An Overview of Pluripotent Stem Cells [chapter]

Deepa Bhartiya, Punam Nagvenkar, Kalpana Sriraman, Ambreen Shaikh
2013 Pluripotent Stem Cells  
of literature suggesting that mesenchymal stem cells (MSCs) have pluripotent characteristics and can transdifferentiate [12] . We have recently published that adult gonads [13, 14] umbilical cord blood/tissue, bone marrow [15] etc. harbor a sub-population of similar kind of pluripotent stem cells termed very small embryonic-like stem cells (VSELs). We also developed a case for VSELs which may be resulting in ES-like colonies rather than de-differentiation of spermatogonial stem cells into
more » ... otent state [16] . Moreover, the VSELs have confused the field of MSCs, since they are always present as a sub-population amongst MSCs but have remained unnoticed and the pluripotent properties were conferred incorrectly on to the MSCs. VSELs are not widely accepted at present, but have been shown to have promising application towards regenerative medicine. Thus the aim of the present chapter is to update the readers with the recent advances with embryonic stem cells, induced pluripotent stem cells and VSELs which have been implicated with maximum potential for use in cell-based therapies. Embryonic stem cells Embryonic stem (ES) cells, as the name suggests, are derived from embryos, more specifically from the inner cell mass (ICM) of the blastocyst. ES cells are characterized by two hallmark properties viz., self-renewal -ability to proliferate indefinitely and pluripotency -capacity to give rise to cells of all the three embryonic germ lineages such as ectoderm, mesoderm and endoderm. They possess a high nucleo-cytoplasmic ratio and telomerase activity. ES cells display high activity of endogenous alkaline phosphatase and express several nuclear and cellsurface markers of pluripotency. They tend to cluster together when cultured in suspension on a non-adherent surface to form 3D aggregates known as embryoid bodies that may be simple or cystic. Moreover, they produce teratomas on injection in immune deficient (SCID) mice, are clonogenic and are capable of producing chimeras when injected into blastocysts in the mouse model. Mouse ES cells ES cells were first derived from ICM of mouse blastocyst stage embryos [17, 18] . Besides ICM of blastocyst mouse ES (mES) cells have also been derived from cleavage stage embryos and even from biopsied individual blastomeres of two-to eight-cell stage embryos [19] [20] [21] . In general, mES cells can be cultured on a layer of mitotically inactive mouse embryonic fibroblasts (MEF) in the presence of serum and leukaemia inhibitory factor (LIF). The cytokine LIF sustains the self-renewing and pluripotency features of mES cells. LIF, a soluble glycoprotein of interleukin (IL)-6 family of cytokines acts via binding to heterodimers of the LIF-receptor and the signal transducer gp130 resulting in activation of STAT3 signaling [22] [23] [24] . In absence of serum, LIF is incapable of maintaining pluripotency of mES cells; however, in combination with bone morphogenetic protein-4 (BMP4) prevents differentiation of mES cells [25] . BMP4
doi:10.5772/55130 fatcat:crb67g5rajcsfgwxl57dxvpmye