Hematopoietic differentiation of umbilical cord blood-derived very small embryonic/epiblast-like stem cells

Abstract

A population of CD133+lin−CD45− very small embryonic-like stem cells (VSELs) has been purified by multiparameter sorting from umbilical cord blood (UCB). In order to speed up isolation of these cells, we employed anti-CD133-conjugated paramagnetic beads followed by staining with Aldefluor to detect aldehyde dehydrogenase (ALDH) activity; we subsequently sorted CD45−/GlyA−/CD133+/ALDHhigh and CD45−/GlyA−/CD133+/ALDHlow cells, which are enriched for VSELs, and CD45+/GlyA−/CD133+/ALDHhigh and CD45+/GlyA−/CD133+/ALDHlow cells, which are enriched for hematopoietic stem/progenitor cells (HSPCs). While freshly isolated CD45− VSELs did not grow hematopoietic colonies, the same cells, when activated/expanded over OP9 stromal support, acquired hematopoietic potential and grew colonies composed of CD45+ hematopoietic cells in methylcellulose cultures. We also observed that CD45−/GlyA−/CD133+/ALDHhigh VSELs grew colonies earlier than CD45−/GlyA−/CD133+/ALDHlow VSELs, which suggests that the latter cells need more time to acquire hematopoietic commitment. In support of this possibility, real-time PCR analysis confirmed that, while freshly isolated CD45−/GlyA−/CD133+/ALDHhigh VSELs express more hematopoietic transcripts (e.g., c-myb), CD45−/GlyA−/CD133+/ALDHlow VSELs exhibit higher levels of pluripotent stem cell markers (e.g., Oct-4). More importantly, hematopoietic cells derived from VSELs that were co-cultured over OP9 support were able to establish human lympho-hematopoietic chimerism in lethally irradiated NOD/SCID mice 4–6 weeks after transplantation. Overall, our data suggest that UCB-VSELs correspond to the most primitive population of HSPCs in UCB.

Pluripotent Stem Cells in Bone Marrow and Cord Blood

“…VSELs-derived HSCs harvested from these co-cultures reconstitute murine bone marrow after total body irradiation [43]. The Umbilical Cord Blood (UCB)-purified VSELs have also been reported to differentiate into neural cells [44] and after co-culture over OP-9 stroma cells were specified into HSCs similar to murine BM-derived VSELs [45]. Apart from umbilical cord blood and bone marrow, VSELs have also been reported in Wharton's jelly and gonadal tissue [46][47][48][49][50][51].…”

Potentiality of Very Small Embryonic-Like Stem Cells to Repair Myocardial Infarction

“…VSELs were also identified in neonatal retina and involved in optic nerve retinal regeneration in a rodent model [34]. VSELs may also play a major role as populations of cells that preferentially give rise to induced pluripotent stem cells (iPSCs) when BM-derived stromal cells are induced to pluripotency by genetic manipulation [35].In particular, VSELs derived by parthenogenesis have also been identified successfully [36].…”

“…Further study demonstrated that VSELs can not primarily reveal hematopoietic ability immediately from isolation and expansion, but may eventually acquire hematopoietic potential following co-culture in hematopoiesis permissive environment over OP9 stroma feeder layer and reconstitute hematopoiesis in lethally irradiated mice 4-6 weeks after transplantation [26].…”

Novel view of the adult stem cell compartment – of germline and parental imprinting

“…VSELs fulfill the above-listed in vitro criteria, despite the fact that they are highly quiescent in culture, and special conditions are needed to differentiate them into various lineages [61,62,[74][75][76][77][78][79][80]. However, VSELs do not fulfill the in vivo criteria, as they do not complete blastocyst development and do not grow teratomas [25,81].…”