The Concept of Mesenchymal Stem Cells

Abstract

In this chapter we examine whether criteria usually defining adult tissue stem cells apply to mesenchymal stem cells (MSCs) that give rise to cells of the skeletal connective tissues. MSCs appear to constitute a heterogeneous population of undifferentiated and committed, lineage-primed cells, capable of: homing upon engraftment to a number of growth microenvironments, extensive proliferation, producing large numbers of differentiated progeny, and functional tissue repair after injury. In addition, MSCs are extensively distributed throughout tissues, and bone marrow MSCs provide the stromal component of the niche of hematopoietic stem cells. The capacity of apparently differentiated mesenchymal cells to shift their differentiation pathway with changing microenvironmental conditions (known as differentiation plasticity) may be due to de-differentiation and reprogramming in MSCs. Because they present several features setting them apart from other stem cells, MSCs may constitute another paradigm for stem cell systems, where self-renewal and hierarchy are no longer essential, but where plasticity is the major characteristic.

Gene expression during induced differentiation of sheep bone marrow mesenchymal stem cells into osteoblasts

“…BMSCs are believed to have multiple antigen markers and exhibit non-uniqueness; thus, a specific antigen marker for BMSCs remains to be found (Pittenger et al, 1999;Zhu et al, 2004;Delorme et al, 2006;Stolzing and Scutt, 2006;Sun et al, 2010). BMSCs and hematopoietic stem cells coexist in the bone marrow.…”

The Effect of Hypoxia on Mesenchymal Stem Cell Biology

“…We can say that cells in hypoxic conditions are less differentiated than cells in normoxia, the nuclei are larger and less complex, and there exist more abundant nucleoli and a higher nuclei/cytoplasm index, while the size of the cells is alike in both situations. 15,70,71 Effect of hypoxia on MSC differentiation In hypoxic microenvironments, haematopoietic and stromal stem cells (HSCs, MSCs) adapt themselves to hypoxia. 15,70,71 Consequently, several reports exist of the differentiation capacity of HSCs and MSCs cultured in hypoxic conditions.…”

“…15,70,71 Effect of hypoxia on MSC differentiation In hypoxic microenvironments, haematopoietic and stromal stem cells (HSCs, MSCs) adapt themselves to hypoxia. 15,70,71 Consequently, several reports exist of the differentiation capacity of HSCs and MSCs cultured in hypoxic conditions. 60,[72][73][74][75][76][77][78][79][80] Typical surface markers are expressed by bone marrow MSCs in human cells, and they have the potential to differentiate into adipogenic, osteogenic and chondrogenic lineages.…”

Epigenetic regulation of specific transcription factors in osteogenicdifferentiation of mesenchymal stem cells

“…It should be mentioned that multipotent cell populations derived from adipose tissue, bone marrow, and skeletal muscle have all been confirmed to meet the abovementioned criteria (Morizonoc et al, 2003;Delorme et al, 2006;Kern et al, 2006;Péault et al, 2007;da Silva Meirelles et al, 2008). These different MSC populations have several common characteristics.…”