As an emerging modality of hematopoietic stem cell transplantation, umbilical cord blood transplantation (UCBT) has demonstrated unique clinical value in the treatment of various hematologic diseases. From January 9–11, 2026, the 6th China Hematology Discipline Development Conference (CASH) was held in Tianjin, bringing together leading hematology experts from China and abroad to explore cutting-edge research and national health priorities. During the conference, Professor Zimin Sun from the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences, shared in-depth insights into the current clinical status, technical advantages, and evolving research landscape of UCBT.From a “Niche Option” to a Strategic Alternative: Global Trends and China’s Opportunity
Professor Zimin Sun:
Umbilical cord blood transplantation (UCBT) is an important form of allogeneic hematopoietic stem cell transplantation (allo-HSCT), with nearly 40 years of clinical application. However, its utilization rate remains relatively low worldwide—including in Europe, the United States, and China—typically accounting for only 3%–5% of all allogeneic transplants. In contrast, Japan has emerged as a global leader in this field, where cord blood transplantation represents nearly 60% of unrelated donor transplants.
According to 2024 registry data from the Hematopoietic Stem Cell Transplantation Application Group of the Chinese Society of Hematology, approximately 700 UCBT procedures were performed in China in one year, accounting for about 5% of total allogeneic transplants. Overall, UCBT remains a relatively underutilized transplant modality in both China and globally.
However, the next two to three decades may present a significant growth opportunity for UCBT in China. Due to the long-term impact of the one-child policy, many patients aged 30–40 years lack matched sibling donors and must rely on unrelated donor registries. Although the China Marrow Donor Program currently includes approximately 3.6 million registered volunteers, only about 2,000 actual stem cell donations were completed in 2024, leaving a portion of patients unable to find suitable donors. In this context, cord blood represents a critical alternative donor source, with increasing clinical relevance and expansion potential.
Lower Chronic GVHD and Reduced Relapse: Key Clinical Advantages of UCBT
Professor Zimin Sun:
Umbilical cord blood transplantation offers two major clinical advantages:
- Significantly reduced incidence of chronic graft-versus-host disease (cGVHD):
Compared with bone marrow or peripheral blood stem cell transplantation, UCBT is associated with substantially lower cGVHD rates, leading to better long-term quality of life for transplant recipients. - Lower relapse rates in hematologic malignancies:
Particularly in high-risk, refractory, or relapsed hematologic cancers, UCBT demonstrates a strong graft-versus-leukemia (GVL) effect, contributing to lower post-transplant relapse rates and favorable overall outcomes.
Overcoming Concerns About Cell Dose: Evidence on Engraftment and Immune Reconstitution
Professor Zimin Sun:
Umbilical cord blood contains fewer hematopoietic stem cells, typically one-tenth to one-twentieth of those found in bone marrow or peripheral blood, and cannot be expanded through donor mobilization. Early clinical concerns focused on two main issues:
- Whether the lower cell dose is sufficient for successful engraftment
- Whether the predominance of naïve T cells might delay immune reconstitution and increase infection risk
However, large-scale retrospective analyses and modeling studies indicate that hematopoietic recovery is not solely determined by CD34⁺ cell dose. Although a lower CD34⁺ dose may delay engraftment, it does not significantly impair immune reconstitution or long-term survival outcomes.
In a retrospective cohort study of 1,838 patients, immune recovery following UCBT was found to be comparable to, or not slower than, other transplant modalities:
- NK cells began recovering approximately 30 days post-transplant
- CD4⁺ T cells showed superior recovery between days 91–180 compared with matched sibling, haploidentical, and unrelated donor transplants
- CD19⁺ B cells exhibited notable recovery between days 180–270
These immune reconstitution patterns may partially explain the lower rates of cGVHD and relapse observed after UCBT.
Looking forward, integrated basic research and multicenter clinical studies will be essential to further elucidate the immunological mechanisms underlying UCBT, particularly its roles in immune regulation and anti-tumor effects, thereby supporting continued optimization of clinical application.
Expert Profile
Professor Zimin Sun
Institute of Hematology & Blood Diseases Hospital,
Chinese Academy of Medical Sciences
- Distinguished Expert, Regenerative Medicine Center – Cord Blood Transplantation & Cell Therapy Unit
- Chief Physician, Second-Level Professor, PhD Supervisor
- Recipient of State Council Special Government Allowance
- Honorary Director, Institute of Blood and Cell Therapy, University of Science and Technology of China
- Former Standing Committee Member, Chinese Society of Hematology
- Deputy Leader, HSCT Application and Experimental Groups, Chinese Society of Hematology
- Vice Chair, China Cord Blood Application Committee
- Vice Chair, Chinese Society for Hematologic Immunology
- Specialty: Umbilical cord blood transplantation; completed 2,000+ unrelated UCBT procedures
- Published 300+ scientific papers in journals including Blood, Nature Communications, and American Journal of Hematology
