall, M.J. Dalby, M. Salmeron-Sanchez. Nanoscale coatings for ultralow dose BMP-2-driven regeneration of critical-sized bone defects. Advanced Science 2018, 6.