Human tendon-on-a-chip for modeling vascular inflammatory fibrosis.

Understanding vascular inflammation and myofibroblast crosstalk is critical to developing therapies for fibrotic diseases. Here we report the development of a novel human Tendon-on-a-Chip (hToC) to model this crosstalk in peritendinous adhesions, a debilitating fibrotic condition affecting flexor tendon, which currently lacks biological therapies. The hToC enables cellular and paracrine interactions between a vascular compartment harboring endothelial cells and monocytes with a tissue hydrogel compartment containing tendon fibroblasts and macrophages. We find that the hToC replicates in vivo inflammatory and fibrotic phenotypes in preclinical and clinical samples, including myofibroblast differentiation and tissue contraction, excessive ECM deposition, and inflammatory cytokines secretion. We further show that the fibrotic phenotypes are driven by the transmigration of monocytes from the vascular to the tissue compartments of the chip. We demonstrate significant overlap in fibrotic transcriptional signatures in the hToC with human tenolysis samples, including mTOR signaling, a regulatory nexus of fibrosis across various organs. Treatment with rapamycin suppressed the fibrotic phenotype on the hToC, which validates the hToC as a preclinical alternative for investigating fibrosis and testing therapeutics.