Parkinson’s Disease (PD) and Stem Cells

In the United States, Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease, and its incidence is increasing with the aging population (1). PD is a chronic and progressive movement disorder, characterized by tremor, rigidity, bradykinesia, and postural instability, which results from the loss of dopamine-producing cells in the substantia nigra of the brain (2). The cause of PD is unknown in most cases, although a small percentage of cases are attributed to genetic mutations or environmental toxins (1). There is currently no cure for PD, and treatments are only symptomatic, meaning they do not slow or stop the progression of the disease. The most common PD symptom, tremor, is caused by the loss of dopamine-producing cells in the substantia nigra, which results in an imbalance of excitatory and inhibitory input to the thalamus (2). The thalamus is a key structure in the brain responsible for motor control, and when excitatory input exceeds inhibitory input, tremor results (2). Bradykinesia, or slowness of movement, is also caused by the loss of dopamine-producing cells in the substantia nigra, which results in an imbalance of excitatory and inhibitory input to the motor cortex (2). The motor cortex is responsible for planning and executing movements, and when inhibitory input exceeds excitatory input, bradykinesia results (2). Rigidity, or muscle stiffness, is caused by the loss of dopamine-producing cells in the substantia nigra, which results in an imbalance of excitatory and inhibitory input to the motor cortex and the basal ganglia (2). The basal ganglia are responsible for modulating motor output, and when excitatory input exceeds inhibitory input, rigidity results (2). Postural instability, or difficulty maintaining balance, is caused by the loss of dopamine-producing cells in the substantia nigra, which results in an imbalance of excitatory and inhibitory input to the motor cortex, the thalamus, and the cerebellum (2). The cerebellum is responsible for coordinating movement, and when excitatory input exceeds inhibitory input, postural instability results (2). Currently, PD is treated with a combination of levodopa, a dopamine precursor, and a dopamine receptor agonist (1). Levodopa is converted to dopamine in the brain and replaces the dopamine that is lost in PD (1). dopamine receptor agonists mimic the action of dopamine in the brain and help to increase the amount of dopamine available (1). These medications can be effective in treating the symptoms of PD, but they do not slow or stop the progression of the disease. In recent years, there has been increasing interest in the use of stem cells for the treatment of PD (3). Stem cells are unspecialized cells that have the ability to differentiate into specialized cells, and they have the potential to replace the dopamine-producing cells that are lost in PD (3). There are two main types of stem cells that have been studied for the treatment of PD: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) (3). ESCs are derived from the inner cell mass of a human embryo, and iPSCs are derived from adult cells that have been “reprogrammed” to an embryonic-like state (3). ESCs have the ability to differentiate into any type of cell in the body, and they have the potential to replace the dopamine-producing cells that are lost in PD (3). However, there are several ethical concerns associated with the use of ESCs, and they have not yet been approved for use in humans (3). iPSCs are derived from adult cells that have been “reprogrammed” to an embryonic-like state, and they have the ability to differentiate into any type of cell in the body (3). iPSCs have the potential to replace the dopamine-producing cells that are lost in PD, and they offer a potential ethical advantage over ESCs because they can be derived from the patient’s own cells (3). There are several clinical trials currently underway that are evaluating the use of stem cells for the treatment of PD (4). One clinical trial is evaluating the safety and efficacy of transplanted ESCs in patients with PD (4). Another clinical trial is evaluating the safety and efficacy of transplanted iPSCs in patients with PD (4). The results of these clinical trials will help to determine whether or not stem cells are an effective treatment for PD. At this time, there is no cure for PD, and treatments are only symptomatic, meaning they do not slow or stop the progression of the disease. However, there is increasing interest in the use of stem cells for the treatment of PD, and there are several clinical trials currently underway that are evaluating the safety and efficacy of transplanted stem cells in patients with PD. The results of these clinical trials will help to determine whether or not stem cells are an effective treatment for PD.

 "The promise and potential of stem cells in Parkinson's disease." 29 Sep. 2021, https://www.nature.com/articles/d41586-021-02622-3. Accessed 20 Oct. 2022.

 "Stem Cell Therapy for Parkinson's Disease in 2022 - DVC Stem." https://www.dvcstem.com/post/stem-cell-therapy-for-parkinsons. Accessed 20 Oct. 2022.

 "Stem Cell Therapy for Parkinson's: Current Developments - Healthline." 1 Aug. 2022, https://www.healthline.com/health/parkinsons/stem-cell-therapy-for-parkinsons. Accessed 20 Oct. 2022.

The information below is the recommended stem cell therapy protocol for this condition 

Route of AdministrationDoseTime (Days)Total Cells
IV50,000,0003150,000,000
Intrathecal50,000,000150,000,000
Vitamins (Myers cocktail/NAD)1N/A
Total200,000,000