Intratesticular transplantation of testicular cells from leukemic rats causes transmission of leukemia

A rat T-cell leukemia model was used to study the safety of germ cell trans plantation as a mean of preventing infertility in males undergoing gonadoto xic cancer treatment. Donor germ cells were harvested from the testes of te rminally ill leukemic rats and were either used directly or cryopreserved a nd thawed before transplantation by rete testis microinjection, All rats tr ansplanted with testicular cells from leukemic donors developed signs of te rminal rat T-cell leukemia, whereas control animals remained healthy. Cryop reservation of the donor germ cells caused a 3- to 6-day delay in the termi nal phase of leukemia. When a known number of leukemic cells were mixed wit h germ cells and microinjected into the testis, the rate of appearance of t erminal leukemia was directly related to the number of transferred leukemic lymphoblasts. As few as 20 leukemic cells were able to cause a cancer rela pse resulting in terminal leukemia 21 days after transplantation in three o f five transplanted animals. Our results demonstrate that germ cell transpl antation with the presently used techniques is not safe enough for clinical use, Improved methods for purging testicular specimens of cancer cells or totally new approaches with transient xenogenetic host models to detect con tamination of malignant cells must be developed before this technique can b e offered to patients without fear of disease relapse.