Identification of stem cells from human umbilical cord blood with embryonic and hematopoietic characteristics

Towards stem-cell therapy in the endocrine pancreas

Many approaches of stem-cell therapy for the treatment of diabetes have been described. One is the application of stem cells for replacement of nonfunctional islet cells in the native endogenous pancreas; another one is the use of stem cells as an inexhaustible source for islet-cell transplantation. During recent years three types of stem cells have been investigated: embryonic stem cells, bone-marrow-derived stem cells and organ-bound stem cells. We discuss the advantages and limitations of these different cell types. The applicability for the treatment of dysfunction of beta cells in the pancreas has been demonstrated for all three cell types, but more-detailed understanding of the sequence of events during differentiation is required to produce fully functional insulin-producing cells.

Turning blood into beta cells - it's time for down-to-earth research

PURPOSE OF REVIEW

The recent findings in the field of blood or bone-marrow transdifferentiation into insulin-producing beta cells are summarized. Possible future goals in this exciting area of research are described.

RECENT FINDINGS

A number of recent studies examined the differentiation potential of bone marrow, peripheral blood, spleen or cord blood towards pancreatic beta cells, both in vivo and in vitro.

SUMMARY

The available in-vivo studies do not prove a physiological role of blood or bone marrow in the normal turnover, regeneration or repair of pancreatic islets. They rather argue against that notion. The in-vitro derivation of beta-like cells from blood or bone marrow has been reported by several groups. Nevertheless, there is still room for scepticism as robust and readily reproducible differentiation protocols are lacking and exhaustive analyses of bone marrow-derived beta-like cells have yet to be completed.

Cord blood in regenerative medicine: do we need immune suppression?

Cord blood is currently used as an alternative to bone marrow as a source of stem cells for hematopoietic reconstitution after ablation. It is also under intense preclinical investigation for a variety of indications ranging from stroke, to limb ischemia, to myocardial regeneration. A major drawback in the current use of cord blood is that substantial morbidity and mortality are associated with pre-transplant ablation of the recipient hematopoietic system. Here we raise the possibility that due to unique immunological properties of both the stem cell and non-stem cell components of cord blood, it may be possible to utilize allogeneic cells for regenerative applications without needing to fully compromise the recipient immune system. Issues raised will include: graft versus host potential, the immunogenicity of the cord blood graft, and the parallels between cord blood transplantation and fetal to maternal trafficking. The previous use of unmatched cord blood in absence of any immune ablation, as well as potential steps for widespread clinical implementation of allogeneic cord blood grafts will also be discussed.

Induction of human umbilical cord blood-derived stem cells with embryonic stem cell phenotypes into insulin producing islet-like structure

Success in islet-transplantation-based therapies for type I diabetes, coupled with a worldwide shortage of transplant-ready islets, has motivated efforts to develop renewable sources of islet-replacement tissue. Embryonic stem cells (ESCs) have been successfully induced into insulin producing islet-like structure in several studies. However, the source of the ESCs has presented ethical and technical concerns. Here, we isolated a population of stem cells from human cord blood (UCB), which expressed embryo stage specific maker, SSEA-4, and the multi-potential stem cell marker, Oct4. Subsequently, we successfully induced them into insulin-producing islet-like structures, which co-express insulin and C-peptide. These findings might have a significant potential to advance human UCB derived stem-cell-based therapeutics for diabetes.

Bone marrow-derived very small embryonic-like stem cells: Their developmental origin and biological significance

Data from our and other laboratories provide evidence that bone marrow (BM) contains a population of stem cells that expresses early developmental markers such as (1) stage-specific embryonic antigen (SSEA) and (2) transcription factors Oct-4 and Nanog. These are the markers characteristic for embryonic stem cells, epiblast stem cells, and primordial germ cells (PGC). The presence of these stem cells in adult BM supports the concept that this organ contains some population of pluripotent stem cells that is deposited in embryogenesis during early gastrulation. We hypothesize that these cells could be direct descendants of the germ lineage that, to pass genes on to the next generations, has to create soma and, thus, becomes a "mother lineage" for all somatic cell lineages present in the adult body. Germ potential is established after conception in totipotent zygotes and retained in blastomeres of morula, cells from the inner cell mass of blastocyst, epiblast, and population of PGC. We will present a concept that SSEA(+) Oct-4(+) Nanog(+) cells identified in BM could be descendants of epiblast cells as well as some rare migrating astray PGC.

