Image: Close up of 3D printer printing heart-on-a-chip MPD (Photo courtesy of Harvard University).
Multi-material three-dimensional (3D) printing may one day be used to design organs-on-chips that match the properties of a specific disease, or even an individual patient’s cells.
Researchers at Harvard University (Cambridge, MA, USA) have developed a new technique to fabricate instrumented cardiac microphysiological devices (MPDs) that uses a mix of six functional inks that are based on piezo-resistive, high-conductance, biocompatible soft materials. By using 3D printing, the researchers were able to print a physio-mimetic, laminar cardiac tissue MPD that integrates soft strain sensors into the micro-architecture of the tissue, all in a single, continuous procedure.
The chip contains multiple wells, each with separate tissues and integrated sensors, which allows the researchers to study many engineered cardiac tissues at once. To demonstrate the efficacy of the device, the researchers first validated that the embedded sensors provided non-invasive, electronic readouts of tissue contractile stresses inside cell incubator environments. They then used the MPD to study drug responses, as well as the contractile development of human stem cell-derived laminar cardiac tissues over four weeks. The study was published on October 24, 2016, in Nature Materials.
“Researchers are often left working in the dark when it comes to gradual changes that occur during cardiac tissue development and maturation, because there has been a lack of easy, non-invasive ways to measure the tissue functional performance,” said lead author Johan Ulrik Lind, PhD. “These integrated sensors allow researchers to continuously collect data while tissues mature and improve their contractility. Similarly, they will enable studies of gradual effects of chronic exposure to toxins.”
“Our microfabrication approach opens new avenues for in vitro tissue engineering, toxicology, and drug screening research,” said study co-author professor of bioengineering and applied physics Kit Parker, PhD. “Translating microphysiological devices into truly valuable platforms for studying human health and disease requires that we address both data acquisition and manufacturing of our devices. This work offers new potential solutions to both of these central challenges.”
MPDs, also known as organs-on-chips, mimic the structure and function of native tissue in-vitro and have emerged as a promising alternative to traditional animal testing; but the fabrication and data collection process is expensive and laborious. Currently, these devices are built in clean rooms using a complex, multi-step lithographic process, and collecting data requires microscopy or high-speed cameras, since they do not have integrated sensors.