Inducible disruption of the c-myb gene allows allogeneic bone marrow transplantation without irradiation

Abstract

Allogeneic bone marrow (BM) transplantation enables the in vivo functional assessment of hematopoietic cells. As pre-conditioning, ionizing radiation is commonly applied to induce BM depletion, however, it exerts adverse effects on the animal and can limit experimental outcome. Here, we provide an alternative method that harnesses conditional gene deletion to ablate c-myb and thereby deplete BM cells, hence allowing BM substitution without other pre-conditioning. The protocol results in a high level of blood chimerism after allogeneic BM transplantation, whereas immune cells in peripheral tissues such as resident macrophages are not replaced. Further, mice featuring a low chimerism after initial transplantation can undergo a second induction cycle for efficient deletion of residual BM cells without the necessity to re-apply donor cells. In summary, we present an effective c-myb-dependent genetic technique to generate BM chimeras in the absence of irradiation or other methods for pre-conditioning.

Ontogeny of arterial macrophages defines their functions in homeostasis and inflammation

“…It is therefore an unsuitable method to determine steady-state turnover of tissue-resident macrophages. We established a genetic BM-transplantation model that harnesses conditional gene deletion to ablate the transcription factor c-myb and thereby depletes BM cells, hence allowing BM substitution without other preconditioning and circumventing the critical issues of irradiation mentioned above 24 .…”

“…8A ). In adult Mx1 Cre c-myb flox/flox ; CD45.2 mice conditional activation of the Mx1 promoter is achieved by application of poly(I:C) resulting in the depletion of c-myb -dependent BM precursors 24 . Transplantation of CD45.1 BM resulted in high chimerism in blood monocytes (Supplementary Fig.…”

“…The Mx1 Cre mouse strain carrying an interferon inducible Cre-cassette 58 , was used to conditionally delete the floxed Myb gene in adult Myb flox/flox mice. Depletion was performed as previously described 9 , 24 . To substitute for the depletion of hematopoietic cells, mice were transplanted with 1 × 10 6 CD45.1 Myb +/+ BM cells at 24 h after the last of four poly(I:C) injections.…”

The Kidney Contains Ontogenetically Distinct Dendritic Cell and Macrophage Subtypes throughout Development That Differ in Their Inflammatory Properties

“…injections of polyinosinic-polycytidylic acid (polyI:C) every other day at a dose of 10 mg/g body wt. 44 Mice were then transplanted with 1310 7 CD45.1 + congenic wild-type bone marrow cells. At 3 and 9 months after bone marrow transplantation, mice were euthanized, and kidney and liver were analyzed by flow cytometry.…”

“…To this end, CD45.2 + Mx-1 Cre Myb flox/flox mice were treated with polyI:C, which leads to a rapid loss of HSCs and their progeny that can be rescued without further preconditioning by transfer of congenic CD45.1 + bone marrow. 12,44 Three months after bone marrow rescue, chimeras were analyzed for bone marrow contribution to kidney MP subsets (Figure 5B). As expected, because of their HSC origin, cDCs were completely donor derived (Figure 5B).…”