A Muse cell (Multi-lineage differentiating stress enduring cell) is an endogenous non-cancerous pluripotent stem cell. [1] [2] They reside in the connective tissue of nearly every organ including the umbilical cord, bone marrow and peripheral blood. [3] [1] [4] [5] [6] They are collectable from commercially obtainable mesenchymal cells such as human fibroblasts, bone marrow-mesenchymal stem cells and adipose-derived stem cells as 1~several percent of the total population. [7] [8] [9] Muse cells are able to generate cells representative of all three germ layers from a single cell both spontaneously and under cytokine induction. Expression of pluripotency genes and triploblastic differentiation are self-renewable over generations. Muse cells do not undergo teratoma formation when transplanted into a host environment in vivo. This can be explained in part by their intrinsically low telomerase activity, eradicating the risk of tumorigenesis through unbridled cell proliferation. They were discovered in 2010 by Mari Dezawa and her research group. [1] Clinical trials for acute myocardial infarction, [10] stroke, [11] epidermolysis bullosa, [12] spinal cord injury, amyotrophic lateral sclerosis, [13] acute respiratory distress syndrome (ARDS) related to novel coronavirus (SARS-CoV-2) infection, are conducted. Physician-led clinical trial for neonatal hypoxic-ischemic encephalopathy was also started. [14] The summary results of a randomized double-blind placebo-controlled clinical trial in patients with stroke was announced. [11] [15]
Muse cells are identified as cells positive for SSEA-3+, [24] a well-known marker for undifferentiated human ES cells. [25] Their size is 13~15 μm in diameter. Muse cells do not express CD34 (markers for hematopoietic stem cells, adipose stem cells, VSELs) and CD117 (hematopoietic stem cells markers), Snai1 and Slug (skin-derived precursors markers), CD271 and Sox10 (neural crest-derived stem cells markers), NG2 and CD146 (perivascular cells) or CD31 and von Willebrand factor (endothelial progenitor markers). This indicates that Muse cells do not belong to previously investigated stem cell types. [1] [26]
Muse cells can differentiate into:
Muse cells are shown to home into the damage site by S1P-S1P recptor 2 axis and spontaneously differentiate into tissue-compatible cells according to the microenvironment to contribute to tissue regeneration when infused into the blood stream [1] as shown in animal models with fulminant hepatitis, [1] partial hepatectomy, [21] muscle degeneration, [1] epidermolysis bullosa, [29] skin injury, [23] [1] [30] stroke [22] and spinal cord injury. [31] The spontaneous differentiation into tissue-compatible cells was explained by the phagocytosis-dependent differentaition: after homing to damaged tissue, Muse cells phagocytose damaged cells, similar to macrophages, recycle the differentiation signals (e.g., transcription factors) obtained from the damaged cells and rapidly differentiate into the same cell type as the damaged cell. [28]
Muse cells are characterized by low telomerase activity, not a strong indicator of tumorigenicity. Hela cells and human fibroblast-derived iPS cells showed high telomerase activity while Muse was at nearly the same level as that in somatic cells such as fibroblasts (these data are shown without running control for the telomerase activity, the comparison is not scientific thought). This indicates the non-tumorigenic nature of Muse cells. [1] [8] [19]
The expression 'pattern' of genes related to pluripotency in Muse cells was almost the same as that in ES and iPS cells, while the expression 'level' was much higher in ES and iPS cells and that in Muse cells. [4] In contrast, genes related to cell cycle progression and tumorigenicity in Muse cells were at the same level as those in somatic cells, while the same genes were very high in ES and iPS cells. These gene expression pattern and level may explain why Muse cells are pluripotent but without tumorigenic activity. [32]
Unlike ES and iPS cells, transplanted Muse cells in testes of immunodeficient mice -a commonly used experiment to test the tumorigenicity of stem cells- have not been reported to form teratomas, even after six months. [1] Thus, Muse cells are pluripotent but are non-tumorigenic. [24] Similarly, epiblast stem cells cultured under certain conditions also do not form teratomas in testes, even though they show pluripotency in vitro. [33] Thus, pluripotent stem cells do not always show teratoma formation when transplanted in vivo.
