Impaired migration but not differentiation of haematopoietic stem cells in the absence of β1 integrins

Abstract

ADHESIVE interactions mediated by integrins of the β₁ subfamily¹ are thought to be critical in controlling differentiation and migration of blood cell precursors^2–7. Here we report that chimaeric mice generated with β₁-integrin-deficient embryonic stem (ES) cells^8,9 lack β^−/− cells in blood and in haematopoietic organs such as spleen, thymus and bone marrow. Chimaeric embryos contain β₁,-null haematopoietic cells in the yolk sac and in fetal blood but not in fetal liver. We show that such β^−/− haematopoietic stem cells derived from yolk sac of 10.5-day-old chimaeric embryos readily generate erythroid and myeloid colonies and that β₁^−/− ES cells can differentiate into mature B lymphocytes in vitro. Our results indicate that haematopoietic stem cells lacking β₁, integrins can form and differentiate into different lineages but cannot colonize the fetal liver.