Cell Stretching Systems
Stretch the limits of In-Vitro possibilities
Effortless Stretch Pattern Discovery
Finding your ideal stretch pattern can take a great deal of effort and we believe every researcher should be able to take their research to the next phase with ease. That is why we did the hard work for you. Effortlessly implement cell stretching into your research to consider mechanotransduction in your analysis with our pre-programmed ideal stretch patterns.
Stretch and Analyze with Ease
Avoid feeling stressed when confronted with the effort traditional systems require to analyze your cell cultures. STREX cell stretching devices and Etaluma microscopes fit perfectly in your incubator to make mechanotransduction research stress-free and effortless. Get a live feed of your analyses all while keeping your Cells Stretching Device and microscope in a controlled environment.
Ready Upon Arrival
Learning a new procedure should never be difficult with the right support. Bring your research into the next phase immediately after your Cell Stretching Device arrives. STREX’s PDMS chambers come plasma treated and are ready to use after following provided and easy to understand protocols.
Cell Stretching System Models for Different Applications
The comprehensive guide to setting up a successful cell stretch experiment
Cell stretching experiments are an important tool for modeling biological function and are the focus of great interest in research and industry. This guide provides advice on how to set up a stretch experiment.
The proprietary STREX Cell Stretching System induces an equal mechanical stretch to cultured cells in ultra-thin flexible PDMS stretch chambers.
Simulate Physiological Conditions Using Our Specialized Cell Stretching Devices
Mechanical forces are involved in almost every biological process and are required for many cellular functions. From the moment of conception, the growth and development of every cell is affected by mechanical forces, and every cell is continuously subjected to mechanical forces.
To name a few cell types: cardiomyocytes, endothelial cells, smooth muscle cells, and osteocytes, which are constantly stretched or compressed. Cells detect their mechanical environment through receptors and channels called mechanoreceptors. They respond to these stimuli by altering their adhesion, proliferation, locomotion, morphology, and synthetic profile, and studying cell mechanical stress and cell mechanostress can provide valuable insights into these cellular responses. But none of the stimuli in a living environment have been replicated under standard in-vitro conditions for analysis.
The STREX Cell Stretching Systems can mechanically stimulate cells growing in culture by stretching and compressing them. This occurs via adhering cells to our unique PDMS stretch chambers. And subjecting them to mechanical strain while being able to conduct observations inside of an incubator.
Strex has two main types of devices. Broken up into high throughput, long-term stretching models, and microscope mountable options for live-cell imaging.
Every cell is subjected to a nearly uniform strain along the stretch axis (less than <5% variability). Ensuring that experiments are highly reproducible. But in the non-axial direction, the secondary load is much weaker.
The high-precision, high-torque stepping motor in the stretch unit allows for a consistent range of motion at a variety of speeds and stretch ratios. This motion stability, combined with the superior characteristics of the silicone film chamber, produces mechanical stretching that is highly reproducible, regardless of the stretching speed or distance.
Wide Range of Stretch Patterns
We can configure the system for eight different settings for the stretch ratio — degree of stretch desired — and eight for the frequency of the stretch movement. This results in 64 pre-programmed stretching patterns. We can manufacture custom patterns at high speed or stretch ratios at an extra cost.
Unique Stretch Chamber
Specifically developed for STREX machines, the PDMS chambers made from a silicone film help a variety of lab analysis techniques, including cell fixation and fluorescent imaging.
Extracellular matrix coatings, such as fibronectin or collagen, applied to the stretch chamber promote cell adhesion and ease a seamless cell culture. The adhered cells are then stretched and compressed. Versions of the system that mount on microscope stages enable real-time observation of the changes that the cells manifest in response to these applied stress loads.
1. Seed cells onto a stretch chamber which is pre-treated with an extracellular matrix coating.
2. Cells adhere to the stretch chamber beginning an overnight culturing process.
3. Post cell proliferation, a stretching pattern is chosen, and the cycle begins. Cells are stretched as specified by the selected stretch pattern.
4. Conduct cell observation. (Cells in culture can be observed under the microscope if using the microscope mountable version)
5. Harvest/treat cells under the objectives of the experiment.
1. Biochemical experiments: Alteration of gene and protein expression, signal transmission, cell extract recovery and analysis, northern blotting, western blotting, and more.
