Stem Cell Key Terms | California’s Stem Cell Agency

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The term stem cell by itself can be misleading. In fact, there are many different types of stem cells, each with very different potential to treat disease.

Stem Cell Pluripotent Embryonic Stem Cell Adult Stem Cell iPS Cell Cancer Stem Cell

By definition, all stem cells:

Pluripotent means many "potentials". In other words, these cells have the potential of taking on many fates in the body, including all of the more than 200 different cell types. Embryonic stem cells are pluripotent, as are induced pluripotent stem (iPS) cells that are reprogrammed from adult tissues. When scientists talk about pluripotent stem cells they mostly mean either embryonic or iPS cells

Embryonic stem cells come from pluripotent cells, which exist only at the earliest stages of embryonic development. In humans, these cells no longer exist after about five days of development.

When isolated from the embryo and grown in a lab dish, pluripotent cells can continue dividing indefinitely. These cells are known as embryonic stem cells.

James Thomson, a professor of Anatomy at the University of Wisconsin, isolated the first human embryonic stem cells in 1998. He now shares a joint appointment at the University of California, Santa Barbara, a CIRM-funded institution.

Adult stem cells.are found in the various tissues and organs of the human body. They are thought to exist in most organs where they are the source of new cells throughout the life of the organism, replacing cells lost to natural turnover or to damage or disease.

Adult stem cells are committed to becoming a cell from their tissue of origin, and cant form other cell types. They are therefore also called tissue-specific stem cells. They have the broad ability to become many of the cell types present in the organ they reside in. For example:

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Stem Cell Key Terms | California's Stem Cell Agency

Generating Mice from Induced Pluripotent Stem Cells | Protocol

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JoVE Biology

Michael J. Boland1, Jennifer L. Hazen1, Kristopher L. Nazor1, Alberto R. Rodriguez2, Greg Martin2, Sergey Kupriyanov2, Kristin K. Baldwin1

1Dorris Neuroscience Center & Department of Cell Biology, The Scripps Research Institute, 2Mouse Genetics Core Facility, The Scripps Research Institute

Generating induced pluripotent stem cell (iPSC) lines produces lines of differing developmental potential even when they pass standard tests for pluripotency. Here we describe a protocol to produce mice derived entirely from iPSCs, which defines the iPSC lines as possessing full pluripotency1.

Date Published: 11/29/2012, Issue 69; doi: 10.3791/4003

Keywords: Stem Cell Biology, Issue 69, Molecular Biology, Developmental Biology, Medicine, Cellular Biology, Induced pluripotent stem cells, iPSC, stem cells, reprogramming, developmental potential, tetraploid embryo complementation, mouse

Boland, M. J., Hazen, J. L., Nazor, K. L., Rodriguez, A. R., Martin, G., Kupriyanov, S., et al. Generation of Mice Derived from Induced Pluripotent Stem Cells. J. Vis. Exp. (69), e4003, doi:10.3791/4003 (2012).

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also produce a source of patient-matched cells for regenerative therapies. iPSCs may be generated using multiple protocols and derived from multiple cell sources. Once generated, iPSCs are tested using a variety of assays including immunostaining for pluripotency markers, generation of three germ layers in embryoid bodies and teratomas, comparisons of gene expression with embryonic stem cells (ESCs) and production of chimeric mice with or without germline contribution2. Importantly, iPSC lines that pass these tests still vary in their capacity to produce different differentiated cell types2. This has made it difficult to establish which iPSC derivation protocols, donor cell sources or selection methods are most useful for different applications.

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Generating Mice from Induced Pluripotent Stem Cells | Protocol

induced pluripotent stem cells – RCN Corporation

Stem cells are cells that divide by mitosis to form either

How the choice is made is still unknown. However, several genes have been found whose activity prevents a daughter cell from differentiating.

The only totipotent cells are the fertilized egg and the first 4 or so cells produced by its cleavage (as shown by the ability of mammals to produce identical twins, triplets, etc.).

