Intra-peritoneal transplantation for efficient and easy generation of experimental acute myeloid leukemia in mice

Abstract: Objective: There is an unmet need for novel therapies to treat acute myeloid leukemia (AML) and the associated relapse that involves leukemia stem cells (LSCs). An experimental AML rodent model to test therapies based on successfully transplanting these cells via retro-orbital injections in recipient mice is fraught with challenges. The aim of this study was to develop an easy, reliable, and consistent method to generate a robust murine model of AML using an intra-peritoneal route. Methods: Bone marrow cells were transduced with a retrovirus expressing human MLL-AF9 fusion oncoprotein. Efficiency of lineage negative (Lin-) and Lin-Sca-1+c-Kit+ (LSK) populations as donor LSCs in the development of primary AML was tested. We developed a new method to generate AML by intra-peritoneal injection and discuss the pros and cons of intra-peritoneal and retro-orbital injections in serial transplantations. Results: Both Lin- and LSK cells transduced with human MLL-AF9 virus engrafted well in the bone marrow and spleen of recipients, leading to a full-blown AML. Intra-peritoneal injection of donor cells established AML in recipients upon serial transplantation. Infiltration of AML cells was detected in the blood, bone marrow, spleen, and liver of recipients by flow cytometry, qPCR, and histological analyses. Conclusions: 1. Intra-peritoneal injection is an efficient method of AML induction using serial transplantation of donor cells. 2. Delayed homing to bone marrow, seen in intra-peritoneal injection that impedes the progression of AML, can be easily overcome by increasing the number of transplanted donor cells. 3. Increasing the number of transplanted donor cells can also help shorten the duration of onset of AML. 4. Sorting of LSK population within donor cells is not necessary in the generation of MLL-AF9-induced primary AML given that Lin- population are equally efficient as LSK donor cells in primary transplantation of AML in mice.