2.2 development of CSC Theory
CSC concept originated through a rare gonadal malignancy termed an embryonal carcinoma (EC). Together far back as the late 1800s, pathologists had explained ECs together a disorganized caricature of the tissues (endoderm, mesoderm, and also ectoderm) of very early stage embryo. This resulted in the postulation the ECs may develop from a pluripotent cabinet in a parallel fashion come the embryo. By the 1960s, single EC cell (ECCs) had been isolated and also shown to be qualified of reproducing their original malignancy in xenograft models <11>. Through the 1980s, pluripotent ECCs had been arisen into what was in impact the an initial CSC cell society model <12–16>, return the “CSC” term to be not used at the time. Cell from a well-differentiated EC termed a “teratocarcinoma” could be preserved in the SR state in society and readily identified by the addition of all-trans retinoic acid (ATRA) <16>. In parallel, bone marrow research had actually attracted an extensive interest following the destructive effects of the 1945 nuclear strikes in Japan. Comprehensive progress to be made in understanding bone marrow stem cell (HSCs and MSCs), which eventually led to the identification of Leukemia SCs (LSCs) in 1997, as soon as the term “CSC” was coined <17,18>. At this point, however, it was no clear whether CSCs were affiliated in other malignancies.
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The “Coming that Age” because that CSC concept arrived in 2001 v the publishing of the critical Reya et al. Review short article <19>. For the very first time, CSC concept was linked into a single concept after i m sorry CSC Theory came to be widely respected if no universally accepted. CSC concept is based top top the monitoring that some, if not all, malignancies are initiated and driven by a subpopulation that cells the behave akin come SCs <19,20>. The principle implication native CSC concept was the targeting malignancy en masse need to be complimented with particular targeting the CSC populations <19>. For example, whereby a single CSC stayed postintervention, CSC theory holds the this is enough to describe recurrence. Through 2001, it to be clear that CSC targeting had actually to be arisen to enhance existing cancer targeting strategies. However, prior to CSCs from specific malignancies can be understood, they very first had to be identified, isolated, and also studied.
Joseph Feher, in Quantitative person Physiology (Second Edition), 2017
The Cell theory Is a Unifying rule of Biology
The cabinet theory claims that all biological organisms are composed of cells; cells space the unit that life and also all life come from preexisting life. The cell theory is so developed today the it develops one the the unifying principles of biology.
The word cell was very first used by Robert Hooke (1635–1703) as soon as he looked at cork with a basic microscope and also found what appeared to be block of material making up the cork. The term today defines a microscope unit that life that separates chin from its next site by a thin partition, the cell membrane.
Most biologists think that life occurred spontaneously from meaningless matter, however the details of exactly how this can have happened remain unknown, and the time scale was long. Rudolf Virchow, a German pathologist (1821–1902), famously wrote “omnis cellula e cellula”—all cell come from other cells—meaning that spontaneous generation the living things from inanimate matter does not occur over periods as quick as ours lifetimes.
Michael G. Palmgren, in breakthroughs in botanical Research, 1998
1 Stimuli that activate/inhibit the plasma membrane H+-ATPase
In theory, cells can rapidly and also reversibly change solute transport prices by transforming the kinetics of transport proteins resides in the plasma membrane, e.g. Vmax, Km for ATP and pH dependency (Fig. 9). The fast nature of most of the results on H+ extrusion and membrane hyperpolarization observed argues that a readjust in activity of the plasma membrane H+-ATPase might be a most likely mechanism.
A couple of examples are recognized where exterior stimuli an outcome in rapid transforms in the kinetic properties of H+-ATPase positioned in the membrane. Plasma membrane H+-ATPase in membrane vesicles isolated from NaCl-adapted tobacco cells has higher affinity for ATP than in those native unadapted cell (Reuveni et al., 1993). These data indicate that, in an answer to salt stress, the kinetic properties of the plasma membrane H+-ATPase are transformed by post-transcriptional modification of the enzyme. Similarly, complying with mechanical stimulation of Bryonia dioica intemodes (Bourgeade and Boyer, 1994) and application of the fungal toxin fusicoccin to tree tissues (see below), the plasma membrane H+-ATPase affinity for ATP increases.
