Stem Cells: What’s the latest?
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We discuss the latest research exploring the potential of using stem cells as a treatment and therapy for Parkinson’s.
This blog has been updated to reflect the latest news about the STEM-PD trial in November 2022.
Parkinson’s is caused by a decrease in dopamine, a chemical made in the brain. The cells that produce dopamine either stop working properly or are lost over time, leading to the range of symptoms that someone with Parkinson’s can experience.
Current treatments for Parkinson’s work by boosting dopamine levels in the brain, helping to manage some of these symptoms. However they don’t slow or stop the progression of the condition, as dopamine producing cells continue to be damaged. But, what if there was a way to replace the lost and damaged cells with new ones? This is where stem cell therapies might hold the answer.
Research into this area has been happening for over a decade and a lot has already been learnt, although most clinical trials are still in the early stages of development.
Currently, there is no approved stem cell therapy or treatment available that has been shown to slow or reverse Parkinson’s in clinical trials. A word of caution — there are a number of organisations and agencies from other countries that falsely claim they can deliver stem cell therapy. When in doubt, please get in touch with us at research@parkinsons.org.uk where we can answer any research questions you might have.
This blog explains the science behind the potential of stem cell therapies and highlights some of the latest research.
What are stem cells and how could they help in Parkinson’s?
Stem cells are a powerful type of cell. They are the original cells that everything in the body is made from and they are responsible for repairing tissues and organs when they get damaged. This is possible because stem cells have the ability to develop into different types of specialised cells — from muscle cells to brain cells. These properties make them attractive to researchers looking to find new treatments for various health conditions, including for Parkinson’s, where they could be used to replace lost brain cells and potentially slow or reverse the condition.
Before we look at the current research that’s underway, it’s important to understand there are different types of stem cells and approaches being investigated for Parkinson’s.
Different types of stem cells:
- Adult stem cells are found all over the body and they help regenerate old and damaged tissues and cells. However, they are limited in what types of cells they can change into, and the stem cells present in our brains (called neural stem cells) are not able to prevent or repair the damage being done in Parkinson’s. This is why adult stem cells are less commonly used in stem cell research.
- Embryonic stem cells are found inside developing embryos and they can change into any type of cell in the whole body — the scientific term for this is pluripotent. These cells are a powerful tool for research but they come with additional ethical considerations. In the UK, stem cells from human embryos can be collected from leftover embryos produced as part of in vitro fertilisation (IVF) programmes that would otherwise be destroyed. There are strict legal guidelines for using embryonic cells for research from the Human Fertilisation and Embryology Authority (HFEA).
- Induced Pluripotent Stem (iPS) Cells are stem cells that have been made in the lab. Scientists can turn specialised adult cells, such as skin cells, into stem cells which can go on to develop into any type of cell, for instance brain cells. This means that researchers could use cells from a person with Parkinson’s to generate new dopamine producing brain cells to study in the lab or for a possible transplant. This reduces the risk of the body rejecting the new cells as they have originated from the recipient.
Although iPS cells are slowly becoming the go to stem cell to use in research, they haven’t long been discovered so let’s take a look back at stem cell research in Parkinson’s…
Key breakthroughs in stem cell research and Parkinson’s:
1960s — Adult stem cells were first discovered in the bone marrow
1980s — Embryonic stem cells discovered and first fetal cell transplant for Parkinson’s
Embryonic stem cells were discovered in mice in 1980. After successful preclinical experiments in rats, researchers in Sweden transplanted the first fetal stem cell into people with Parkinson’s. The results were initially positive with the cells replacing lost dopamine producing cells however some participants experienced unwanted side effects as a result so further investigations and research was needed.
2002 — Transplanting stem cells may reverse some Parkinson’s symptoms
In 2002, Scientists in the US showed that transplanting stem cells into the brain in rats may indeed be able to reverse some symptoms of Parkinson’s.
2006 — Scientists turn adult cells into stem cells — iPS cells
One of the biggest breakthroughs came when researchers in Japan were able to generate iPS cells in the lab. They used human skin cells and turned them back into stem cells.