2. Cell biology experiments: Cytoskeleton and cytoplasm rearrangement for observation of fixed and stained cells.
3. Cell physiology experiments: Real-time observation of Ca2+ influx, based on various electrochemical conditions.
Research papers produced on Strex Systems can be found here.
Note: Supported applications vary, depending on the instrument employed.
Automated Cell Stretching System
- The system is capable of stretching cells in culture by applying a stress load to cells growing in-vitro.
- The system stretches cells in up to either 6 or 8 chambers at the same time for easy comparison between parallel samples and has 64 pre-programmed stretch patterns to save researchers time.
- The mechanical stretching unit operates inside an incubator and the control unit sits outside for remote access and the stretch chamber mounting unit can be transferred to a clean bench for aseptic operations and an easier workflow.
Two main stretch unit versions are available, with chamber sizes of 4 cm2 or 10 cm2. The smaller version supports up to 8 parallel chambers, while the larger version, best suited for biochemical research and large cell types, supports up to 6 chambers.
The controller has a microcomputer with 64 stretch patterns, adjustable stretch ratio and frequency using DIP switch, regulates water flow for motor cooling, and allows for long-term observation of stretching experiments.
Stretching System Main Unit:
ST-1440 (for 4 cm² stretch chambers)
ST-1400 (for 10 cm² stretch chambers
Generates stretching patterns, regulates motor-based cooling and can be reprogrammed to work with different stretching models, unique to the main unit.
Connect the main stretching unit and controller, including a signal cable and tubing for cooling main unit’s motor and a cable for reprogramming the control unit.
Coolant Tank and Tube:
Cool the stretching unit during long-term experiments with water.
ST-1440: Uses 4 cm² chambers.
Supports up to 8 units in parallel.
ST-1410: Uses 10 cm² chambers.
Supports up to 6 units in parallel.
The detachable stretch chamber mounting hook assembly can be covered with a lid and placed in a culture plate.
Stretching Patterns: Up to 64 patterns
Stretch Direction: Uniaxial
Stretch Ratio: Up to 20%
High-speed models are available upon request.
Manual Cell Stretching System
The Manual Cell Stretching System applies stretching and compression force to cells, but it is manually operated by hand. It is used for evaluative purposes in considering the introduction of a fully automated stretching system, such as the ST-1400. The manual system employs the same chambers as the ST-1400 system. Two versions are available, depending on the size of the stretch chamber desired; 4 cm2 or 10 cm2.
Conducting observations using the manual cell stretching system under a microscope: To capture images under a microscope, fix the chamber with the device in a flipped position, opposite to the normal orientation. This will allow for the observation of cells in real-time. However, note that the reproducibility of this machine is much lower than that of an automated machine, such as the ST-1400.
Main Stretch Unit:
ST-0040 (for 4 cm2 chambers)
ST-0100 (for 10 cm2 and multi-well chambers)
Note: Cells should be cultured by placing the stretch system into a culture plate.
ST-0040: Uses 4 cm² chamber.
ST-0100: Uses 10 cm² chamber.
Stretch Ratio: Up to 20% max. Each turn of the dial increases the ratio by 0.5 mm (equating to a 2.5% increase for the ST-0040 system and 1.6% for the ST-0100).
Uniaxial Cell Stretching System
- The system stretches cells in culture by applying a stress load and can stretch cells in a single chamber in one direction for observing the cells’ response to stretch.
- 64 pre-programmed stretch patterns are available to save researchers time. The system’s mechanical stretching unit can be mounted to an existing microscope stage and operated with a microscope that can image inside an incubator.
- The system can capture an image at up to 40x resolution, but the resolution is limited by the thickness of the chamber membrane. For higher resolution, custom chambers with thinner membranes are available.
ST-1500 – Main Unit
ST-1500 – Control Unit
Mounted ST-1500 Close-up
SP-1500 Cover Glass Applicator
The included SP-1500 Cover Glass Stage applies 2 glass slides to the bottom of the chamber to minimize friction when stretching and maintain the rigidity of the chambers. A 200 µm gap is created between the slides where cells under observation are seeded.
The chamber is then positioned in the ST-1500 with pins that pierce the thick sides of the chamber from the top (glass slides are on the bottom).
