Complex 3D Architectures Based on Knitting Technologies for Bone Tissue Engineering Applications

Textile-based technologies are particularly interesting in tissue engineering since it allow for producing finely tuned fiber-based porous structures, thus offering superior control over the material design (size, porosity, fibre alignment) and manufacturing. Scaffolds with very reproducible and interconnected microarchitectural geometry can be processed, increasing the surface area for cell attachment and tissue ingrowth. We describe for the first time the processing of silk yarns into 3D weft-knitted fabrics spaced by a monofilament of polyethylene terephthalate (PET). A comparative study is established using a more stable polymeric system based on a warp-knitted spacer construct made entirely of PET. The obtained knitted spacer constructs are described in terms of morphology and mechanical properties, which has an impact over the resulting cell behaviour at the surface and into the biotextiles. The in vitro osteogenic differentiation response of human adipose-derived stem cells (hASCs) and in vivo biocompatibility were investigated. HASCs constitute an emerging possibility for regenerative medicine and tissue replacement therapies, including for bone tissue engineering. Cells were cultured over 28 days in standard basal and osteogenic conditions being able to attach to the scaffolds fibres, proliferate and differentiate into the osteogenic lineage. The developed scaffolds allowed cells infiltration and supported its proliferation as observed by SEM, where a massive production of mineralized extracellular matrix could also be seen. The efficacy and high level of control of the knitting spacer technology allied to high potential of hASCs for osteogenic differentiation makes the designed scaffolds attractive for specific bone tissue engineering applications. The in vivo results also showed weak inflammatory response after 2 and 4 weeks of subcutaneous implantation in mice models. This work constitutes a first validation step of a silk-based 3D spacer biotextile as viable scaffold for bone tissue engineering applications. Considering the efficacy and reproducibility of the knitting technology, the three-dimensionality reached through the spacer textiles and the interesting structural and mechanical properties of the developed constructs it is expected that our scaffolds can be attractive for the development of versatile and adaptable systems according to the specific bone tissue anatomy and function.