Romiplostim Versus rhTPO for Platelet Engraftment After Transplant in MDS and AA

Inclusion Criteria: 1. Age 18-65 years (inclusive). 2. Diagnosis of Myelodysplastic Syndrome (MDS) per WHO criteria, or Severe/Very Severe Aplastic Anemia (SAA/VSAA) per Camitta criteria, and deemed eligible for allogeneic hematopoietic stem cell transplantation (allo-HSCT). 3. Planned to receive allo-HSCT from a matched sibling, haploidentical, or unrelated donor (including cord blood). 4. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. 5. Persistent platelet count \<20×10⁹/L with platelet transfusion dependence between post-transplant days +4 and +10. Transfusion dependence is defined as platelet count not doubling within 24-48 hours after transfusion or ongoing need for prophylactic transfusion. 6. Adequate cardiac, hepatic, and renal function as required for transplantation, per investigator assessment. 7. Voluntary participation with written informed consent obtained prior to any study-specific procedures. Exclusion Criteria: 1. Active, uncontrolled bacterial, fungal, or viral infection at the time of enrollment. 2. History of arterial thrombosis, or venous thromboembolism within the past 6 months (unless cured or stable for over 6 months). 3. Active transplant-associated thrombotic microangiopathy (TA-TMA). 4. Pre-transplant bone marrow biopsy showing fibrosis grade ≥ MF-2 (according to WHO criteria). 5. Known hypersensitivity to Romiplostim, recombinant human thrombopoietin (rhTPO), or any of their excipients. 6. Pregnant or lactating women. 7. Women of childbearing potential or men with partners of childbearing potential who are unwilling to use highly effective contraception during the study period and for at least 3 months after the last dose of study drug. 8. Any other condition that, in the opinion of the investigator, would make the patient unsuitable for participation in the study.