Splenic stromal niches support hematopoiesis of dendritic-like cells from precursors in bone marrow and spleen
Received 14 May 2009; received in revised form 2 June 2009; accepted 9 June 2009. published online 18 June 2009.
Objective
The aims of this study are to test the ability of stromal cells from murine spleen to support hematopoiesis, to define the tissue source of precursors that seed these hematopoietic niches, and to determine the type of cells produced.
Materials and Methods
Cloned isolates of murine spleen stroma have been developed that support hematopoiesis. Analysis has been investigated in terms of tissue source of progenitors. Type and number of cells produced were analyzed by flow cytometry.
Results
Hematopoietic precursors that seed cocultures exist in spleen and bone marrow (BM), but not thymus. Cell production is highest if overlay cells are enriched for hematopoietic precursors. BM contains more precursors than spleen, but the cell types produced are different. Cocultures established from spleen maintain a high proportion of a distinct class of dendritic-like cells produced in only low numbers in BM cocultures. These reflect the immature myeloid dendritic cell (DC) produced continuously in long-term spleen cultures established previously in this laboratory. Stroma-conditioned medium alone does not support DC development, but does support early outgrowth of myelomonocytic cells from precursors in both spleen and BM.
Conclusion
The outcome has been development of a coculture system that supports hematopoiesis of immature myeloid dendritic-like cells in vitro. Although production of monocytes can occur in the presence of stroma-conditioned medium alone, production of DC is dependent on stromal cell interaction. Results presented here raise questions about the role of spleen as a site for DC hematopoiesis from endogenous precursors.
Research School of Biology, The Australian National University, Canberra, Australia
Offprint requests to: Helen C. O'Neill, Ph.D., Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
ABSTRACT