In mammals, the expression totipotent stem cells is a misnomer totipotent cells cannot make more of themselves.

Three types of pluripotent stem cells occur naturally:

All three of these types of pluripotent stem cells

In mice and rats, embryonic stem cells can also:

Using genetic manipulation in the laboratory, pluripotent stem cells can now be generated from differentiated cells. These induced pluripotent stem cells (iPSCs) are described below.

Multipotent stem cells are found in adult animals; perhaps most organs in the body (e.g., brain, liver, lungs) contain them where they can replace dead or damaged cells. These adult stem cells may also be the cells that when one accumulates sufficient mutations produce a clone of cancer cells.

Examples:

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iPS cells and reprogramming: turn any cell of the body …

The discovery of iPS cells

In 2006, Shinya Yamanaka made a groundbreaking discovery that would win him the Nobel Prize in Physiology or Medicine just six years later: he found a new way to reprogramme adult, specialized cells to turn them into stem cells. These laboratory-grown stem cells are pluripotent they can make any type of cell in the body - and are called induced pluripotent stem cells, or iPS cells. Only embryonic stem cells are naturally pluripotent. Yamanakas discovery means that theoretically any dividing cell of the body can now be turned into a pluripotent stem cell.

So how are these iPS cells made? Yamanaka added four genes to skin cells from a mouse. This started a process inside the cells called reprogramming and, within 2 3 weeks, the skin cells were converted into induced pluripotent stem cells. Scientists can now also do this with human cells, by adding even fewer than four genes.

This short clip introduces the science behind reprogramming. View the full 16-minute film to see the whole story of Shinya Yamanaka's discovery.

IPS cells and embryonic stem cells are very similar. They are self-renewing, meaning they can divide and produce copies of themselves indefinitely. Both types of stem cell can be used to derive nearly any kind of specialized cell under precisely controlled conditions in the laboratory. Both iPS cells and embryonic stem cells can help us understand how specialized cells develop from pluripotent cells. In the future, they might also provide an unlimited supply of replacement cells and tissues for many patients with currently untreatable diseases.

In contrast to embryonic stem cells, making iPS cells doesnt depend on the use of cells from an early embryo. Are there any other differences? Current research indicates that some genes in iPS cells behave in a different way to those in embryonic stem cells. This is caused by incomplete reprogramming of the cells and/or genetic changes acquired by the iPS cells as they grow and multiply. Scientists are studying this in more detail to find out how such differences may affect the use of iPS cells in basic research and clinical applications. More research is also needed to understand just how reprogramming works inside the cell. So at the moment, most scientists believe we cant replace ES cells with iPS cells in basic research.

An important step in developing a therapy for a given disease is understanding exactly how the disease works: what exactly goes wrong in the body? To do this, researchers need to study the cells or tissues affected by the disease, but this is not always as simple as it sounds. For example, its almost impossible to obtain genuine brain cells from patients with Parkinsons disease, especially in the early stages of the disease before the patient is aware of any symptoms. Reprogramming means scientists can now get access to large numbers of the particular type of neurons (brain cells) that are affected by Parkinsons disease. Researchers first make iPS cells from, for example, skin biopsies from Parkinsons patients. They then use these iPS cells to produce neurons in the laboratory. The neurons have the same genetic background (the same basic genetic make-up) as the patients own cells. Thus scientist can directly work with neurons affected by Parkinsons disease in a dish. They can use these cells to learn more about what goes wrong inside the cells and why. Cellular disease models like these can also be used to search for and test new drugs to treat or protect patients against the disease.

Reprogramming holds great potential for new medical applications, such as cell replacement therapies. Since iPS cells can be made from a patients own skin, they could be used to grow specialized cells that exactly match the patient and would not be rejected by the immune system.If the patient has a genetic disease, the genetic problem could be corrected in their iPS cells in the laboratory, and these repaired iPS cells used to produce a patient-specific batch of healthy specialized cells for transplantation. But this benefit remains theoretical for now.