2010s — Success of iPS cells in animal models
Researchers in the USA showed that Parkinson’s symptoms improved after they transplanted dopamine producing brain cells generated from iPS cells in a rat model. Japanese researchers used a similar technique to then show similar results in monkeys in 2017. This showed that the transplanted dopamine producing cells made from iPS cells did successfully produce dopamine.
These breakthroughs have paved the way for ongoing clinical trials using embryonic stem cells and iPS cells to potentially treat Parkinson’s. These studies involve either surgically inserting stem cells into the affected parts of the brain, or directly into your bloodstream through a vein in your arm. Due to this research area being fairly new and novel, stem cell trials are usually longer than other research trials because it’s important to understand if transplanted cells survive over time amongst other things. We take a look at some of the latest clinical trials…
What’s the evidence from clinical trials?
Trial name: TRANSEURO
Location: Across Europe including the UK
Aim: This trial aims to test the effectiveness and safety of transplanting dopamine producing brain cells from foetal tissue into the brain.
Recruitment status: Trial completed, awaiting results
Update: This phase 1 trial began in 2012 and finished in the first half of 2021; 40 people with Parkinson’s participated across Europe. Initial results have shown that this trial had several limitations, including challenges sourcing enough tissue needed for the transplants. The full research trial results are yet to be published.
Based on these difficulties the researchers are now building on their experience to start a new research trial, STEM-PD.
Trial name: STEM-PD
Location: Sweden and UK
Aim: The research aims to see if using embryonic stem cells has benefits for people with Parkinson’s. The research will make dopamine producing neurons from embryonic stem cells.
Recruitment status: Recruitment in Sweden began in October 2022 following approval from the health authority. The UK arm is awaiting approval.
Trial name: Human Embryonic Stem Cell Therapy (MSK-DA01) For Advanced Parkinson’s
Location: USA and Canada
Aim: This study is using dopamine producing nerve cells made from human embryonic stem cells (DA01) to be transplanted into 10 people with Parkinson’s. The main aim of this study is to assess the safety and how well tolerated the stem cell transplants are after 1 year. The study will also monitor to see if the transplanted cells survive and if there are any effects on motor symptoms such as walking after 1 and 2 years.
Recruitment status: Recruiting in the US, trial started
Update: This phase 1 trial began in May 2021 with one participant out of 10 having already undergone the cell transplantation. There is an estimated completion date of January 2024, so we have a while to wait before we see any results.
Trial name: Mesenchymal stem cell trial
Location: USA
Aim: This study will use mesenchymal stem cells, a type of adult stem cell, that are found in the bone marrow. These cells are important for making and repairing tissues so using them may prevent the loss of nerve cells in Parkinson’s. This phase 2 research will look at how safe, as well as how many stem cell treatments are potentially needed to slow down the progression of Parkinson’s. Participants will receive 2 to 3 stem cell doses through an infusion going into the bloodstream over the course of a year.
Recruitment status: Recruiting 45 people with Parkinson’s in Texas
Update: This phase 2 clinical trial follows on from an initial phase 1 trial which has recently published results. Phase 1, involving 20 people with Parkinson’s, found that there were no serious side effects or immune reactions to the stem cells which came from a donor bone marrow. As well as showing that the treatment was safe, it also showed a reduction in Parkinson’s motor symptoms such as freezing, tremor etc.
Trial name: Aspen Neuroscience
Location: California, USA
Aim: Aspen Neuroscience is developing a stem cell therapy using iPS cells made from a participants own skin that will be turned into dopamine producing nerve cells. This therapy will aim to avoid the risk of cell transplant rejection that can happen if cells do not come from the participant.
Recruitment status: Not yet recruiting
Update: This biotech company is currently seeking ethical approval to then begin clinical trials in 2022.
There have been huge developments over the past 40 years in stem cell research but there are still a number of questions left to answer. Researchers are busy addressing these for Parkinson’s and a collaborative approach has been established with GFORCE-PD — a global initiative for stem cell based therapies in Parkinson’s — being set up in 2014. This involves regular meetings for researchers in this field to share ideas and learnings to make research in this area as efficient as possible.
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