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Mitochondrial DNA sequence heterogeneity in circulating normal human CD34 cells and granulocytes
Myung Geun Shin1, Sachiko Kajigaya, Magdalena Tarnowka
1Hematology Branch and Flow Cytometry Core Facility, National Heart, Lung and Blood Institute, National Institutes of Health, Bldg 10, Rm 7C103, 9000 Rockville Pike, Bethesda, MD 20892-1652, USA.
Blood
|March 16, 2004
Summary
Mitochondrial DNA (mtDNA) mutations accumulate with age and expand clonally in hematopoietic stem cells. Peripheral blood analysis of mtDNA heterogeneity can track these mutations, serving as a biomarker for mutagen exposure and disease.
Area of Science:
- Cellular and Molecular Biology
- Genetics
- Hematology
Background:
- Mitochondrial DNA (mtDNA) sequence heterogeneity has been observed in individual CD34+ clones from adult bone marrow (BM).
- Age-dependent accumulation of mtDNA mutations occurs in mitotically active tissues like bone marrow.
Purpose of the Study:
- To provide direct evidence of clonal expansion of cells containing mtDNA mutations.
- To establish peripheral blood (PB) as a viable source for determining mtDNA sequences in CD34+ cells.
- To explore the utility of mtDNA as a biomarker for mutagen exposure and disease detection.
Main Methods:
- Analysis of 594 circulating CD34+ clones for mtDNA sequence heterogeneity.
- Examination of single granulocytes from six individuals to assess mtDNA heterogeneity.
- Comparison of mtDNA sequences between circulating CD34+ cells, bone marrow CD34+ cells, and their progeny granulocytes.
Main Results:
- 25% of circulating CD34+ clones exhibited mtDNA sequences different from the donor's aggregate sequence.
- 29% of single granulocytes showed mtDNA heterogeneity compared to aggregate tissue sequences.
- Circulating and BM CD34+ cells displayed similar patterns of mtDNA heterogeneity, with changes reflected in progeny granulocytes.
Conclusions:
- Peripheral blood sampling is effective for studying mtDNA heterogeneity in hematopoietic stem cells.
- mtDNA sequence analysis can serve as a marker for cumulative or recent mutagen exposure.
- mtDNA analysis holds potential for tracking hematopoietic progenitor/stem cell expansion and detecting minimal residual disease in hematologic malignancies.