Saw a 7 year old boy on tv asking people to become stem cell donors to let him have more time with his dad. You can sign up if you are anywhere in the world, the exclusions are less stringent than for blood donors but you do have to be 17-55. You may never be asked to donate but for 90% of those who are it's now like giving blood - except they put the blood back after taking stem cells out.
You make up the cells in a few weeks and if your employer wont give you paid time off (it takes several hours) you can get a loss of income payment.
No need to join if you are already on a register, but blood donors are NOT automatically on the register.
10000donors.com/