This study is about testing a new treatment called *Haploidentical Stem Cell Transplantation (SCT)* for adults with severe sickle cell disease (SCD). SCD is a blood disorder causing abnormal red blood cells, leading to pain and other health problems. The treatment uses stem cells from a half-matched family member to help replace the patient's blood-forming cells.

Eligibility: Participants must be 18 or older, have a half-matched donor, and have severe SCD. This means they've had serious health issues like strokes, frequent chest problems, or severe pain despite treatment. They should also be able to handle the transplant process with stable heart, lung, and kidney function.

Key Points:

• The study is for adults who have tried other treatments without success.
• Participants cannot have a fully matched sibling donor and must not be pregnant or breastfeeding.
• Participants should be ready to use effective contraception if they can conceive.