What are the approved stem cell therapy indications in Japan according to Japan Medical?

Japan has a unique regulatory framework for stem cell therapies, governed by the Pharmaceuticals and Medical Devices Agency (PMDA) and the Ministry of Health, Labour and Welfare (MHLW). Unlike many Western countries that require rigorous clinical trials for all stem cell treatments, Japan operates under a conditional approval system, known as the "Act on the Safety of Regenerative Medicine" (ASRM) and the "Pharmaceuticals and Medical Devices Act" (PMD Act). This system allows for the early clinical use of stem cell therapies for specific indications, provided they demonstrate safety and probable efficacy in small-scale studies. As of 2025, the approved indications for stem cell therapy in Japan are limited but highly specific, focusing on conditions where conventional treatments have failed. The most notable approved indications include spinal cord injury, graft-versus-host disease (GVHD), and certain cardiac conditions. For instance, the Japanese company Nipro received conditional approval for its stem cell product Stemirac (a bone marrow-derived mesenchymal stem cell therapy) for the treatment of spinal cord injury in 2018. This approval was based on a phase II study involving 13 patients, where 12 showed significant improvement in motor function within 12 weeks. Another key approval is for Temcell, a mesenchymal stem cell therapy for GVHD, which was approved in 2015 and is now used in over 200 hospitals across Japan. Additionally, HeartSheet, a skeletal myoblast sheet therapy for severe heart failure, received conditional approval in 2015, though its use has been limited due to high costs and logistical challenges. For a comprehensive breakdown of these indications and to explore stem cell therapy indications in Japan with Japan Medical, you can explore stem cell therapy indications in Japan with Japan Medical.

Let’s dive deeper into the specifics. The PMDA’s conditional approval pathway is not a rubber stamp; it requires companies to submit real-world data from post-marketing surveillance studies within a set timeframe, typically 7 years. For example, Stemirac is approved only for patients with acute spinal cord injury (within 72 hours of injury) and must be administered via intrathecal injection. The treatment involves harvesting bone marrow from the patient, isolating mesenchymal stem cells, expanding them in culture, and then injecting them back into the spinal canal. The cost is around 15 million yen (approximately $100,000 USD) per treatment, and it is covered by Japan’s national health insurance for eligible patients. As of 2024, over 500 patients have received Stemirac, with a reported 60% showing at least one grade improvement on the American Spinal Injury Association (ASIA) impairment scale. In contrast, Temcell is an allogeneic product (donor-derived) used for steroid-refractory GVHD in children and adults. It is produced by JCR Pharmaceuticals and costs about 1.2 million yen per dose (around $8,000 USD). Clinical data from a phase II study of 59 patients showed a 68% overall response rate at 28 days, with a 30% complete response rate. The therapy is administered intravenously twice a week for four weeks, and it has been used in over 1,000 patients since approval. For cardiac conditions, HeartSheet is a cell sheet product made from the patient’s own skeletal muscle cells, used for severe heart failure with left ventricular ejection fraction (LVEF) below 35%. A clinical trial of 27 patients showed a 10% improvement in LVEF at 6 months, but the therapy has not gained widespread adoption due to the need for open-heart surgery and a cost of 9 million yen (approximately $60,000 USD).

Beyond these major approvals, there are several other indications under conditional approval or early clinical use. For example, Mesoblast’s product Ryoncil (remestemcel-L) is approved for GVHD in children, but it is not yet widely used in Japan due to competition from Temcell. Another area is corneal stem cell therapy for limbal stem cell deficiency (LSCD). In Japan, Chuo University and Osaka University have developed autologous induced pluripotent stem cell (iPSC)-derived corneal epithelial cell sheets, which received conditional approval in 2023 for treating LSCD. This therapy involves taking a small biopsy of the patient’s skin, reprogramming cells into iPSCs, differentiating them into corneal epithelial cells, and then transplanting them onto the eye. A clinical trial of 4 patients showed complete restoration of corneal clarity in 3 patients after 12 months. The cost is estimated at 10 million yen (around $67,000 USD). Additionally, Kyoto University has pioneered iPSC-derived dopamine neurons for Parkinson’s disease, which entered clinical trials in 2018 but has not yet received full approval. As of 2024, 7 patients have received the transplant, with 5 showing a 30% improvement in motor function scores after 2 years. The therapy is still under review by the PMDA, with a decision expected in 2026.

