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approaches to managing OA. However, the range of drugs levels. This is especially significant in replicating intricate
available that specifically target cartilage degeneration is multi-organ interactions, including those of the heart,
relatively limited and primarily focused on symptom relief. lungs, liver, and kidneys. 11,12 Nguyen et al. explored the
13
The regenerative effects on the cartilage itself are minimal. therapeutic potential and biodistribution of extracellular
Therefore, there is a critical need to develop and screen new vesicles from mesenchymal stromal cells by employing
drugs that not only alleviate symptoms but also promote a multi-organ-on-a-chip model that integrated kidney
cartilage repair and regeneration. and liver organoids. Although research on bone-on-a-
However, the development and screening of drugs chip is less common, this field is rapidly evolving. For
14
for OA related to cartilage degeneration continue to face example, Lipreri et al. developed a chip for osteocyte
significant challenges due to the complex cellular and drug screening, offering new insights for our research in
biochemical environment of cartilage. This complexity, treating OA. The bone-on-a-chip can effectively simulate
3
along with the involvement of multiple cell types and OA in vitro, thereby representing an important method
4,5
molecular pathways in OA pathogenesis, increases for clinical OA drug screening. This technology can more
accurately simulate OA, offering a new platform for drug
the complexity and cost of research and development. screening.
Commonly used drug screening methods include animal
models and in vitro cell-based models. Animal models are To bridge these advancements, we constructed a
rapid and can mimic human disease progression closely, cartilage-on-chip using primary chondrocytes embedded
but differences in physiological and metabolic between in gelatin methacryloyl (GelMA) hydrogel and simulated
species may occur. In contrast, traditional in vitro models the natural state of cartilage by adjusting the cellular
6,7
offer better repeatability and controllability, as well as environment in the microfluidic system. This model
time and cost efficiency, and they can avoid ethical issues leverages the unique capabilities of 3D tissue platforms
related to animal experiments. However, they fall short to emulate the intricate biological environment more
of encapsulating the complexity of natural tissues and effectively. By introducing interleukin-1 beta (IL-1β), we
systemic physiological processes, limiting their capability induced an inflammatory environment to mimic the OA
to simulate real biological responses comprehensively. model. Subsequently, we tested the chip’s response to two
8
While these models can replicate certain pathological types of drugs (chemical and biological) for drug screening
changes of OA to some extent, they still fail to fully (Figure 1). This method offers a new, more physiologically
reproduce the complexity of human OA. Thus, the greatest relevant model for OA research and drug screening.
challenge in OA drug development is the lack of models
that can accurately mimic the pathology of human OA. 2. Materials and methods

In recent years, various emerging models have been 2.1. Reagents and equipment
developed in the fields of tissue engineering and disease The main reagents used in this study were: DMEM-F1/2
modeling. These include three-dimensional (3D) cell medium (Corning Inc., United States of America [USA]),
culture models, where cells are cultivated in scaffold type II collagenase (Worthington Biochemical Corporation,
materials or suspension media to form 3D structures, USA), anhydrous ethanol (Shanghai Titan Technology
1
and bioprinting technology, which constructs cells and Co., Ltd., China), trypsin-ethylenediaminetetraacetic
scaffold materials layer by layer. However, despite the acid (EDTA) (Corning Inc., USA), GelMA lysis solution
2,3
contributions of these static culture models to advancing (Suzhou Forever Precision Equipment Co., Ltd., China),
research, the development of organ-on-a-chip has opened photoinitiator LAP, DEPC water, 4% paraformaldehyde
new possibilities for drug screening. Organ-on-a-chip, fixative, Alcian blue staining solution, Safranin O/Fast
4-6
through advanced microfluidic systems and 3D culture green staining (SO/FG) solution (Shanghai Beyotime
environments, can simulate more dynamic physiological Biotechnology Co., Ltd., China); phosphate-buffered
conditions, including continuous nutrient supply, waste saline (PBS; Corning Inc., USA), 75% ethanol, chloroform
removal, and the application of mechanical loads (such (Shanghai Titan Technology Co., Ltd., China), Live/Dead
as shear forces or stress). Unlike static models (e.g., 3D Dual Staining Kit, Trizol (Tokyo Chemical Industry Co.,
7,8
cell culture and bioprinting), organ-on-a-chip can simulate Ltd., Japan), PrimeScript™ RT Master Mix (Takara Bio
cell-cell and cell-matrix interactions with spatial and Inc., China), TB Green® Premix Ex Taq™ (Takara Bio Inc.,
physicochemical diversity, enabling a more accurate China), instant protein loading buffer, transfer buffer, TBST,
replication of the fundamental features of organs, which PAGE gel electrophoresis quick preparation kit, protein-free
include barrier-like interfaces, complex tissue structures, quick blocking solution (Shanghai Yenzyme Biotechnology
and interorgan interactions. 5,9,10 The fundamental strength Co., Ltd., China), anti-MMP13 rabbit pAb (Wuhan
of organ-on-a-chip technology is its capability to mimic Sanying Biotechnology Co., Ltd., China), anti-Sox9 mouse
essential organ functions at both the cellular and tissue mAb (Wuhan Sanying Biotechnology Co., Ltd., China),

Volume 1 Issue 1 (2025) 2 doi: 10.36922/or.8461