Bone can be used for people with serious bone injuries. Even if you're over seventy, your corneas can still be used to bring sight to two blind people. There are long lists of people waiting for organs or tissue, and many people on those lists, who aren't governors of large states just north of the Mason Dixon Line, die while waiting for a compatible organ. Please, sign up to be an organ donor. Don't just assume that your own organs aren't needed.
Bone marrow is donated by live, compatible donors.
These selfless donors can be close family members or unrelated people who have compatible marrow. There's a computer database of people who have given a blood sample for tissue typing. People who would otherwise die of cancer or aplastic anemia and need a bone marrow transplant can access this list if they don't have a compatible sibling or parent. During one search for marrow donors, my wife, my daughter, and I registered. So far, we haven't been matched with recipients.