Stem Cells In Order Research Articles

Regulating embryo models in the UK.

One of this century's most dramatic scientific developments is the reprogramming of stem cells in order to create self-organizing embryo-like entities, known as stem cell based embryo models (SCBEMs). The science is moving very quickly, but if, as increasingly appears to be the case, scientists are capable of creating entities that are effectively indistinguishable from sperm and egg derived embryos, important legal questions arise. In countries like the UK, where a strict regulatory regime applies to research on embryos, should this be extended to SCBEM research, or would a different regulatory response be appropriate? Drawing on the 1984 Warnock Report, the Human Fertilisation and Embryology Act 1990 and the latest guidelines from the International Society for Stem Cell Research, this article considers principles for the regulation of the creation and use of SCBEMs.

In Vivo Skin Regeneration and Wound Healing Using Cell Micro-Transplantation.

Background: The accumulation of senescent cells in tissues alters tissue homeostasis and affects wound healing. It is also considered to be the main contributing factor to aging. In addition to losing their ability to divide, senescent cells exert detrimental effects on surrounding tissues through their senescence-associated secretory phenotype (SASP). They also affect stem cells and their niche, reducing their capacity to divide which increasingly reduces tissue regenerative capacity over time. The aim of our study was to restore aged skin by increasing the fraction of young cells in vivo using a young cell micro-transplantation technique on Fischer 344 rats. Employing the same technique, we also used wild-type skin fibroblasts and stem cells in order to heal Dominant Dystrophic Epidermolysis Bulosa (DDEB) wounds and skin blistering. Results: We demonstrate that implantation of young fibroblasts restores cell density, revitalizes cell proliferation in the dermis and epidermis, rejuvenates collagen I and III matrices, and boosts epidermal stem cell proliferation in rats with advancing age. We were also able to reduce blistering in DDEB rats by transplantation of skin stem cells but not skin fibroblasts. Conclusions: Our intervention proves that a local increase of young cells in the dermis changes tissue homeostasis well enough to revitalize the stem cell niche, ensuring overall skin restoration and rejuvenation as well as healing DDEB skin. Our method has great potential for clinical applications in skin aging, as well as for the treatment of various skin diseases.

Therapeutic potential of human stem cell transplantations for Vanishing White Matter: A quest for the Goldilocks graft.

IntroductionVanishing white matter (VWM) is a leukodystrophy that leads to neurological dysfunction and early death. Astrocytes are indicated as therapeutic target, because of their central role in VWM pathology. Previous cell replacement therapy using primary mouse glial precursors phenotypically improved VWM mice.AimsThe aim of this study was to determine the translational potential of human stem cell‐derived glial cell replacement therapy for VWM. We generated various glial cell types from human pluripotent stem cells in order to identify a human cell population that successfully ameliorates disease hallmarks of a VWM mouse model. The effects of cell grafts on motor skills and VWM brain pathology were assessed.ResultsTransplantation of human glial precursor populations improved the VWM phenotype. The intrinsic properties of these cells were partially reflected by cell fate post‐transplantation, but were also affected by the host microenvironment. Strikingly, the spread of transplanted cells into the white matter versus the gray matter was different when grafted into the VWM brain as compared to a healthy brain.ConclusionsTransplantation of human glial cell populations can have therapeutic effects for VWM. For further translation to the clinic, the microenvironment in the VWM patient brain should be considered as an important moderator of cell replacement therapy.

Potential Role of Growth Factors Controlled Release in Achieving Enhanced Neuronal Trans-differentiation from Mesenchymal Stem Cells for Neural Tissue Repair and Regeneration.