Immune regulation of T lymphocyte by a newly characterized human umbilical cord blood stem cell

Previous work identified a novel type of stem cell from human umbilical cord blood, designated cord blood-stem cells (CB-SC). To further evaluate their immune characteristics, we cocultured CB-SC with allogeneic peripheral blood lymphocytes in the presence of phytohaemagglutinin (PHA) or interleukin-2 (IL-2). Results showed that CB-SC could significantly inhibit lymphocyte proliferation and reduce tyrosine phosphorylation of STAT5 in both PHA- and IL-2-stimulated lymphocytes, along with the regulation on the phenotypes of CD4+ and CD8+ T cells. Additionally, CB-SC also suppressed the proliferation of IL-2-stimulated CD4+CD25+ regulatory T cells. Mechanism studies revealed that programmed death receptor-1 ligand 1 (PD-L1) expressed on CB-SC membrane, together with a soluble factor nitric oxide (NO) released by PHA-stimulated CB-SC, not prostaglandin E2 (PGE2) and transforming growth factor-beta1 (TGF-beta1), mainly contributed to the T cell suppression induced by CB-SC, as demonstrated by blocking experiments with a nitric oxide synthase inhibitor (Nomega-nitro-l-arginine, l-NNA) and a neutralizing antibody to PD-L1. Our findings may advance our understanding of the immunobiology of stem cells and facilitate the therapeutic application of cord blood stem cells.

Establishing clonal cell lines with endothelial-like potential from CD9(hi), SSEA-1(-) cells in embryonic stem cell-derived embryoid bodies

Background

Differentiation of embryonic stem cells (ESCs) into specific cell types with minimal risk of teratoma formation could be efficiently directed by first reducing the differentiation potential of ESCs through the generation of clonal, self-renewing lineage-restricted stem cell lines. Efforts to isolate these stem cells are, however, mired in an impasse where the lack of purified lineage-restricted stem cells has hindered the identification of defining markers for these rare stem cells and, in turn, their isolation.

Methodology/Principal Findings

We describe here a method for the isolation of clonal lineage-restricted cell lines with endothelial potential from ESCs through a combination of empirical and rational evidence-based methods. Using an empirical protocol that we have previously developed to generate embryo-derived RoSH lines with endothelial potential, we first generated E-RoSH lines from mouse ESC-derived embryoid bodies (EBs). Despite originating from different mouse strains, RoSH and E- RoSH lines have similar gene expression profiles (r² = 0.93) while that between E-RoSH and ESCs was 0.83. In silico gene expression analysis predicted that like RoSH cells, E-RoSH cells have an increased propensity to differentiate into vasculature. Unlike their parental ESCs, E-RoSH cells did not form teratomas and differentiate efficiently into endothelial-like cells in vivo and in vitro. Gene expression and FACS analysis revealed that RoSH and E-RoSH cells are CD9^hi, SSEA-1⁻ while ESCs are CD9^lo, SSEA-1⁺. Isolation of CD9^hi, SSEA-1⁻ cells that constituted 1%–10% of EB-derived cultures generated an E-RoSH-like culture with an identical E-RoSH-like gene expression profile (r² = 0.95) and a propensity to differentiate into endothelial-like cells.

Conclusions

By combining empirical and rational evidence-based methods, we identified definitive selectable surface antigens for the isolation and propagation of lineage-restricted stem cells with endothelial-like potential from mouse ESCs.