Purpose: Bone marrow (BM)-derived stem cells are thought to possess extensive differentiation capacity. The present study was conducted to investigate the characteristics and distribution of these cells in the normal mouse cornea.
Methods: BM cells and BM-derived hematopoietic stem/progenitor cells (HSCs) from enhanced GFP (eGFP) transgenic mice (lin(-), Sca-1(+)) were intravenously transplanted into irradiated wild-type C57BL/6 mice. At 4 to 6 months after transplantation, the mice were killed, and their whole corneas examined by histologic and immunohistochemical methods (CD11c, CD11b, and CD45).
Results: At 2 weeks after BM cell transplantation, GFP(+) cells gradually migrated into the cornea from the limbal area. At 2 to 6 months, they were distributed over the entire cornea. In cross sections of whole cornea, GFP(+) cells comprised 27.3% +/- 11.1% (BM) and 24.0% +/- 8.01% (HSC) of total cells in the peripheral corneal stroma. In the center of the corneal stroma, GFP(+) cells were 7.58% +/- 2.63% (BM) and 8.06% +/- 1.76% (HSC) of total cells. Immunohistochemistry showed that GFP(+) CD11c(+), CD11b(+), CD11c(-), and CD11b(-) cells occupied the entire corneal stroma.
Conclusions: The present study provides direct evidence of the distribution of BM-derived cells in the mouse cornea. Immunohistochemical study showed that some of these cells are BM-derived antigen-presenting cells such as dendritic cells and macrophages. Some elements of BM-derived cells may continue to exist in the corneal stroma.