Mouse Bmi1 Lentivirus (CMV)

Responsible for transporting oxygen and exchanging carbon dioxide, red blood cells (RBCs) are essential for our health. As the population ages, the need for RBC transfusions is expected to increase, necessitating the need for alternative RBC sources to meet this need. Researchers previously discovered that RBCs derived from early mouse embryos can undergo extensive self-renewal in vitro for up to several months. To better understand the mechanisms regulating extensive RBC self-renewal, researchers analyzed global gene expression datasets of self-renewing and differentiating RBCs and revealed differential expression of Bmi-1. Bmi-1 overexpression confers extensive self-renewal capacity to adult bone marrow-derived self-renewing RBCs, which normally have limited proliferative potential. Importantly, Bmi-1 transduction did not interfere with the ability of extensively self-renewing erythrocytes (ESREs) to terminally mature in vitro or in vivo. Bmi-1-induced ESREs can be used to generate in vitro models of intrinsic erythrocyte diseases and ultimately serve as a source of cultured RBCs for transfusion therapy.

Here, researchers used a gain-of-function approach to determine whether Bmi-1 could extend the proliferative capacity of adult bone marrow-derived SREs, which normally proliferate for only 1-2 weeks ex vivo. Lentiviral transduction of mice with Bmi-1 resulted in extended proliferation of bone marrow-derived SREs grown in erythroid expansion medium. Adult SREs transduced with an empty lentiviral vector ceased proliferation within 2 weeks, consistent with their limited in vitro self-renewal capacity. In contrast, erythroid cells from 10 of 11 cultures of bone marrow-derived SREs transduced with Bmi-1 proliferated for at least 25 days (Figure 1A), and 3 cultures of Bmi-1-induced ESREs (iESREs) were maintained for more than 100 days (Figure 1B). iESREs were also generated from adult mice with an inherited hemolytic anemia caused by a deficiency in protein 4.1R, providing proof of principle that this experimental approach can be used to generate large numbers of mutant erythroblasts that can facilitate the study of red cell-intrinsic disorders.

Figure 1. Lentiviral transduction of mouse Bmi-1 led to prolonged proliferation of bone-marrow-derived SREs grown in erythroid expansion media. (Kim A R, et al., 2015)