Until recently, making iPS cells involved permanent genetic changes inside the cell, which can cause tumours to form. Scientists have now developed methods for making iPS cells without this genetic modification. These new techniques are an important step towards making iPS-derived specialized cells that would be safe for use in patients. Further research is now needed to understand fully how reprogramming works and how iPS cells can be controlled and produced consistently enough to meet the high quality and safety requirements for use in the clinic.

February 2013 Nature news article on planned clinical trial using iPS cells Stem cells the future: an introduction to iPS cells Research into reprogrammed stem cells: an interactive timeline Stem cell school - multimedia learning module on cellular reprogramming Alzheimer Research Forum 4-part article on iPS cells and disease (September 2010) Nature news feature on challenges in the iPS field (May 2011)

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Induced Pluripotent Stem Cells (iPS) | UCLA Broad Stem …

iPSC are derived from skin or blood cells that have been reprogrammed back into an embryonic-like pluripotent state that enables the development of an unlimited source of any type of human cell needed for therapeutic purposes. For example, iPSC can be prodded into becoming beta islet cells to treat diabetes, blood cells to create new blood free of cancer cells for a leukemia patient, or neurons to treat neurological disorders.

In late 2007, a BSCRC team of faculty, Drs. Kathrin Plath, William Lowry, Amander Clark, and April Pyle were among the first in the world to create human iPSC. At that time, science had long understood that tissue specific cells, such as skin cells or blood cells, could only create other like cells. With this groundbreaking discovery, iPSC research has quickly become the foundation for a new regenerative medicine.

Using iPSC technology our faculty have reprogrammed skin cells into active motor neurons, egg and sperm precursors, liver cells, bone precursors, and blood cells. In addition, patients with untreatable diseases such as, ALS, Rett Syndrome, Lesch-Nyhan Disease, and Duchenne's Muscular Dystrophy donate skin cells to BSCRC scientists for iPSC reprogramming research. The generous participation of patients and their families in this research enables BSCRC scientists to study these diseases in the laboratory in the hope of developing new treatment technologies.

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Pluripotency of Induced Pluripotent Stem Cells

Volume 11, Issue 5, October 2013, Pages 299303

Special Issue: Induced Pluripotent Stem Cells

Edited By Qi Zhou

Induced pluripotent stem (iPS) cells can be generated by forced expression of four pluripotency factors in somatic cells. This has received much attention in recent years since it may offer us a promising donor cell source for cell transplantation therapy. There has been great progress in iPS cell research in the past few years. However, several issues need to be further addressed in the near future before the clinical application of iPS cells, like the immunogenicity of iPS cells, the variability of differentiation potential and most importantly tumor formation of the iPS derivative cells. Here, we review recent progress in research into the pluripotency of iPS cells.

Induced pluripotent stem (iPS) cells can be derived from mouse somatic cells via the ectopic expression of four defined factors, Oct4, Sox2, Klf4 and c-Myc (also known as Yamanaka factors) [1]. The mouse iPS cells express pluripotency markers and both X chromosomes are reactivated, allowing differentiation into various cell types of three germ layers when injected into a blastocyst. iPS technology makes reprogramming much easier [2]and[3] in comparison to early reprogramming methods such as somatic cell nuclear transfer (SCNT) [4]and[5], iPS technology also circumvents the ethical problems arising from the use of human oocytes. In addition, the generation of patient-specific iPS cells could be used to screen new drugs [6]and[7]. However, there are currently several limitations in applying iPS cells clinically. Efficiency of converting somatic cells to iPS cells is still very low. In particular, only approximately 0.1% to 1% of somatic cells experience changes at the transcriptional level and finally become pluripotent stem cells when non-integration approaches are used [8]. Moreover, compared to embryonic stem (ES) cells, the developmental potential and differentiation capacity of iPS cells is significantly reduced and there is increased variability among all iPS cell lines [9]. In mice, only small proportions of these cells are fully reprogrammed based on the most stringent tetraploid complementation assay for evaluating pluripotency [10], [11], [12]and[13]. Therefore, it is necessary to establish a strict molecular standard system to distinguish fully reprogrammed iPS cells from those partially reprogrammed, as we currently lack suitable in vivo pluripotency tests for human iPS cells.

