Human cardiac muscle cells pulse rhythmically under the microscope. They are arranged like a mini 3D heart on a chip, known as a microelectrode array (MEA). Every few seconds, the heart muscle cells contract and relax again. All at the same time. Rhythmically. Tiny electrodes measure the voltage discharged by the cells.
Dr. Udo Kraushaar disturbs them by adding substances and observing if they still pulse regularly, lose their rhythm or stop pulsing altogether. A monitor records the voltage discharged from the cells on a curve, like an ECG. Udo Kraushaar would rather test the effects of particular substances on the heart cells now before “someone falls off their bike because they can't tolerate a painkiller pill,” he says. This is not a fictitious example: Udo Kraushaar tests possible side effects of new substances on human cardiac organoids and cells from many other organs and helps to sift out unsuitable candidates for new drugs.
When a pharmaceutical company wants to develop a new agent, it starts with 100,000 to 200,000 substances and systematically reduces the number to the most promising candidates. When there are about fifty to a hundred left, Udo Kraushaar and his team come into play. Organoids resemble a small white lump, large enough to be seen by the naked eye on the microelectrode chip under the microscope. Cells for forming the organoids had to be removed from a volunteer’s skin once by biopsy and then grown into heart muscles using adult stem cells. The cells behave as expected: They contract and relax again. Like a heart.
In this phase of drug development, usually between five and ten years have already passed. Only when two to five drug candidates remain does the clinical phase, the test on humans themselves, begin. “If a pharmaceutical company puts a substance into the clinical phase and fails, a billion euros is wasted,” says Udo Kraushaar. That’s why his work is essential in selecting the right substances. Animal testing also takes place before the clinical phase. The experiments in Udo Kraushaar's lab at NMI Natural and Medical Sciences Institute however, are closer to the physiology of humans and reduce the need for animal experiments.
Udo Kraushaar can only measure the cells’ electrical activity because the cells are on a chip with microelectrodes. Under the microscope, they are about the size of a cell and evenly distributed in the center of the board. From there, 60 electrically conductive tracks lead in uniform patterns to a square formation of contact pads. From here, the voltage pulses are amplified and digitized.
