Stem Cell Factor (SCF) is a potent hematopoietic growth factor that mediates recruitment, survival and differentiation of inflammatory progenitor cells. SCF exists both in a membrane-bound form and as a soluble mediator and acts through binding to the c-kit tyrosine kinase receptor present on target cells. Bone marrow stromal cells, fibroblasts, osteoblasts and gingival fibroblasts produce both isoforms. The presence of SCF in the dental pulp has not been explored. Objectives: The purpose of this study is to determine whether primary cultures of human dental pulp cells produce SCF and to explore patterns of SCF expression. Methods: Non-erupted human teeth extracted for clinical reasons were obtained and the pulp was aseptically removed, minced and placed in tissue culture medium containing a-MEM, 2mM l-glutamine, 10% fetal calf serum and 100 IU/ml of penicillin/streptomycin. After 2 weeks, adherent cells were trypsinized and passaged in a T-75 flask. Medium was changed every three days. After passage 4, the cells were seeded in six-well plates. Supernatants and cellular protein lysates were collected from replicate dishes at different timepoints during culture and cell counts were also performed at the time of each collection. Supernatants were analyzed by ELISA to detect the presence of soluble SCF, and protein lysates were analyzed by Western Blotting to determine cell-associated SCF. Three different primary cultures of human dental pulp were assayed. Results: Primary cultures of human dental pulp cells produce soluble and cell-associated SCF. The production of soluble SCF appears to increase as the culture ages. Conclusions: This study constitutes the first reported evidence that primary cultures of stromal cells isolated from human dental pulp produce SCF and provides us with a model in which to explore the role of this novel mediator in human pulp biology.

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