Thinking In Vitro

Since the 19th century, beginning with the introduction of germ theory and the production of vaccinations, mankind has made remarkable discoveries in medicine and science, taking leaps and bounds towards a brighter future with less illness and a greater standard of living. Since this spark of discovery, medicine has also grown into a raging fire of experimentation and treatment. Now, with the help of modern medical practices, it is possible for doctors and surgeons to compensate for illnesses with manufactured medications, replace broken body parts and organs, and psychoanalyze patients with mental disorders.

Yet, there still seem to be some achievements that are just out of reach of modern medicine. The causes of many neurological disorders are sometimes unknown, and there are few of which the cause is known that can be treated and cured. Replacement organs and structural parts are often less resilient and break within short time frames. Some organs are too complex or are not understood well enough to recreate.

Until the past few months, the brain was considered one of these organs, too complex to recreate or transplant.

But, recent breakthroughs in stem cell research have allowed researchers to recreate brain tissue in vitro.  While these brains are limited by lack of blood supply (~4mm diameter) and are not structurally comparable to fully-developed human brains, they offer possible venues for research on complex neurological disorders such as Parkinson's or Alzheimer's disease. When studying the brain, researchers had begun to notice the limitations of animal research, and "the more we [tried] to model human disease in the mouse," says Harvard researcher Christopher Walsh, "the more we recognize the limitations of animal models." Breakthroughs with in vitro brain synthesis could lead to observation of neurological ailments to a scale relevant to the size of the human brain.

A slice of genetically engineered brain, about 4mm in diameter

Funded by the BRAIN initiative, a $100 million, government-funded project expected to rival the scale of the human genome project, researchers hope that these test-tube brains will provide a way to test the effectiveness of medications and treatments on actual, human neuronal tissue. But how effective can these tests be? One must beg the question... What is the external validity of research on brain tissue tested in a lab, without contact to the outside world? And will the results of experimentation vary due to the lack of structural similarity between in vitro brain tissue and fully-developed, adult brain tissue? Right now, this study is too immature to make any lasting conclusions, but many hope that continued development in this neurobiological research will lead to more relevant conclusions on illness and treatment of illness in human neuronal tissue.

These advances also raise ethical concerns for some, but as of right now, the project doesn't seem to raise any serious negative moral implications. While researchers on the "minibrain" project assure naysayers that the brain-in-the-dish "lack the complexity needed for consciousness." In addition, the stem cells used to synthesize the "minibrain" were obtained from healthy skin cells, so researchers don't feel the need to reassure pro-life advocated. Yet, the future of this project - if researchers can solve the problem to the lack of adequate blood flow - might mean larger, more complex, and possibly sentient brain tissue. When/if that time comes, the ethical implications of this project will need to be addressed.

But, for the time being, this scientific breakthrough has offered researchers the chance to directly study the effects of illness and medication on the brain without a serious fear of ethical outcries. Who knows what the future may bring, but many hope that it will provide a solution for the "diagnose, but not cure" stigma in neurology today.

http://motherboard.vice.com/blog/scientists-are-now-modeling-disease-in-test-tube-brains-grown-from-stem-cells

http://www.nih.gov/science/brain/