title: Direct contact with stroma inhibits proliferation of human long-term culture initiating cells.
abstract: Significantly less long-term culture initiating cells (LTC-IC) are recovered from cultures in which progenitors are cultured in contact with stroma (stroma-contact) than when cultured separated from stroma by a transwell (stroma-noncontact). This suggests that direct contact with stroma inhibits either proliferation or survival of LTC-IC. Using the membrane intercallating fluorochrome, PKH-26, we demonstrated that significantly less LTC-IC plated for 14 days in stroma-contact cultures proliferated than in stroma-noncontact cultures (16+/-7 vs 50+/-10%). Furthermore, when LTC-IC were sorted singly in stroma-contact cultures for 2 weeks, only 25+/-4% of individual LTC-IC progeny could initiate two secondary stromal cultures and had therefore proliferated, whereas 45+/-6% of single sorted LTC-IC progeny proliferated when cultured in stroma-conditioned medium without stromal feeder. However, LTC-IC survival was similar in both culture systems. Finally, proliferation inhibition occurred even when LTC-IC were cultured in contact with glutaraldehyde-fixed stroma, which is no longer capable of producing growth inhibitory or stimulatory cytokines. Thus, direct adhesive interactions between LTC-IC and stromal components inhibits their proliferation.
authors.affiliation: Department of Medicine, University of Minnesota, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Verfaillie
authors.forename: P
authors.initials: P
authors.lastname: Catanzaro
mesh_terms: D001854:Bone Marrow Cells; D002448:Cell Adhesion; D002455:Cell Division; D002470:Cell Survival; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D009930:Organic Chemicals; D017154:Stromal Cells / Q000166:cytology; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D009930:Organic Chemicals; C070080:PKH 26