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Objective To evaluate the safety and efficacy of the collection of peripheral blood stem cells (PBSCs) in pediatric patients with thalassemia major (TM) weighing 20 kg or less. Methods PBSCs collection data of 170 pediatric patients with TM weighing 20 kg or less from January 2013 to December 2020 in our center were reviewed. Safety was assessed by the occurrence of adverse events during apheresis procedures, and efficacy was evaluated by the number of CD34+ cells collected. Results A total of 171 PBSCs procedures were performed on 170 patients with TM weighing 20 kg or less, with a median age of (4.98±1.53) years and a median weight of (17.30±2.18) kg. The probability of collecting at least 1×106 CD34+ cells/kg during a single course of apheresis was 99.41% (169/170), with a median (5.88±4.23) ×106 CD34+ cells collected per kg of weight of the recipient. A minimum pre-apheresis hemoglobin (Hb) of 60 g/L in patients with TM weighing 20 kg or less was safe and feasible. The most common adverse event of G-CSF mobilization in TM patients is bone pain, with the incidence of 7.65% (13/170), which was higher than that of healthy children donors in our center. The most common adverse events during the collection were pain at the puncture site of the femoral vein (6.47%, 11/170) and low pressure of the fluid (2.92%, 5/170). And no serious complications related to PBSCs mobilization, central venous catheter(CVC)placement or the apheresis procedure occurred. Conclusion PBSCs collection by COM.TEC blood cell separator in children weighing 20 kg or less is safe and efficacious.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation is the only effective method to cure thalassemia major. However, the risk factors influencing the prognosis of transplantation remain unclear. OBJECTIVE: To analyze the distribution of common complications and cause of death after allogeneic hematopoietic stem cell transplantation in children with thalassemia major, and to explore the prognostic factors so as to provide references for improving the survival rate of patients. METHODS: This retrospective cohort study included 257 patients with β-thalassemia major who underwent allogeneic hematopoietic stem cell transplantation at Department of Hematology and Oncology, Guangzhou Women and Children Medical Center between September 2013 and September 2019. There were 172 males and 85 females, with a median age of 6 years at the time of transplantation. The basic clinical data before transplantation and complications after transplantation were compared between the surviving group and dead group using single factor. The overall survival rate was analyzed by the Kaplan-Meier method, and the overall survival rate was compared by the Log-rank test. Multivariate Cox regression was used to analyze factors affecting survival. RESULTS AND CONCLUSION: The median follow-up time was 29 months, and no cases were lost to follow-up. (1) Univariate analysis results showed that there were significant differences in the risk classification between surviving patients and dead patients (P=0.033). Patients with higher risk class had an increased risk of death after transplantation. Multivariate analysis showed that risk classification and severe pneumonia were independent risk factors for overall survival after thalassemia major hematopoietic stem cell transplantation (P < 0.05). (2) Among 20 dead patients, there were 13 patients with severe pneumonia and respiratory failure, 2 patients with grade IV intestinal graft-versus-host disease, 1 patient with intracranial hemorrhage due to thrombocytopenia, 1 patient with thrombocytopenia with acute pulmonary hemorrhage, 1 patient with sepsis with shock, and 1 patient with myasthenia gravis. (3) Totally 17 cases died within 1 year after transplantation, while the rest 3 patients died of severe pneumonia more than 1 year after transplantation. (4) The incidence of bronchiolitis obliterans was significantly higher in patients who died after transplantation than in those who survived (P < 0.000 1). (5) It is concluded that the important factors that affect survival rate in thalassemia major patients after hematopoietic stem cell transplantation are infection and severe graft-versus-host disease. The risk of death increased in patients with bronchiolitis obliterans after transplantation. [ABSTRACT FROM AUTHOR]