Mouse erythropoietic stem cell lines function normally 100 months: loss related to number of transplantations.

Marrow stem cell lines from old and young donors in parallel experiments were transplanted into genetically anemic W/WV recipients. These recipients were populated and their anemias were cured by stem cell lines from WCB6F1 or C57BL/6 dorons that had been repeatedly transplanted up to five times at annual intervals into successive W/WV recipients. Old marrow cell lines produced erythrocytes normally for as long as 2600 to 3000 days. However, after three to four serial transplantations many stem cell lines failed to cure at least two-thirds of the recipients, and all failed by transplantation six. This decline occurred in a similar pattern whether the original stem line donor was old or young. Two experiments suggested that the decline was caused by the transplantation procedure: (1) chromosomally marked donor cells from old and young donors permanently populated lymph nodes in lethally irradiated recipients after the first transplantation, but under the same conditions cell lines from the same donors transplanted a second time were substantially infiltrated by regenerating recipient cells; (2) the ability to compete with the same chromosomally marked cell line in populating irradiated recipients declined markedly in both old and young marrow stem cell lines that had been previoulsy transplanted.