Researchers funded by the National Institute of Biomedical Imaging and Bioengineering (NIBIB) have created a new type of tissue chip that can better represent human tissues compared with current chips, and can be more widely used for drug testing. By engineering the chips as a silk gel, the researchers circumvented many of the problems with existing devices. The new chip also has the potential to someday be an implantable treatment itself.
Tissue chips are collections of cells that mimic both the anatomy and physiology of a tissue or organ, making it possible to test treatments in the lab more accurately than using cells grown in a single layer in a dish. To engineer a tissue outside the body, the cells need a three-dimensional structure on which to grow. Such scaffolds are often made of polydimethylsiloxane (PDMS), a silicon-based polymer, and contain microfluidic chambers, representing blood vessels or respiratory tracts, running through them.
These microfluidic systems have various advantages. Some systems are great for developing and testing treatments in the lab; some allow living cells to be embedded within them, while others can replicate a variety of tissue types (bone and bone marrow, say). Other systems have qualities that may allow them to be implanted in the body as part of the treatment itself; one such quality is the ability to eventually degrade away when no longer needed. But, none of the current biomaterials can do all of the above. PDMS is particularly problematic because it is non-degradable, and it sucks up lipids, such as fat molecules or steroid hormones. Many potential medications are lipid based, so PDMS absorbs them before their effects can be measured, making it difficult to test drugs. Additionally, an implant made of PDMS would absorb the body’s lipids, and since lipids are vital to the body’s function, a PDMS microchip can’t be implanted in humans.
Pinpoints subtle but critical changes in cells to reveal vital health information
Knowing the exact number of molecules located at specific junctures in cells can be a critical measure of health as well as disease. For example, abnormally high numbers of growth factor receptors on cells can be an indication of cancerous and precancerous states; specific proteins located at the junction where neurons connect in the brain may affect brain function as they accumulate or disperse.
Until recently, researchers have had to use either very expensive microscope hardware, or highly complex — and often imprecise — microscopy software, to see individual, fluorescently-labeled molecules in tightly bunched groups in cells. Now, a simplified method known as qPAINT uses the blinking pattern of the light that marks each molecule, to find, count and study individual molecules that are just a few nanometers apart — all using the standard microscopes already found in laboratories.
“qPAINT allows identification of each point of light coming from a labeled molecule without the need for complex and sometimes inexactmicroscopy calculations,” explains Behrouz Shabestari, Ph.D., Director of the NIBIB program in Optical Imaging and Spectroscopy. “The method overcomes the problem that occurs when trying to visualize molecular structures that are in very close proximity: light diffuses as it leaves the spot where it originates. This masks exactly how many points of light—each representing a single molecule—are actually creating the light.”
The National Institute of Biomedical Imaging and Bioengineering (NIBIB) is the newest of the National Institutes of Health (NIH) research institutes and centers and was formed in the United States when President Bill Clinton signed it into law on December 29, 2000.
The Institute is committed to integrating the physical and engineering sciences with the life sciences to advance basic research and medical care. This is achieved through: research and development of new biomedical imaging and bioengineering techniques and devices to fundamentally improve the detection, treatment, and prevention of disease; enhancing existing imaging and bioengineering techniques; advocating related research in the physical and mathematical sciences; encouraging research and development in multidisciplinary areas; developing technologies for early disease detection and assessment of health status; and developing advanced imaging and engineering techniques for conducting biomedical research at multiple scales.
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National Institute of Biomedical Imaging and Bioengineering (NIBIB) research articles from Innovation Toronto
- A wearable blood-flow sensor for vascular disease monitoring – February 4, 2016
- New material developed for accelerated skin regeneration in major wounds – December 17, 2015
- Silk and Ceramics Offer Hope for Long-term Repair of Joint Injuries – September 26, 2015
- Spinal Stimulation Helps Four Patients with Paraplegia Regain Voluntary Movement – April 9, 2014
- Light-guiding Gels Provide New Avenues for Drug Detection and Delivery
- New handheld imaging device to aid doctors on the ‘diagnostic front lines’
- Ultrathin “Diagnostic Skin” Allows Continuous Patient Monitoring
- Ultrasound Patch Heals Venous Ulcers in Human Trial
After training, men move legs independently, without stimulation
Five men with complete motor paralysis were able to voluntarily generate step-like movements thanks to a new strategy that non-invasively delivers electrical stimulation to their spinal cords, according to a new study funded in part by the National Institutes of Health. The strategy, called transcutaneous stimulation, delivers electrical current to the spinal cord by way of electrodes strategically placed on the skin of the lower back. This expands to nine the number of completely paralyzed individuals who have achieved voluntary movement while receiving spinal stimulation, though this is the first time the stimulation was delivered non-invasively. Previously it was delivered via an electrical stimulation device surgically implanted on the spinal cord.
In the study, the men’s movements occurred while their legs were suspended in braces that hung from the ceiling, allowing them to move freely without resistance from gravity. Movement in this environment is not comparable to walking; nevertheless, the results signal significant progress towards the eventual goal of developing a therapy for a wide range of individuals with spinal cord injury.
“These encouraging results provide continued evidence that spinal cord injury may no longer mean a life-long sentence of paralysis and support the need for more research,” said Roderic Pettigrew, Ph.D., M.D., director of the National Institute of Biomedical Imaging and Bioengineering at NIH. “The potential to offer a life-changing therapy to patients without requiring surgery would be a major advance; it could greatly expand the number of individuals who might benefit from spinal stimulation. It’s a wonderful example of the power that comes from combining advances in basic biological research with technological innovation.”