Source: Scientific Inquirer (September 11, 2026). AI-generated summary by biochip.com, published . Not independently reviewed.
Key takeaways
- A Nanjing-led Nano Research review identifies pressure, flow, stretch and stiffness as essential inputs for realistic organoid and organ-on-chip models.
- Microfluidics, flexible membranes, bioprinting and magnetic levitation can apply organ-specific forces to models of lung, heart, gut, kidney, liver and tumors.
- The field still lacks standardized, durable systems that combine multiple mechanical cues and validate their long-term performance.
Researchers from three universities in Nanjing argue that organoids and organs-on-chips will not closely resemble human tissues unless they also reproduce the forces that shape cells inside the body. Their review in Nano Research examines how pressure, fluid flow, stretching, tissue stiffness and cell-generated pulling forces influence laboratory models of organs. These physical inputs are easy to overlook because cell culture has traditionally focused on nutrients, genes and chemical signals. Yet cells experience mechanical stimulation continuously, from the pulse of blood through vessels to the expansion of lungs during breathing. The team, led by Yang Zhang of Nanjing University of Chinese Medicine with collaborators at Nanjing University of Posts and Telecommunications and Nanjing University of Information Science and Technology, calls mechanics a necessary design principle rather than an optional extra. They map the tools used to add those forces, including microfluidic devices, flexible membranes, bioprinting and magnetic levitation. The review also connects mechanical design to practical uses, such as studying cancer invasion, improving drug testing and modeling organ development. Its central message is straightforward: a tissue model may contain the right cell types but still behave unrealistically if it lacks the physical conditions of a living organ.
Why Cells Need Physical Signals
Cells do not simply sit in place and respond to molecular instructions. They also detect whether their surroundings are soft or rigid, whether liquid is sweeping past them, and whether neighboring cells are pulling or compressing them. Like a person adjusting their balance on a moving bus, a cell changes its behavior when the physical conditions around it shift.
In biological terms, this process is called mechanotransduction, the conversion of mechanical forces into biochemical signals inside a cell. Those signals can alter cell shape, movement, growth and specialization. Zhang and colleagues argue that these responses help determine whether cultured cells organize into structures that perform the jobs expected of a lung, heart, kidney, liver or intestine.
From Static Cultures to Dynamic Chips
Older cell culture approaches often relied on static scaffolds, supportive materials that give cells a surface on which to grow. Such systems can be useful, but they generally cannot recreate the continuously changing conditions within a body. The review traces a shift toward dynamic platforms built to deliver controlled physical stimulation.
Microfluidics is one major approach. These devices use tiny channels to move small volumes of liquid across cells, much like miniature plumbing. Flow can create shear stress, the frictional force that fluid exerts as it moves along a surface, which is particularly relevant for blood vessels and organs exposed to circulating fluids. Other systems use flexible membranes to stretch tissues rhythmically, while bioprinting can arrange cells and materials into defined three-dimensional shapes and magnetic levitation can position cell assemblies without a conventional solid support.
Every Organ Has Its Own Mechanical Signature
The review emphasizes that no universal force setting can make every organ model more realistic. A lung experiences repeated expansion and contraction, so lung-on-a-chip devices use cyclic strain, repeated stretching, to mimic breathing. That movement can help maintain the alveolar-capillary barrier, the thin interface where oxygen passes from air spaces into the blood.
Heart-on-a-chip platforms face a different task. They combine mechanical stretching with electrical pacing to encourage cardiomyocytes, the muscle cells that power the heartbeat, to mature in ways that better reflect working cardiac tissue. For gut models, flexible systems can recreate peristalsis, the wave-like contractions that push food through the intestine, alongside fluid movement through the channel.
Kidney and liver systems also depend on carefully managed flow and pressure because those organs process fluid as part of their core function. Controlled circulation can supply nutrients, remove waste and expose cells to forces closer to their normal environment. Wei Wang of Nanjing University of Posts and Telecommunications describes these tailored conditions as each organ's distinct mechanical signature, a feature that chip designers must engineer rather than assume will arise on its own.
Mechanics and Disease Modeling
The value of mechanical control becomes especially clear in cancer models. Tumors often develop a stiffer surrounding matrix, the network of molecules that supports cells, as well as elevated interstitial pressure, meaning pressure within the spaces between cells. Tumor-on-a-chip systems can reproduce aspects of this environment to explore how physical conditions contribute to cancer-cell invasion and resistance to drugs.
That capability does not mean a chip can fully replace an animal study or predict a patient's response on its own. It does offer a way to isolate particular features of a disease environment and watch how cells respond under defined conditions. The review positions mechanically tuned models as complements to static cultures and animal experiments, particularly when researchers need a closer look at human tissue behavior.
The Engineering Problems Still Ahead
Building these systems remains difficult because real organs experience many forces at once, operating from the scale of individual molecules to whole tissues. A platform might reproduce flow well but omit stretching, or maintain a mechanical stimulus for a short experiment but lose precision during longer culture periods. The Nanjing team identifies long-term stability, multi-force integration and materials that can change dynamically like native tissue as central technical challenges.
Standardization is another hurdle. If laboratories apply forces differently or measure outcomes with incompatible methods, comparing models becomes difficult. The review also points toward multi-organ systems, in which linked chips could help researchers study conditions that affect several tissues at once rather than treating each organ as an isolated unit.
Why This Matters
Organoids, three-dimensional clusters of cells that imitate some features of organs, and organs-on-chips are often presented as more human-relevant alternatives to simple cell cultures. Their usefulness depends not only on which cells they contain but on whether those cells receive the cues that guide real tissue function. Bringing mechanics into the design could make laboratory models more informative for questions about development, regeneration, disease progression and drug responses.
The researchers envision mechano-intelligent platforms that use sensors to monitor physical conditions and automatically adjust them in real time, much like a smart climate-control system maintains a room. Coupling that feedback with advanced biomaterials and artificial intelligence could eventually support organ models tailored to specific biological questions. Before such systems can serve as reliable digital counterparts of human organs, researchers will need durable materials, shared protocols and evidence that increasingly complex models deliver reproducible biological insights.