Background: In the field of stem cells (SCs) biology there is great need for a universal marker that can effectively identify the rare populations of SCs in order to characterize and isolate them for research and therapeutic purposes. In line with this idea, the measurement of aldehyde dehydrogenase (ALDH) activity shows promising potential as a common marker for the identification of SCs. Recently discovered very small embryonic-like stem cells (VSEL SCs) have a pluripotent nature and high long-term repopulating hematopoietic potential. The aim of the present study was to determine whether VSEL SCs isolated from umbilical cord blood (CB) and different murine organs express high ALDH activity.
Material/Methods: To address this issue, 12 CB units were analyzed by employing flow cytometry to detect the following populations: (i) CXCR4+/Lin–/CD45–/ALDHhigh, (ii) CD34+/Lin–/CD45–/ALDHhigh and (iii) CD133+/Lin–/CD45–/ALDHhigh. Additionally, selected organs from 16 5-week-old female inbred C57BL/6J mice and 16 7-month-old female C57BL/6J mice were analyzed for detection of the following populations: (i) Sca-1+/Lin–/CD45– and (ii) Sca-1+/Lin–/CD45+. All these populations were assessed for ALDH activity.
Results: We found that CB contains VSEL SCs with high ALDH activity. We also observed that ALDHhigh cells constitute a modest percentage of VSEL SCs present in selected murine organs.
Conclusions: We demonstrated that CB and adult murine organs possess a subpopulation of ALDHhigh VSEL SCs. Above all, the observed high level of ALDH activity can be considered a functional marker of organ-derived pluripotent SCs and allows for simple, efficient isolation of cells with primitive features for their utility in targeted cell therapies.

Keywords: very small embryonic-like stem cells, aldehyde dehydrogenase, stem cell therapy, haematopoiesis, human umbilical cord blood, biomarkers and biomolecules