A plethora of human pluripotent stem cells.

At the early stages of mammalian development, a number of developmentally plastic cells appear that possess the ability to give rise to all of the differentiated cell types normally derived from the three primary germ layers - unique character known as pluripotency. To date, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have been shown to be truly pluripotent. However, recent studies have revealed a variety of other cells that demonstrate pluripotentiality, including very small embryonic-like stem cells (VSELs), amniotic fluid stem cells (AFSCs), marrow-isolated adult multilineage inducible cells (MIAMI) and multipotent adult precursor cells (MAPCs). This review summarises key features of these six kinds of pluripotent and potentially pluripotent stem cells (ESCs, iPSCs, VSELs, AFSCs, MIAMI and MAPCs) and the evidence for their pluripotency properties.

Pluripotent Stem Cells in Adult Tissues: Struggling To Be Acknowledged Over Two Decades.

Stem cells have fascinated scientists for a long time and huge research efforts have been put into them as they have the potential to regenerate diseased organs. Besides embryonic stem cells (ES) and induced pluripotent stem cells (iPS), it has been postulated that pluripotent stem cells (PSCs) may also exist in various adult tissues. They are thought to be more primitive than the adult stem cells (ASCs), serve as a backup pool to give rise to ASCs and thus play a crucial role in maintaining life-long homeostasis. These PSCs could also be the embryonic stem cells in adult tissues that were proposed to initiate cancers according to the Embryonic Rest Hypothesis put forth in the nineteenth century. However, the very presence of PSCs in adult tissues is mired with controversies. This article is a sincere attempt to review research carried out by various investigators over the last two decades and various attempts to demonstrate their presence in adult tissues. Such adult PSCs could be the ideal stem cell candidates to bring about endogenous regeneration compared to ES/iPS cells grown in Petri dish and also score better over ASCs which in fact are tissue committed progenitors with limited regenerative potential that differentiate from the PSCs. PSCs in adult tissues have remained elusive until now as they possibly get unknowingly discarded due to their small size and inability to pellet at 1000-1200 rpm (250 g). They will likely prove to be a game changer in the field of stem cells biology, for regenerative medicine and for our understanding of cancer initiation.

Efficacy of a Cellular Allogeneic Bone Graft in Foot and Ankle Arthrodesis Procedures.

A cellular allogeneic bone graft can be used in patients at high risk for nonunion after arthrodesis surgery. This study explores the utility and efficacy of MAP3 in foot and ankle arthrodesis procedures. Map3 is a cellular allogeneic bone graft that contains osteogenic, osteoconductive, osteoinductive, and angiogenic properties. A total of 23 mostly high-risk patients were included in this study. The overall fusion rate was 83%. Univariate analysis demonstrated diabetic patients remain at risk of recurrent nonunion (P<.001) despite supplementation with MAP3. These data demonstrate successful fusion in high-risk patients when MAP3 is used.

New methods for inducing the differentiation of amniotic-derived mesenchymal stem cells into motor neuron precursor cells.

Our study investigates the differentiation of amniotic-derived mesenchymal stem cells (ADMSCs) into motor neuron (MN) precursor cells induced by a combination of extracellular matrix (ECM) and multi-cell factors. Membrane-like ECM was made by an enzymatic and chemical extraction method and exhibited good biological compatibility. Cells in the experimental group (EG) were treated with ECM and multi-cell factors in a multi-step induction process, while the control group (CG) was treated similarly, except without ECM. In the EG, after induction, the cells formed processes that connected with neighboring cells to form a net that had directionality. In these cells, neuron-specific enolase (NSE) and synaptophysin (SYN) expression levels increased and glial fibrillary acidic protein (GFAP) expression decreased. The SYN expression in the EG cells was higher compared with those in the CG. In the CG, NSE expression increased, while the expression of Nestin and SYN did not change. These were several changes in the levels of other genes: ADMSCs at passage 1 expressed Nanog, SOX2, octamer-binding transcription factor 4 (OCT4) and Nestin. In the EG, at the beginning of induction, the expression of Nanog decreased and that of SOX2 and Nestin increased. After 2 days, the cells expressed Nestin, OCT4 and SYNIII, and after 3 days, they expressed Olig2, OCT4, Nestin, SYNII and Islet1 (ISL1). Finally, at day 6, the cells expressed Nestin, SYNI, SYNIII, ISL-1, homeobox 9 (Hb9) and oligodendrocyte lineage transcription factor 2 (Olig2). In the CG, the cells never expressed SYNI, SYNII or Hb9. Our studies therefore demonstrate that the extracted ECM was capable of promoting the maturation of synapses. Human ADMSCs are composed of multiple cell subsets, including neural progenitor cells. The multi-step induction method used in this study causes human ADMSCs to differentiate into MN precursor cells.