In this review, we mainly focus on recent progress on rodent, non-human primate and human iPS cells, and point out some key questions which need to be addressed in the near future, such as the pluripotency level of human iPS cells and the establishment of a new standard to assess the pluripotency level of human iPS cells.

Takahashi and Yamanaka reprogrammed mouse embryonic fibroblasts by the ectopic expression of four reprogramming factors using retroviral vectors, and finally produced iPS cells which resemble ES cells [1]. This original iPS reprogramming approach used viral vectors, including retrovirus and lentivirus which possess high reprogramming efficiency [14]and[15]. The genome may be mutated by integrating other gene sequences, thus raising concerns on the safety issue. In addition, the insertion of oncogenes, like c-Myc, increases the risk of tumor formation [16]and[17]. Subsequently, several modified methods were used to obtain much safer iPS cells, for instance, piggyBac transposon [18], adenovirus [19], sendai virus [20], plasmid [21], episomal vectors [22] and minicircle vectors [23]. However, the reprogramming efficiency is significantly decreased and it takes longer to reactivate the key pluripotency markers to achieve full reprogramming. Therefore, efficient generation of non-integrated iPS cells by new approaches may promote their clinical application.

Recent studies have described several reprogramming methods using proteins, RNAs and small-molecule compounds to derive safe iPS cells [24], [25]and[26]. Zhou et al. obtained iPS cells induced by recombination of the proteins of the four Yamanaka factors obtained by fusing the C-terminus of the proteins with poly-arginine (11R) [24]. A recent study reported that mouse and human iPS cells can be efficiently generated by miRNA mediated reprogramming [25]. Miyoshi et al. [26] successfully generated iPS cells by direct transfection of human somatic cells using mature miRNA. iPS cells can also be generated by synthetic RNAs, which bypass the innate response to viruses [27]. Recently, Houet et al. [28] showed that pluripotent stem cells can be generated from mouse somatic cells at an efficiency of 0.2% by using a combination of seven small-molecule compounds. Compared to traditional viral methods, the aforementioned approaches can be used to generate qualified iPS cells (Table 1) without the risk of insertional mutagenesis. Nonetheless, some familiar drawbacks exist, such as a longer and less efficient reprogramming process. In other words, what we need to do next is to optimize non-integration induction systems in order to resolve these drawbacks.

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Pluripotency of Induced Pluripotent Stem Cells

Induced stem cells – Wikipedia, the free encyclopedia

Induced stem cells (iSC) are stem cells artificially derived from somatic, reproductive, pluripotent or other cell types by deliberate epigenetic reprogramming. They are classified as either totipotent (iTC), pluripotent (iPSC) or progenitor (multipotentiMSC, also called an induced multipotent progenitor celliMPC) or unipotent -- (iUSC) according to their developmental potential and degree of dedifferentiation. Progenitors are obtained by so-called direct reprogramming or directed differentiation and are also called induced somatic stem cells.

