The primary disadvantage of cord blood as a source of cells for transplantation , the number of cells is small , usually less than 1 billion times, allowing operation only in children under 30 kg , while the majority of recipients has a larger weight. Hence the idea of simultaneous use of several units of cord blood , which together are designed to provide a sufficient number of cells for transplantation to an adult recipient. The bottom line is that the immune cells in cord blood , as young cells should not be able to cross- reactions against each other. Such reactions are the biggest threat to the success of the idea and therefore first tested whether co-culture of hematopoietic cells from two different cord blood units associated with their interaction affecting the number of generated hematopoietic colonies . Such tests revealed no differences in terms of mean values ​​, results were also observed but the opposite , i.e. both inhibition and stimulation in different combinations. We performed a clinical trial in an adult male with acute myeloid leukemia without remission , which przeszczepiliśmy cells with two different units of umbilical cord blood . We obtained documented implanting one of these two units and normalization of neutrophils . Overall , these results suggest that the test method of therapeutic promise for the future routine use in recipients who do not have either Kindred or unrelated donor bone marrow.