Bone marrow-derived cells contribute to cerulein-induced pancreatic fibrosis in the mouse

Bone marrow (BM) cells may transdifferentiate into circulating fibrocytes and myofibroblasts in organ fibrosis. In this study, we investigated the contribution and functional roles of BM-derived cells in murine cerulein-induced pancreatic fibrosis. C57/BL6 female mice wild-type (WT) or Col 1α1 ^r/r male BM transplant, received supraphysiological doses of cerulein to induce pancreatic fibrosis. The CD45 ⁺Col 1 ⁺ fibrocytes isolated from peripheral blood (PB) and pancreatic tissue were examined by in situ hybridization for Y chromosome detection. The number of BM-derived myofibroblasts, the degree of Sirius red staining and the levels of Col 1α1 mRNA were quantified. The Y chromosome was detected in the nuclei of PB CD45 ⁺Col 1 ⁺ fibrocytes, confirming that circulating fibrocytes can be derived from BM. Co-expression of α-smooth muscle actin illustrated that fibrocytes can differentiate into myofibroblasts. The number of BM-derived myofibroblasts, degree of collagen deposition and pro-collagen I mRNA expression were higher in the mice that received Col 1α1 ^r/r BM, (cells that produce mutated, collagenase-resistant collagen) compared to WT BM, indicating that the genotype of BM cells can alter the degree of pancreatic fibrosis. Our data indicate that CD45 ⁺Col 1 ⁺ fibrocytes in the PB can be BM-derived, functionally contributing to cerulein-induced pancreatic fibrosis in mice by differentiating into myofibroblasts.