Developmental Potential of Hematopoietic and Neural Stem Cells: Unique or All the Same?

Abstract

Like many other animals, mammals develop from fertilized oocytes – the ultimate stem cells. As embryogenesis proceeds, most cells lose developmental potential and eventually become restricted to a specific cell lineage. The result is the formation of a complete and structured mature organism with complex organs composed of a great variety of mature, mostly mitotically quiescent effector cells. However, along the way, some exceptional cells, known as somatic stem cells (SSCs) are set aside and maintain a high proliferation and tissue-specific differentiation potential. SSCs, in contrast to embryonic stem (ES) cells, which are able to give rise to all cell types of the body, have been regarded as being more limited in their differentiation potential in the sense that they were thought to be committed exclusively to their tissue of origin. However, recent studies have demonstrated that somatic stem cells from a given tissue can also contribute to heterologous tissues and thus show a broad nontissue restricted differentiation potential. The question arises: how plastic are somatic stem cells? To provide a tentative answer, we describe and review here recent investigations into the developmental potentials of two somatic stem cell types, namely hematopoietic and neural stem cells.

Plasticity of hematopoietic stem cells and cellular memory

“…Limiting dilution analysis of Lin – , Sca‐1 + , c‐kit + cells has shown that this cell population is capable of long‐term and multilineage hematopoietic reconstitution of lethally irradiated mice (25). Our own experiments revealed that 20 cells with the lin – , c‐kit + Sca‐1 + phenotype are sufficient to repopulate the hematopoietic system of lethally irradiated mice recipients (32).…”

Chimaerism and erythroid marker expression after microinjection of human acute myeloid leukaemia cells into murine blastocysts

“…HSCs into 3.5-day-old murine blastocysts, chimaeric foetal and adult mice are generated (Geiger et al, 1998;Harder et al, 2002;Kirchhof et al, 2002 …”

Ist der klinische Einsatz von Stammzellen greifbar?

“…Es sind seltene Zellen mit einem hohen regenerativen Potenzial, die in vitro angereichert werden können [3]. Weniger als 20 isolierte hämatopoeti-sche Stammzellen können das komplette Blutsystem letal bestrahlter Tiere lebenslang repopulieren [4].…”