I'm very sorry to hear about your brother.
Aplastic anemia is a very serious condition. The
bone marrow shuts down and no longer makes any white blood cells (protective immune cells), red blood cells (vital oxygen carrying cells), or platelets (clotting cells). This can happen due to cancers,
radiation exposure, certain drugs, and many other causes.
Treatments vary and include
steroids, injectable colony stimulating factors, transfusions (putting the cells in), and sometimes bone marrow
transplantation. Transplantation is very hard to do because there must be an exact match (often a family member or child must donate, but even then a match is not guaranteed). However sometimes, depending on the actual reason for the anemia in the first place, the body starts making cells again on its own. Providing supportive care in the hospital is sometimes all we can do.
I hope things get better for your brother and I will keep him and your family in my thoughts.