Muse cells act as tissue repairing cells in vivo. When systemically administrated, naive Muse cells (without cytokine treatment or gene introduction) migrate to damaged site, home into the site and spontaneously differentiate into tissue-compatible cells to replenish new functional cells. This phenomenon was observed by the infusion of green fluorescent protein-labeled naive human Muse cells into animal models with fulminant hepatitis, [1] partial hepatectomy, [21] muscle degeneration, [1] skin injury, [23] [1] [30] stroke [22] and spinal cord injury. [34] [35] [36] Infused Muse cells integrated into each damaged tissue and differentiated into human albumin- and human anti-trypsin-expressing hepatocytes in the liver, [1] human dystrophin-expressing cells in the muscle, [1] neurofilament and MAP-2-expressing neuronal cells in the spinal cord [34] [35] [36] and brain, [22] [37] desmoglein-3-, cytokerain14- and cytokeratin 15-expressing epidermal cells in the skin, [23] [1] [30] [29] glomerular cells in the kidney, [38] corneal epithelial cells in the cornea [39] and physiologically functional cardiac cells in the heart, [20] respectively.
Muse cells have great advantages for regenerative medicine. Without need of cytokine induction or artificial gene manipulation, Muse cells are capable of repairing tissues when directly infused into the blood stream. Hence, the clinical applications of Muse cells appear promising. [7]
Pluripotency, namely pluripotent marker expression, triploblastic differentiation and self-renewability, are recognized in Muse cells directly collected from BM aspirates, indicating that their characteristics are not newly acquired by in vitro manipulation nor are they modified under culture conditions. [1]
Muse cells are not generated by stress, cytokine induction or exogenous gene transfection. They are preexisting pluripotent stem cells that normally reside in the bone marrow, peripheral blood and connective tissue of every organ including the umbilical cord. [3][1][4][5][6] ] In the bone marrow, they represent one out of 3000 mono-nucleated cells. Other than mesenchymal tissues, Muse cells locate in connective tissue of every organ and in the peripheral blood. [1] [4] [5] [6]
Muse cells are pluripotent-like, express pluripotency genes at moderate levels, exhibit triploblastic-lineage differentiation, and self-renew at the single-cell level. After homing to damaged tissue, Muse cells phagocytose damaged cells, similar to macrophages. They then recycle the differentiation signals (e.g., transcription factors) obtained from the damaged cells and rapidly differentiate into the same cell type as the damaged cell. [28] Because Muse cells are pluripotent-like, they can differentiate into multiple cell types that comprise various tissues.
In cell suspension, Muse cells begin to proliferate and to form clusters that are very similar to embryoid bodies formed from ES cells in suspension. Muse cell clusters are positive for pluripotency indicators such as alkaline phosphatase reactivities, Nanog, Oct3/4, Sox2 and PAR4. One of remarkable properties of Muse cells is that they are capable of forming clusters from a single cell in suspension. A single Muse cell-derived cluster is shown to spontaneously generate cells representative of all three germ layers on a gelatin-coated dish, proving the pluripotency of Muse cells.
Muse cells proliferate at a speed of ~1.3 day/cell division in adherent culture. This is slightly slower than that of human fibroblasts (~1 day/cell division). [31]
Muse cells are able to self-renew, maintaining their proliferative activity, pluripotency marker expression and a normal karyotype. [31]
Muse cells can be collected from bone marrow aspirate, whose collection is a well known procedure done daily in clinics. They can also be isolated from skin fibroblasts obtained via skin biopsy, adipose tissue obtained by liposuction and from the umbilical cord; a safe and non-invasive procedure often used for cosmetic surgery interventions [9] Easy accessibility of Muse cells allows them to be auto- or allo-transplanted in regenerative clinical applications. Muse cells are also isolated from commercially available mesenchymal cell cultures, which ensure their availability and accessibility.
Muse cells can be collected by several techniques:
There are major differences between Muse cells and non-Muse cells in present within mesenchymal cell population. When mesenchymal cells (sometimes called mesenchymal stem cells) are separated into Muse and non-Muse cells by SSEA-3 cell sorting, the following differences are observed:
In 2009, a study showed that only SSEA-3+ cells generate induced pluripotent stem (iPS) cells in human fibroblasts. [44] In 2011, it was suggested that iPS cells are generated only from Muse cells. When the technique for generation of iPS cells was applied to both Muse and non-Muse cells, iPS cells were successfully generated only from Muse cells. In contrast, non-Muse cells did not show elevation in Sox2 and Nanog, master genes of pluripotent stem cells, even after receiving the four Yamanaka factors. These results support the elite model of iPS cell generation rather than the stochastic model. Divergent from their Muse cell origin, iPS cells showed tumorigenecity. Since Muse cells are originally pluripotent without tumorigenic activity, what the Yamanaka factors newly conferred to Muse cells was not 'pluripotency' but tumorigenic activity. These results collectively suggest that only preexisting cells with promising pluripotency can be programmed into iPS cells. [26] [4]
Muse cells from different sources are capable of in vitro differentiation into various cell types.
