Genomic and Proteomic Analysis of the Impact of Mitotic Quiescence on the Engraftment of Human CD34+ Cells

Abstract

It is well established that in adults, long-term repopulating hematopoietic stem cells (HSC) are mitotically quiescent cells that reside in specialized bone marrow (BM) niches that maintain the dormancy of HSC. Our laboratory demonstrated that the engraftment potential of human HSC (CD34+ cells) from BM and mobilized peripheral blood (MPB) is restricted to cells in the G0 phase of cell cycle but that in the case of umbilical cord blood (UCB) -derived CD34+ cells, cell cycle status is not a determining factor in the ability of these cells to engraft and sustain hematopoiesis. We used this distinct in vivo behavior of CD34+ cells from these tissues to identify genes associated with the engraftment potential of human HSC. CD34+ cells from BM, MPB, and UCB were fractionated into G0 and G1 phases of cell cycle and subjected in parallel to microarray and proteomic analyses. A total of 484 target genes were identified to be associated with engraftment potential of HSC. System biology modeling indicated that the top four signaling pathways associated with these genes are Integrin signaling, p53 signaling, cytotoxic T lymphocyte-mediated apoptosis, and Myc mediated apoptosis signaling. Our data suggest that a continuum of functions of hematopoietic cells directly associated with cell cycle progression may play a major role in governing the engraftment potential of stem cells. While proteomic analysis identified a total of 646 proteins in analyzed samples, a very limited overlap between genomic and proteomic data was observed. These data provide a new insight into the genetic control of engraftment of human HSC from distinct tissues and suggest that mitotic quiescence may not be the requisite characteristic of engrafting stem cells, but instead may be the physiologic status conducive to the expression of genetic elements favoring engraftment.

The nucleotide sugar UDP-glucose mobilizes long-term repopulating primitive hematopoietic cells

“…Functional characteristics of HSPCs, such as homing, engraftment, cell cycle status, and self-renewal activity vary according to their tissue of origin (14,48). For example, circulating blood stem cells can not compete effectively against bone marrow-derived stem cells for long-term multilineage repopulation (49).…”

No evidence of clonal dominance after transplant of HOXB4-expanded cord blood cells in a nonhuman primate model

“…More recent analysis of the genomic and proteomic variation in the mitotic state of CD34 + cells derived from bone marrow, peripheral blood, and cord blood has also indicated the unique nature of cord blood cells. Analysis of 484 target genes and 646 proteins [24] showed that engraftment potential of bone marrow or peripheral blood cells was only evident in the G0 phase of the cell cycle, whereas in cord blood, cell cycle status was not a limiting factor in engraftment potential. Research by Jin et al (2013) confirms that mesenchymal stromal cells derived from cord blood have significantly higher clonality (and lower expression of cell senescence markers) than those derived from bone marrow [25].…”

Bone Marrow, Peripheral Blood, or Umbilical Cord Blood: Does the Source of Allogeneic Hematopoietic Progenitor Cells Matter?

“…An example is the increasing use of new "mobilizing" agents such as plerixafor in addition to G-CSF, which leads to a higher content of more primitive progenitor cells in PB grafts [23]. Recent results suggest that genomic and proteomic analysis may become important, since mitotic quiescence and differential gene expression patterns appear to be significant for engraftment [24]. Further recent findings are that the genotype of Ig-like receptor on donor natural killer cells has impact on both immunity status and infections [25] and relapse-free survival after unrelated HPC transplantation for acute myeloid leukemia [26].…”