Michael Campoli, ... Xinhui Wang, in advances in Cancer Research, 2010
d Expression on CSC in Basal chest Carcinoma, SCCHN, and also Melanoma
According to the CSC theory, the failure of current cancer therapies to abrogate recurrence and also metastasis reflects their inability to adequately target CSC (Lobo et al., 2007; Visvader and Lindeman, 2008). In this regard, CSC are characterized by their magnified chemo- and also radioresistance and high tumorigenicity in immunodeficient mice and also play an essential role in tumor maintenance and progression. The main role CSC play in tumor maintenance and progression has actually emphasized the need to build novel therapeutic methods to eradicate CSC for successful treatment the malignant disease. The attention in applying immunotherapy to target CSC and the potential the CSPG4 together a target that immunotherapy has actually prompted investigations to identify whether CSPG4 is express on CSC. As we have actually recently explained (Wang et al., 2010a,b), in SCCHN and in basal chest cancer, CSPG4 is express on CSC, identified by the high expression the aldehyde dehydrogenase 1 family members member A1 (ALDH1), a i decide enzyme responsible for the oxidation of intracellular aldehyde. In melanoma, the assessment of CSPG4 expression on CSC has to be addressed with caution given the conflicting information around the identification of CSC in this disease. The mite reported to identify CSC include the ATP-Binding Cassette Subfamily B member 5 (ABCB5), CD133, CD271, nestin, and JARIDB (Boiko et al., 2010; Klein et al., 2007; Monzani et al., 2007; Roesch et al., 2010; Schatton et al., 2008). The validity of this markers to recognize CSC in melanoma has been wondered about by Quintana et al. (2008) who have actually reported that melanoma does not follow a CSC model and also that tumorigenic potential is generally present in all melanoma cells. This authors as well as Clarke et al. (2006) have actually reported that the tumorigenicity the melanoma cell in immunodeficient mice, which represents the conventional assay to evaluate tumor self-renewal, is affected by several variables. Among them space the term of the xenotransplantation assay and the degree of immunodeficiency the the mouse strain supplied for the xenotransplantation experiments. This variables are most likely to pat a role in the various results released in the literature.
At present, that is an overwhelming to advice the validity the the markers reported in the literary works to determine CSC in melanoma, since with very couple of exceptions, reagents have not to be exchanged among laboratories and couple of studies have attempted come reproduce results acquired in other laboratories, utilizing the experimental problems described in the original publication. Come the ideal of our knowledge, just Shackleton and also Quintana (Shackleton and also Quintana, 2010) have actually reported to have actually not been able to reproduce the results freshly published through Weissman and also his associates (Boiko et al., 2010). Specifically, the CD271+ cell subpopulation isolated from surgically removed melanoma lesions was not enriched in tumorigenic potential. However, this comparison needs to be construed with caution, due to the fact that the experimental conditions used in the two researches were various in regards to tumor cradle protocol, mice provided for xenotransplantation, and also anatomic site offered for injection the melanoma cells. For this reason far, we have been unable to confirm the specificity that the ABCB5-specific mAb supplied by open minded et al. (2003; Schatton et al., 2008) to determine melanoma CSC. Clearly there is debate as to whether the CSC theory deserve to account for melanoma cabinet heterogeneity and also to whether melanomas room organized into subpopulations that tumorigenic and also nontumorigenic cells. In stimulate to administer an explanation for the absence of reproducibility of CSC studies in melanoma, Herlyn and his associates (Roesch et al., 2010) have actually redefined the function of melanoma CSC as cells capable of continuously keeping a tumor cell population but not capable of tumor initiation. Studies aimed in ~ comparing the markers as well as the reagents and also techniques utilized to determine CSC space unmistakably needed to an ext appropriately define and also characterize tumor cell populaces in melanoma. In our experience, melanoma cells that express both ABCB5 and high levels of ALDH1A1 satisfy the criteria to be classified together CSC, due to the fact that they are tumorigenic at short numbers in SCID mice. These cells demonstrate CSPG4 expression. It is remarkable that, back the identification of CSC in melanoma is still an open up question, CSPG4 is much more than most likely to it is in expressed on this cells provided its expression on more than 95% of cells in melanoma cell lines and in melanoma cell populations isolated from surgically eliminated primary and metastatic lesions.