Main Unit: Compatible with Nikon, Olympus, Zeiss, and Leica Microscopes.
We will need stage drawings to build the stage adapter.
Control Unit: Activates the main unit to put in place the desired stretching pattern for one cell culture.
Note: Video output through computer/monitor is not provided. STREX does not sell these.
ST-1500: Employs 1 cm² chamber.
Stretching Patterns: Up to 64 patterns. High speed and single stretch patterns with up to 30% ratio are available for a custom price.
Stretch Direction: Uniaxial
Compatible Stretch Chamber: Silicone Strain Chamber SC-0022
Biaxial Cell Stretching System
- The system is capable of stretching cells in culture by applying stress load and can stretch cells in a single chamber in one or two directions while allowing for imaging before and after stretch.
- The system’s mechanical stretching unit operates inside an incubator on top of a microscope, while the control unit and video output are placed outside, has 64 pre-programmed stretch patterns which make it easy to get experiments started.
- The system can stretch cells in two directions, but also allows uniaxial stretch as well.
Control Unit: Actuates the main unit to implement the desired stretching pattern for one cell culture.
Note: Video output through computer/monitor is not provided. STREX does not sell these.
ST-1900: Employs 4 cm² chamber designed for XY bidirectional stretching
Stretching Patterns: Up to 64 patterns. Custom patterns for high-velocity stretch are available for purchase.
Stretch Direction: Biaxial stretch, but is capable of a uniaxial stretch as well.
Compatible Stretch Chamber: SC-0042
|Applications||• Cytoskeleton rearrangements|
• Cell morphology
• Gene or protein expression
• For continuous mode/sustained stretch applications
|• Cytoskeleton rearrangements|
• Cell morphology
•Gene or protein expression
• Signal transduction
• Long duration studies (hours-days)
|No. of chambers||1||1||8||6|
|Chamber size-culture surface area||4 cm²||10 cm²||4 cm²||10 cm²|
|Strain||Uniaxial stretch||Uniaxial stretch||Uniaxial stretch||Uniaxial stretch|
|Incubator||Fits in standard incubator *²||Fits in standard incubator *²||Fits in a standard incubator||Fits in a standard incubator|
|No. strain programs||Manual continuous/sustained stretch||Manual continuous/sustained stretch||Automated/64 patterns||Automated/64 patterns|
|Applications||• Cytoskeleton rearrangements|
• Cell morphology
• Ion mobilization
• Calcium Influx
• Nitric oxide production
• Real-time observation of cultures
• Short duration studies (15-20 minutes) without a micro incubator
|No. of chambers||1||1|
|Chamber size-culture surface area||1 cm²||4 cm²|
|Strain||Uniaxial stretch||Biaxial stretch & compression|
|Microscope mountable||Fits Nikon and Olympus *1||Fits Nikon and Olympus *1|
|Incubator||Fits in a standard incubator||Fits in a standard incubator|
|No. strain programs||Automated/64 patterns||Automated/64 patterns|
*1: Optional stage adapter available for Zeiss and Leica
*2: Stretch chamber placed in a culture dish
FAQs on Cultured Cells
Stretch Chambers and Stretching Stimulation
- Does autoclaving affect cell adhesion on stretch chambers?
Autoclaving does not affect adhesion, however, you should not use aluminum foil. Use special sterilized bags.
- Can we reuse the stretch chambers?
The stretch chambers are intended for one-time use. Cross-contamination between experiments cannot be completely removed, and the reuse of stretch chambers may compromise the integrity of the experiment.
- What are the materials and characteristics of the stretch chambers?
The material of our stretch chambers is a thin silicone elastomer whose main part is made of Polydimethylsiloxane (PDMS). The surface has strong hydrophobic and weak cell adhesiveness. In cell culture, the chambers must be first coated with an extracellular matrix (e.g. fibronectin, collagen, laminin, gelatin) to strengthen the cell adhesiveness of the culture surface (see coating protocols). PDMS chambers bounce back from stretching and compression with their original properties intact. Thus, the chambers demonstrate good reproducibility in applications requiring continuous mechanical stretching over prolonged periods. An optically transparent, ultra-thin (100 – 200 μm) membrane at the well bottom not only makes stretch chambers compatible with optical microscopy techniques but with fluorescence detection and microscopy as well.
