New Non-Invasive Brain Monitoring Technique Shows Promise in Monkeys

A new non-invasive brain monitoring technique, Released Markers of Activity (RMAs), has demonstrated effectiveness in monkeys, building upon its earlier success in mice. This development, detailed in a recent study published in the journal Neuron, offers a method to track gene expression within the brain through a simple blood test, potentially advancing research into neurological diseases and complex cognitive processes.

Overview of Released Markers of Activity (RMAs)

RMAs are engineered proteins designed to traverse the blood-brain barrier and remain in the bloodstream for several hours. This mechanism allows for the non-invasive collection of information regarding gene expression in the brain through a simple blood test. The technology provides a high level of precision, capable of tracking activity from tens to hundreds of neurons.

The study, led by Rice University bioengineer Jerzy Szablowski with collaborators including Vincent Costa's lab at Emory University, represents a significant step in translating laboratory discoveries into clinical treatments.

"No existing imaging or monitoring technique offers this level of precision," Szablowski noted, also highlighting the ease of translating this technique between species.

Key Features and Future Applications

RMA technology is designed for adaptability. Different serum markers can be engineered to monitor multiple genes across various brain regions. Future applications could involve multiplexed protein detection, allowing for the identification of numerous distinct synthetic serum markers in a single sample using biochemical methods such as mass spectrometry or single-molecule protein sequencing.

Significance for Brain Research

Monitoring gene expression within a living, intact brain can provide insights into cellular activity, complex cognitive processes, and the initiation and progression of neurological diseases. Accessing this information via a blood test makes it feasible to track changes in the same individual over extended periods.

This longitudinal monitoring is crucial for understanding how gene expression influences disease or physiology over time, providing a more comprehensive understanding than "snapshot" readouts from biopsies or terminal studies.

The ability to track gene expression non-invasively holds promise, much like gene therapy has successfully been applied to treat various diseases, including immune deficiencies, hereditary blindness, hemophilia, and Huntington's disease.

Development Background

The development of the RMA platform by Szablowski was informed by observations that antibody therapies often failed due to antibodies rapidly migrating from the brain into the blood. He identified a specific protein segment responsible for enabling antibodies to cross the blood-brain barrier and utilized this segment as a building block for the synthetic reporters. This protein piece also facilitates the exit of the protein from the cell into the extracellular matrix. The system was adapted for rhesus macaques by modifying the mouse version of this protein domain.

Vincent Costa, an associate professor of psychiatry and behavioral sciences at Emory and a co-corresponding author, collaborated with Szablowski after reviewing an initial preprint of the RMA platform.

"This platform provides an advance in primate neuroscience by potentially reducing the complexities and resource demands associated with repeated brain imaging, thereby facilitating long-term studies," Costa stated.

The research was supported by the David and Lucile Packard Foundation and the National Institutes of Health.