However, in doing so the chemotherapy, agents removes all your current defense against infection and so the real risk of this procedure is that you can have a lethal infection. This "cure of the week" in mice reports on a way of clearing out the stem cells from the bone marrow and allowing you to replace them.
This has prompted many MS websites to shout loud we can now do HSCT without chemotherapy agents and with no risk of infection so sign me up I see a load of you say.
So what is this wonder treatment?
Mast/stem cell growth factor receptor (SCFR), also known as proto-oncogene c-Kit or tyrosine-protein kinase Kit or CD117, is a receptor tyrosine kinase protein. Haematopoietic stem cells (HSC), multipotent progenitors (MPP), and common myeloid progenitors (CMP) express high levels of CD117. Common lymphoid progenitors (CLP) express low surface levels of CD117. CD117 also identifies the earliest thymocyte progenitors in the thymus. It is also a marker for mouse prostate stem cells. In addition, mast cells, melanocytes in the skin, and interstitial cells of Cajal in the digestive tract express CD117.
CD117 is a
cytokine receptor expressed on the surface of
haematopoietic stem cells as well as other cell types. CD117 is a
receptor tyrosine kinase type III, which binds to
stem cell factor (a substance that causes certain types of cells to grow), also known as "steel factor" or "c-kit ligand". When this receptor binds to
stem cell factor (SCF) it forms a
dimer that activates its intrinsic tyrosine kinase activity, that in turn phosphorylates and activates signal transduction molecules that propagate the signal in the cell. Signalling through CD117 plays a role in cell survival, proliferation, and differentiation.
Importantly, in this context Haematopoietic progenitor cells are normally present in the blood at low levels. Mobilization is the process by which progenitors are made to migrate from the bone marrow into the bloodstream, thus increasing their numbers in the blood. Mobilization is used clinically as a source of haematopoietic stem cells for
haematopoietic stem cell therapy (HSCT). Signaling through CD117 has been implicated in mobilization. At the current time,
G-CSF is the main drug used for mobilization . G-CSF indirectly activates CD117. Another drug that does this is
cyclophosphamide which is a chemotherapy agent (but there are others) that makes your hair fall out.
The stem cells can be removed by macrophages and this function was enhanced by adding another antibody targeting CD47.
CD47 (Cluster of Differentiation 47) is