How to rewire the brain with artificial axons to replace damaged pathways

January 23, 2016


Penn State scientists have grown improved artificial transplantable artificial axons (brain pathways) in the lab. The new “micro-tissue engineered neural networks” (micro-TENNS) replace broken axon pathways when implanted in the brains of rats.

(Neurons are connected by long fibrous projections known as axons. When these connections are damaged, they have very limited capacity to regenerate — unlike many other cells in the body — thus permanently disrupting the body’s signal transmission and communication structure.)

The new lab-grown axons could one day replace damaged axons in the brains of patients with severe head injuries, strokes, or neurodegenerative diseases and could be safely delivered with minimal disruption to brain tissue, according to new research from Penn Medicine’s department of Neurosurgical Research. Their (literally) pathfinding work is published in an open-access paper in the Journal of Neural Engineering.

Senior author D. Kacy Cullen, PhD, an assistant professor of Neurosurgery and his team, previously reported in a 2015 publication in Tissue Engineering that micro-TENNS could be delivered into the brains of rats. The research team has now developed a new, less-invasive delivery method to minimize the body’s reaction and improve the survival and integration of the neural networks.

Micro-TENN axon fabrication process (credit: J P Harris et al./Journal of Neural Engineering)

The team replaced needles with a molded cylinder of agarose (a sugar) filled with an extracellular matrix (ECM) supporting structure through which axons — and associated neurons — could grow in the cerebral cortex and the thalamus. The new axons maintained their architecture for several weeks and successfully integrated into existing brain structures, softening immediately following insertion to better match the mechanical properties of the native brain tissue.

Cullen and team plan to perfect their processes and further integrate neuroscience and engineering to come up with unique ways to aid patients suffering from brain injury or common neurodegenerative diseases. “Additional research is required to directly test micro-TENN neuron survival and integration for each of these insertion methods,” Cullen said.

“We hope this regenerative medicine strategy will someday enable us to grow individualized neural networks that are tailored for each patient’s specific need,” he said, “ultimately, to replace lost neural circuits and improve brain function.”


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