Hematopoietic stem cells: can old cells learn new tricks?

Abstract

Since the establishment of cell lines derived from human embryonic stem (ES) cells, it has been speculated that out of such "raw material," we could some day produce all sorts of replacement parts for the human body. Human pluripotent stem cells can be isolated from embryonic, fetal, or adult tissues. Enormous self-renewal capacity and developmental potential are the characteristics of ES cells. Somatic stem cells, especially those derived from hematopoietic tissues, have also been reported to exhibit developmental potential heretofore not considered possible. The initial evidences for the plasticity potential of somatic stem cells were so encouraging that the opponents of ES cell research used them as arguments for restricting ES cell research. In the past months, however, critical issues have been raised challenging the validity and the interpretation of the initial data. Whereas hematopoietic stem-cell therapy has been a clinical reality for almost 40 years, there is still a long way to go in basic research before novel therapy strategies with stem cells as replacement for other organ systems can be established. Given the present status, we should keep all options open for research in ES cells and adult stem cells to appreciate the complexity of their differentiation pathways and the relative merits of various types of stem cells for regenerative medicine.

Biomimetic Three-Dimensional Cultures Significantly Increase Hematopoietic Differentiation Efficacy of Embryonic Stem Cells

“…[7][8][9][10] Use of ES cells could provide new directions in tissue regeneration by creating multiple tissue types and organized organ structures inside a single scaffold (i.e., hybrid tissues). [11][12][13] In addition, direct transplantation of stem cells (bone marrow transplants) and stem cell-derived cell lineages has proven successful in a variety of complex disorders. The ultimate clinical applicability of stem cell-based therapeutics and tissue engineering requires a fundamental understanding of their behavior under 3D biomimetic conditions and the development of efficient technologies for high-throughput production of progenitors and therapeutic cells suitable for on-demand transplantation.…”

Molecular evidence for stem cell function of the slow-dividing fraction among human hematopoietic progenitor cells by genome-wide analysis

“…Using hematopoietic stem cells (HSCs) as a model, these characteristics have been used to define stem cells for over 40 years, but the knowledge of the processes involved in regulating self-renewal versus differentiation is still only rudimentary. 1 Several surrogate markers and assay systems have been developed, but all in vitro systems have failed to definitively identify the ultimate HSCs. The CD34 ϩ / CD38 Ϫ immunophenotype seems to be associated with a primitive population in human bone marrow and cord blood.…”

Stem cells as a potential future treatment of pediatric intestinal disorders

“…The adult body has a limited number of somatic stem cells in certain tissues and organs25-27. These adult stem cells possess the ability to regenerate the tissue from which they are derived.…”