Jessica Wright, in development in brain Research, 2018
Ventricular localization, or cell theory, is very first attested in Christian texts of the fourth and fifth century CE. That remained leading in learned medicine until the seventeenth century. Contrary to typical representation, the earliest thinkers of ventricular localization were no trying to displace the faculties of the rational heart from the problem of the mind to the empty spaces and also spirit within. Rather, they considered the substance and also structure that the brain vital come the operations of the soul. Late antique account of ventricular localization envision the ventricles as “instruments” of the soul. These tools are finest imagined through the old figure of the lyre, together hollow structures that resonate v the i of air and also the motion of strings, or nerves.
Serdar E. Bulun, in Williams Textbook of Endocrinology (Thirteenth Edition), 2016
Two-Cell concept for Ovarian Steroidogenesis
The classic two-cell concept is supported by molecular findings. Ovarian steroidogenesis in the preovulatory follicle takes location through LH receptor on theca cells and FSH (possibly likewise LH) receptor on granulosa cells (see Fig. 17-17). CAMP production and also increased SF1 (product that the NR5A1 gene) binding to multiple steroidogenic promoters mediate LH activity in theca cells.102 The STAR protein is the main regulator of production of androstenedione, which consequently diffuses right into granulosa cells to serve as the estrogen precursor.93 In the preovulatory follicle, cholesterol in theca cell arises from circulating lipoproteins and de novo biosynthesis. FSH is responsible for follicular growth and also estrogen formation. FSH induces cAMP formation, activation the protein kinase A and particular MAP kinases, and also increased binding activity of LRH1 or SF1 to the CYP191A1 promoter in preovulatory granulosa cells to type estrone and also then estradiol mostly through aromatization that androstenedione (see Fig. 17-17). The loved one roles the SF1 and also LRH1 in estrogen formation in human ovarian granulosa cells are not well understood.102
In the corpus luteum, big deposits the cholesterol (which provide the yellow color) arise mainly from turn around lipoproteins to support the manufacturing of extremely high quantities of progesterone.103 Other key anatomic events in formation of the corpus luteum room the disruption that the basement membrane between the granulosa and also theca cells and strikingly increased vascularization of granulosa-lutein cell (see Fig. 17-15). Theca-lutein cell possess LH receptors and also produce androstenedione. CAMP, SF1, and STAR induced by LH stay as the an essential regulators because that biosynthesis that androstenedione, which serves together the estrogen precursor in neighboring granulosa-lutein cell (see Fig. 17-17).
The granulosa-lutein cell of the corpus luteum is anatomically and functionally various from its equivalent in the preovulatory follicle in number of ways. First, this cells are characterized by big and granular cytoplasms, are greatly vascularized, and also contain big quantities of cholesterol. Second, granulosa-lutein cells contain high levels of LH receptor in enhancement to FSH receptors. Third, castle produce large quantities that progesterone; this role is regulated mainly by LH and also STAR. Granulosa-lutein cells likewise aromatize androstenedione that thecal origin and also eventually provide rise to estradiol formation through FSH action and CYP19A1. The known mediators that LH and also FSH in person granulosa-lutein cells are cAMP and also increased LRH1 levels.102,103 The family member roles the LRH1 and SF1 because that progesterone and estradiol manufacturing in granulosa-lutein cells space not clear. Particular functions of the two gonadotropins (i.e., differentiation, growth, and progesterone matches estradiol formation) are probably determined by countless modifying determinants (see Fig. 17-17).
Ibrahim Sammour, in Encyclopedia of tissue Engineering and Regenerative Medicine, 2019
Since their recognition as cornerstones in cabinet theory, stem cells have sparked a most interest in scientists in the areas of biology, cytology, and also medicine. This unique group of cells through their self-renewal and differentiation ability are necessary for the presence of cell-based life-forms together we know it. Castle have permitted us to explore the mechanisms underlying embryologic development, organ formation, and also have noted life-saving therapies such as bone marrow transplantation. These cells likewise have the potential to help build the therapeutic foundation upon which regenerative medication is being built. This testimonial represents a beginning point concerning the history of stem cells, your characteristics, classification, and sources.
