One trial testing ESC therapy in Parkinson's disease will be the first clinical trial of human embryonic stem cells (ESCs) in China, as well as the first trial in the world to examine ESCs for the treatment of Parkinson's, according to a report in Nature News. Both studies will be led by stem cell specialist Dr Qi Zhou at the First Affiliated Hospital of Zhengzhou University.
The only previous study of this type started in Australia last year: patients with the degenerative disease are being treated with cells derived from parthenogenetic embryos. These stem cells were harvested from unfertilised eggs induced into embryonic development, sidestepping many of the ethical issues with using viable embryos. ESCs are pluripotent stem cells taken from the inner cell mass of human embryos and have the potential to develop into any of the 200-plus specialised cell types in the adult body.
In Parkinson's disease, a specialised type of brain cell that produces the neurotransmitter dopamine are lost. Dr Zhou's team will inject four million immature cells derived from ESCs into the striatum area of patients' brains with the aim of reducing symptoms. This follows an unpublished four-year study led by Dr Zhou which showed promising results in 15 monkeys.
A second team will treat patients with age-related macular degeneration (AMD), in which vision is compromised by the loss of pigmented retinal epithelia in the eye. Building on pre-clinical trials carried out in South Korea and the US, ESC-derived retinal epithelial cells will be injected into the retinas of AMD patients in a bid to stop the disease progressing.
Using ESCs in treatment is controversial on ethical grounds, as well as fears that they could cause tumours. Some scientists are concerned that the Parkinson's patients are being injected with cells that may not become the desired type of neurone. 'Not knowing what the cells will become is troubling.' said Dr Jeanne Loring at the Scripps Research Institute, California. However, pre-clinical work for the Australian trial found that 97 percent of the ESC-derived precursor cells developed into dopaminergic neurons.
In 2015, China announced new regulations for stem cell therapies aiming both to enable legitimate human trials, and curb administration of unapproved treatments. Zhou's clinical trials will be fully compliant, using government-certified ESC lines and the clinicians have been granted approval by a central government committee for their use.
Committee member Dr Pei Xuetao, a stem-cell scientist at the Beijing Institute of Transfusion Medicine, called the study a 'major new direction for China'. Other groups of scientists are already planning trials for the testing of ESC therapy for other targeted treatments, such as encouraging growth and repair following spinal cord injuries.