Patients with refractory immune thrombocytopenia (ITP) frequently encounter substantial bleeding risks and demonstrate limited responsiveness to existing therapies. Umbilical cord-derived mesenchymal stem cells (UC-MSCs) present a promising alternative, capitalizing on their low immunogenicity and potent immunomodulatory effects for treating diverse autoimmune disorders. This prospective phase I trial enrolled eighteen eligible patients to explore the safety and efficacy of UC-MSCs in treating refractory ITP. The research design included administering UC-MSCs at escalating doses of 0.5 × 10⁶ cells/kg, 1.0 × 10⁶ cells/kg, and 2.0 × 10⁶ cells/kg weekly for four consecutive weeks across three cohorts during the dose-escalation phase, followed by a dose of 2.0 × 10⁶ cells/kg weekly for the dose-expansion phase. Adverse events, platelet counts, and changes in peripheral blood immunity were monitored and recorded throughout the administration and follow-up period. Ultimately, 12 (with an addition of three patients in the 2.0 × 10⁶ cells/kg group due to dose-limiting toxicity) and six patients were enrolled in the dose-escalation and dose-expansion phase, respectively. Thirteen patients (13/18, 72.2%) experienced one or more treatment emergent adverse events. Serious adverse events occurred in four patients (4/18, 22.2%), including gastrointestinal hemorrhage (2/4), profuse menstruation (1/4), and acute myocardial infarction (1/4). The response rates were 41.7% in the dose-escalation phase (5/12, two received 1.0 × 10⁶ cells/kg per week, and three received 2.0 × 10⁶ cells/kg per week) and 50.0% (3/6) in the dose-expansion phase. The overall response rate was 44.4% (8/18) among all enrolled patients. To sum up, UC-MSCs are effective and well tolerated in treating refractory ITP (ClinicalTrials.gov ID: NCT04014166).

难治性免疫性血小板减少症（ITP）患者经常遇到严重的出血风险，并且对现有疗法的反应有限。脐带间充质干细胞（UC-MSC）提供了一种有前途的替代方案，利用其低免疫原性和有效的免疫调节作用来治疗多种自身免疫性疾病。这项前瞻性 I 期试验招募了 18 名符合条件的患者，以探索 UC-MSC 治疗难治性 ITP 的安全性和有效性。研究设计包括在剂量递增阶段，在三个队列中连续四周以每周0.5 × 10 ^{6 个}细胞/kg、1.0 × 10 ^{6 个}细胞/kg 和 2.0 × 10 ^{6 个}细胞/kg 的递增剂量施用 UC-MSC ，随后剂量扩展阶段每周剂量为 2.0 × 10 ^{6 个}细胞/kg。在整个给药和随访期间监测和记录不良事件、血小板计数和外周血免疫的变化。最终，12 名患者（由于剂量限制性毒性，在 2.0 × 10 ⁶细胞/kg 组中增加了 3 名患者）和 6 名患者分别进入剂量递增和剂量扩展阶段。 13 名患者（13/18，72.2%）经历了一种或多种治疗中出现的不良事件。 4例患者（4/18，22.2%）发生严重不良事件，包括消化道出血（2/4）、月经过多（1/4）、急性心肌梗塞（1/4）。剂量递增阶段的缓解率为 41.7%（5/12，两名患者每周接受 1.0 × 10 ^{6 个}细胞/kg，三名患者每周接受 2.0 × 10 ^{6 个}细胞/kg）和 50.0% (3/6)在剂量扩展阶段。所有入组患者的总体缓解率为 44.4% (8/18)。综上所述，UC-MSC 在治疗难治性 ITP 方面有效且耐受性良好（ClinicalTrials.gov ID：NCT04014166）。