3D mimicry of native-tissue-fiber architecture guides tendon-derived cells and adipose stem cells into artificial tendon constructs

Tendon and ligament (T/L) function is intrinsically related with their unique hierarchically and anisotropically organized extracellular matrix. Their natural healing capacity is, however, limited. Here, continuous and aligned electrospun nanofiber threads (CANT) based on synthetic/natural polymer blends mechanically reinforced with cellulose nanocrystals are produced to replicate the nanoscale collagen fibrils grouped into microscale collagen fibers that compose the native T/L. CANT are then incrementally assembled into 3D hierarchical scaffolds, resulting in woven constructions, which simultaneously mimic T/L nano-to-macro architecture, nanotopography, and nonlinear biomechanical behavior. Biological performance is assessed using human-tendon-derived cells (hTDCs) and human adipose stem cells (hASCs). Scaffolds nanotopography and microstructure induce a high cytoskeleton elongation and anisotropic organization typical of tendon tissues. Moreover, the expression of tendon-related markers (Collagen types I and III, Tenascin-C, and Scleraxis) by both cell types, and the similarities observed on their expression patterns over time suggest that the developed scaffolds not only prevent the phenotypic drift of hTDCs, but also trigger tenogenic differentiation of hASCs. Overall, these results demonstrate a feasible approach for the scalable production of 3D hierarchical scaffolds that exhibit key structural and biomechanical properties, which can be advantageously explored in acellular and cellular T/L TE strategies. M.L. and R.M.A.D. contributed equally to this work. Dr. P. Babo is acknowledged for acquiring the Micro-CT data. Authors acknowledge the financial support from FCT (Fundacao para a Ciencia e a Tecnologia), for the fellowship SFRH/BPD/112459/2015 (RD), SFRH/BD/96593/2013 (RCA), and for the Career Consolidation Grant IF/00593/2015 (MEG). This article is a result of the project "Accelerating tissue engineering and personalized medicine discoveries by the integration of key enabling nanotechonologies, marine-derived biomaterials and stem cells," supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). R.L.R. acknowledges the European Research Council for the project CornplexiTE grant agreement ERC-2012-ADG 20120216-321266.