Analyzing cell fusion events within the central nervous system using bone marrow chimerism.

It has emerged that cells which typically reside in the bone marrow have the capacity to cross the blood brain barrier and contribute genetic material to a range of neuronal cell types within the central nervous system. One such mechanism to account for this phenomenon is cellular fusion, occurring between migrating bone marrow-derived stem cells and neuronal cells in-situ. Biologically, the significance as to why cells from distinct lineages fuse with cells of the central nervous system is, as yet, unclear. Growing evidence however suggests that these cell fusion events could provide an efficient means of rescuing the highly complex and differentiated neuronal cell types that cannot be replaced in adulthood. To facilitate further understanding of cell fusion within the central nervous system, we describe here a technique to establish chimeric mice that are stably reconstituted with green fluorescent protein expressing sex-mismatched bone marrow. These chimeric mice are known to represent an excellent model for studying bone marrow cell migration and infiltration throughout the body, while in parallel, as will be described here, also provide a means to neatly analyze both bone marrow-derived cell fusion and trans-differentiation events within the central nervous system.