The first strategy involves giving NK cells from another individual to the patient (in other words, donor- or haploidentical-NK cells). This is done because NK cells from an individual who is haploidentical (half-matched genetic make-up) are still able to effectively kill the cancer cells. Unfortunately, only a limited number of NK cells can be obtained from a donor. So, to increase the number of cancer-killing NK cells that will be given to the patient, the donor NK cells will first be grown in a sterile laboratory environment and allowed to multiply many-fold before they are infused into the patient. This growing process also activates the donor NK cells, which increases their ability to kill cancer cells.