Three techniques are widely recognized:[1]

Back in 1895, Thomas Morgan remove one of the two frog blastomeres and found that amphibians are able to form whole embryo from the remaining part. This meant that the cells can change their differentiation pathway. Later, in 1924, Spemann and Mangold demonstrated the key importance of cellcell inductions during animal development.[20] The reversible transformation of cells of one differentiated cell type to another is called metaplasia.[21] This transition can be a part of the normal maturation process, or caused by an inducing stimulus. For example: transformation of iris cells to lens cells in the process of maturation and transformation of retinal pigment epithelium cells into the neural retina during regeneration in adult newt eyes. This process allows the body to replace cells not suitable to new conditions with more suitable new cells. In Drosophila imaginal discs, cells have to choose from a limited number of standard discrete differentiation states. The fact that transdetermination (change of the path of differentiation) often occurs for a group of cells rather than single cells shows that it is induced rather than part of maturation.[22]

The researchers were able to identify the minimal conditions and factors that would be sufficient for starting the cascade of molecular and cellular processes to instruct pluripotent cells to organize the embryo. They show that opposing gradients of bone morphogenetic protein (BMP) and Nodal, two transforming growth factor family members that act as morphogens, are sufficient to induce molecular and cellular mechanisms required to organize, in vivo or in vitro, uncommitted cells of the zebrafish blastula animal pole into a well-developed embryo.[23]

Some types of mature, specialized adult cells can naturally revert to stem cells. For example, "chief" cells express the stem cell marker Troy. While they normally produce digestive fluids for the stomach, they can revert into stem cells to make temporary repairs to stomach injuries, such as a cut or damage from infection. Moreover, they can make this transition even in the absence of noticeable injuries and are capable of replenishing entire gastric units, in essence serving as quiescent reserve stem cells.[24] Differentiated airway epithelial cells can revert into stable and functional stem cells in vivo.[25]

After injury, mature terminally differentiated kidney cells dedifferentiate into more primordial versions of themselves, and then differentiate into the cell types needing replacement in the damaged tissue[26] Macrophages can self-renew by local proliferation of mature differentiated cells.[27] In newts, muscle tissue is regenerated from specialized muscle cells that dedifferentiate and forget the type of cell they had been. This capacity to regenerate does not decline with age and may be linked to their ability to make new stem cells from muscle cells on demand.[28]

A variety of nontumorigenic stem cells display the ability to generate multiple cell types. For instance, multilineage-differentiating stress-enduring (Muse) cells are stress-tolerant adult human stem cells that can self-renew. They form characteristic cell clusters in suspension culture that express a set of genes associated with pluripotency and can differentiate into endodermal, ectodermal and mesodermal cells both in vitro and in vivo.[29][30][31][32][33]

Other well-documented examples of transdifferentiation and their significance in development and regeneration were described in detail.[34]

Induced totipotent cells can be obtained by reprogramming somatic cells with somatic-cell nuclear transfer (SCNT). The process involves sucking out the nucleus of a somatic (body) cell and injecting it into an oocyte that has had its nucleus removed[3][5][35][36]

Using an approach based on the protocol outlined by Tachibana et al.,[3] hESCs can be generated by SCNT using dermal fibroblasts nuclei from both a middle-aged 35-year-old male and an elderly, 75-year-old male, suggesting that age-associated changes are not necessarily an impediment to SCNT-based nuclear reprogramming of human cells.[37] Such reprogramming of somatic cells to a pluripotent state holds huge potentials for regenerative medicine. Unfortunately, the cells generated by this technology, potentially are not completely protected from the immune system of the patient (donor of nuclei), because they have the same mitochondrial DNA, as a donor of oocytes, instead of the patients mitochondrial DNA. This reduces their value as a source for autologous stem cell transplantation therapy, as for the present, it is not clear whether it can induce an immune response of the patient upon treatment.

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Induced stem cells - Wikipedia, the free encyclopedia

Induced Pluripotent Stem Cells (IPSCs) – HowStuffWorks

Save Those Teeth

Dentists usually discard wisdom teeth after they've been extracted -- but maybe they should start saving them; they just might be useful in make stem cells. Recently, a group of Japanese scientists made induced pluripotent stem cells (IPSCs) from the tooth pulp of extracted wisdom teeth. They used viruses to deliver stem cell factors to mesenchymal stromal cells isolated from the pulp of third molars. The resulting IPSCs were similar to embryonic stem cells.

