Perspectives On Medical Research

Volume 5, 1995

Aping Science

A Critical Analysis of Research at the Yerkes
Regional Primate Research Center

1. Parkinson's Disease (PD)

Yerkes officials have claimed that their research has been central to PD treatment:

Yerkes studies with rhesus monkeys were the first to demonstrate the feasibility of surgically implanting dopamine-producing tissue into the brain as a treatment for Parkinson's disease. Research results were presented in 1985 by Emory neurosurgeon and initial Yerkes Affiliate Scientist Dr. Roy Bakay who conducted the studies and who has been performing the surgery on humans with Parkinson’s disease at Emory University Hospital.¹

This claim is misleading because it confuses two different surgical procedures to treat PD; transplanting fetal tissue derived from a member of the same species (fetal homotranspiantation), and non-fetal tissue (usually adrenal) from a human patient's own body (autotranspiantation) to the defective brain area. Although Yerkes and other researchers have conducted extensive nonhuman primate fetal homotransplantation experimentation,² the first autotranspiantation to treat PD had already been conducted in Sweden, in 1982, without prior nonhuman primate trials.³ The Swedish investigators used the patient’s own dopamine-producing adrenal tissue.

Bakay and colleagues stated their intention to demonstrate the clinical "feasibility" of their primate fetal adrenal tissue homotransplant work, but they never did apply their monkey findings to patients. In fact, the clinical transplants to which the Yerkes publication refers consisted of adrenal autotransplants. Bakay, Ray Watts and colleagues attempted to duplicate their human findings with adrenal autografts in nonhuman primates.^4,5 However, the animal subjects were not suffering from PD, but rather from an induced Parkinson-like syndrome related to exposure to the neurotoxin MPTP.⁶ While this condition shares many features with PD, there are several important differences. PD is a progressive condition, while MPTP-induced Parkinsonism is not.² PD patients characteristically show microscopic Lewy bodies in their brains whereas MPTP-treated monkeys do not.⁷ Also, the locus ceruleus of the brain is damaged in PD, but only older monkeys administered low-dose MPTP exhibit similar damage (possibly analogous to PD being found in older humans.)^8,9 Given the cost of raising monkeys to old age, researchers generally use young adults. Bakay and colleagues have not specified the monkeys' ages, so they, too, likely have used younger monkeys,⁵ further diminishing the probability that nonhuman primate experiments with autotransplants at Yerkes and elsewhere apply to human patients.


1. Yerkes Regional Primate Research Center, Public Affairs Division. Annual Report: The 60th Year, 1989-1990. Atlanta, 1990.

2. Bakay RAE, Herring Ci. Central Nervous system grafting in the treatment of parkinsonism. Stereotactic and Functional Neurosurgery 1989;53:1-20.

3. Backlund E-O, Granberg PO, Hamberger B, et al. Transplantation of adrenal medullary tissue to striatum in parkinsonism: First clinical trials. Journal of Neurosurgery 1985;62:169-173.

4. Watts RL, Bakay RAE, luvone P, Watts N, Graham S. Autologous adrenal-caudate transplantation in patients with parkinson’s disease (PD). Neurology 1988;38(Suppl 1): 143.

5. Watts RL, Bakay RAE, Herring Ci, et al. Preliminary report on adrenal medullary grafting and cografting with sural nerve in the treatment of hemiparkinson monkeys. Progress in Brain Research 1990;82:581-591.

6. Bakay RAE. Neural transplantation--what are the real possibilities, in Black PML (ed). Clinical Neurosurgery. Baltimore, Williams and Wilkins, 1991 (vol 37), pp 179-192.

7. Forno LS, Langston JW, DeLanney LE, Irwin I. An electron microscopic study of MPTP-induced inclusion bodies in an old monkey. Brain Research 1988;448:150-157.

8. Burns RS, Chiueh CC, Markey SP, et a!. A primate model of parkinsonism: Selective destruction of dopaminergic neurons in the pars compacta of the substantia nigra by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Proceedings of the National Academy of Science of the United States 1983;80:4546-4550.

9. Jenner P, Nadie MT, Ruaniak SR, et al. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine induced parkinsonism in the common marmoset. Neuroscience Letters 1984;50:85-90.