A Study Evaluating the Safety and Efficacy of the BD211 Drug Product in β-Thalassemia Major Participants

Inclusion Criteria: 1. 5 to 35 years of age. 2. Be eligible for allogeneic HSCT based on institutional medical guideline, but without a matched related donor. 3. Transfusion-dependent β-Thalassemia Major, regardless of the genotype, with the diagnosis confirmed by Hb studies. Subjects must be stable and maintained on an appropriate iron chelation regimen. Transfusion dependence is defined as requiring at least 100 mL/kg/year of packed red blood cells(pRBCs). 4. Have been treated and followed for at least the past 2 years in a specialized center that maintained detailed medical records, including transfusion history. 5. Be willing and able, in the Investigator's opinion, to comply with the study procedures outlined in the study protocol. If a pediatric subject, the subject's parent/legal guardian also must be willing and able to comply with the study procedures outlined in the study protocol. Exclusion Criteria: 1. Availability of a willing matched HLA-identical sibling hematopoietic cell donor. 2. Positive for presence of human immunodeficiency virus, human T-lymphotropic virus, vesicular stomatitis virus G antibody. 3. Clinically significant, active bacterial, viral, fungal, or parasitic infection. 4. A white blood cell (WBC) count\<3x109/L and/or platelet count\<120x109/L 5. Receipt of an allogeneic transplant. 6. Receipt of erythropoietin within 3 months before HSCT harvest. 7. Contraindication to anesthesia for bone marrow harvesting. 8. Any of prior or current malignancy, myeloproliferative or immunodeficiency disorder. 9. Active relapsing malaria 10. Immediate family member with a known or suspected Familial Cancer Syndrome. 11. Diagnosis of significant psychiatric disorder of the subject that could seriously impede the ability to participate in the study. 12. Pregnancy or breastfeeding in a postpartum female or absence of adequate contraception for fertile subjects. 13. Any other condition that would render the subject ineligible for HSCT, as determined by the attending transplant physician. 14. History of major organ damage.including Liver, Heart, Kidney disease, pulmonary hypertension ,severe iron overload, which in the opinion of the physician is grounds for exclusion. 15. Participation in another clinical study with an investigational drug within 30 days of screening. 16. Hydroxyurea therapy within 3 months before hematopoietic stem cell collection. 17. An assessment by the Investigator that the subject or parents of the subject will not comply with the study procedures outlined in the study protocol. 18. Subjects who have the desire to become a parent within the 27-month study period. 19. Prior receipt of gene therapy.