In foundations of modern-day Biochemistry, 1995
The period of classical Microscopy: ca. 1840-1940
The fall and also resurrection of the cell theory were the evaluation in chapter 2. Under the microscope the cell nucleus of the cell to be its most influential feature; its border was assumed to it is in delineated by a membrane v the room between fill by a homogeneous transparent liquid which can contain granules (Schwann, 1839). Thomas Huxley in 1850 explained the cell together a nucleus and protoplasm surrounded by a membrane (periplast), although the visibility of a membrane chemically differentiated from the protoplasm was no universally accepted. Words “protoplasm” is thought to have actually been used very first by Purkinje (1839) to describe matter possessing a molecular constitution permitting it to manifest life—a an interpretation posing the question “which cell constituents to be alive? by 1850 Ferdinand Cohn had actually recognized the the protoplasm most generally observed in plant cells must have properties similar to the contractile substance, sarcode, in animal cells. Protoplasm to be the primary location of “life as action.”
Virchow, that was largely responsible because that the acceptance of the cell theory, arisen microscopy of cells from normal and diseased tissues together a major tool (histopathology) in the clinical armory. He believed the an essential functions of the cell, growth, maintenance, and also multiplication were discharged through its nucleus; the specialised, differentiating functions to be made possible by the extranuclear constituents. In a Sunday evening lecture in Edinburgh in 1868, “On the Physical basis of Life”, cutting board Huxley defined cells as protoplasmic masses usually furnished through nuclei. Cells to be the constitutive elements of plants and animals. Protoplasm to be semifluid, contractile (vital), albumoid, coagulable (protein), and self-replicatory—the physical basis of life.
Problems end the an interpretation of “protoplasm” ended up being increasingly acute as more intracellular inclusions came to be visible. Kollicker in the middle of the nineteenth century defined granules in muscle (sarcosomes); components of the mitotic apparatus were likewise seen together were fat droplets, starch granules, and also pigmented bodies. The Golgi device was defined in 1898 and also mitochondria in 1903 (Benda). Countless of these bodies multiplied and also divided apparently synchronously with the division of the cell. Pfluger thought about protoplasm to it is in a gigantic molecule whose next chains were affiliated in assimilation and also oxidation. Fermentation was a role of protoplasm together a whole. In 1875 he defined life as “intracellular warmth” i m sorry was produced by oxidative disruption the “giant albumen molecules” which might multiply with polymerization. Ideas around protein structure were tho constrained by the colloid concept (Chapter 10).
By the early on years that this century the cabinet was generally recognized as the the smallest unit qualified of live independence life. Gowland Hopkins in 1913 first clearly formulated ideas which would certainly be the death of “protoplasm.” “Life is the expression the a certain dynamic equilibrium i beg your pardon obtains in polyphasic equipment … life is a residential property of the cell together a whole.”
Larry W. Swanson, in fundamental Neuroscience (Fourth Edition), 2013
The Nerve net is the Simplest kind of concerned System
In his provocative 1919 book The Elementary nervous System, George Parker outlined a reasonable script for just how nervous systems evolved. An updated version starts with the an initial multicellular animals—similar to modern sponges—that emerged over half a billion year ago. They are seemingly amorphous animals that spend their adult resides immobile, submerged in water. Their relatively simple actions is mediated largely by a collection of primitive smooth muscle cell (myocyte) sphincters regulating water flow through body wall surface pores. These committed cells are called independent effectors due to the fact that their convulsion is evoked by stimuli like stretch or environmental chemicals acting directly on the plasma membrane of separation, personal, instance cells.
The first animal phylum through a nervous device was the Cnidaria, which has jellyfish, corals, sea anemones, and also the elegantly basic hydra. In contrast to sponges, hydra locomote and also show energetic feeding habits (Fig. 2.1). These actions are coordinated and mediated by a worried system, a network of dedicated units or cells referred to as nerve cell or neurons (Box 2.1).
