What are the effects of neural transplantation in patients with Parkinson disease (PD)?

Updated: Jan 24, 2019
  • Author: Robert A Hauser, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Transplantation of autologous adrenal medullary cells and fetal porcine cells has not been found to be effective in double-blind studies and has been abandoned. Although open-label studies of fetal dopaminergic cell transplantation yielded promising results, 3 randomized, double-blind, sham-surgery–controlled studies found no net benefit. In addition, some patients receiving these transplants developed a potentially disabling form of dyskinesia that persisted even after withdrawal of levodopa. Features such as gait dysfunction, freezing, falling, and dementia are likely due to nondopaminergic pathology and hence are unlikely to respond to dopaminergic grafts. [95]

Lewy body–like inclusions have been found in grafted nigral neurons in long-term transplant recipients; these inclusions stained positively for alpha-synuclein and ubiquitin and had reduced immunostaining for dopamine transporter, suggesting that Parkinson disease may affect grafted cells. [14]

Human retinal pigment epithelial cells produce levodopa, and retinal pigment epithelial cells in gelatin microcarriers have been implanted into the putamen in preliminary studies. A phase II double-blind, randomized, multicenter, sham-surgery–controlled study of this technique has been completed. [96, 97] Parkinson disease patients received no benefit from this procedure compared to sham surgery. In addition, in one case study, postmortem examination in a patient who died 6 months after surgical implantation of 325,000 retinal pigment epithelial cells found only 118 surviving cells. [98]


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