Human dermal fibroblast-derived Muse cells are a practical source for melanocyte induction. Application of a cytokine induction system comprising Wnt3a, SCF, ET-3, basic fibroblast growth factor, linoleic acid, cholera toxin, L-ascorbic acid, 12-O-tetradecanoylphorbol 13-acetate, insulin, transferrin, selenium, and dexamethasone to both human dermal fibroblast-derived Muse and non-Muse cells induces only the Muse cells into L-DOPA–reactive functional melanocytes capable of melanin production in a 3D cultured skin model. [45] The application of a set of cytokines also differentiates dermal-Muse cells into melanocytes. [46]
Human adipose tissue-derived Muse cells differentiate into keratinocytes by spontaneous differentiation on a gelatin culture dish [47] or by cytokine induction containing bone morphogenetic protein-4 and all trans retinoic acid. [48] [49]
Human bone marrow- and fibroblast-derived Muse cells spontaneously differentiate into neural lineage cells with a lower proportion on a gelatin culture. [24] Cells expanded from single Muse cell-derived clusters on gelatin-coated culture dishes express the neural markers nestin (1.9%), MAP-2 (3.8%), GFAP (3.4%), and O4 (2.9%), suggesting the ability of Muse cells to differentiate into neural-lineage cells. [22] The cells positive for MAP-2 or GFAP were increased following induction with basic fibroblast growth factor, forskolin, and ciliary neurotrophic factor. [50]
Muse cells can spontaneously differentiate in vitro into hepatocyte lineage cells positive for DLK, alpha-fetoprotein, cytokeratin 19, and cytokeratin 18 on gelatin-coated culture dishes. [51] In the presence of insulin-transferrin-selenium, dexamethasone, hepatocyte growth factor, and fibroblast growth factor-4, Muse cells differentiate into alpha-fetoprotein(+), albumin(+) cells. [52]
Muse cells differentiate in vitro into renal lineage-cells with increased expression of developmental renal markers WT1 and EYA1 compared with non-Muse cells after 3 weeks following the application of a cytokine induction cocktail containing all trans retinoic acid, activin A, and bone morphologic protein-7. [38]
Treatment of Muse cells with 5’ -azacytidine in suspension culture; then transferring the cells onto adherent culture and treatment with early cardiac differentiation factors wingless-int (Wnt)-3a, bone morphogenetic proteins (BMP)-2/4, and transforming growth factor (TGF) b 1; further treatment with late cardiac differentiation cytokines including cardiotrophin-1 converted Muse cells into cardiomyocyte-like cells that expressed a -actinin and troponin-I with a striation-like pattern. [53]
Expanded cells from Muse clusters differentiate into adipocytes by the application of 1-methyl-3-isobutylxanthine, dexamethasone, insulin, and indomethacin. These induced adipocytes contain lipid droplets and stain positive for oil red O. In addition, Muse cluster expanded cells differentiate into osteoblasts positive for osteocalcin using dexamethasone, ascorbic acid, and β-glycerophosphate. [50]
Muse cells from different sources demonstrate reparative effects in animal disease models.
