Bone marrow stromal dysfunction in mice administered cytosine arabinoside.
OBJECTIVE
The aim of the study was to investigate ex-vivo the bone marrow (BM) stroma of mice under conditions of low- and high-dose cytosine arabinoside (Ara-C), a cycle-specific drug (S-phase) and to assess possible stromal damage, apart from the killing of hematopoietic cells. Stroma consists of mesenchymal elements generally not in the cell cycle; therefore it could not be a target for the killing effect of Ara- C.


METHODS
The stromal function was studied by the following: the incidence of stromal stem cells, i.e. CFU-F; formation of stromal layers under growth conditions of long-term culture (LTC) followed by irradiation and overlayering of test cells in contact and non-contact co-cultures; subsequent culture of the test cells in a semi-solid medium to assay the incidence of hyperproliferative potential cells (HPPC); production of GM-CSF, IL-3, IL-4, IL-6 and IFNgamma in the conditioned medium (CM) of confluent stromal layers. All tests and assays were carried out on BM specimens, 1-4 d after Ara-C administration and on controls.


RESULTS
Low-dose Ara-C induces a marked decrease of CFU-F, compensated by cycle induction of pre-CFU-F, young-type stromal stem cells. High-dose Ara-C causes a CFU-F decrease to almost zero level. The time length to layer confluency is normal after low-dose Ara-C ( approximately 10 d) and prolonged after a high dose ( approximately 30 d). The confluent layers from mice receiving low- or high-dose Ara-C support hematopoiesis adequately. Among the growth factors and cytokines assayed, only IL-6 is detected in CM layers. IL-6 decreases after a low dose of Ara-C and increases after a high dose. The cause of IL-6 fluctuations is yet to be investigated. It is, however, evident that IL-6 is not an essential factor in support of hematopoiesis.


CONCLUSIONS
Taken together, the current study in mice indicates that Ara-C administration, in particular a high dose, induces bone marrow stromal damage and/or disfunction. The long period of time to reach layer confluency after a high Ara-C dose might reflect the in-vivo situation of slow stromal regeneration.
Ben-Ishay
Z
Z
Department of Anatomy and Cell Biology, Hebrew University Hadassah Medical School and Immunology Laboratory for Tumor Diagnosis, Oncology Department, Hadassah Medical Center, Jerusalem, Israel.
Barak
V
V
D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D002455:Cell Division / Q000502:physiology; D018920:Coculture Techniques; D003114:Colony-Forming Units Assay; D003561:Cytarabine / Q000008:administration & dosage / Q000494:pharmacology*; D016207:Cytokines / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology; D006133:Growth Substances / Q000378:metabolism; D006410:Hematopoiesis / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013234:Stem Cells / Q000187:drug effects; D017154:Stromal Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
D016207:Cytokines; D006133:Growth Substances; D003561:Cytarabine