With an increase in the incidence of neurodegenerative diseases, a need to replace incapable conventional methods has arisen. To overcome this burden, stem cells therapy has emerged as an efficient treatment option. Endeavours to accomplish this have paved the path to neural regeneration through efficient neuronal transdifferentiation. Despite their potential, the use of stem cells still entails several limitations, such as low differentiation efficiency and difficulties in guiding differentiation. The process of neural differentiation through the stem cells is achieved through the use of chemical inducers or growth factors and their direct introduction reduces their bioavailability in the system. To address these limitations, neural regeneration ventures require growth factors to be effectively implemented on stem cells in order to produce functional neuronal precursor cells. An efficient technique to achieve it is through the delivery of growth factors via microcarriers for their sustained release. It ensures the presence of commensurable concentration even at later stages of neuronal transdifferentiation. Nanofibers and nanoparticles, along with liposomes and such, have been used to implement this. The interaction between such carriers and the growth factors is mainly electrostatic. Such interaction enables them to form a stable assembly through immobilisation of the growth factor either onto their surfaces or within the core of their structures. The rate of sustained release depends upon the release kinetics associated with the polymeric structure employed and its interaction with the encapsulated growth factor. The sustained release ensures that the stem cells immerse under the effect of the growth factors for a prolonged period, ultimately aiding in the formation of cells showing ample characteristics of neuron precursors. This review analyses the various carriers that have been employed for the release of growth factors in an orderly fashion and their constituents, along with the advantages and the limitations they pose in delivering the growth factors for facilitating the process of neuronal transdifferentiation.

Enhanced Extracellular Matrix Deposition on Titanium Implant Surfaces: Cellular and Molecular Evidences.

The surface structure of the titanium dental implants can modulate the activity of mesenchymal stem cells in order to promote the upregulation of osteoblastic related genes and the release of extracellular matrix (ECM) components. The present work was focused on the in vitro evaluation of the interaction of human periodontal ligament stem cells (hPDLSCs) and two different implant titanium surfaces topography (CTRL and TEST). This study was aimed at analyzing the cytotoxicity of the dental implant surfaces, the cellular adhesion capacity, and the improvement in the release of ECM molecules in an in vitro model. These parameters were carried out by means of the microscopic evaluation, viability assays, immunofluorescence, Western blot and RT-PCR investigations. The knowledge of the cell/implant interaction is essential for implant healing in order to obtain a more performing surfaces that promote the ECM release and provide the starting point to initiate the osseointegration process.

Cryopreserved fragments of testicular seminiferous tubules of rats as a source of spermatogonial stem cells

The use of modern technologies of cryopreservation of testicular tissue samples in prepubertal patients is one of the ways to maintain their fertility in the future. The purpose of the study was to investigate the proliferative potential, morphological characteristics and expression of specific markers of cell culture obtained from cryopreserved and vitrified fragments of seminiferous tubules (FSTs) of rats' testis. Materials and methods. The isolation of cells from native, cryopreserved and vitrified FSTs of immature rats was performed by incubation in a solution of collagenase type IV (1 mg/mL) + DNase (500 μg/mL). Cell viability was determined by Trypan blue staining. Monoclonal antibodies CD9-FITC, CD24-PE, CD45-FITC, CD90-FITC were used for immunophenotype analysis. Morphological characteristics, proliferative activity (MTT assay), relative number of cells positive for MAGE-B1 and vimentin were assessed in the obtained cultures. Results. The analysis of phenotypic characteristics showed that cells from native, cryopreserved and vitrified FSTs were characterized by high expression level of CD9 (≥ 40 %), CD24 (≥ 70 %), CD90 (≥ 70 %) and low expression of the CD45 (≤ 1 %). In cell culture in vitro, the studied cells from cryopreserved and vitrified rat's FSTs had the ability to adhere and proliferate while maintaining a cells population positive for MAGE-B1 and vimentin. Conclusions. The results can be the basis for the development of effective protocols for the cultivation and cryopreservation of testicular spermatogonial stem cells in order to restore fertility in men.

MiRNAs and Muscle Regeneration: Therapeutic Targets in Duchenne Muscular Dystrophy.

microRNAs (miRNAs) are small non-coding RNAs required for the post-transcriptional control of gene expression. MicroRNAs play a critical role in modulating muscle regeneration and stem cell behavior. Muscle regeneration is affected in muscular dystrophies, and a critical point for the development of effective strategies for treating muscle disorders is optimizing approaches to target muscle stem cells in order to increase the ability to regenerate lost tissue. Within this framework, miRNAs are emerging as implicated in muscle stem cell response in neuromuscular disorders and new methodologies to regulate the expression of key microRNAs are coming up. In this review, we summarize recent advances highlighting the potential of miRNAs to be used in conjunction with gene replacement therapies, in order to improve muscle regeneration in the context of Duchenne Muscular Dystrophy (DMD).