Rabbit autograft, allograft, and xenograft (human) bone marrow-Muse cells were intravenously administrated in a rabbit acute myocardial infarction model. In vivo dynamics of Muse cells showed preferential homing of the cells to the postinfarct heart at 3 days and 2 weeks, with ≈14.5% of injected Muse cells estimated to be engrafted into the heart at 3 days. The migration and homing of the Muse cells were shown to be mediated through the S1P (sphingosine monophosphate)-S1PR2 axis. After homing, Muse cells spontaneously differentiated into cells positive for cardiac markers, such as cardiac troponin-I, sarcomeric α-actinin, and connexin-43, and vascular markers, and GCaMP3-labeled Muse cells that engrafted into the ischemic region exhibited increased GCaMP3 fluorescence during systole and decreased fluorescence during diastole, suggesting their functionality as working cardiomyocytes. Infarct size was reduced by ≈52%, and the ejection fraction was increased by ≈38% compared with vehicle injection at 2 months, ≈2.5 and ≈2.1 times higher, respectively, than that induced by mesenchymal stem cells. Muse cell allografts and xenografts efficiently engrafted and recovered functions, and allografts remained in the tissue and sustained functional recovery for up to 6 months without immunosuppression. [20] The similar therapeutic effect was observed in swine acute myocardial infarction model that received human-Muse cell intravenous injection. [54]
The neural regeneration capability of Muse cells has been demonstrated in several models. In a rat stroke model induced by ischemic-reperfusion of middle cerebral artery occlusion (MCAO), 3 x 104 human dermal-Muse cells topically injected into three sites in the infarct area (each site received 1 x 104 Muse cells) delivered statistically significant functional recovery compared to vehicle and non-Muse fibroblast cell-injected groups after ~2.5 months. The functional recovery was supported by the incorporation of human Muse cells into rat pyramidal and sensory tracts with normalized hind limb somatosensory evoked potentials. [22] Similarly, topically injected human bone marrow-Muse cells integrate into infarct region and replenish new neuronal cells and oligodendrocytes in mouse permanent MCAO and mouse lacunar stroke models. [37] [55] In the mouse lacunar stroke model, human Muse cells-derived neuronal cells integrated into the pyramidal tract, leading to statistically meaningful functional recovery. [55] In a mouse intracerebral hemorrhage model, topically injected human bone marrow-Muse cells spontaneously differentiate into neuronal cells. Mice recovered motor function and spatial learning and memory ability. [56]
Intravenously injected human bone marrow-derived Muse cells are able to repair an immunodeficient mouse (SCID) model of CCL4-induced liver cirrhosis. Human Muse cells spontaneously differentiate in vivo into hepatocytes without fusing with host hepatocytes, and express mature functional markers such as human CYP1A2 (detoxification enzyme) and human Glc-6-Pase (enzyme for glucose metabolism) at 8 weeks after homing. [51] Human bone marrow-derived Muse cells injected intravenously into a partial hepatectomy model in SCID mice differentiate spontaneously into major liver components, namely hepatocytes (74.3% of green fluorescent protein-positive integrated Muse cells), cholangiocytes (17.7%), sinusoidal endothelial cells (2.0%), and Kupffer cells (6.0%) after migrating and homing into the injured liver. [52] Non-Muse bone marrow MSCs are not detected in the liver from the early stage (~ 1 week) to the end-point in either model. [51] [52] In the pig hepatectomy model, allogenic Muse cell intravenous injection delivered liver tissue repair and functional recovery. [42] In the rat partial liver transplantation model, intravenously injected human Muse cells effectively protected sinusoid endothelial cells and micro-vascular flows. [57]
Human bone marrow-derived Muse cells injected intravenously repair SCID and BALB/c mouse models of focal segmental glomerulosclerosis without added immunosuppression. Injected human Muse cells preferentially integrate into the damaged glomeruli and spontaneously differentiate into cells expressing markers of podocytes (podocin; ~31%), mesangial cells (megsin; ~13%), and endothelial cells (CD31; ~41%) without fusing with host glomerular cells; attenuate glomerular sclerosis and interstitial fibrosis; and induce the recovery of renal function, including creatinine clearance. [38]
Human adipose tissue-derived Muse-rich cells significantly accelerate wound healing in skin ulcers of a mouse type 1 diabetes model. Subcutaneously injected human Muse cells integrate into the epidermis and dermis and differentiate into keratinocytes, vascular endothelial cells, and other cell types in the dermis. Ulcers treated with human Muse cells heal faster with a thick epidermal layer than those treated with non-Muse cells, with a wound closure duration even shorter than that in wild-type mice. [58]
Therapeutic efficacy of intravenous injection of human bone marrow-Muse cells into a SCID mouse aortic aneurysm model was evaluated. At 8 weeks, infusion of human Muse cells attenuated aneurysm dilation, and the aneurysmal size in the Muse group corresponded to approximately 45.6% in the vehicle group. Infused Muse cells were shown to migrate into aneurysmal tissue from the adventitial side and penetrated toward the luminal side. Histologic analysis demonstrated robust preservation of elastic fibers and spontaneous differentiation of Muse cells into endothelial cells and vascular smooth muscle cells. [59]
