Lab on a Chip Blog

A heart-on-a-chip device could help detect drugs that limit heart tissue contraction, say US scientists.

The device was created using small thin strips of tissue made from heart muscle cells that are connected to electrodes to stimulate contraction. Observing the contraction response of the tissue allows scientists to study the effect of physiological factors or test drugs for cardiotoxicity. Replicating segments of heart tissue makes it possible to rapidly measure contraction data at the tissue level, rather than just studying individual cells.

The researchers, led by Kevin Parker from Harvard University, Cambridge, created up to eight separate strips of tissue on one chip by growing a sheet of heart muscle cells in a flat film and then cutting away sections to leave isolated strips that were only connected to the film by one edge. Creating several strips on one chip allowed the team to conduct multiple experiments at once. The contraction experiments were observed by looking vertically down onto the chip and monitoring the change in length as the strips contracted and bent up. ‘The heart-on-a-chip allows us to capture in 2D what a healthy or diseased heart might look like and look at how much force the tissue will generate,’ says Anna Grosberg, a member of the research team.

The team then used the heart-on-a-chip to investigate the effects of different environments on contraction response. Experiments with epinephrine (adrenaline) showed the device can be used to measure the dose-dependent effect of drugs on contraction response. The team also showed that the heart-on-a-chip can be used as a platform to investigate the effect of cell architecture on tissue contraction.

‘The heart-on-a-chip technology is the first scalable technique that recapitulates in vitro the anisotropic cell organisation of native cardiac muscle, while simultaneously allowing coupled electrical and mechanical function to be quantitatively assayed,’ says Andrew McCulloch, an expert in cardiac bioengineering at the University of California, San Diego, US. ‘Once this technology can be deployed using human stem cell-derived cardiomyocytes, we will have a powerful new platform for screening new drugs for heart diseases like arrhythmia and heart failure.’

Ensembles of engineered cardiac tissues for physiological and pharmacological study: Heart on a chip
Anna Grosberg, Patrick W. Alford, Megan L. McCain and Kevin Kit Parker
DOI: 10.1039/C1LC20557A

Original article published at Chemistry World

Microfluidic devices have been hailed as the technology that will revolutionise areas such as diagnostics in medicine, food safety, drug development and genetic sequencing since their conception in the late 1980s. However, a limiting factor in translating neat microfluidic ideas to practical, portable devices has been integrating all the necessary components. The microfluidic chip may be small and perfectly formed, but the power source, pumps and control electronics for sample analysis are often external, bulky components – existing in the macroscale rather than the microscale.

Now, a team led by Neus Sabaté at the Institute of Microelectronics of Barcelona has integrated a micro direct methanol fuel cell into a microfluidic platform, which is capable of producing up to 4mW, sufficient to power the device. The carbon dioxide produced as a by-product of the fuel cell reaction is used to push liquids through the microchannels, removing the need for an external pump. The team has shown that by controlling the fuel cell operating conditions, they can control the flow rate of the liquid, which bears an almost linear relationship to the current generated in the device.

Jonathan Cooper, an expert in lab-on-a-chip technologies from the University of Glasgow, UK, comments: ‘A real strength of this work is the excellent job the researchers have done in integrating and packaging the device to show a working prototype. The flow rates are high enough for devices to function for several minutes and the device offers the prospect of enabling autonomous functionality on chip.’

The next step for Sabaté is to show that the device can truly function independently. ‘We are trying to prove that we can indeed perform measurements on analytes by integrating a low power electronic chip module and amperometric sensors,’ she says.  Her team is also working on higher degrees of device integration by fabricating them from just one type of polymer and experimenting with different fuels such as glucose.

Fuel cell-powered microfluidic platform for lab-on-a-chip applications
Juan Pablo Esquivel, Marc Castellarnau, Tobias Senn, Bernd Löchel, Josep Samitier and Neus Sabaté
DOI: 10.1039/C1LC20426B

Read the original article in Chemistry World