Tissue and data from living donors speed research on brain and genetic disorders

By Calley Jones

An illustration of neurons

Image credit: Colin Behrens on Pixabay

SEATTLE — A century ago the U.S. Supreme Court ruled that “every human being of adult years and a sound mind has a right to determine what shall be done with his own body.” Today, science and society still grapple with how that applies to donation of body parts for biomedical research, as well as how data from tests, and tissue samples from clinical procedures, can be repurposed for research.

“Patients want to donate their tissue, and if they want to, they should be able to,” said Emory University neuroethicist Karen Rommelfanger during a Feb. 14 session at the annual meeting of the American Association for the Advancement of Science. “Volunteerism is what prevents humans from being reduced to a standing reserve of tissues, organs and body parts.”

Tissue from living donors has powered scientific advances with potentially far-reaching impact, including on neurological conditions such as Parkinson's and Alzheimer's.

During the course of many routine medical procedures such as colonoscopies and tumor removals, doctors may also remove healthy tissue from a living donor. Sometimes, the patient has the option to donate that tissue for research.

In a 2009 study by the Eastern Cooperative Oncology Group, about 88% of more than 30,000 patients consented to storing their tissue for research — a process called biobanking. The levels of consent varied, however, depending on the type of tissue. Patients who had thoracic cancer or multiple myeloma were more reluctant to donate than those who had leukemia, breast cancer or gastrointestinal cancer.

Similarly, many people hesitate to donate tissue from the brain, which is intimately connected with thought and personality. But healthy brain tissue from living donors is crucial to neuroscience research.

Unlike tissue from cadavers, living tissue can show scientists how brain cells function and communicate in real time. That’s especially important when the brains of animal models can’t quite compare. The thousand-fold size difference between human and mouse brains is just one of the variables that limits how well the rodents can serve as a stand-in.

“We don’t really understand the complexity of the brain very well, and we’re trying to treat diseases of an organ that we don’t understand,” said neurobiologist Ed Lein, of Seattle-based Allen Institute for Brain Science.

To illuminate some of the mystery, Lein is developing what he calls a periodic table of cell types within the brain, a project that is only possible using living human tissue.

But how is brain tissue retrieved while patients are alive?

Sometimes to get to diseased areas of the brain during surgery, doctors have to remove small portions of healthy tissue. Instead of being discarded, that tissue — with patient consent — can be used by researchers like Lein, who examines it on a cell-by-cell basis.

Using a relatively new method called single-cell RNA sequencing, Lein investigates how each brain cell differs from its neighbors based on the expression of different genes. Culturing these cells in a lab allows him to activate them with electrical signals or expose them to drugs and analyze the corresponding gene expression changes in real time. Gene expression acts as a blueprint for cellular function, so these methods using donated brain tissue can help scientists understand how each cell responds to disease, which, in turn, can aid development of new treatments.

As with brain tissue, people often regard their genetic data as highly personal, which can discourage them from agreeing to its use in research.

But the for-profit genetic testing company 23andMe seems to have found success in this area. The company provides direct-to-consumer testing of genetic markers associated with ancestry and health, using cheek swabs sent in via mail. Customers can view their results in an online portal. There, they can also consent to the use of their genetic data for research — and about 80% do, according to the company’s vice president of research, Joyce Tung. This contrasts with the finding that 38% of respondents in a recent survey by the American Society for Human Genetics and Research!America felt “cautious” about human genetic research.

How does 23andMe put consumers’ minds at ease?

By emphasizing choice, privacy and ethics, Tung said. “As a consumer, you want to be treated well, and if the company doesn’t treat you well, you walk away.”

Most of the company’s research is done via easily accessible online surveys through which participants answer questions about their health, characteristics and behaviors. Scientists then look for genetic markers that people with certain diseases or traits have in common. That can lead to new information about the genetic causes of disease, which can help scientists find new ways to treat patients.

Survey results and genetic data are generally de-identified, and participants can withdraw their consent at any time. The company also keeps individual volunteers informed about scientific progress made using their data. Participants receive an email when a paper uses their information, and they can keep track via their online accounts.

“It’s really important for us to give back to our participants so they can feel good about the contributions that they’re making,” Tung said.

Several biobanks at not-for-profit research institutions offer similar levels of communication with patients.

This practice aligns with findings from a Tohoku Medical Megabank Project survey that 80-90% of volunteers said they would like to receive results of research that used their genetic data.

“They feel it’s a way for their illness to help others,” Rommelfanger said.

Using brain tissue from living donors, Lein found that serotonin receptors activate different patterns of gene expression in different cell types. That could have a significant impact on the treatment of mood disorders, seizures, Alzheimer’s disease, and other conditions in which serotonin receptors play a role. Similarly, 23andMe has used genetic data from patients with Parkinson’s disease to study new mutations that might affect how the disease progresses.

“I actually think that we’re moving in the right direction, and that the technologies are dramatically moving forward now,” Lein said. “This could only be done through the generosity of donors.”

Calley Jones is a molecular biology Ph.D. student at the Mayo Clinic Graduate School of Biomedical Sciences. She has written for Mayo Clinic’s research magazine Discovery’s Edge, and plans to continue writing about basic biology and health sciences. Follow her on Twitter @CalleyJSciWri or email her at cjjones252@gmail.com.

Apr. 8, 2020

Drexel University Online