Type XVII collagen (Col17)-knockout (KO) mice that simulate junctional EB and recurrent skin injuries received 5.0 × 10^4 human Muse cells or human non-Muse-mesenchymal stem cells (MSCs) by intravenous injection into the tail vein. Ex vivo imaging of dissected injured skin confirmed the homing of injected Muse cells but not of non-Muse-MSCs. Human Muse cells homed to the mouse epidermis expressed keratin 14 and human desmoglein-3. Notably, all the mice in the Muse group showed the linear deposition of human type VII COL (hCOL7) at the injury site of the mouse skin whereMuse-derived cells were intensively integrated. Similarly, four of the five mice in the Muse group showed the deposition of human COL17 in association with Muse cell-derived basal cells. [29]
Seven-day-old rats underwent ligation of the left carotid artery then were exposed to 8% oxygen for 60 min, and 72 hours later intravenously transplanted with 1 × 10^4 of human-Muse and -non-Muse cells, collected from bone marrow-mesenchymal stem cells as stage-specific embryonic antigen-3 (SSEA-3)+ and -, respectively, or saline (vehicle) without immunosuppression. Muse cells distributed mainly to the injured brain at 2 and 4 weeks, and expressed neuronal and glial markers until 6 months. In contrast, non-Muse cells lodged in the lung at 2 weeks, but undetectable by 4 weeks. Magnetic resonance spectroscopy and positron emission tomography demonstrated that Muse cells dampened excitotoxic brain glutamatergic metabolites and suppressed microglial activation. Muse cell-treated group exhibited significant improvements in motor and cognitive functions at 4 weeks and 5 months. Intravenously transplanted Muse cells afforded functional benefits in experimental HIE possibly via regulation of glutamate metabolism and reduction of microglial activation. [60]
In G93A-transgenic ALS mice, intravenous injection of 5.0 × 10^4 Muse cells revealed successful homing to the lumbar spinal cords, mainly at the pia-mater and underneath white matter, and exhibited glia-like morphology and GFAP expression. In contrast, such homing or differentiation were not recognized in human mesenchymal stem cells but were instead distributed mainly in the lung. Relative to the vehicle groups, the Muse group significantly improved scores in the rotarod, hanging-wire and muscle strength of lower limbs, recovered the number of motor neurons, and alleviated denervation and myofiber atrophy in lower limb muscles. These results suggest that Muse cells homed in a lesion site-dependent manner and protected the spinal cord against motor neuron death. [61]
Shiga toxin-producing Escherichia coli (STEC) causes hemorrhagic colitis, hemolytic uremic syndrome, and acute encephalopathies that may lead to sudden death or severe neurologic sequelae. Severely immunocompromised non-obese diabetic/severe combined immunodeficiency (NOD-SCID) mice orally inoculated with 9 × 10^9 colony-forming units of STEC O111 and treated 48 h later with intravenous injection of 5 × 10^4 Muse cells exhibited 100% survival and no severe after-effects of infection. Suppression of granulocyte-colony-stimulating factor (G-CSF) by RNAi abolished the beneficial effects of Muse cells, leading to a 40% death and significant body weight loss, suggesting the involvement of G-CSF in the beneficial effects of Muse cells in STEC-infected mice. Thus, intravenous administration of Muse cells could be a candidate therapeutic approach for preventing fatal encephalopathy after STEC infection. [62]
Corneal scarring
Human Muse cells, collected from lipoaspirate, were activated by forming spheroid in the dynamic rotary cell culture system. These activated Muse spheroids enabled ready differentiation into corneal stromal cells (CSCs) expressing characteristic marker genes and proteins in vitro. Implantation of Muse cells–differentiated CSCs (Muse-CSCs) laden assembled with two orthogonally stacked stretched compressed collagen (cell-SCC) in mouse and tree shrew wounded corneas prevented the formation of corneal scarring, increased corneal re-epithelialization and nerve regrowth, and reduced the severity of corneal inflammation and neovascularization. cell-SCC retained the capacity to suppress corneal scarring after long-distance cryopreserved transport. [39]
Radiation injury model
An acute injury model of the gastrointestinal tract was created by administering 18 Gy radiation to the abdomen of mice. Intravenous injection of human umbilical cord-derived Muse cells increased the survival rate and the protection/repair of the gastrointestinal tract. [63]
Spinal cord injury model
In a rat compression spinal cord injury model, functional recovery was observed when human Muse cells were administered intravascularly during the acute and subacute stages. [34] [35] [36]
Muse cells are present in the human bone marrow of healthy donors. [64] The number of peripheral blood-Muse cells is drastically elevated in stroke patients 24 h after onset. [64] In acute myocardial infarction patients, peripheral blood-Muse cells significantly increase 24 h after onset, concomitant with an increase in serum sphingosine-1-phosphate, and return to baseline levels with 2~3 weeks. Importantly, patients with an increased peripheral blood-Muse cell number in the acute phase show cardiac function recovery and avoidance of heart failure at 6 months after onset, suggesting the reparative function of endogenous Muse cells. [65]
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells, which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type.
