Is it time to revisit our current hematopoietic progenitor cell quantification methods in the clinic?

Abstract

In the clinical practice of hematopoietic SCT, the minimum numbers of cells required for a successful engraftment are defined on the basis of their CD45 and CD34 expression profiles. However, the quantity of earlier progenitors or CD34-positive cells at different differentiation stages within stem cell grafts is not generally taken into consideration. During the last decade, various teams have quantified the number of cells expressing various combinations of CD34, CD38, CD133, CD90 co-expression and/or aldehyde dehydrogenase functional capacity using flow cytometry. Some of these studies resulted in the greater appreciation that combinations of these Ags were associated with varied myeloid, erythroid and platelet engraftment rates whereas others showed that the relative absence or presence of these markers could define cells responsible for either short-or long-term engraftment. These findings were also extended to differences between progenitor cell populations found within BM vs peripheral or cord-blood grafts. Cells harvested from donors are also generally frozen and stored; thawed cells have variable levels of viability and functional capacity based on the time tested post thaw, which also can be assessed by flow cytometry. Finally, flow cytometry has the potential for analysis of cells carrying a mesenchymal stem cell phenotype, which may be quiescent within some of the stem cell products. This review will address the need for stem cell subpopulation quantification and summarize existing published data to identify some Ags and functional characteristics that can be applicable to daily clinical practice.

Hematopoietic Stem/Progenitor Cells Express Myoglobin and Neuroglobin: Adaptation to Hypoxia or Prevention from Oxidative Stress?

“…S5). This subset of the cell population represents more primitive HSPCs endowed with higher clonogenic and long‐term hemopoietic recovery capacity . Most notably, although the whole cell content of Mb did not change in CD34‐related HSPCs subsets, nevertheless, a different intracellular distribution of the Mb‐related fluorescence was evident thereof.…”

Differential Expression of the Transcription Factor ARID3a in Lupus Patient Hematopoietic Progenitor Cells

“…Reported survival rates following transplant, range from 62%–84%, with relapse rates ranging from 32–66% (51–53). In most cases, transplantation uses total lineage negative CD34 + cells as a source of progenitors (reviewed in 54). Our data suggest that those progenitors may differ functionally based on numbers of cells that express ARID3a.…”

CD34+ cell subclasses and lymphocyte subsets in blood grafts collected after various mobilization methods in myeloma patients

“…However, more detailed characterization of CD34+ cells in stem cell grafts have become a keen point of interest. It has been stated that some of these characterizations should be implemented in clinical practice too 25 . Also various lymphocyte subsets in the graft may be of importance in terms of immunologic reconstitution as well as outcome of the patients 6 .…”