Kintsugi and kidney care: Young nephrologists in Japan share insights ahead of WCN’26
In Japan, the art of kintsugi repairs broken pottery with adhesive and powdered gold, transforming fracture into renewed strength.
As the global kidney care community prepares to gather in Yokohama for WCN’26, Japan’s approach to kidney health offers a compelling parallel: working with impairment to preserve function, extending quality of life in an aging society, and continuously strengthening systems of care through early detection and innovation.
The ISN Young Nephrologists Committee spoke with young nephrologists across Japan* to explore how these principles translate into everyday practice. Their perspectives offer practical insights for clinicians and researchers worldwide.
An aging population
Japan is the world’s most aged society, with nearly 29% of its population being 65 years or older.
“Like many developed countries, Japan is now facing a super-aging society, and this trend is also evident in kidney disease. In Japan, more than 20% of patients who start maintenance dialysis are over 80 years old. Therefore, slowing the progression of kidney disease and determining appropriate approaches to end-stage kidney disease in elderly patients have become critically important issues,” shared Yosuke Hirakawa from the Department of Nephrology and Endocrinology at the University of Tokyo Hospital.
Emerging evidence also links chronic kidney disease (CKD) with cognitive impairment and neurodegeneration, reinforcing the need for integrated approaches in aging populations.
Ryusuke Umene, from the Department of Physiology of Visceral Function and Body Fluid, Graduate School of Biomedical Sciences, Nagasaki University, explains, “In Japan’s super-aging society, CKD is increasingly recognized as a bidirectional brain–kidney disorder, in which aging disrupts this reciprocal regulation. Uremia and cerebral blood flow dysregulation contribute to cognitive impairment and neurodegeneration, while efferent autonomic signals—including sympathetic pathways—modulate renal inflammation, blood pressure control, and kidney protection. Deeper understanding of this neuro–renal axis is essential to curb CKD progression and improve kidney health worldwide.”
Early detection and KDIGO guideline implementation
An estimated 13% of adults in Japan have CKD. IgA nephropathy is the most common primary glomerulonephritis in Japan and remains a leading cause of kidney failure.
Yoshihito Nihei, from the Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, observes, “Japan’s healthcare system is characterized by routine school and workplace health checkups that include urinalysis, allowing asymptomatic hematuria and proteinuria to be detected at an early stage. This screening system facilitates the early diagnosis of glomerulonephritis, such as IgA nephropathy. As a result, patients can be identified, monitored, and treated before significant renal dysfunction develops. Nevertheless, many patients still progress to end-stage kidney disease, and this remains an important unresolved clinical issue in Japan.”
“IgA nephropathy is the most common primary glomerulonephritis in Japan. Until recently, treatment options were largely limited to renin–angiotensin system inhibitors and systemic corticosteroids. However, after the U.S. FDA accepted a reduction in proteinuria as a surrogate endpoint, numerous clinical trials for IgA nephropathy have been initiated, and some agents with proven efficacy are now being introduced into clinical practice. A distinctive feature of IgA nephropathy management in Japan is the use of tonsillectomy, which is also described in the KDIGO guidelines. Despite these advances, many patients still progress to end-stage kidney disease. Approval of new therapies in Japan is eagerly anticipated.”
Kidney transplantation
Japan performs fewer deceased donor kidney transplants per capita than most high-income countries, resulting in long waiting times despite strong clinical outcomes.
“In Japan, post-transplant long-term graft survival is among the highest worldwide, supported by careful donor–recipient matching, advances in immunosuppressive management, and structured systems for long-term follow-up. However, kidney transplantation in Japan remains highly dependent on living donors due to the scarcity of deceased donor organs. The limited availability of donor organs continues to constrain access to transplantation for many patients on the waiting list. In response, xenotransplantation and regenerative medicine have been cautiously explored as strategies to address organ shortages, including approaches such as fetal kidney xenotransplantation for congenital renal failure. Bridging the gap between organ demand and supply while maintaining graft durability and ethical responsibility will be critical for preserving kidney health across the lifespan,” states Kenji Matsui, Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo.
Bioengineering the kidney
Since the discovery of induced pluripotent stem cells (hiPSCs) in 2006, Japan has positioned regenerative medicine as a pillar of national science and health policy. Institutions such as Kyoto University’s Center for iPS Cell Research and Application (CIRA) have become central to this coordinated national effort.
Hiraku Tsujimoto, who works at CIRA, explains, “Japan is the birthplace of hiPSCs, and creating a fully functional kidney from hiPSCs represents the ultimate goal of kidney regeneration. Under a strong government commitment to developing iPS cell-based therapies, Japan has established a nationwide support system for regenerative medicine. In recent years, substantial public funding and strategic policy initiatives have accelerated research, clinical applications, and the development of manufacturing infrastructure. As a result, innovation and development in this field are being vigorously driven by both academia and industry.”
Like kintsugi, the Japanese approach to kidney care deliberately works to restore function and resilience for the long term. We look forward to deepening the conversation on these and other cutting-edge topics at WCN’26.
*The ISN thanks Kenji Matsui, Hiraku Tsujimoto, Yoshihito Nihei, Yosuke Hirakawa, Yuka Sugawara, Megumi Oshima, Ayumi Matsumoto, and Ryusuke Umene for their contributions to the development of this article.
References
Statistics Bureau of Japan. Statistical Handbook of Japan 2023.
KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases.
Japan Society for Transplantation. Annual Report on Organ Transplantation in Japan.
Cyranoski D. Japan’s approval system for regenerative medicine products. Nature Biotechnology. 2019.