A fibroblast is a type of biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals.
Bone marrow is a semi-solid tissue found within the spongy portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production. It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. Bone marrow comprises approximately 5% of total body mass in healthy adult humans, such that a man weighing 73 kg (161 lbs) will have around 3.7 kg (8 lbs) of bone marrow.
Embryonic stem cells (ESCs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells. Isolating the inner cell mass (embryoblast) using immunosurgery results in destruction of the blastocyst, a process which raises ethical issues, including whether or not embryos at the pre-implantation stage have the same moral considerations as embryos in the post-implantation stage of development.
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Adult stem cells are undifferentiated cells, found throughout the body after development, that multiply by cell division to replenish dying cells and regenerate damaged tissues. Also known as somatic stem cells, they can be found in juvenile, adult animals, and humans, unlike embryonic stem cells.
A stem cell line is a group of stem cells that is cultured in vitro and can be propagated indefinitely. Stem cell lines are derived from either animal or human tissues and come from one of three sources: embryonic stem cells, adult stem cells, or induced pluripotent stem cells. They are commonly used in research and regenerative medicine.
Stem-cell therapy uses stem cells to treat or prevent a disease or condition. As of 2024, the only FDA-approved therapy using stem cells is hematopoietic stem cell transplantation. This usually takes the form of a bone marrow or peripheral blood stem cell transplantation, but the cells can also be derived from umbilical cord blood. Research is underway to develop various sources for stem cells as well as to apply stem-cell treatments for neurodegenerative diseases and conditions such as diabetes and heart disease.
Induced pluripotent stem cells are a type of pluripotent stem cell that can be generated directly from a somatic cell. The iPSC technology was pioneered by Shinya Yamanaka and Kazutoshi Takahashi in Kyoto, Japan, who together showed in 2006 that the introduction of four specific genes, collectively known as Yamanaka factors, encoding transcription factors could convert somatic cells into pluripotent stem cells. Shinya Yamanaka was awarded the 2012 Nobel Prize along with Sir John Gurdon "for the discovery that mature cells can be reprogrammed to become pluripotent."
Mesenchymal stem cells (MSCs) are multipotent cells found in multiple human adult tissues, including bone marrow, synovial tissues, and adipose tissues. Since they are derived from the mesoderm, they have been shown to differentiate into bone, cartilage, muscle, and adipose tissue. MSCs from embryonic sources have shown promise scientifically while creating significant controversy. As a result, many researchers have focused on adult stem cells, or stem cells isolated from adult humans that can be transplanted into damaged tissue.
Cell potency is a cell's ability to differentiate into other cell types. The more cell types a cell can differentiate into, the greater its potency. Potency is also described as the gene activation potential within a cell, which like a continuum, begins with totipotency to designate a cell with the most differentiation potential, pluripotency, multipotency, oligopotency, and finally unipotency.
Mesenchymal stem cells (MSCs) also known as mesenchymal stromal cells or medicinal signaling cells, are multipotent stromal cells that can differentiate into a variety of cell types, including osteoblasts, chondrocytes, myocytes and adipocytes.
Adult mesenchymal stem cells are being used by researchers in the fields of regenerative medicine and tissue engineering to artificially reconstruct human tissue which has been previously damaged. Mesenchymal stem cells are able to differentiate, or mature from a less specialized cell to a more specialized cell type, to replace damaged tissues in various organs.
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Craniofacial regeneration refers to the biological process by which the skull and face regrow to heal an injury. This page covers birth defects and injuries related to the craniofacial region, the mechanisms behind the regeneration, the medical application of these processes, and the scientific research conducted on this specific regeneration. This regeneration is not to be confused with tooth regeneration. Craniofacial regrowth is broadly related to the mechanisms of general bone healing.
Stem cellfat grafting is the autotransplantation of adipose-derived stem cells (ADSCs) extracted from fat-abundant donor sites to other areas such as the face, breast, and hip to reconstruct the operative areas into desirable shapes. ADSCs are multipotent stem cells found in adipose tissues, displaying similar differentiation potentials to bone marrow-derived mesenchymal stem cells (BM-MSCs).