In 2003, an NIH researcher, Sangtao Shi, extracted stem cells from his daughter's baby teeth. The stem cells grew in culture and could form bone when implanted into mice. Potentially, you could bank stem cells from your teeth for future use, but it would be an expensive process.

Maybe that's what the tooth fairy does with all those teeth?

Whether from embryos or adult tissues, stem cells are few. But many are needed for cell therapies. There have been ethical and political problems with using embryonic stem cells -- so if there were a way to get more stem cells from adults, it might be less controversial. Enter the IPSC.

Every cell in the body has the same genetic instructions. So what makes a heart cell different from a liver cell? The two cells express different sets of genes. Likewise, a stem cell turns on specific sets of genes to differentiate into another cell. So, is it possible to reprogram a differentiated cell so that it reverts back to a stem cell? In 2006, scientists did just that. They used a virus to deliver four stem cell factors into skin cells. The factors caused the differentiated stem cells to go into an embryonic-stem-cell-like state. The resulting cells, called induced pluripotent stem cells (IPSCs), shared many characteristics with human embryonic stem cells. The structures of IPSCs were similar, they expressed the same markers and genes, and they grew the same. And the researchers were able to grow the IPSCs into cell lines.

There are many more differentiated cells in the human body than stem cells, embryonic or adult. So, vast amounts of stem cells could be made from a patient's own differentiated cells, like skin cells. Making IPSCs does not involve embryos, so this would circumvent the ethical and political issues involved in stem cell research. However, making ISPSCs is a recent development, so scientists need to do more research before they can be used for therapies. First, we need to understand the "reprogramming" process better. And then we need to investigate whether IPSCs are just similar enough or are actually identical to embryonic stem cells. Current research is focused on these questions, but reprogramming cells to make IPSCs has great potential.

Now that you have a good idea of what stems cells are and how they work, let's see how they can be used to treat diseases.

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Induced Pluripotent Stem Cells (IPSCs) - HowStuffWorks

piggyBac transposition reprograms fibroblasts to induced …

Transgenic expression of just four defined transcription factors (c-Myc, Klf4, Oct4 and Sox2) is sufficient to reprogram somatic cells to a pluripotent state. The resulting induced pluripotent stem (iPS) cells resemble embryonic stem cells in their properties and potential to differentiate into a spectrum of adult cell types. Current reprogramming strategies involve retroviral, lentiviral, adenoviral and plasmid transfection to deliver reprogramming factor transgenes. Although the latter two methods are transient and minimize the potential for insertion mutagenesis, they are currently limited by diminished reprogramming efficiencies. piggyBac (PB) transposition is host-factor independent, and has recently been demonstrated to be functional in various human and mouse cell lines. The PB transposon/transposase system requires only the inverted terminal repeats flanking a transgene and transient expression of the transposase enzyme to catalyse insertion or excision events. Here we demonstrate successful and efficient reprogramming of murine and human embryonic fibroblasts using doxycycline-inducible transcription factors delivered by PB transposition. Stable iPS cells thus generated express characteristic pluripotency markers and succeed in a series of rigorous differentiation assays. By taking advantage of the natural propensity of the PB system for seamless excision, we show that the individual PB insertions can be removed from established iPS cell lines, providing an invaluable tool for discovery. In addition, we have demonstrated the traceless removal of reprogramming factors joined with viral 2A sequences delivered by a single transposon from murine iPS lines. We anticipate that the unique properties of this virus-independent simplification of iPS cell production will accelerate this field further towards full exploration of the reprogramming process and future cell-based therapies.

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Embryonic and induced pluripotent stem cells Part 1 – Video

Embryonic and induced pluripotent stem cells Part 1
In this video we discuss embryonic and induced pluripotent stem cells. Topics discussed include the origins of cell specialization, the master transcription regulators of pluripotency and the...

By: Ben Garside

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Embryonic and induced pluripotent stem cells Part 1 - Video