Up until very recently in historical terms there was literally nothing anyone could do for brain injury, whether from trauma, stroke, hypoxia, or other cause. Physicians of past centuries could provide little more than comfort for the neurologically damaged.

Modern medicine has made an important advance in learning, in some but not all situations, interventions that minimize the damage or provide the best opportunity for recovery. So for acute stroke we know we need to optimize blood pressure and treat fevers, and if we get to patients quickly enough we can even give a powerful drug (TPA) to break up a blood clot and restore blood flow. For trauma we know we need to minimize swelling. We are also getting better at preventing such events from happening in the first place – such as anti-platelet therapy to reduce the risk of stroke, or just modifying risk factors.

But these interventions serve to prevent neurological damage. They do nothing to help fix the damage once it occurs. The current state of the art in terms of fixing damage is rehabilitation. Rehab is extremely important, but it is difficult to tease out from the evidence if physical therapy and similar intervention sare actually promoting neurological regeneration, rewiring, and recovery or are they simply improving functional strength and mobility while natural recovery is occurring at its own pace. Without getting into this complex and thorny area, I would just summarize my opinions by saying that there is no definitive evidence that any intervention leads to greater neurological (as opposed to functional) recovery.

Don’t get me wrong – rehabilitation therapy is vitally important to final outcomes for many conditions. I just don’t think we can say that it actually causes neurons to regrow and rewire themselves beyond what would occur inherently. In the final analysis we do not really have any therapies that significantly (if at all) cause or promote regeneration of neurological tissue. So prevention is still the name of the game.

However, it is also an exciting time for neuroscience because we appear to the on the cusp of transitioning into the next phase of neurological intervention – to treatments that cause or promote regeneration.

One possible avenue to such treatments is stem cells. A recent study published in Nature Neuroscience looks at the fat of embryonic cortical tissue transplanted into the brains of mice with damage to the motor cortex. Embryonic tissue is not the same as embryonic stem cells, but it is similar in that it has the potential to grow and differentiate into the desired mature tissue type.

Prior experience with embryonic cortical tissue has been mixed. While a great idea in theory the problem has been getting neurons from transplanted embryonic tissue to take up shop – meaning to form working connections with other neurons. Studies have shown that few or no such connections are made. This latest study engineered the embryonic tissue so it overexpressed a gene for a flourescent protein. This enabled the researchers to see where the transplanted tissue was and distinguish it from the host’s tissue.

What they found was:

Host and transplanted neurons formed synaptic contacts and numerous graft efferents were myelinated. These findings demonstrate that there is substantial anatomical reestablishment of cortical circuitry following embryonic cortex grafting into the adult brain. They suggest that there is an unsuspected potential for neural cell transplantation to promote reconstruction after brain injury.

That’s great news. If this is confirmed with later research that would mean that embryonic brain tissue can survive and make new connections when transplanted. That is the first step. We would need to also verify that the cells actually add function and improve clinical outcome, and they don’t cause any problems (like forming tumors).

This is just one baby step in a complex area of research, but it is pointing the way to this next phase of neuroscience where we can actually improve the regeneration of injured neural tissue. I certainly hope to see this line of research come to fruition during my career. I certainly appreciate the value of disease prevention, neuroprotective interventions, and rehabilitation – but it would be nice to be able to actually fix something that’s broken.