- Is a uniform stress load applied to every cell in the stretch chamber?
Our unique stretching system enables uniform stress loading due to the materials and methods employed and the shapes of stretch chambers. The STREX Cell Stretching System is designed to achieve stretching in a single, parallel direction, with only a very weak secondary load. Research has demonstrated that the STREX system enables highly reproducible cyclic stretching over prolonged periods at ratios of 1 – 20%. (Ref) Naruse. K., et al. (1998), Oncogene,17:455-463.
- What is the difference in cell response between sustained stretching and cyclic stretching?
It is reported that the signal transduction systems and biochemical responses stimulated in the cells under sustained cellular stretching and those under periodic cellular stretching differs. (Ref) Sasamoto et al, 2005, 288, C1012-22.
- Are the stretch chambers sterilized?
Stretch chambers as sold are non-sterile. The chamber must be autoclaved for 20 minutes at 180°C. Aluminum foil should not be used in the autoclaving process. Rather, autoclave bags (sterilization pouches) are recommended.
Note: Chambers are disposable and heat-resistant from 0° to 180°C. Product quality and cell adhesion performance are not guaranteed when the chambers are reused, or used outside the range of heat resistance.
- Are you able to manufacture chambers larger than shown in your catalog?
We manufacture stretch chambers for mass cultures by special order.
- Can we preserve coated chambers for future use?
We recommend coating the chambers just before use.
- Are there any solutes that may emerge from the stretching system?
PDMS or polymerization initiators with low molecular weight may emerge, however, we have never received a report saying these substances harm the experiments.
- The culture medium is not of uniform thickness. Why is that?
Due to the thinness of the elastic silicone membrane, the chamber may slack in the center. The ultra-thin film (100 – 200 μm) facilitates the observation of samples. Our experience shows that this variation in chamber thickness does not considerably affect uniform stress load.
- Why does the culture medium evaporate after a few days while using an STB-1400 stretching system?
The STB-1400 is not suitable for long-term culture, as it requires daily replenishment of culture fluid. We recommend using our stretching systems suitable for long-term culture. Additionally, check that the lid of the system is put on during the experiment. Placing a 35 mm or 60 mm dish with water at any location within the stretching system will slow the evaporation of the culture fluid. The velocity of the evaporation of culture fluid heavily depends on the condition of the incubator. Check the condition of evaporation dishes, and confirm that sufficient coolant is in the plastic container attached to the stretching system and it circulates properly. If you do not have any problems with the above and still have the evaporation problem, try to put cotton wool with purified water near the chamber of the stretching system.
- We use reagents with phenols for RNA extraction. How much will the silicone materials of the chambers degrade when we add the reagents directly?
We recommend that you dispose of the chambers after a single use as they are not intended for multiple uses.
- Do you have any recommendations for gels to use for 3D cyclic stretching?
We recommend collagen gels for use in 3D cyclic stretching at this time. We have successfully used the following gel in-house: KOKEN’s DME-02 Neutral collagen solution DMEM 2 mg/mL Atelocollagen, DMEM.
- Can we coat chambers under UV rays?
It is not recommended to coat chambers under UV rays. UV exposure after coating may denature proteins in the extracellular matrix on the chamber and may affect adhesiveness.
- Cell adhesion appears to be different from chamber to chamber. What could be the cause?
In producing the stretch chambers, STREX works to assure that there are no creases or other imperfections on any of the surfaces. However, given the exceptionally thin membranes involved, creases can easily develop. Therefore it is important to use great care with the bottom surface when seeding the cells. To avoid creases, first, treat a culture dish by dripping a bit of ethanol on it. Then set the chamber on the dish and tilt the dish and chamber, taking care not to introduce any air between the two. Allow some time for the ethanol to evaporate. The chamber will then be in optimal condition for seeding and culturing the cells with high adhesion.
- Does the silicone film need to be hydrophilic before applying the coating agents?
Stretch chambers become hydrophilic with plasma processing before shipping.
- How do you confirm the completion of a coating?
Some cells adhere without coating. For example, some cells secrete collagens, such as smooth muscle cells and fibroblasts. You can check the degree of coatings on the chambers using antibodies, however, this method sacrifices a chamber.
