Characterization of engraftable hematopoietic stem cells in murine long-term bone marrow cultures.
OBJECTIVE
Long-term bone marrow cultures (LTBMC) are a potential source of hematopoietic stem cells (HSC) for transplantation. Previous reports indicate that feeding LTBMCs induces hematopoietic progenitor cycling, and other studies link HSC cycle phase with engraftability. Our study was initiated to further characterize LTBMC engraftability and determine if a cycle phase-related engraftment defect affects HSC from LTBMCs.


METHODS
Competitive repopulation of lethally irradiated BALB/c females was used to examine engraftability of LTBMCs under "fed" or "unfed" conditions at 3 to 5 weeks culture. Tritiated thymidine suicide was used to determine the cycle status of HPP-CFC and CFU-S from LTBMCs.


RESULTS
Total cell number in LTBMCs decreases from input. Quantitatively, both fed and unfed 3-, 4-, or 5-week cultures compete strongly with fresh marrow for 2 and 8 weeks, but not 6 months, after transplantation. Short-term engraftable HSCs expand between 3 and 5 weeks of culture. Clonal assays indicate no peak in S-phase of CFU-S at 24 and 48 hours after feeding, and fluctuation in both content and cycle status of HPP-CFC after feeding.


CONCLUSIONS
Our LTBMCs engraft in all conditions, and the level of engraftment capability does not correlate with cell-cycle phase of CFU-S or HPP-CFC, or with time from feeding. Although the total cell number decreases from input, the proportion of short- and intermediate-term engrafting HSC in whole LTBMCs approximates that of fresh marrow and expands from 3 to 5 weeks in culture, whereas long-term engraftable HSCs are decreased in culture.
Frimberger
A E
AE
Cancer Center, University of Massachusetts Medical Center, Worcester, Mass, USA. afrimberger@hotmail.com
Stering
A I
AI
Quesenberry
P J
PJ
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D018929:Cell Culture Techniques / Q000379:methods; D002453:Cell Cycle; D002478:Cells, Cultured / Q000637:transplantation; D003470:Culture Media / Q000494:pharmacology; D005260:Female; D006085:Graft Survival; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011828:Radiation Chimera; D013997:Time Factors
D003470:Culture Media