In the living brain, many chemical cues guide the development of neurons. The types and amounts of various chemicals determine when, where, and how far neurons grow. The process is difficult to study because so many variables are involved, but engineers at Johns Hopkins University have developed a chip that works as a mini-laboratory for studies of neuronal growth.
The research team, led by Andre Levchenko, associate professor of biomedical engineering, describes the new chip in the February issue of the British journal Lab on a Chip.
Levchenko says the new chip is a major improvement on existing experimental platforms that generate and control chemical gradients but cannot present many cues at the same time. The response of single nerve cells to a mixture of substances can be observed and measured on the new chip.
The researchers grew spinal neurons from frog embryos on prototype chips. They used two nerve-growth-altering substances: laminin, a glycoprotein that affects how cells organize into tissues; and brain-derived neurotrophic factor (BDNF), a protein that promotes neuronal growth and differentiation. The laminin was bound to the chip’s surface. The BDNF was dissolved in a solution, and it diffused along the chip.
Levchenko found that the surfacebound laminin fine-tuned how the nerve grew in response to varying concentrations of BDNF. This result suggests that the chip can mimic the conditions that neurons encounter in living tissues—and can produce similar outcomes.
“The chip we’ve developed will make experiments on nerve cells much simpler to conduct and to control,” Levchenko says.