MadSci Network: Immunology
Query:

Re: can you die from not enough bone marrow?

Date: Mon Aug 20 18:00:48 2007
Posted By: Cenk Sumen, Post-doc/Fellow, Immunology, Memorial Sloan-Kettering Cancer Center
Area of science: Immunology
ID: 1178423518.Im
Message:

Yes, we can die from lack of bone marrow. The cells that are housed in the stromal niches in the bone marrow are required for proper function of a human (or other mammal). These include stem cells and other progenitors, such as CLPs (common lymphoid progenitors) that give rise to T and B cells among others. If these cells are damaged, for example through radiation therapy, then the bone marrow needs to be re-seeded with an appropriate number of stem cells to restore full function of the blood system. The bone marrow also serves as a secondary lymphoid organ in its own right, housing antigen-specific T cells and B cells that make antibody for an optimal immune response. An interesting corollary is the question "What if bones were solid and didn't have soft cores where cells can live? Where would these stem cells go then?" We don't have a clear answer, but a mouse mutant overexpressing a factor called OPG (osteoprotegerin) does indeed have solid bones which are otherwise similar in size and shape, due to a block in bone resorption. Curiously, these mice also show splenomegaly (enlarged spleen), and an analysis of the spleen shows that increased numbers of stem cells and progenitors can indeed be found there (Simonet et al. Cell 89, 1997, p.309). Perhaps there are other alternative locations in the body where stem cells can be housed, but evolution has clearly favored the insides of bones where these fragile and precious cells can be protected from DNA-damaging radiation and other hazards from the environment.

Reference:
Simonet WS, Lacey DL, Dunstan CR, Kelley M, Chang MS, Luthy R, Nguyen HQ, Wooden S, Bennett L, Boone T, Shimamoto G, DeRose M, Elliott R, Colombero A, Tan HL, Trail G, Sullivan J, Davy E, Bucay N, Renshaw-Gegg L, Hughes TM, Hill D, Pattison W, Campbell P, Sander S, Van G, Tarpley J, Derby P, Lee R, Boyle WJ. (1997) Osteoprotegerin: a novel secreted protein involved in the regulation of bone density. Cell. 89(2):309-19.


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