The cell theory, which says that all organisms are composed of individual cells, to be developed roughly the middle of the nineteenth century through Mattias Schleiden and also Theodor Schwann. However, this unitary vision of the to move nature the life was not immediately applied to the nervous system, as most biologists at the time thought in the cytoplasmic continually of nervous device cells. Later in the century, the most significant advocate of this reticularist view was Camillo Golgi, that proposed that axons entering the spinal cord in reality fuse with other axons (Fig. 2.2A). The reticularist view was tested most extensively by Santiago Ramón y Cajal, a founder of modern neuroscience and without doubt the biggest observer that neuronal architecture. In beautifully written and also carefully reasoned deductive arguments, Cajal gift us through what is now recognized as the neuron doctrine. This an excellent concept in essence states the the cabinet theory applies to the nervous system: each neuron is an separation, personal, instance entity, the an easy unit that neural circuitry (Fig. 2.2B). The acrimonious debate in between reticularists and proponents of the neuron theory raged because that decades. Over the years, the validity that the neuron doctrine has been supported by a wide range of accumulated data. Nevertheless, the reticularist check out is not completely incorrect, since some neurons perform act syncytially via dedicated intercellular gap junctions, a function that is an ext prominent throughout embryogenesis.
In 1897, Charles Sherrington postulated that neurons establish functional contact with one another and also with various other cell species via a theoretical framework he dubbed the synapse (Greek synaptein, to fasten together). It to be not until 50 years later that the structural existence of synapses was prove by electron microscopy (see Fig. 3.3). The synaptic complex is built roughly an adhesive junction, and also in this and other respects the complex is quite comparable to the desmosome and the adherens junctions the epithelia. In fact, similarities in ultrastructure between the adherens junction and also the synaptic facility of main nervous organization were noted even in beforehand electron microscopic researches (see Peters, Palay, & Webster, 1991).
Hydra's body wall is simple, through an outer ectoderm great contacting the outside environment, an inside endoderm layer facing the human body cavity's interior environment and also promoting digestion and also waste elimination, and also a vague center or meso layer in between. Neurons probably differentiated initially from the ectoderm, and perhaps the an initial to evolve were sensory neurons. One cytoplasmic expansion of these bipolar cells dealing with the external environment became committed to recognize stimuli lot weaker than those activating independent effectors, vice versa, the various other pole became specialized to transmit information about these stimuli come a group of elevation effectors (Fig. 2.3). Experimental proof indicates that sensory neurons administer four significant selective benefits in evolution:•
Increased stimulus sensitivity•
Faster effector cell responses•
Stronger behavior responses because multiple effector cells space influenced•
Sensory neurons responding to various stimulus modalities can be dispersed strategically in various body regions
Figure 2.3. Activation the effector cell (e) in an easy animals. (A) Sponges absence a worried system; stimuli act directly on effector cells, which space thus dubbed independent effectors. (B) In cniderians, bipolar sensory neurons (s) differentiate in the ectoderm. The sensory neuron outer extension detects stimuli and is therefore a dendrite. The inner expansion of part sensory neurons transmits information straight to effector cells and is therefore an axon. Since this type of sensory neuron innervates effector cells directly, it is in reality a sensorimotor neuron. (C) many cniderian sensory neurons send their axon to motoneurons (m), which in turn send one axon to effector cells. Cniderian motoneurons may additionally have lateral extensions connecting with other motoneurons, and also these extensions commonly conduct info in either direction via mutual chemical synapses (and are for this reason amacrine extensions). Arrows show the direction of details flow.
