Pluripotent nontumorigenic multilineage differentiating stress enduring cells (Muse cells): a seven-year retrospective.

Multilineage differentiating stress enduring (Muse) cells, discovered in the spring of 2010 at Tohoku University in Sendai, Japan, were quickly recognized by scientists as a possible source of pluripotent cells naturally present within mesenchymal tissues. Muse cells normally exist in a quiescent state, singularly activated by severe cellular stress in vitro and in vivo. Muse cells have the capacity for self-renewal while maintaining pluripotent cell characteristics indicated by the expression of pluripotent stem cell markers. Muse cells differentiate into cells representative of all three germ cell layers both spontaneously and under media-specific induction. In contrast to embryonic stem and induced pluripotent stem cells, Muse cells exhibit low telomerase activity, a normal karyotype, and do not undergo tumorigenesis once implanted in SCID mice. Muse cells efficiently home into damaged tissues and differentiate into specific cells leading to tissue regeneration and functional recovery as described in different animal disease models (i.e., fulminant hepatitis, muscle degeneration, skin ulcers, liver cirrhosis, cerebral stroke, vitiligo, and focal segmental glomerulosclerosis). Circulating Muse cells have been detected in peripheral blood, with higher levels present in stroke patients during the acute phase. Furthermore, Muse cells have inherent immunomodulatory properties, which could contribute to tissue generation and functional repair in vivo. Genetic studies in Muse cells indicate a highly conserved cellular mechanism as seen in more primitive organisms (yeast, Saccharomyces cerevisiae, Caenorhabditis elegans, chlamydomonas, Torpedo californica, drosophila, etc.) in response to cellular stress and acute injury. This review details the molecular and cellular properties of Muse cells as well as their capacity for tissue repair and functional recovery, highlighting their potential for clinical application in regenerative medicine.

Muse Cells: Nontumorigenic Pluripotent Stem Cells Present in Adult Tissues-A Paradigm Shift in Tissue Regeneration and Evolution.

Muse cells are a novel population of nontumorigenic pluripotent stem cells, highly resistant to cellular stress. These cells are present in every connective tissue and intrinsically express pluripotent stem markers such as Nanog, Oct3/4, Sox2, and TRA1-60. Muse cells are able to differentiate into cells from all three embryonic germ layers both spontaneously and under media-specific induction. Unlike ESCs and iPSCs, Muse cells exhibit low telomerase activity and asymmetric division and do not undergo tumorigenesis or teratoma formation when transplanted into a host organism. Muse cells have a high capacity for homing into damaged tissue and spontaneous differentiation into cells of compatible tissue, leading to tissue repair and functional restoration. The ability of Muse cells to restore tissue function may demonstrate the role of Muse cells in a highly conserved cellular mechanism related to cell survival and regeneration, in response to cellular stress and acute injury. From an evolutionary standpoint, genes pertaining to the regenerative capacity of an organism have been lost in higher mammals from more primitive species. Therefore, Muse cells may offer insight into the molecular and evolutionary bases of autonomous tissue regeneration and elucidate the molecular and cellular mechanisms that prevent mammals from regenerating limbs and organs, as planarians, newts, zebrafish, and salamanders do.

Intrafollicular cortisol levels inversely correlate with cumulus cell lipid content as a possible energy source during oocyte meiotic resumption in women undergoing ovarian stimulation for in vitro fertilization.

OBJECTIVE: To determine whether follicular fluid (FF) cortisol levels affect cumulus cell (CC) lipid content during oocyte meiotic resumption, and whether CCs express genes for glucocorticoid action. DESIGN: Prospective cohort study. SETTING: Academic medical center. PATIENT(S): Thirty-seven nonobese women underwent ovarian stimulation for in vitro fertilization (IVF). INTERVENTION(S): At oocyte retrieval, FF was aspirated from the first follicle (>16 mm in size) of each ovary and pooled CCs were collected. MAIN OUTCOME MEASURE(S): Follicular fluid cortisol and cortisone analysis was performed with the use of liquid chromatography-tandem mass spectrometry. CCs were stained with lipid fluorescent dye Bodipy FL C16 to determine lipid content with the use of confocal microscopy. Quantitative real-time polymerase chain reaction was used to detect CC gene expression of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) types 1 and 2, glucocorticoid receptor (NR3C1), lipoprotein lipase (LPL), and hormone-sensitive lipase (HSL). RESULT(S): Adjusting for maternal age, FF cortisol levels negatively correlated with CC lipid content and positively correlated with numbers of total and mature oocytes. CCs expressed genes for 11ß-HSD type 1 as the predominant 11ß-HSD isoform, NR3C1, LPL, and HSL. CONCLUSION(S): FF cortisol levels may regulate CC lipolysis during oocyte meiotic resumption and affect oocyte quality during IVF.