- Do we have to air-dry after a four-hour standing?
We coat it with fibronectin just before using it and have never done air-drying. However, some users have reported air-drying after coating with collagen.
- Do you coat with fibronectins without pretreatment on the methyl groups on the surface?
We do not recommend conducting any treatments on the surface of the chambers. Some chamber treatments during the manufacturing process such as plasma processing may cause nonspecific absorption with cells. If you want to observe specific bonding between fibronectins, collagens, and integrins, you may special order the chambers without plasma processing, giving them strong hydrophobic properties.
- Which extracellular matrix works best for cell adhesion? Fibronectin, gelatin, or collagen?
Cell adhesion to the stretch chamber membrane is entirely dependent on the cells binding to the extracellular matrix coating. The cells themselves vary in adhesive properties from one cell type to another and even vary between different cell lines of the same cell type. Therefore, before conducting any stretching experimentation or research, it is important to be aware of the adhesiveness and the required conditions for whatever coating is to be employed.
See coating protocols as a reference.
- Adhesion to the stretch chamber was confirmed under the microscope before the stretch stimulus was initiated, yet after the stretching, the cells no longer adhered. What could have caused the cells to detach from the chamber surface?
There are three possible causes:
1. Cell density
The cell concentration of the culture may be too dense. Generally speaking, over-confluence will cause the adhesive force between cells to increase beyond the adhesive force between the cells and the extracellular matrix. This relative decrease in extracellular adhesion can lead to cells detaching from the stretch chamber.
2. Enzyme treatment
Trypsin and other enzyme treatment can damage cells. However, this may not be obvious in experiments conducted with standard dishes, because the binding to the dishes’ plastic wells is nonspecific. By contrast, when stretch chambers are employed, adhesion is attained solely by the extracellular matrix coating. Thus, relatively severe enzyme damage will cause stretch chamber adhesion to fail. Please see the tip on trypsin treatment (below) that addresses this issue.
Cells will not adhere to the stretch chamber if the coating is insufficient. This insufficiency is indicated when the chamber surface easily repels liquid after the applied coating has been absorbed. Extend the coating application and setting time should this occur.
- Cells seeded onto the stretch chamber sometimes aggregate at the center of the chamber. Is there any technique to avoid this aggregation?
Cells may be migrating toward the center of the stretch chamber due to the vibration of the incubator. If that is the issue, seed the cells normally, then after 15 minutes, gently tilt the chamber from side to side.
- Are rounded cells difficult to be stretched even though they adhere to the chamber?
Rounded cells are generally more difficult to be stretched in comparison with flat-shaped cells.
- In a long-term experiment with the cells in culture under continuing stress, what is the longest period that the stretching stimulus can be applied?
Generally speaking, cells in the incubator can be stretched for two weeks. However, in these long-term experiments, the culture fluid has to be replaced at 2-3 day intervals. Also, there must be enough motor coolant to ensure the motor is running at a safe temperature throughout the long-term culture. Insufficient coolant may cause the temperature in and around the motor to rise, in turn destroying the cells and/or damaging the equipment.
- What is the optimal cell count to be placed on the chamber?
In general, 200,000 cells/chamber (4 mL of culture medium) is proper from our experience.
- Is it preferred to do the coating at room temperature?
The manufacturer recommends the coating at room temperature.
- We are planning an experiment using neurons. Is it okay to coat them with laminin?
We do not foresee any problems with laminin coating, but unfortunately, we do not have any experience using laminin coating.
- What density of cells is adequate when we put them on chambers?
It depends on the experiment you are planning. As a general guide, we say that the cells of 5 × 104 cm2 are adequate.
Cells to Use
- Do you have any videos of cells recorded in time-lapse capturing?
Unfortunately, no videos are available. Please refer to the following paper for photos of fluorescent images of GFP-actin-transferred cells in the stretched state on stretch chambers.
- Can we stretch myocardial cells?
Yes. Please see this reference.
- Can we load shear stress on cells?
The system is intended to work with adhesive cells, therefore it is not possible to load shear stress with this system.
- Can we stretch cells undergoing gene transfer?
You can conduct gene transfer directly on stretch chambers. However, the transfer work damages cells so it becomes difficult to snap high-quality images. We recommend that you conduct the transfer on cells in dishes before being placed on the stretch chamber.
