Spinal Cord Injury Stem Cell Clinical Trials: 116 Studies on Timing and Route, and Japan

Summary — Spinal cord injury stem cell clinical trials continue to grow worldwide. Four overseas papers published between May and July 2026 show the trend clearly. Researchers at Sun Yat-sen University in China pooled 116 clinical studies of cell therapy in patients and compared outcomes by timing and route; a team at Qingdao University analysed 80 registered trials and found Japan among the leading countries with 10 trials. In Japan, researchers at the University of Osaka reviewed 41 regenerative medicine plans for spinal cord injury under the Act on the Safety of Regenerative Medicine, and a UC San Diego team reported five-year follow-up after neural stem cell transplantation. This article summarises what these studies show about the current state of spinal cord injury stem cell research.

Why people look for therapies that support recovery alongside rehabilitation

Spinal cord injury occurs when the spinal cord is damaged by an accident or fall, reducing movement, sensation and autonomic functions such as bladder control below the injury. Cervical injuries can affect both arms and legs. Severity is graded with the ASIA Impairment Scale (AIS), where A means a complete injury with no function below the level. Standard care is surgical stabilisation, management of complications and long-term rehabilitation. Inflammation and secondary injury follow the initial damage, and scar tissue later blocks nerve regeneration. Controlling this process or replacing lost circuits is the starting point for stem cell research. An overview is on our spinal cord injury stem cell page.

116 spinal cord injury stem cell clinical studies: timing and route matter

A spine surgery team at the Third Affiliated Hospital of Sun Yat-sen University (Kang J, Yao S, et al.) published an analysis of 116 clinical studies of cell therapy for spinal cord injury since 2005 in BMC Medicine on 20 July 2026. Every study involved patients receiving cells and reported safety outcomes. Overall, 59.5% were phase 1 and 63.8% were single-arm studies without a control group, and autologous bone marrow-derived cells were the most common. Chronic-phase patients made up 58.3% of the populations studied.

Safety profiles differed by cell type and delivery method. Mesenchymal stem cells (MSCs) were associated with transient fever (P=0.038), and intrathecal delivery with procedural symptoms such as headache (P<0.001). The authors attributed these mainly to the procedure and the biology of the cells, and concluded that the baseline safety of cell transplantation has been established.

For efficacy, timing was the key variable. Patients treated in the acute or subacute phase showed higher rates of neurological improvement. Intrathecal delivery, which disturbs the cord less, showed an advantage in preserving sensory pathways. The authors recommended more controlled designs and the use of imaging and electrophysiology to identify patients most likely to respond.

Japan has 10 of 80 registered trials: spinal cord injury stem cell research by country

A team at the Affiliated Hospital of Qingdao University (Wei Y, et al.) published an analysis of a registered-trial database in Frontiers in Neurology on 19 June 2026. Of 80 interventional stem cell trials for spinal cord injury registered by the end of 2025, numbers rose steadily from 2008, with new trials still starting in 2024 and 2025. By country there were 20 in China, 13 in the United States, 10 in Spain, 10 in Japan and 7 in India. 57.5% had been completed, and academic institutions were the main sponsors. MSCs were the predominant platform, while neural-lineage cells and products derived from induced pluripotent stem (iPS) cells are emerging.

As an example of a new trial, the Sun Yat-sen team published a protocol in BMJ Open in July 2026 for a phase 1 study giving iPS cell-derived motor neuron progenitors intrathecally to 12 to 24 adults with subacute spinal cord injury. It has clearance from both China's NMPA and the US FDA (NCT06976229) and will assess AIS grade, motor and sensory scores and the Spinal Cord Independence Measure up to 360 days.

Regenerative medicine for spinal cord injury under Japan's law: the Osaka survey

A paper by the University of Osaka orthopaedics department (Prof. Seiji Okada and colleagues) with a researcher from the Ministry of Health, Labour and Welfare appeared in Regenerative Therapy on 25 May 2026. The team analysed 41 non-research regenerative medicine provision plans for spinal cord injury filed under the Act on the Safety of Regenerative Medicine. Adipose-derived MSCs were used in 68% and bone marrow-derived cells in 32%. Routes were intravenous in 71% and intrathecal in 27%; culture usually took about four weeks, and the most common dose was 1.0×10⁸ cells.

The paper also noted that clinical research under the Act and approved products mainly target subacute patients, with standardised cell sources, dosing and safety evaluation. Because cell preparation and timing vary between plans, the authors suggested further scientific standardisation. News on Stemirac, Japan's approved bone marrow stem cell product, is in our spinal cord injury bone marrow stem cell article, and the legal framework is in our Japan regenerative medicine timeline.

Five-year follow-up of neural stem cell transplantation: UC San Diego phase 1

A UC San Diego neurosurgery team (Abraham ME, Ciacci JD, et al.) reported long-term results in Stem Cell Reports on 21 May 2026 from a phase 1 study that implanted NSI-566, a human spinal cord-derived neural stem cell line, into the cervical cord of patients with chronic injury. Three patients with complete injury (AIS A) were followed prospectively for 60 months for adverse events, function and neurophysiology. Over five years no tumour formation or procedure-related complications were reported; neurophysiological changes and some functional gains were observed. The authors see this as evidence that direct intraparenchymal delivery is feasible in chronic patients and named larger controlled trials as the next step.

How to read the stage of each study

The 116-study and 80-trial papers pool many trials to show trends; the UC San Diego study is a three-patient phase 1, and the Sun Yat-sen iPS cell study is a phase 1 that is just starting. Phase 1 confirms safety and dose, and efficacy figures become clearer in controlled phase 2 and 3 trials. It also helps to consider the effect of rehabilitation. 'Improvement was reported' is different from 'efficacy has been proven for every patient'. Japanese research on knee joints is covered in our knee meniscus stem cell article.

Frequently asked questions

When is spinal cord injury stem cell treatment reported to work best?

In the 116-study analysis, patients treated in the acute or subacute phase showed higher rates of neurological improvement. Natural recovery also occurs in this period, so timing and method are decided by the treating medical team based on the patient's condition.

Can people with chronic spinal cord injury join clinical trials?

Yes. 58.3% of the 116 studies enrolled chronic-phase patients, and the UC San Diego study followed patients with chronic cervical injury for five years. Eligibility such as time since injury and AIS grade differs by trial, so check each trial's public information.

What side effects have been reported with spinal cord injury stem cell treatment?

The 116-study analysis highlighted transient fever after MSC infusion and procedure-related symptoms such as headache after intrathecal delivery. Most were temporary, and the medical team monitors patients before and after administration.

Conclusion

Spinal cord injury stem cell clinical trials are increasing worldwide, and Japan ranks among the leading countries by number of registered trials. Evidence that timing and route shape outcomes, five years of maintained safety after neural stem cell transplantation and newly launched iPS cell trials show that the field is moving to a more precise stage. Suitability and risks are judged by the treating medical team, and we will update this summary from the original papers as new results appear.

This article summarises published journal papers. Names of universities and institutions are given to identify sources and are not an introduction to or recommendation of any medical institution. Suitability for treatment is judged by the treating medical team.

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