This study is looking at a special kind of stem cell transplant called **haploidentical T-depleted stem cell transplantation** for people with sickle cell disease (**SCD**). SCD is a blood disorder where red blood cells are shaped like a sickle, causing pain and other problems. A **stem cell transplant** can cure SCD, but usually, only siblings with a perfect match can be donors. This study is testing if a *half-matched donor* (haploidentical) can also work safely and effectively. - **Key Points**: - The study is for people aged 2 to 35 with serious SCD complications. - Participants must be able to follow the study rules and will need to have regular medical check-ups. - There are risks like infection or rejection, but the study aims to reduce these with a special treatment plan. Participants cannot have certain health issues like uncontrolled diseases or be pregnant. If you join, the doctors will closely watch your health to ensure your safety. This study hopes to offer a new treatment option for more people with SCD.