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finding revealed the self-organizing and regenerative 3.2.1. Evolution of cultivation techniques from two-
capabilities of cells, laying the foundation for organoid dimensional to three-dimensional
research. The modern era of organoid technology began The development of tendon organoids is still in its early
in 2009, when Hans Clevers’ team successfully cultured stages, evolving from rudimentary beginnings. Initial
the first intestinal organoid using adult stem cells from research focused on 2D culture systems, where tendon cells
mouse intestines, marking the dawn of organoid research. or stem cells were seeded in culture dishes and exposed to
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In 2013, Lancaster et al. developed brain organoids from specific growth factors and mechanical stimuli to study
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human pluripotent stem cells, followed by the successful cell proliferation, differentiation, and matrix synthesis.
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generation of liver, kidney, and pancreatic organoids. These studies provided insights into the basic biological
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These advancements have significantly contributed to the behaviors of tendon cells in vitro and laid the foundation
study of organ development and disease modeling, while also for subsequent 3D culture systems. However, 2D systems
advancing personalized medicine and targeted therapeutic have significant limitations, as they fail to replicate the 3D
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strategies. In the same year, organoid technology was structure and complex mechanical environment of native
recognized as one of the top ten breakthroughs by Science tendons, resulting in functional discrepancies between
magazine. The rapid advancement of organoid technology, cultured cells and real tendon tissue. Strategies beyond
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along with its improved ability to simulate organ structure simple monolayer culture emerged to better recapitulate
and function, has provided powerful tools for research aspects of the tendon niche within 2D or transitional
in organogenesis, disease modeling, drug screening, and systems. For instance, indirect co-culture approaches,
precision medicine. 50,51 where target cells are exposed to the secretome of tendon
Today, organoid technology is experiencing renewed tissue explants or tenocytes without direct contact, have
growth through interdisciplinary integration. Biomedical demonstrated significant potential in programming cells
engineering technologies, such as hydrogels, microfluidics, toward tenogenic differentiation. 67
and 3D printing, are addressing current limitations, Cell sheet technology has been adopted, where
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including high heterogeneity, low maturity, and structural stem cells are cultured on specific substrates, such as
simplicity in organoids. 58-60 These innovations are enhancing decellularized tendon slices, 69-71 to form cell sheets with
the ability of organoids to replicate the complexity of real defined thickness and structure. This approach provides
organs. Organ-on-a-chip systems, which fall within the a microenvironment closer to that of in vivo conditions,
realm of biomedical engineering technologies, facilitate paving the way for the construction of 3D structures.
the construction of higher-fidelity organoids by precisely Advanced 3D culture techniques now utilize biocompatible
controlling the cellular microenvironment. 61-63 For and biodegradable scaffolds (e.g., collagen hydrogels,
example, Hu et al. developed a Bone/Cartilage Organoid- poly(lactic-co-glycolic acid) ) to seed stem cells and create
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on-Chip device, bridging the gap between ex vitro 3D tendon-like tissues through in vitro cultivation. These
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cell culture, animal models, and human pathological 3D systems better replicate the mechanical and biological
conditions. This system allows organoids to exhibit specific functions of native tendons, marking a significant step
pathophysiological features observed during bone and forward in tendon organoid research.
cartilage diseases. Furthermore, advancements in omics,
imaging, genetics, and AI are driving the evolution of 3.2.2. Breakthroughs in scale and function from micro
organoid technology. 12,64 AI is increasingly being applied to to macro
address challenges related to organoid assembly complexity Research on tendon organoids has expanded beyond
and data analysis, including rapid screening of construction microscopic-level cell behavior and matrix synthesis to
strategies, cost-effective extraction of multiscale image the development of functional tissues at macroscopic
features, streamlined analysis of multi-omics data, and scales. These larger-scale organoids not only exhibit
precise preclinical evaluation. 12 enhanced mechanical strength but also better replicate the
physiological functions of native tendons. Early studies
3.2. Development of tendon organoids
primarily focused on the microscopic scale, such as
Although the construction of fully functional tendon optimizing cell differentiation and functional expression
organoids has not yet been achieved, research in this by modulating the composition and mechanical properties
field has progressed from simple 2D cultures to more of the ECM. In recent years, research on centimeter-scale
complex 3D structures. This evolution reflects a shift from tendon organoids has not yet been achieved, with most
microscopic to macroscopic approaches and from single- efforts concentrated on millimeter-scale models. However,
tissue to multi-tissue collaborative construction, laying the advancements in tissue engineering technologies are laying
groundwork for future tendon organoids that more closely the groundwork for the construction of centimeter-scale
mimic physiological environments. organoids. For instance, the concept of “Bioprinting-

Volume 1 Issue 3 (2025) 5 doi: 10.36922/OR025170016