The Response of Fibrocytes to Targeted Thoracic and Forelimb Bone Marrow Radiation Exposure
Uniformed Services University of the Health Sciences Bethesda United States
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Fibrocytes have recently stepped out from underneath the shadow of fibrotic diseases. The unique cells that are characterized by their expression of both hematopoietic and mesenchymal cell markers are becoming increasingly recognized in the context of non-fibrotic diseases. Fibrocytes have been shown to aid and abet metastatic tumors evade the host immune system as well as participate in the development of Graves disease. However, there is still a long list of maladies that have yet to be examined under the lens of fibrocytes, including radiation-induced bone marrow injury. We developed a model of thoracic and partial bone marrow irradiation by selectively exposing the thoracic cavity and humeri of mice to various doses of radiation. 14Gy irradiation effectively depleted exposed bone marrow at 60 days post irradiation. We used this model to study the response of fibrocytes to partial bone marrow irradiation-induced injury. We quantified the number and relative collagen expression of fibrocytes and CD45ColI cells isolated from peripheral blood mononuclear cells PBMC, the spleen, and shielded bone marrow using flow cytometry. Circulating PBMC and splenic fibrocyte levels peaked 30 days post irradiation. The number of fibrocytes in the spleen drastically decreased soon after irradiation. Additionally, in all tissues the relative collagen expression of fibrocytes was highest at the earlier time points post irradiation. These data demonstrate that fibrocytes respond to thoracic and partial bone marrow irradiation, and that this response is temporally mediated and tissue specific.
- Medicine and Medical Research