If you or one of your loved ones has Parkinson's disease (PD), you’re probably already aware that the symptoms of PD are caused by a lack of a brain chemical called dopamine.  Dopamine is produced by specialized nerve cells in the brain and is essential to the pathways that regulate muscle movement.  You’re probably also aware that the medications that help control the symptoms of Parkinson’s, e.g., carbidopa/levodopa, work to replace that lack of dopamine.  Unfortunately, these medications can lose their effectiveness or cause intolerable side-effects when the dosages are high enough to work.

Some studies had shown that taking dopamine-producing nerve cells from embryonic tissue and transplanting those cells into the brains of patients with Parkinson’s resulted in improvement in PD symptoms.  However, none of the trials had control patients with whom results could be compared.

A study published in 2001 was designed to remedy this situation by comparing the results of PD patients who had the transplants with results of PD patients who had “sham” surgery.  The actual surgery injected the embryonic cells into the affected portion of the brain.  Both the sham and real surgeries consisted of having four holes drilled into the frontal bone, but embryonic cells were not transplanted into the brains of the control group.  Even the neurosurgeons performing the surgery didn’t know prior to entering the operating room which patients would be receiving transplants. (After the study was completed the control group was offered the real transplant surgery.)

The study reached several conclusions: 1) patients’ ages has no effect on whether transplanted nerve cells survived; 2) transplantation had some benefits in patients 60 years old or younger, but not in older patients; and 3) after the first year of having the transplanted cells, some of the symptoms of Parkinson’s worsened.  The study’s authors concluded that the surgical technique needed further refinement, and that research needed to be done on the optimum number of cells to transplant (it was suggested that perhaps too many cells were transplanted and their regeneration actually was counterproductive).


For further information refer to: “Transplantation of Embryonic Dopamine Neurons for Severe Parkinson’s Disease,” Freed, C MD; Greene, P MD; Breeze, R MD; Tsai, W PhD; DuMouchel, W PhD; Kao, R; Dillon S RN; Winfield, H RN; Culver, S NP; Trojanowski, J MD PhD; Eidelberg D MD; Fahn, S MD, The New England Journal of Medicine, vol 344, no 10, March 8, 2001