Stem cell implants helped 9 Parkinson's patients move better, maker says

Nine people with moderate to advanced Parkinson’s disease who had lab-grown brain cells implanted moved better six months later, according to the Chinese company that makes the treatment.¹ The therapy, called XS411, comes from XellSmart. It is meant to replace the dopamine-making nerve cells that Parkinson’s destroys.¹ The company also said a larger follow-up trial has finished signing up patients.²

The results were presented at the International Congress of Parkinson’s Disease and Movement Disorders, held October 4 to 8 in Seoul, South Korea, and announced in a company press release.¹² They have not been published in a peer-reviewed journal.

What happened

In Parkinson’s, the nerve cells that make dopamine die off. Dopamine is a chemical messenger the brain needs to control movement. As it fades, people develop tremors, stiff muscles and slow movement.¹ Drugs such as levodopa can ease these symptoms, but they do not replace the lost cells.¹

XS411 tries to replace them. It starts with induced pluripotent stem cells: mature cells that are reprogrammed in a lab back into a flexible, stem-cell-like state. These are then steered into young dopamine-making nerve cells.¹ Surgeons place the cells into the putamen, a brain area involved in movement, where they are expected to mature and connect to the brain’s existing wiring.¹

The cells come from donors rather than from each patient. That means they can be made in batches ahead of time and used for many people. Patients do not need cells matched to their own immune type, but they take a standard set of immune-suppressing drugs to help keep the body from rejecting the cells.¹²

The evidence so far

The first trial was small and designed mainly to check safety. Nine people took part, in three groups of three, with each group getting a higher dose than the last.¹ They had lived with Parkinson’s for about 10 years on average and still had major movement problems despite standard treatment.¹ Everyone knew they were getting the cells, and there was no comparison group.²

The company reported these findings:

• Safety: no dose-limiting side effects, no serious side effects and no side effects considered related to XS411 during follow-up.² Repeated MRI scans showed no abnormal cell overgrowth or tumors, and no unwanted, jerky movements caused by the cells were seen.²
• Movement: on a standard doctor-scored test of Parkinson’s movement symptoms (the MDS-UPDRS Part III, where a lower score is better), scores dropped by an average of more than 30 points at six months.¹ Patients were tested in the “off” state, when their usual medicines had worn off.¹
• Daily life: patient diaries showed an average gain of more than five hours a day of “good on time,” meaning periods when symptoms are well controlled without troublesome involuntary movements.¹ Answers to a 39-question quality-of-life survey also improved.²
• Brain scans: a type of PET scan that tracks dopamine activity showed more signal in the putamen than before treatment, in spots matching where the cells were injected.²

The company said all nine people improved by more than the smallest change considered meaningful to patients, that gains kept growing in longer follow-up, and that the higher doses showed a trend toward bigger effects.² XellSmart says the scans show the cells survive and make dopamine.² Independent coverage described the scans more cautiously, as “consistent with” working grafted cells.³

What it does not show yet

Because patients and doctors both knew who was treated, the movement scores and diaries can be biased by hope and expectation. The company’s own release acknowledges this risk for open-label trials, meaning trials where no one is kept in the dark about the treatment.² Independent trade outlet The Clinical Trial Vanguard called the design “an inherent limitation” for both doctor-rated and patient-reported measures and said the brain scans are the strongest evidence the company can offer at this stage.³

Nine people is also far too few to judge rare side effects, and the follow-up so far is short. The release did not give detailed per-patient numbers or say how long the longest follow-up has run.² The registry record lists the main efficacy measure as the movement score at 12 months, not six.⁴ And the need for immune-suppressing drugs brings its own questions. One outlet noted that whether that drug regimen keeps rejection low across a larger, more varied group will only show in the next trial’s results.³

Who is behind it

XellSmart is based in China, and its founder and CEO is Xiang Li.⁵ The trial is sponsored by the company and led by Beijing Tiantan Hospital.⁴⁶ The lead investigator, Professor Feng Tao of Beijing Tiantan Hospital, said earlier this year that the first trial had “confirmed preliminarily that this novel therapy is safe and effective.”⁶ All the efficacy and safety figures reported so far come from the company and its investigators; no independent group has checked them.

U.S. regulators have taken notice. The FDA cleared the therapy for testing in the United States in 2025 and gave it fast-track status on July 28, 2026, a label that can speed up review if later data are positive.³¹ The FDA and Chinese regulators have also cleared trials in multiple system atrophy, a rarer condition with Parkinson’s-like symptoms.¹

How it fits the field

Several groups are trying to replace lost dopamine cells with stem cell products. In February 2026, Japan gave conditional approval to Raguneprocel, a similar stem-cell-based dopamine cell therapy from Kyoto University.³ Other companies take a different route. U.S. firm Aspen Neuroscience, for example, makes cells from each patient’s own skin, which it says lowers rejection risk and avoids immune-suppressing drugs, though it is a personalized process rather than a ready-made batch.⁷

XellSmart’s bet is the ready-made, donor-cell approach, which is easier to scale but requires immune suppression.⁵ The company says XS411 has also shown benefits in a separate trial in people with early-onset Parkinson’s.¹ That trial is still recruiting, with up to 90 people planned.⁸

What to watch next

The next test is a 30-person trial at four hospitals in China, which finished enrolling in July 2026.³ Two in three patients get the cells and one in three stays on standard Parkinson’s drugs, and everyone is followed for 12 months.⁶ Patients still know which group they are in, but the outcomes are scored by independent evaluators who do not.³ People in the drug-only group may be offered the cells later if eligible.⁶

The company expects these results to shape a larger final trial that could support an approval request.¹ A stronger design is planned in the early-onset study: its second stage would compare the cells with a sham (fake) surgery, so neither patients nor doctors know who got the real treatment.⁸ Results from those comparisons, rather than the nine-person data, will show how much of the reported improvement comes from the cells themselves.