Pluripotent muse cells derived from human adipose tissue: a new perspective on regenerative medicine and cell therapy.

In 2010, Multilineage Differentiating Stress Enduring (Muse) cells were introduced to the scientific community, offering potential resolution to the issue of teratoma formation that plagues both embryonic stem (ES) and induced pluripotent (iPS) stem cells. Isolated from human bone marrow, dermal fibroblasts, adipose tissue and commercially available adipose stem cells (ASCs) under severe cellular stress conditions, Muse cells self-renew in a controlled manner and do not form teratomas when injected into immune-deficient mice. Furthermore, Muse cells express classic pluripotency markers and differentiate into cells from the three embryonic germ layers both spontaneously and under media-specific induction. When transplanted in vivo, Muse cells contribute to tissue generation and repair. This review delves into the aspects of Muse cells that set them apart from ES, iPS, and various reported adult pluripotent stem cell lines, with specific emphasis on Muse cells derived from adipose tissue (Muse-AT), and their potential to revolutionize the field of regenerative medicine and stem cell therapy.

A mystery unraveled: nontumorigenic pluripotent stem cells in human adult tissues.

INTRODUCTION: Embryonic stem cells and induced pluripotent stem cells have emerged as the gold standard of pluripotent stem cells and the class of stem cell with the highest potential for contribution to regenerative and therapeutic application; however, their translational use is often impeded by teratoma formation, commonly associated with pluripotency. We discuss a population of nontumorigenic pluripotent stem cells, termed Multilineage Differentiating Stress Enduring (Muse) cells, which offer an innovative and exciting avenue of exploration for the potential treatment of various human diseases. AREAS COVERED: This review discusses the origin of Muse cells, describes in detail their various unique characteristics, and considers future avenues of their application and investigation with respect to what is currently known of adult pluripotent stem cells in scientific literature. We begin by defining cell potency, then discuss both mesenchymal and various reported populations of pluripotent stem cells, and finally delve into Muse cells and the characteristics that set them apart from their contemporaries. EXPERT OPINION: Muse cells derived from adipose tissue (Muse-AT) are efficiently, routinely and painlessly isolated from human lipoaspirate material, exhibit tripoblastic differentiation both spontaneously and under media-specific induction, and do not form teratomas. We describe qualities specific to Muse-AT cells and their potential impact on the field of regenerative medicine and cell therapy.

Awakened by cellular stress: isolation and characterization of a novel population of pluripotent stem cells derived from human adipose tissue.

Advances in stem cell therapy face major clinical limitations, particularly challenged by low rates of post-transplant cell survival. Hostile host factors of the engraftment microenvironment such as hypoxia, nutrition deprivation, pro-inflammatory cytokines, and reactive oxygen species can each contribute to unwanted differentiation or apoptosis. In this report, we describe the isolation and characterization of a new population of adipose tissue (AT) derived pluripotent stem cells, termed Multilineage Differentiating Stress-Enduring (Muse) Cells, which are isolated using severe cellular stress conditions, including long-term exposure to the proteolytic enzyme collagenase, serum deprivation, low temperatures and hypoxia. Under these conditions, a highly purified population of Muse-AT cells is isolated without the utilization of cell sorting methods. Muse-AT cells grow in suspension as cell spheres reminiscent of embryonic stem cell clusters. Muse-AT cells are positive for the pluripotency markers SSEA3, TR-1-60, Oct3/4, Nanog and Sox2, and can spontaneously differentiate into mesenchymal, endodermal and ectodermal cell lineages with an efficiency of 23%, 20% and 22%, respectively. When using specific differentiation media, differentiation efficiency is greatly enhanced in Muse-AT cells (82% for mesenchymal, 75% for endodermal and 78% for ectodermal). When compared to adipose stem cells (ASCs), microarray data indicate a substantial up-regulation of Sox2, Oct3/4, and Rex1. Muse-ATs also exhibit gene expression patterns associated with the down-regulation of genes involved in cell death and survival, embryonic development, DNA replication and repair, cell cycle and potential factors related to oncogenecity. Gene expression analysis indicates that Muse-ATs and ASCs are mesenchymal in origin; however, Muse-ATs also express numerous lymphocytic and hematopoietic genes, such as CCR1 and CXCL2, encoding chemokine receptors and ligands involved in stem cell homing. Being highly resistant to severe cellular stress, Muse-AT cells have the potential to make a critical impact on the field of regenerative medicine and cell-based therapy.