But since 2009, silk scaffolding has found new uses — such as providing a 3-D scaffolding for brain neurons.
The key to generating the brain-like tissue was the creation of 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 compartmentalization, 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 center 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 center of the donut that was separate from the surrounding grey matter (where the cell bodies were concentrated).
Over a period of several weeks, the researchers conducted experiments to determine the health and function of the neurons growing in their 3D brain-like tissue and to compare them with neurons grown in a collagen gel-only environment or in a 2D dish.
The researchers found that the neurons in the 3D brain-like tissues had higher expression of genes involved in neuron growth and function. In addition, 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. In regard to function, neurons in the 3D brain-like tissue exhibited electrical activity and responsiveness that mimic signals seen in the intact brain, including a typical electrophysiological response pattern to a neurotoxin.
These “artificial brain cortex” constructs will first be used for all types of lab research on how cortical networks respond to various drugs, toxins, and other provocations. But as the research grows ever more sophisticated, we will see the creation of specialised brain structures besides cortex — including thalamus, hippocampus, substantia nigra, cerebellum, and other special nerve complexes.
Finding the right scaffolding remains a big challenge. Once the scaffold materials are proven to be safe and immunologically nonreactive, a person’s own stem cells can be used to grow brain and body structures to replace structures damaged by trauma or disease.
A 2012 article on regenerative medicine from Al Fin Longevity This article describes the use of “bioscaffolds,” or biological organs that have been stripped of cells with only the acellular matrix remaining. At this time, that may be the best approach to growing new organs — but the 3-D silk scaffolding seems to be making great strides.