Researchers at Sungkyunkwan University have built a chip that uses light to follow dopamine release from lab-grown human brainstem tissue. In a 12-hour experiment, it tracked the tissue's response to L-DOPA, a drug used to treat Parkinson's disease.
Dopamine helps nerve cells communicate, and Parkinson's disease damages the cells that produce it. Following its release over time can help researchers study how tissue responds to a drug. But tests that require staining or destroying cells make continuous observation of living tissue difficult.
Reading dopamine with light
The team used brainstem organoids, small three-dimensional tissue models grown from human stem cells. Each organoid sits in a microfluidic chip, which uses tiny channels to deliver the liquid that keeps the tissue alive, along with the drug being tested. The sensor measures dopamine released into that surrounding liquid.
The sensor's gold surface contains tiny holes and carries an aptamer, a DNA molecule designed to bind dopamine. Binding changes the light signal from the surface. In calibration tests, the researchers reported a detection limit of 8.3 picomolar, meaning the sensor could distinguish dopamine at that low concentration. They also found little interference from chemically related substances.
Measuring the organoids' drug response
In tests without continuous fluid flow, organoids made from a Parkinson's disease cell line released less dopamine before treatment than those from a healthy cell line. Parkinson's-targeted drugs increased dopamine release in the disease models; the other drugs tested did not produce the same response.
For continuous monitoring, the researchers supplied L-DOPA through the chip and recorded dopamine changes over 12 hours. They converted the changing optical signal into a record of dopamine concentration over time, showing how the tissue's chemical response developed during treatment.
The work, published in ACS Nano on September 18, offers a way to study drug responses before clinical trials. The findings concern lab-grown tissue: they do not establish a safe dose or a treatment benefit for patients.