Why Your Cells Might Be Craving a Good Stretch
For decades, scientists have grown cells in static, rigid plastic dishes—environments that bear little resemblance to the dynamic, stretchy environments inside living bodies. This fundamental limitation has hampered our understanding of how physical forces influence health and disease. Now, a breakthrough technology called FleXert is changing the game by bringing the rhythm of life into the lab dish.
FleXert is a soft, actuatable multi-well plate insert that allows researchers to grow cells and tissues while applying precisely controlled stretching forces. Imagine a miniature, flexible cell culture surface that can rhythmically expand and contract, mimicking everything from breathing lungs to beating hearts. This innovative tool is bridging the critical gap between traditional static cell culture and the dynamic reality of human physiology, opening new frontiers in everything from drug testing to tissue engineering.
Within the human body, most cells are constantly subjected to mechanical forces. Lung tissue stretches and relaxes with every breath, blood vessels expand and contract with each heartbeat, and muscles flex with movement. These physical cues are not merely background noise—they play an active role in directing cellular behavior, influencing how cells grow, specialize, and function.
Mechanical forces experienced by cells in different tissues
Traditional cell culture methods using rigid plastic dishes fail to replicate these mechanical environments. As noted in research on mechanical stimulation, cells cultured on stiff substrates without dynamic forces often undergo dedifferentiation, exhibiting phenotypes not representative of living tissue 1 . This limitation has profound implications—drugs that appear effective in static dishes may fail in living systems, and disease processes influenced by physical forces remain poorly understood.
"Integration of mechanical cues in conventional 2D or 3D cell culture platforms is an important consideration for in vivo and ex vivo models of lung health and disease" 2 .
The development of technologies that introduce mechanical forces to cell culture addresses this critical gap. FleXert represents a significant advancement in making these dynamic culture platforms more accessible and versatile.
At its core, FleXert is an ingeniously simple yet sophisticated system designed to integrate seamlessly with standard laboratory equipment:
Made of polydimethylsiloxane (PDMS), a biocompatible silicone material that serves as the flexible foundation for cell growth. The membrane contains microscopic pores that allow for nutrient transport and air exchange.
Using nothing more than a standard syringe pump, researchers can precisely control air pressure to stretch the FleXert membrane. This elegantly simple approach means no expensive custom equipment is required.
Designed to fit into standard six-well culture plates, FleXert doesn't require costly fabrication equipment or custom-built culture chambers, making it a versatile and low-cost solution 3 .
What truly sets FleXert apart is its programmability and flexibility. Researchers can recreate various physiological conditions by adjusting air pressure and pumping rates—from gentle rhythmic stretches mimicking normal breathing to more extreme patterns that might simulate disease states or exercise conditions. The system can achieve tensile strains of up to 30%, covering the full range of physiological mechanical forces experienced by tissues in the body 3 .
Tensile strain capabilities of FleXert compared to physiological ranges
Mimics natural breathing rhythms
To understand FleXert's capabilities, let's examine how researchers validated its performance in stimulating mechanobiological responses—the cellular changes triggered by mechanical forces.
The validation process followed a systematic approach to confirm that FleXert could not only deliver precise mechanical forces but also elicit meaningful biological responses:
Researchers created the FleXert inserts using PDMS, a material known for its flexibility and biocompatibility. The porous PDMS membrane was specifically engineered to serve as both a mechanical actuator and cell support structure.
To ensure cells would properly adhere to the stretching membrane, the PDMS surface was treated with fibronectin—a natural protein that helps cells attach. For more complex 3D cultures, a polydopamine coating was applied to anchor collagen gels containing human dermal fibroblasts.
Human dermal fibroblasts (cells crucial for tissue repair and regeneration) were subjected to controlled stretching regimens using the pneumatic actuation system. The specific patterns, duration, and magnitude of stretch were carefully programmed to mimic physiological conditions.
After 24 hours of mechanical stimulation, researchers examined the cells for signs of mechanotransduction—the process by which cells convert mechanical stimuli into biochemical signals. Specifically, they measured levels of alpha-smooth muscle actin (α-SMA), a protein marker that indicates fibroblast activation and differentiation.