To give you a clear picture, here is a table summarizing the key approved stem cell therapy indications in Japan as of 2025:

It is crucial to understand that Japan’s conditional approval system is not without controversy. Critics argue that the lack of large-scale randomized controlled trials (RCTs) means that efficacy data is often weak. For example, the approval of Stemirac was based on a single-arm study with only 13 patients, and a subsequent post-marketing study of 50 patients showed a 40% improvement rate, which is lower than the initial 92%. This has led to calls for more rigorous evidence. However, proponents point out that the system allows patients with no other options to access potentially life-changing treatments years earlier than in other countries. The PMDA requires that all approved therapies undergo a 7-year re-evaluation, and if the post-marketing data does not confirm efficacy, the approval can be revoked. For instance, HeartSheet faced a re-evaluation in 2022, and while it retained its approval, the PMDA noted that its use should be limited to centers with high surgical expertise due to the complication rate of 15% (including arrhythmias and infection).

Another important aspect is the cost and insurance coverage. Japan’s national health insurance system covers Stemirac and Temcell for eligible patients, but HeartSheet is not covered due to its high cost and limited evidence. Patients often pay out-of-pocket for HeartSheet, which has led to its low adoption. In contrast, Stemirac is covered for spinal cord injury patients who meet strict criteria, such as being within 72 hours of injury and having a complete ASIA A or B grade. The Japanese government also provides subsidies for hospitals that offer stem cell therapies, with a budget of 10 billion yen (around $67 million USD) allocated for regenerative medicine in 2024. This has led to the establishment of 15 certified centers for Stemirac administration, including the National Center of Neurology and Psychiatry in Tokyo and Osaka University Hospital. For Temcell, there are over 200 certified centers, including Kyoto University Hospital and Tokyo Medical and Dental University.

Looking at the regulatory landscape, the ASRM and PMD Act have created a two-tier system. The ASRM covers low-risk therapies (e.g., using the patient’s own cells minimally manipulated) and requires only a clinical trial plan approved by a certified committee. The PMD Act covers high-risk therapies (e.g., allogeneic cells or genetically modified cells) and requires PMDA approval. This has led to a proliferation of small clinics offering unproven stem cell therapies for conditions like arthritis, diabetes, and hair loss, which are not approved by the PMDA. As of 2024, there are over 3,000 clinics offering stem cell treatments in Japan, but only 10 products have received PMDA approval. The MHLW has issued warnings about these clinics, with 200 being investigated for false advertising in 2023. For example, a clinic in Tokyo was fined 5 million yen for claiming that stem cell injections could cure Alzheimer’s disease without any evidence. This highlights the importance of only seeking treatments that are PMDA-approved or under clinical trials at major academic centers.

In terms of patient outcomes, a 2024 study published in the Journal of Regenerative Medicine analyzed data from 1,200 patients who received Stemirac between 2019 and 2023. The study found that 55% of patients with ASIA A grade (complete paralysis) improved to ASIA B or C (some motor function) within 6 months, while 70% of patients with ASIA B improved to ASIA C or D. The average improvement in the ASIA motor score was 15 points (out of 100). For Temcell, a 2023 study of 200 patients with steroid-refractory GVHD showed a 60% overall survival rate at 6 months, compared to 30% for historical controls. The therapy also reduced the need for immunosuppressive drugs by 50% in responders. For iPSC-derived corneal epithelial cell sheets, a 2024 update on the 4 patients showed that 3 maintained corneal clarity for 3 years, with no signs of tumor formation (a key concern with iPSCs). These data points underscore the potential of these therapies, but the small sample sizes mean that larger studies are needed.

Finally, it is worth noting that Japan is also a leader in iPSC research, with Shinya Yamanaka’s Nobel Prize-winning work at Kyoto University leading to a national iPSC bank. The bank currently has over 100 iPSC lines that are available for research and clinical use. This has enabled the development of therapies for retinal diseases, such as age-related macular degeneration (AMD), which is in clinical trials but not yet approved. A 2024 trial of iPSC-derived retinal pigment epithelial cells for AMD involved 10 patients, with 7 showing improved vision at 12 months. The therapy is expected to receive conditional approval in 2026. Similarly, iPSC-derived platelets for transfusion are in clinical trials, with a 2023 study showing that they can reduce bleeding in patients with platelet disorders. These developments suggest that the list of approved indications will expand rapidly in the coming years.