Guillermo donated bone marrow without going through the operating room or having to take days of rest. Contrary to what many people believe, this is what happens in most cases. "I walked out and went to do my shopping at Mercadona," he explains. He had spent three hours lying down with a needle in each arm while a machine extracted stem cells from his blood and returned the rest to him. "It was as simple as donating blood, just a little longer." He is 25 years old, is from Malaga, lives in Palma, and signed up in 2023 to the Bone Marrow Donor Registry (Redmo), which is managed by the Josep Carreras Foundation.