The bipolar form of sensory neurons is basically important. The prototypical theory around neural circuit company was presented by Santiago Ramón y Cajal in his standard “bible” of structure neuroscience, The Histology that the Nervous system in Man and Vertebrates (1909–1911). Follow to the cornerstone functional polarity theory, information usually flows in one direction through most neurons, and also thus through most neural circuits—from dendrites and also cell body, the input or receptive components of the neuron, come a solitary axon, the calculation or effector part. In other words, most neurons have two class of cytoplasmic extensions: one or more dendrites detecting inputs and a single axon conducting an calculation that have the right to influence many cells through branching or collateralization. At the very least in early on developmental stages, all sensory neurons have actually this an essential bipolar shape, and over the course of advancement they have become devoted to recognize a remarkable range of stimuli indigenous light, temperature, and also a wide range of chemicals and ions, to vibration and also other mechanical deformations.Motor Neurons
A second stage of differentiation or intricacy in hydra's nervous device was the addition of neurons between sensory and also effector. Lock are characterized as motor neurons (motoneurons) because they straight innervate effector cells (usually muscle or gland cells), which in turn receive their inputs from sensory neurons (Figs. 2.2B, 2.3C). Conceptually, this offers a two-layered nervous system, with the an initial or top layer having sensory neurons, and also the 2nd or bottom layer having actually motor neurons. In this prototypical network sensory neurons job (send axon collaterals) come multiple motoneurons, and then every motoneuron innervates a set of effector cell (with a motoneuron and also its effector cell collection defined together a motor unit). Throughout an animal's typical behavior, information flow is unidirectional or polarized from one cell type, sensory neuron, to one more cell type, motoneuron, to a 3rd cell type, effector. This is the basic an interpretation of a straightforward reflex, as identified by Charles Sherrington in his cornerstone of equipment neuroscience, The Integrative activity of the worried System (1906).
In this theoretical scenario (Fig. 2.3) an eco-friendly stimulus recognize by a sensory neuron's dendrite is sent by its axon come the dendrites that a motoneuron population. Climate the axon of every motoneuron innervates one effector cell population. This is the sensible polarity rule used to a simple two-layer, sensory-motor network mediating reflex behavior.
Another general attribute of the hydra two-layered nervous system has been observed: sensory neurons do not innervate one another, conversely, motoneurons do interact directly. Here, motoneurons have actually two estimate classes: one come effector cells and another to other motoneurons. Structurally and also functionally, countless of this hydra motoneurons likewise have two types of calculation extensions. One is a common axon innervating an effector cell population. However, the other is an expansion that contacts homologous expansions from various other motoneurons. Interestingly, countless of this “tangential” extensions between motoneurons transmit details in either direction; one of two people motoneuron deserve to transmit info to the other via this extensions. This is an exception to the sensible polarity rule and also is mediated by reciprocal quite than the more common unidirectional synapses. Cajal (1909–1911) described several instances of neurons that absence a clear axon (in retina, olfactory bulb, and intestine) and called lock amacrine cells. Together an extension of this, that is advantageous to division neuronal expansions into three types: dendritic (input), axonal (output), or amacrine (bidirectional).
Adding a second layer come the nervous device has apparent adaptive benefits related to increased capacity for solution complexity and integration. Think about a economic stimulation to one specific part of the animal or also one sensory neuron. Its influence may radiate to distant parts the the animal because one sensory neuron innervates multiple motoneurons, those motoneurons innervate added motoneurons, and also each motoneuron innervates lot of effector cells—an instance of what Cajal dubbed “avalanche conduction.” There may be an excellent divergence in between stimulus and effector cells producing a response, with the actual aberration pattern shaped by the structure–function architecture of the worried system: exactly how the neurons and also their interconnections space arranged in the body. It is easy to imagine exactly how this arrangement in hydra can coordinate the tentacles to carry a food morsel detected by just one of them come the mouth or exactly how it could coordinate locomotion (Fig. 2.1).
A 2nd basic an effect of this structural arrangement is info convergence in the nervous system. Just take into consideration a certain motoneuron: it can receive input from more than one sensory neuron and also from other motoneurons as well.
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At first glance, hydra's nervous system is distributed fairly uniformly approximately the radially symmetry body wall surface and tentacles (Fig. 2.4). Its basically double-layered arrangement of spread sensory and also motor neurons is called a nerve net. However, in details regions that the body with dedicated function, like roughly the mouth and base of the tentacles, neurons tend to aggregate—a tendency toward centralization the will currently be examined more carefully.