N-Acetylcysteine as Therapy for Transplantation- Associated Thrombotic Microangiopathy

Inclusion Criteria: \- 1. Informed Consent: The patient must have the ability to understand and the willingness to participate in the study and must sign a written Informed Consent Form. 2\. Age: ≥ 18 years old, regardless of gender. 3. Diagnosis: Subjects diagnosed with TA-TMA according to the Harmonizing Definitions, defined as meeting one of the following: * TA-TMA confirmed by renal or intestinal biopsy, OR * Fulfilling at least four of the following seven clinical or laboratory criteria within a 14-day period: 1. Anemia, defined as persistent transfusion dependence after myeloid engraftment, OR a decrease in hemoglobin \>10 g/L, OR new-onset transfusion dependence. 2. Thrombocytopenia, defined as failure of platelet engraftment, OR a higher-than-expected platelet transfusion requirement, OR refractory platelet transfusion, OR a \>50% decrease in platelets after initial engraftment. 3. Lactate dehydrogenase (LDH) level above the upper limit of normal (ULN). 4. Presence of schistocytes on peripheral blood smear. 5. Hypertension (blood pressure ≥140/90 mmHg). 6. sC5b-9 level above the ULN. 7. Proteinuria (random urine protein-to-creatinine ratio ≥1 mg/mg). Exclusion Criteria: * 1\. The subject has received complement blockade therapy (e.g., Eculizumab or Narsoplimab) within the past 3 months. 2\. The subject has a history of drug and/or alcohol abuse within the 6 months prior to enrollment. 3\. The subject has a life expectancy of less than 3 months. 4. The subject is considered by the investigator to be unable or unwilling to cooperate with the study procedures. 5\. The subject is a family member or employee of the investigator. 6. The patient is pregnant or lactating. 7. The subject has a history of Human Immunodeficiency Virus (HIV) infection. 8. The subject has a known allergy to any component of the investigational drug (N-acetylcysteine). 9\. The subject has cardiac insufficiency, defined as an ejection fraction (EF) \<30%, or NYHA Class III or higher heart failure, or other cardiac conditions deemed by the investigator as unsuitable for enrollment. 10\. The subject has contraindications to N-acetylcysteine, such as active bronchial asthma or peptic ulcer disease. 11\. The patient refuses to participate in the study.