Abstract

Small cell volume or diameter (3–7μm) appears to be one of the characteristics that may be used to identify early stem cells. Hematopoietic stem cells may be characterized by the expression of cell surface markers such as CD34, CD117 and CD133. In addition, stem cells such as “SP cells” can be recognized by the efflux of dyes such as Hoechst 33342 and presence of aldehyde dehydrogenase (ALDH). In prior studies we used the Beckman Coulter® Cell Lab Quanta() SC MPL analyzer to determine the electronic cell volume, diameter and marker expression (CD34, CD90, CD117 and CD133) of cells from peripheral blood apheresis (HPC, Apheresis) samples (

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). In the present study, we used this analyzer to determine cell volume, diameter and marker expression of ALDHpositive stem cells from HPC, Apheresis samples of 44 patients with hematologic malignancies mobilized with granulocyte colony-stimulating factor. The mean electronic volume of the ALDHpositive cells was 286μm3 (SD±27) corresponding to a diameter of 8.2μm. The mean percentage of ALDHpositive cells analyzed was 0.51% (SD± 0.004). CD34 expression was seen in 0.13% (SD±0.001) of the ALDHpositive cells. The mean electronic volume of the ALDH and CD34 positive cells was 270μm3 (SD± 33) corresponding to a diameter of 8.0μm. CD133, CD117 and CD90 expression was seen in 0.28% (SD± 0.01), 0.17 (SD± 0.05) and 0.04% (SD± 0.03) of the ALDHpositive cells. The mean electronic volume of the ALDHpositive cells with CD133 expression was 275μm3 (SD±29) corresponding to a diameter of 8.1μm while that of the ALDHpositive cells with CD117 and CD90 expression was 284μm3 (SD± 32) and 265μm3 (SD± 35), corresponding to a diameter of 8.15 and 7.9μm.

Stem Cell Marker Electronic Volume (μm3Diameter (μm) 
CD90 (Thy-1) 300μm3 (SD± 38.5) 8.3μm (95% CI=8.1–8.4) 
CD117 (c-Kit) 349μm 3 (SD± 47.4) 8.7μm (95% CI=8.5–8.8) 
CD133 (Sca-1) 322μm3 (SD± 44.5) 8.5μm (95 % CI= 8.3–8.6) 
ALDH+ 286μm3 (SD± 27.0) 8.2μm (95 % CI= 8.1–8.3) 
ALDH+CD34+ 270μm3 (SD± 33.0) 8.0μm (95 % CI= 7.8–8.2) 
ALDH+ CD90+ 265μm3 (SD± 35.0) 7.9μm (95 % CI= 7.8–8.1) 
ALDH +CD117+ 284μm 3 (SD± 32.0) 8.15μm (95 % CI= 7.9–8.2) 
ALDH +CD133+ 275μm3 (SD± 29.0) 8.1μm (95 % CI= 8.0–8.3) 
Stem Cell Marker Electronic Volume (μm3Diameter (μm) 
CD90 (Thy-1) 300μm3 (SD± 38.5) 8.3μm (95% CI=8.1–8.4) 
CD117 (c-Kit) 349μm 3 (SD± 47.4) 8.7μm (95% CI=8.5–8.8) 
CD133 (Sca-1) 322μm3 (SD± 44.5) 8.5μm (95 % CI= 8.3–8.6) 
ALDH+ 286μm3 (SD± 27.0) 8.2μm (95 % CI= 8.1–8.3) 
ALDH+CD34+ 270μm3 (SD± 33.0) 8.0μm (95 % CI= 7.8–8.2) 
ALDH+ CD90+ 265μm3 (SD± 35.0) 7.9μm (95 % CI= 7.8–8.1) 
ALDH +CD117+ 284μm 3 (SD± 32.0) 8.15μm (95 % CI= 7.9–8.2) 
ALDH +CD133+ 275μm3 (SD± 29.0) 8.1μm (95 % CI= 8.0–8.3) 

The use of electronic cell volume in conjunction with side scatter might provide a useful method for characterization of stem/progenitor cell populations with specific marker expression. In our study, hematopoietic stem cells expressing ALDH and bearing early stem cell markers were relatively larger than those previously reported. Future studies will aim to characterize the long term repopulating capability of this fraction of stem cells in in-vivo models.

Disclosures: No relevant conflicts of interest to declare.

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