Brain Tissue Created from Stem Cells

Japanese researchers have recently published a breakthrough paper about using stem cells. The scientists used stem cells to create viable brain tissue. These researchers were able to create brain tissue of the cerebral cortex. The cerebral cortex is part of the brain's outer layer and is located close to a person's skull. The researchers coaxed the neurons to organize into 4 distinct layers. They discovered that the the brain tissue showed signs of neural activity. In the past I've mentioned about researchers creating neurons from stem cells. However, those previous experiments mostly created single neurons for implantation. This is the first time that such a large collection of brain cells has been created that actually resembles real brain tissue. This is basically tissue engineering and is a much more difficult feat to accomplish than making single neurons. Aggregating a large number of brain cells in the proper 3-dimensional pattern to mimic real brain tissue is a significant step up from previous achievements. Implanting single neurons is of limited utility for many brain disorders. Whole brain tissue, on the other hand, can potentially ameliorate many brain disorders.

In the future this technique may allow scientists to create brain tissue to repair damaged brains. The cortical neurons that they created are functional and transplantable. Currently the amount of brain tissue they created is not enough to repair damage for people like stroke patients. However, I think scientists will increasingly get better in the future at synthesizing brain tissue. This type of brain tissue could also be used to run various experiments and test out different drugs. Creating most areas of the brain from stem cells may eventually become a reality.

Here's the abstract from the paper.

Here, we demonstrate self-organized formation of apico-basally polarized cortical tissues from ESCs using an efficient three-dimensional aggregation culture (SFEBq culture). The generated cortical neurons are functional, transplantable, and capable of forming proper long-range connections in vivo and in vitro. The regional identity of the generated pallial tissues can be selectively controlled (into olfactory bulb, rostral and caudal cortices, hem, and choroid plexus) by secreted patterning factors such as Fgf, Wnt, and BMP. In addition, the in vivo-mimicking birth order of distinct cortical neurons permits the selective generation of particular layer-specific neurons by timed induction of cell-cycle exit. Importantly, cortical tissues generated from mouse and human ESCs form a self-organized structure that includes four distinct zones (ventricular, early and late cortical-plate, and Cajal-Retzius cell zones) along the apico-basal direction. Thus, spatial and temporal aspects of early corticogenesis are recapitulated and can be manipulated in this ESC culture.

Neuron Replacement using Stem Cells

In a recent study, scientists created brain cells (neurons) from stem cells and implanted them into the brains of ten rats who had had strokes artificially induced by the researchers. The stem cells restored some of the rats ability to move. This was the first study showing that implanting neural stem cells in the brain could be done without causing cancer. From Standford's website, it says that someone has a stroke every 45 seconds in America, for a total of 700,000 strokes a year. That is an astounding number. The magnitude of suffering that is the result of these strokes is incalculable. Many people can die from having a stroke, but others are left with incapacitating disabilities. This can be especially difficult for loved ones who have to take care of the stroke victim. The researchers from Stanford think that human trials with stem cells for stroke patients may start as soon as 5 years from now.

Stem cells may also be used for several other conditions in the future. Patients with schizophrenia often show significant losses of gray matter in their brains. The reduction in brain matter can be up to 25% in specific areas. These losses are associated with many schizophrenic symptoms like paranoia, hallucinations, apathy and anhedonia. Other conditions such as depression and bipolar disorder are also associated with reduced brain volume in key areas associated with cognition and mood such as the hippocampus. In the future scientists may be able to implant stem cells directly into patient's brains to improve mental illness. Contrary to past dogma, scientists have discovered that the brain is continually creating new neurons (neurogenesis) in the hippocampus, an area of the brain critical for long term memory. Depression has been associated with reduced neurogenesis in the hippocampus and antidepressant drugs have the ability to increase neurogenesis. Using the new Deep TMS may allow researchers to selectively target the hippocampus with electrical stimulation so as to increase the brain's natural mechanism of generating new neurons. With a more sophisticated understanding of the brain, scientists may be able to achieve neurogenesis in brain areas not normally associated with new neuron growth. Or they may be able to guide the migration of neurons created in the hippocampus to other brain areas that are damaged or in need of repair.

Several researchers have already devised a technique to guide the position of neurons in the brain. They have incorporated iron particles into single neurons created from stem cells. Using targeted magnetic pulses, they may be able to precisely position these newly created neurons to specific brain areas to help ameliorate several conditions. So science will most likely progress to a better and more controlled creation of new neurons and the precise placement of those neurons into the requisite brain areas. For extreme life extension, replacing aging neurons may be necessary from time to time. In the future we may be able to use these techniques to periodically replace dying neurons with new ones. Intelligence enhancement is another area that stem cells may have some value in the future. Scientists may be able to increase the amount of neurons in an individual's brain in areas that are associated with certain performance tasks, such as memory, general intelligence and attention. Overall, these are exciting developments that could improve many currently devastating health conditions and potentially enhance normal people's functioning as well.