The experimental results demonstrated unequivocally that FleXert successfully transduces mechanical forces to cultured cells and elicits specific biological responses:
α-SMA expression increase after mechanical stimulation
These findings validated FleXert as an effective platform for mechanobiology research. The increase in α-SMA is particularly significant as this protein plays a key role in tissue remodeling and repair processes—and its dysregulation is implicated in various fibrotic diseases. As the research noted, FleXert enables study of "mechanotransduction pathways in lung cells and tissues" under physiologically relevant dynamic conditions 3 .
| Parameter | Capability | Biological Significance |
|---|---|---|
| Maximum Strain | Up to 30% tensile strain | Covers physiological range for most tissues including lung |
| Actuation Method | Pneumatic (standard syringe pump) | Accessible to most research labs |
| Compatibility | Standard 6-well plates | No custom equipment required |
| Culture Formats | Submerged monolayer, air-liquid interface, 3D hydrogels, live tissue | Versatile for diverse research applications |
| Membrane Material | Porous PDMS | Biocompatible with tunable properties |
Table 1: FleXert Performance Specifications
Working with FleXert requires specific materials and reagents, each serving a distinct purpose in creating functional dynamic culture systems:
| Component | Function | Specific Example |
|---|---|---|
| PDMS Membrane | Flexible, porous substrate for cell culture | Polydimethylsiloxane with controlled porosity |
| Surface Coatings | Promote cell adhesion to flexible surface | Fibronectin for cell attachment; Polydopamine for hydrogel anchoring |
| Cell Types | Biological systems for mechanobiology studies | Human dermal fibroblasts; Lung tissue explants |
| Extracellular Matrix | Provide 3D environment for tissue models | Collagen gels; Human lung-derived ECM hydrogels |
| Actuation System | Generate controlled mechanical strains | Standard syringe pump for pneumatic pressure |
| Analysis Reagents | Detect mechanobiological responses | Antibodies for α-SMA protein detection |
Table 2: Key Research Reagent Solutions for FleXert Experiments
The development of FleXert represents more than just technical innovation—it signals a paradigm shift in how we approach cell culture and biological research. By replicating the dynamic mechanical environment of living tissues, FleXert enables researchers to ask questions that were previously impossible to investigate in the lab.
FleXert could help identify compounds that specifically target mechanobiological pathways or test how mechanical forces alter drug effectiveness.
It provides a platform to grow more physiologically relevant tissues for transplantation by conditioning them with appropriate mechanical stimuli.
Researchers can recreate the excessive mechanical stresses associated with conditions like pulmonary fibrosis or asthma to better understand their progression.
Study fundamental cellular responses to mechanical forces for deeper understanding of how physical forces shape cellular behavior.
The open-source nature of FleXert's design philosophy is particularly noteworthy. As the developers stated, they aimed to create a system "built with economically feasible and available components" to "increase accessibility to studies of the dynamic lung microenvironment" 3 .
| Field | Application | Potential Impact |
|---|---|---|
| Drug Discovery | Test compound efficacy under physiologically relevant mechanical conditions | More predictive pre-clinical screening |
| Disease Modeling | Recreate pathological mechanical environments | Better understanding of fibrosis, asthma, and other mechanosensitive diseases |
| Tissue Engineering | Condition engineered tissues with appropriate mechanical stimuli | Improved functional outcomes for tissue replacements |
| Basic Mechanobiology | Study fundamental cellular responses to mechanical forces | Deeper understanding of how physical forces shape cellular behavior |
| Toxicology | Assess how environmental exposures interact with mechanical stress | More comprehensive safety testing |
Table 3: Research Applications of FleXert Technology
FleXert exemplifies the growing recognition that biology doesn't happen in a static world. As research continues to reveal how intimately our cells are tuned to their mechanical environment, technologies that incorporate these physical dimensions into experimental systems become increasingly vital.
The developers describe FleXert as "an extensive toolkit for multi-disciplinary mechanobiology studies" 3 —and indeed, its potential applications span across disciplines, from fundamental cell biology to clinical research. As more researchers adopt and adapt this technology, we can anticipate new insights into how physical forces contribute to health and disease, potentially leading to novel therapeutic approaches that target these mechanobiological pathways.