ORIGINAL RESEARCH article
Front. Bioeng. Biotechnol.
Sec. Tissue Engineering and Regenerative Medicine
Synoviocytes-Chondrocyte Triculture Model for Early PTOA: Fibronectin Fragment-Induced Catabolic Effects In-vitro and In-vivo
Provisionally accepted
- 1College of Science, University of Alabama in Huntsville, Huntsville, United States
- 2The University of Alabama in Huntsville College of Engineering, Huntsville, United States
- 3The University of Tennessee Health Science Center, Memphis, United States
- 4VA Memphis Healthcare System, Memphis, United States
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Post-traumatic osteoarthritis (PTOA), a subtype of osteoarthritis initiated by joint trauma, is driven by unresolved early inflammation that ultimately leads to cartilage degeneration. While animal models have advanced our understanding of disease progression, they offer limited resolution of the early molecular events following trauma. In this study, we developed a transwell-based in-vitro triculture model mimicking the early joint environment post-injury, incorporating macrophages, fibroblast-like synoviocytes (FLS), and human articular chondrocytes (HACs). In lieu of commonly employed macrophage activator, lipopolysaccharide (LPS); this study utilizes fibronectin fragments (Fnfs) which belong to the damage-associated molecules released upon trauma to cartilage to activate macrophages and simulate post-traumatic inflammation. The triculture was maintained for twelve days while promoting paracrine-only communication between cell types. Activation of macrophages by Fnfs led to a sustained expression of pNFκB in both HACs and FLS, as shown by immunofluorescence, alongside increased gene expression of inflammatory mediators MMP3, MMP13, and TNFα. Fnfs triggered catabolic signaling across all joint-resident cell types used in this model. To support the translational relevance of the in-vitro findings, a complementary in-vivo experiment where Fnfs were injected intraarticularly showed increased MMPs and reduced COL2A1 gene expression in joint cartilage. The cytokine and gene expression profiles observed in the triculture model closely mirrored those observed in early-stage in-vivo PTOA models and in the patient-derived synovial fluid obtained in the early traumatic phase, underscoring the model's physiological relevance. This triculture platform captures the key aspects of early PTOA processes driven by macrophage activation offers a biologically relevant tool for mechanistic studies and therapeutic screening.
Keywords: Post-traumatic osteoarthritis (PTOA), PTOA model, Macrophages, Fibroblasts like synoviocytes, Chondrocytes, THP-1 monocytes, fibronectin fragments, DAMP (Damage Associated Molecular Pattern)
Received: 10 Aug 2025; Accepted: 10 Nov 2025.
Copyright: © 2025 Khan, Cho, Hasty, Brown, Bhogoju and Subramanian. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Anuradha Subramanian, anu.subramanian@uah.edu
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