Scientists have created 3D brain-like tissue that can be kept alive in the lab for more than two months, an advance that can help them better understand traumatic brain injury and neurological diseases.
The tissue, developed at the Tissue Engineering Resource Center at Tufts University, Boston, functions like and has structural features similar to tissue in the rat brain.
Researchers have used the brain-like tissue to study chemical and electrical changes that occur immediately following traumatic brain injury and, in a separate experiment, changes that occur in response to a drug.
Currently, scientists grow neurons in petri dishes to study their behaviour in a controllable environment. Yet neurons grown in two dimensions are unable to replicate the complex structural organisation of brain tissue, which consists of segregated regions of grey and white matter.
In the brain, grey matter is comprised primarily of neuron cell bodies, while white matter is made up of bundles of axons, which are the projections neurons send out to connect with one another.
Because brain injuries and diseases often affect these areas differently, models are needed that exhibit grey and white matter compartmentalisation.
Now, bioengineers have created functional 3D brain-like tissue that exhibits grey-white matter compartmentalisation.
Researchers created a novel composite structure that consisted of two biomaterials with different physical properties: a spongy scaffold made out of silk protein and a softer, collagen-based gel.
The scaffold served as a structure onto which neurons could anchor themselves, and the gel encouraged axons to grow through it.
To achieve grey-white matter compartmentalisation, the researchers cut the spongy scaffold into a donut shape and populated it with rat neurons. They then filled the middle of the donut with the collagen-based gel, which subsequently permeated the scaffold.
In just a few days, the neurons formed functional networks around the pores of the scaffold, and sent longer axon projections through the centre gel to connect with neurons on the opposite side of the donut.
The result was a distinct white matter region (containing mostly cellular projections, the axons) formed in the centre of the donut that was separate from the surrounding grey matter (where the cell bodies were concentrated).
The researchers found that the neurons in the 3D brain-like tissues had higher expression of genes involved in neuron growth and function compared with neurons grown in a collagen gel-only environment or in a 2D dish.
The neurons grown in the 3D brain-like tissue maintained stable metabolic activity for up to five weeks, while the health of neurons grown in the gel-only environment began to deteriorate within 24 hours.
The study was published in the journal Proceedings of the National Academy of Sciences.
