You know stem cell research is gaining on practical applications when it can go from Petri dish to the in vitro environment. In this case, scientists at Stanford Medical School (California, USA) started with embryonic stem cells. These undifferentiated cells were cultivated in a Petri dish to exhibit initial characteristics of cortical (brain) neuron cells and then transplanted into the brains of newborn mice. The transplanted cells continued to grow, and more importantly made the appropriate connections for the type of neuron.

Yes, this is another ‘works in mice’ procedure. The type of neuron created in the study, one associated with muscle control, is the type damaged by ALS (amyotrophic lateral sclerosis or Lou Gehrig disease). If it can be shown that a stem cell transplant will repair or replace these damaged neurons…there are a lot of people waiting. Crossing the gap from Petri dish to use in a living mammal brain is much wider than the gap of moving from mouse to human brain, although the latter gap requires much more laborious bridging (e.g. testing and official approval).

Until now, making these proper cellular connections has been a fundamental problem in nervous system transplant therapy. In this case, the maturing neurons extended to the appropriate brain structures, and, just as importantly, avoided inappropriate areas. For example, cells transplanted into the visual cortex reached two deep brain structures called the superior colliculus and the pons, but not to the spinal cord; cells placed into the motor area of the cortex stretched into the spinal cord but avoided the colliculus.

[Source: Cell News]

The major advances in this study involve the preparation of stem cells in the Petri dish – a complex matter of nutrients, environment, and appropriate chemistry. Once the cells were partially differentiated, they could much more easily integrate with the neurons in the mouse brain. Here too, advances were made in the placement and growth environment within the brain of the newborn mice. Ultimately the research showed the ability to create the right kind of cell and make the right kind of connectivity within the brain; something of a first with stem cells. The next steps are to attempt the same kind of transplant in adult animals (mostly mice again). Much later, given success, the transplants may be tried with humans.