Researchers develop biodegradable electrodes that may help repair damaged brain tissue

University of Toronto researchers have developed a flexible, biodegradable electrode capable of stimulating neural precursor cells (NPCs) in the brain – a device capable of delivering targeted electrical stimulation for up to seven days before it dissolves naturally.

By harnessing the body’s innate repair mechanisms, the researchers’ approach represents a potential step forward in the treatment of neurological disorders that are a leading cause of disability worldwide. While neurological disorders often result in irreversible cell loss, stimulating NPCs – rare cells capable of repairing neural tissue – has shown promise when it comes to expanding limited treatment options.

However, existing methods such as transcranial direct current stimulation lack precision and can damage tissue. The electrode developed by U of T researchers, on the other hand, provides precise, safe and temporary stimulation without requiring subsequent surgical interventions.  

“Our findings demonstrate that this electrode can stimulate neural repair in a controlled, temporary manner, which is crucial for avoiding complications associated with permanent implants,” says Tianhao Chen, a PhD student in biomedical engineering who is the study’s lead author.  

The research, published in a recent issue of Biomaterials, was led by Hani Naguib, a professor in the departments of materials science and engineering and mechanical and industrial engineering in the Faculty of Applied Science & Engineering, and Cindi Morshead, a professor of surgery in the Temerty Faculty of Medicine who is cross-appointed to the Institute of Biomedical Engineering.

“Neural precursor cells hold significant potential for repairing damaged brain tissue, but existing methods for activating these cells can be invasive or imprecise,” Morshead says.  

“Our biodegradable electrode provides a solution by combining effective stimulation with reduced patient risk.”  

To design the biodegradable neural probe, the team focused on materials that provided both biocompatibility and tunable degradation rates. 

Poly(lactic-co-glycolic) acid (PLGA), a flexible material approved by the U.S. Food and Drug Administration, was chosen for the substrate and insulation layer due to its predictable degradation based on monomer ratios and minimal inflammatory effects.  

Molybdenum was selected for the electrode itself due to its durability and slow dissolution – both qualities essential for maintaining structural integrity during the intended one-week stimulation period.  

The electrodes were implanted in pre-clinical models and demonstrated the ability to stimulate NPCs effectively, increasing their numbers and activity without causing significant tissue damage or inflammation. This testing ensured the electrodes’ safety and efficacy for neural repair stimulation within the targeted time frame.  

“Our plan is to further develop this technology by creating multimodal, biodegradable electrodes that can deliver drugs and gene therapies to the injured brain,” says Morshead.  

“We have exciting data to show that activating brain stem cells with our electrical stimulation devices improves functional outcomes in a preclinical model of stroke.”