The following is general information introducing research findings. Results reported in studies do not mean the same outcome for any individual, and most of these studies are small or early-stage.
Key research results by disease
The table below summarises key stem cell research results reported in published papers and public-agency materials, centred on research from Japanese universities and institutes and including randomised studies from abroad.
| Condition | Reported result | Institution / source | Stage |
|---|---|---|---|
| Spinal cord injury | Autologous bone marrow-derived MSC product granted conditional, time-limited approval in Japan (2018); changes in motor and sensory scores reported in 13 cases (2021) | Sapporo Medical University (Japan) | Conditional approval |
| Acute graft-versus-host disease (GVHD) | Allogeneic MSC product approved in Japan (2015); responses reported in a phase II study of steroid-refractory patients (2008) | Approved by Japan's MHLW / European multicentre study | Approved |
| Parkinson's disease | Phase I/II transplantation of iPS cell-derived dopamine neurons: dopamine production by grafted cells and improved motor scores in some patients reported (2025) | Kyoto University CiRA and Kyoto University Hospital (Japan) | Clinical trial |
| Age-related macular degeneration (eye) | Retinal pigment epithelium made from the patient's own iPS cells transplanted; graft survival and maintained vision over one year reported (2017) | RIKEN and Kobe City Medical Center General Hospital (Japan) | Clinical study |
| Stroke | Changes in neurological scores and imaging after intravenous MSC expanded in autologous serum (2011, 12 patients) | Sapporo Medical University (Japan) | Small study |
| Liver cirrhosis | Improved serum albumin and liver function scores after autologous bone marrow cell infusion (2006, 9 patients) | Yamaguchi University (Japan) | Small study |
| Crohn's disease (perianal fistula) | Difference in remission rate in a randomised phase 3 study of local allogeneic adipose-derived MSC (2016) | European multicentre study | Phase 3 |
| Frailty | Changes in six-minute walk distance and other measures in a randomised, double-blind phase II study of allogeneic MSC (2017) | University of Miami (US) | Phase 2 |
| Cerebral palsy | Changes in motor function in children receiving at least a certain dose in a randomised, placebo-controlled autologous cord blood study (2017) | Duke University (US) | Randomised study |
Details for each condition are on the field pages and condition pages below.
Why Japan stands out in stem cell research
Japan is where Professor Shinya Yamanaka's team at Kyoto University first reported iPS cells (induced pluripotent stem cells) in 2006, and several of the world's first clinical studies using iPS cells have since taken place in Japan. Japan has also created a conditional, time-limited approval pathway for regenerative medical products and a regenerative medicine act, managing stem cell medicine within a regulatory framework.
Types of stem cells
- Mesenchymal stem cells (MSC) — obtained from bone marrow, fat or umbilical cord. In 2006 the International Society for Cellular Therapy (ISCT) proposed minimal criteria for MSC (plastic adherence; CD73, CD90 and CD105 expression; differentiation into bone, fat and cartilage). Japan's approved products and many clinical studies use these cells.
- iPS cells — pluripotent stem cells made by introducing genes into skin or blood cells, used in research that differentiates them into specific cells for transplantation.
- Haematopoietic stem cells and cord blood — blood-forming stem cells; haematopoietic stem cell transplantation for blood cancers is a long-established treatment.
How to read research results
Phase 1 mainly checks safety, phase 2 explores possible efficacy, and phase 3 confirms efficacy and safety in more patients. Results confirmed in randomised controlled studies carry stronger evidence, and 'approval' can be either standard or conditional and time-limited.
The above summarises results reported in published papers and public-agency materials. University and institute names are given to identify research sources, not to introduce or recommend any medical institution. Reported results do not mean the same effect for everyone, and the suitability of any treatment is decided by the medical team.
References
- Honmou O, Yamashita T, Morita T, et al. Intravenous infusion of auto serum-expanded autologous mesenchymal stem cells in spinal cord injury patients: 13 case series. Clin Neurol Neurosurg. 2021;203:106565. View on PubMed
- Le Blanc K, Frassoni F, Ball L, et al. Mesenchymal stem cells for treatment of steroid-resistant, severe, acute graft-versus-host disease: a phase II study. Lancet. 2008;371(9624):1579-1586. View on PubMed
- Sawamoto N, Doi D, Nakanishi E, et al. Phase I/II trial of iPS-cell-derived dopaminergic cells for Parkinson's disease. Nature. 2025. View on PubMed
- Mandai M, Watanabe A, Kurimoto Y, et al. Autologous induced stem-cell-derived retinal cells for macular degeneration. N Engl J Med. 2017;376(11):1038-1046. View on PubMed
- Honmou O, Houkin K, Matsunaga T, et al. Intravenous administration of auto serum-expanded autologous mesenchymal stem cells in stroke. Brain. 2011;134(Pt 6):1790-1807. View on PubMed
- Terai S, Ishikawa T, Omori K, et al. Improved liver function in patients with liver cirrhosis after autologous bone marrow cell infusion therapy. Stem Cells. 2006;24(10):2292-2298. View on PubMed
- Panés J, García-Olmo D, Van Assche G, et al. Expanded allogeneic adipose-derived mesenchymal stem cells (Cx601) for complex perianal fistulas in Crohn's disease: a phase 3 randomised, double-blind controlled trial. Lancet. 2016;388(10051):1281-1290. View on PubMed
- Tompkins BA, DiFede DL, Khan A, et al. Allogeneic mesenchymal stem cells ameliorate aging frailty: a phase II randomized, double-blind, placebo-controlled clinical trial. J Gerontol A Biol Sci Med Sci. 2017;72(11):1513-1522. View on PubMed
- Sun JM, Song AW, Case LE, et al. Effect of autologous cord blood infusion on motor function and brain connectivity in young children with cerebral palsy: a randomized, placebo-controlled trial. Stem Cells Transl Med. 2017;6(12):2071-2078. View on PubMed
- Dominici M, Le Blanc K, Mueller I, et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy. 2006;8(4):315-317. View on PubMed
- Takahashi K, Yamanaka S. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell. 2006;126(4):663-676. View on PubMed
