Jun 30, 2022, 2:40 PM
Room: S4 B

Room: S4 B


Bakht, Syeda Mahwish (3B’s Research Group- i3Bs - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering Regenerative Medicine,Guimarães; ICVS/3B’s—PT Government Associate)


Tendon tissues host different cell populations that play important roles in their physiology and pathophysiology. A hallmark of tendon injuries and diseases is the persistent inflammatory response that can self-amplify and lead to chronicity. The inflammatory phase of tendinopathy is characterized by increased vascularization and influx of immune cells (mast cells, macrophages, T cells) at the healing site. A better understanding of this complex multicellular crosstalk and environmental cues is critical for decoding the healing mechanisms of tendon injuries and to find new therapeutic options. However, the current lack of representative in vitro models of tendinopathy is a major barrier to the progress of this field. The aim of this work is to establish a multicellular organotypic 3D model recreating key signaling hallmarks of that immune response, in particular for the study of the interactions between stromal tenocytes and the circulating T cells in tendon vasculature under healthy and diseased conditions.
To recreate the anisotropic fibrillar architecture of tendon ECM and induce cell alignment in 3D within the chip, we produced magnetically responsive microfibers (MNF@PCL). Microfibes were prepared by cryo-sectioning electrospun PCL meshes incorporated with iron oxide nanoparticle. A three channeled microfluidic chip was used as platform to build the model, where human tendon derived cells (hTDCs) were encapsulated in the central channel in either transglutaminase crosslinked Gelatin or Platelet Lysate (PL) hydrogels along with MNF@PCL. For in-situ alignment of MNF@PCL, the chip was placed under a uniform magnetic field created by two parallel magnets. Hydrogel formation allowed to fix the fiber pattern after removal of the magnetic forces. Microvascular cells were co-cultured in the side channel to recreate the open vasculature of the extrinsic tendon compartment, where T cells can be subsequently circulated for evaluating their interactions with stromal tenocytes.
Analysis of 3D hTDCs cytoskeleton organization within hydrogel matrices showed that the topographical cues created by the microfiber alignment strongly dictates the cell's aspect ratio and orientation. The synergy between the PL matrix bioactivity and magnetically aligned MNF@PCL revealed to be the most effective strategy for inducing cell anisotropic organization within central compartment and maintenance of a tenogenic phenotype. The microvascular cells co-cultured in the side channels organized into compartmentalized tubular monolayer with open lumen. We are currently assessing the effects stemming from the crosstalk between tendon and vascular cells on genes and proteins related with ECM, tenogenic markers and inflammatory signaling pathways. This physiomimetic system is also being explored to study the effects of hTDCs on the behavior of circulating T cells (migration and activation), as well as the impact of these crosstalk mechanisms on the stromal compartment.
In this work, we propose a compartmentalized tendon-on-chip model able to recapitulate ex-vivo some of the characteristic microstructural features of healthy and diseased (fibrotic) tendon stroma interfacing with the vasculature of the extrinsic tendon compartment which is capable of supporting circulating immune cells. This physiomimetic system is being leveraged for better understanding not only the mechanisms of tendinopathy, but also of tendon tissue regeneration and repair.


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