A new rejection prevention technique will spare children who require bone marrow transplants some of the side-effects of chemotherapy.
A technique using antibodies which recognise and kill bone marrow to make space for donor cells has been created by doctors at Great Ormond Street Hospital (GOSH) and the UCL Institute of Child Health.
The risk of rejection is lessened by the new technique - which reduces the need for intensive chemotherapy.
It is thought to have saved lives when used on children with genetic defects of the immune system, who were too sick to undergo a traditional bone marrow transplant.
Previously, for their own bone marrow to be wiped out to create space prior to a transplant, children needed high doses of chemotherapy.
Under the new method, the patients' tissue is wiped out using an antibody directed against a molecule called CD45. The healthy bone marrow can then grow in the space.
Dr Persis Amrolia, a consultant in bone marrow transplant at GOSH who led the research, described the results as "remarkable".