Lab-grown brain tissue might lead to bioengineered implants

A team of researchers from MIT and Harvard Medical School have devised a cheap way of artificially growing three-dimensional brain tissues in the lab. Built layer by layer, the tissues can take on just about any shape and closely mimic the cellular composition of the tissue found in the living brain. The advance could allow scientists to get a closer look at how neurons form connections, predict how cells of individual patients will respond to different drugs, and even lead to the creation of bioengineered implants to replace damaged brain tissue.

In recent years, we've seen big leaps forward in the technology we use to grow artificial bones, cartilage and blood vessels. As of late, scientists have even managed to grow biocompatible (though not naturalistic) brain tissue. One big hurdle remains, however: brain tissue contains thousands of different cell types, all intricately interconnected and present in varying concentrations in different areas of the brain, which is tough to recreate in the lab.

Now, a team of researchers led by associate professors Utkan Demirci and Ed Boyden have gone a long way toward tackling this problem. They have developed 3D hydrogel scaffolds that support the survival and development of a wide range of neural cells, with concentrations similar to what would be found in a normal brain. The system is inexpensive, precise, and makes it possible to generate complex tissue patterns in any three-dimensional shape.

The researchers started by embedding various types of rat brain cells into thin sheets of hydrogel. The sheets were then stacked on top of each other and then, one by one, sealed together by being selectively exposed to UV light using plastic photomasks. By covering the gel with photomasks of varying shapes, the researchers could precisely build the structure layer by layer, with complete control over its shape.

The process is very reminiscent of the way integrated circuits are gradually deposited onto semiconductors. Building a circuit requires lithographic aligners costing tens of thousands of dollars; the researchers' cheap plastic photomasks, on the other hand, were held in place by simple pins and achieved microscale control over the shape of the tissue with approximately US$50 in equipment.

Combined with robotic methods for analyzing single neurons in the living brain, this technology could one day lead to doctors taking cells from a patient with a neurological disorder, growing them in a lab dish, and then exposing the tissue to a range of different drugs to figure out what would benefit the patient the most without risking his or her health.