Experiments after Stretching
- How can cell proteins or mRNA be obtained from the stretch chamber after culturing?
1. Western blotting: Wash with PBS, add electrophoresis sample buffer directly to the stretch chamber, then collect the cell lysate with a cell scraper.
2. Immunoprecipitation: Wash with PBS, add cell solubilizer directly to the stretch chamber, then collect the cell lysate with a cell scraper.
3. mRNA: Wash with PBS suitable for RNA, add cell solubilizer directly to the stretch chamber, then collect the cell lysate with a cell scraper.
- Is there an assay to measure the tension load for fibroblasts?
We recommend phosphorylation of ERK with Western Blotting.
- Could you show any report saying the amount of mRNA in the gene of mechanosensitive channels changes drastically under stretching stimulation?
Some genes in mechanosensitive channels are well known, however many of them have not been identified yet. So we cannot show the references on this topic at this time.
Is there any report saying the amount of β-actin in cells is changed under stress?
The amount of β-actin in cells is not considered to change so drastically under stresses, except for long-term experiments.
Fixation, Staining, and Observation of Cells
- Can we conduct fluorescent staining and observations with the membrane stretched?
Yes. Follow the protocol on page 20 of the manual or use our trial kit with a stretching stand.
- We are planning to stretch the cells on the chambers to observe them after fixation and staining. Do your chambers degrade on the fixation and staining?
If you use acetone or chloroform, the silicone film of the chambers may swell a little. You have no problems with methanol.
Tip: Splicing the silicone chamber film into approx. 5 mm x 5 mm makes your work easier. You can observe good images by putting the cell plane side onto the cover glass.
- Can we use an immersion lens in the observation of fixed and fluorescent-stained cells after stretching? Are there any limitations to the observation?
You can use an immersion lens. However, the choice of chamber is limited following the size of the objective lens to use.
- The microscope observations appear out of focus.
1. Did you use an oil immersion lens? The existing PDMS films swell when they are exposed to oils and make the observation difficult. We recommend using a water-immersion lens if available.
2. Did you use fixed samples for fluorescence observations? We recommend splicing samples with a razor after fixation and staining to enclose them on cover glass in the up-side-down state, and then observe them. In this case, there is no problem with the observations with an oil-immersion lens.
- Can we conduct stretching with a biomembrane attached to the stretch chambers (to conserve the orientation of cells)?
Yes. Usually, we stretch the cell sheets with cell sheet cramps. Otherwise, we can exchange the inner chamber sheet with a biomembrane in the stretching with a double-structured transwell.
- Is there a method for standard observation and photographing stretch-stressed cells in their stretched position, using a standard optical microscope?
With the STB-1400 Cell Stretching System, this is accomplished by employing a static stretch chamber stand, which holds the samples in the stretched state. Alternatively, cells can be observed and photographed using one of the microscope-mountable stretching systems established directly on the microscope stage.
- STB-150W has a limitation of 20 minutes in continuous stretching operation. Can we conduct a continuous observation of 60 minutes (approx.) with long intervals between each stretch?
Yes. You can conduct a continuous observation of one hour if you limit the frequency of stretching up to 10 times/min. In this case, you will need 1) a thermal insulator and 2) a thermostatic reflux system.
- Could you show an approximate figure of this stretching force, depicted with mechanical units?
The stretching force cannot be measured with our equipment. An example of a system that measures loading force on cells under stretching is shown in this paper.
- Do you have any recommendations for antiseptics to add to the coolant container?
We have no recommendations for any particular brand, but you may use the antiseptics used in your laboratory or the antiseptics for incubator water jackets. Alternatively, you can get by with no antiseptics during an experiment if you change the water when you start another experiment.
- Is it okay to wash the inside of the silicone tubes for cooling with a neutral or an alkaline detergent?
No, we suggest washing it with DI water or antiseptics as mentioned above.
- On sterilization: Is it safe to reflux ethanol in the plastic container? Is it safe to use hypochlorous acid?
Reflux with ethanol is okay. Highly concentrated hypochlorous acid may harm the pump valves. Please be cautious about the density in the use of hypochlorous acid (a density of 50-100 ppm is okay).