As usual I found my answer before you people lol. This forum becomes more and more useless with the time.
It is meaned that they take you dna sample from the cheek with a swab, analize it in order to understand if you can be a bone marrow stem cells donor for a patient, who needs bone marrow stem cells transplant, and if you are, you can donate bone marrow stem cells for the someone and save his or her life.
An example:
http://www.hornchurc...save-rajs-life/
"To find out if you are a matching donor for Raj, or someone just like him, all it takes is a simple swab of the inside of your cheek and 5 minutes of your times."
"If you are in good health, between the ages of 18-55 you can become a potential blood stem donor"
A detailed explanation about the procedure of how exactly the matching happens:
https://bethematch.o...ts-are-matched/