Application of the 3R principles: Vertebrae as an additional source of murine bone-marrow cells

Experimental murine models are an essential tool in the field of bone marrow (BM) transplantation research. Therefore, numerous mice are required to obtain a sufficient number of BM cells, which is in contrast with the Reduction principle of the 3R principles. The selection of the cell source and the isolation protocol are therefore critical in obtaining a sufficient yield of cells for experiments. Nowadays, the vertebrae are already used as an extra source of BM cells to enrich the number of isolated cells from the long bones and ilia (LBI), when needed. Yet, little is known if BM cells from LBI and vertebrae share the same characteristics and can be pooled together for further analysis. Therefore, in this study, we aimed to compare the quantity and characteristics of haematopoietic and stromal cell lines in the BM from the LBI and vertebrae. To count haematopoietic and mesenchymal stem/stromal progenitors, colony-forming unit assays were performed. To determine the expansion capacity of mesenchymal stem/stromal cells (MSCs), cultivation of MSCs and measurement of the expression of surface markers by flow cytometry was performed. The characterisation and enumeration of immune cell populations was also performed by flow cytometry. Here, we show that the vertebrae are a comparable source of BM cells to the LBI regarding the analysed parameters.