STEP 5: MAKE THE TRANSPLANTED STEM CELLS PERFORM
After the injection, it was up to the cells to survive in their new environment and produce dopamine.
There was no guarantee that transplanted stem cells would behave as desired. If they didn't receive or respond to the proper signals from their environment, they might have malfunctioned, formed tumors or died.
The researchers measured the patients' progress in a couple of ways. First, they used brain imaging to determine whether the implanted cells were surviving and producing dopamine. Second, they interviewed patients to see if they experienced any changes in their symptoms.
The treatment was partly successful. The implanted cells survived and produced dopamine, and some patients reported a lessening in the severity of their symptoms.
However, some patients who underwent the procedure experienced severe side effects, including involuntary muscle twitching and jerking. While these side effects are treatable, their cause is still not clear.
Future Implications of the Treatment
While the fetal cell implant showed promise for treating patients with Parkinson's disease, it is a milestone of progress rather than a true cure. The procedure needs to be refined so that its benefits will outweigh the risks of adverse side effects.
This work has paved the way for additional Parkinson's disease treatments using stem cells. In the decades since the first fetal-cell implant was performed, researchers have learned much more about the biology of both embryonic and adult stem cells, both of which are now potential candidates for treating Parkinson's disease.
How did the researchers know whether the experiment worked?
Researchers developing the treatment predicted that stem cells in the transplanted fetal tissue would survive, grow and differentiate into dopamine-producing neurons in the brains of Parkinson's patients. But how did they know whether the treatment was successful?
To answer this question, the researchers needed to measure the progress of patients who received the transplant against a set of control patients who received a "sham" surgical procedure and the same pre-and post-surgical care but no fetal tissue implant.
In every scientific experiment, good controls are needed to help ensure that the results are interpreted correctly.
Without the "sham" surgery control, the researchers would not be able to tell whether any observed effects - either good or bad - resulted from the tissue implant itself, the surgical procedure or any other aspect of the treatment.
Do the control patients ever get the chance to have the real surgery?
Yes. After the study was completed, the control patients were given the option to receive the transplant.