Stem cell transfer of mitochondria

The image depicts a specialised process of cellular communication between human mesenchymal stem cells (MSC) (labelled with red fluorescence, specific for mitochondrial labelling) and human macrophages (labelled with blue fluorescence). MSC are adult stem cells which can be easily isolated from bone marrow of adult patients or healthy volunteers and have been shown to be novel potential candidates for a cell-based therapy for conditions such as bacterial pneumonia and sepsis. Macrophages are host white blood cells that have a specialised function in regulating the immune response and killing bacteria during an infection. Past studies have shown that MSC can manipulate macrophage behaviour and this enables them to become less inflammatory whilst simultaneously kill bacteria more efficiently. But the mechanisms behind this process are still unclear. This image shows how MSC are able to transfer their mitochondria (the energy source of the cell) through formation of long tunnelling nanotubules (TNT) (also labelled red). These are long arm-like projections produced by MSC and extend from the plasma membrane. These protrusions can range from 50-200 ?m in length and MSC use these structures as a pathway to deliver cellular entities such as mitochondria to the macrophage (seen by the merging of blue and red creating the pink colour). This image illustrates the importance of how MSC could potentially alleviate debilitating symptoms of inflammatory conditions which are coupled with underlying bacterial infections.