The Effect of Physical Cues of Biomaterial Scaffolds on Stem Cell Behavior.

Stem cells have been sought as a promising cell source in the tissue engineering field due to their proliferative capacity as well as differentiation potential. Biomaterials have been utilized to facilitate the delivery of stem cells in order to improve their engraftment and long-term viability upon implantation. Biomaterials also have been developed as scaffolds to promote stem cell induced tissue regeneration. This review focuses on the latter where the biomaterial scaffold is designed to provide physical cues to stem cells in order to promote their behavior for tissue formation. Recent work that explores the effect of scaffold physical properties, topography, mechanical properties and electrical properties, is discussed. Although still being elucidated, the biological mechanisms, including cell shape, focal adhesion distribution, and nuclear shape, are presented. This review also discusses emerging areas and challenges in clinical translation.

Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples.

Breast cancer stem cells (BCSCs) are cancer cells with inherited or acquired stem cell-like characteristics. Despite their low frequency, they are major contributors to breast cancer initiation, relapse, metastasis and therapy resistance. It is imperative to understand the biology of breast cancer stem cells in order to identify novel therapeutic targets to treat breast cancer. Breast cancer stem cells are isolated and characterized based on expression of unique cell surface markers such as CD44, CD24 and enzymatic activity of aldehyde dehydrogenase (ALDH). These ALDHhighCD44+CD24- cells constitute the BCSC population and can be isolated by fluorescence-activated cell sorting (FACS) for downstream functional studies. Depending on the scientific question, different in vitro and in vivo methods can be used to assess the functional characteristics of BCSCs. Here, we provide a detailed experimental protocol for isolation of human BCSCs from both heterogenous populations of breast cancer cells as well as primary tumor tissue obtained from breast cancer patients. In addition, we highlight downstream in vitro and in vivo functional assays including colony forming assays, mammosphere assays, 3D culture models and tumor xenograft assays that can be used to assess BCSC function.

Abstract 6542: CAL1 vaccinia virus as oncolytic agent and potential use of cell-based platform to enhance its therapeutic effects

Abstract Background: Oncolytic virotherapy is a promising immuno-oncology approach that has not realized its potential due to rapid elimination by humoral immunity mediated by complement and neutralizing antibodies. We propose to use an adipose-derived mesenchymal stemcell-based platform,where the virus can be protected and amplified and potentiated inside the stem cells in order to minimize the clearance by anti-viral immunity. ACAM2000, the smallpox vaccine currently licensed in the U.S., is a clonal derivative of Dryvax® with reduced virulence and a well-documented safety profile in humans. This vaccinia virus strain can potentially be used as an oncolytic virus for cancer treatment. In this study, we evaluate the ability of ACAM2000 to (1) selectively kill cancer cells, (2) to be genetically modified without affecting its natural tumor selectivity, and to (3) determine if a stem cell-based platform can protect the virus from inactivation and potentiate its anti-tumor effects. Methods: ACAM2000 was amplified in CV1 cells and named CAL1. CAL1 was tested for its ability to replicate and selectively kill various human prostate cancer cell lines in vitro and in vivo. Additionally, CAL1 was loaded into adipose-derived mesenchymal stem cells to generate a new therapeutic agent called SuperNova1 (SNV1). Both CAL1 and SNV1 were tested for their ability to kill cancer cells in the presence of active complement and neutralizing antibodies in cell culture as well as in mice. Furthermore, CAL1 was used as the backbone to generate derivative CAL2 viruses using CRISPR/Cas9 technology to insert the gene encoding the fluorescent protein TurboFP into the intergenic locus between ORF-157 and ORF-158 of CAL1 without disrupting any existing CAL1 ORFs. Results: We showed that in vitro CAL1 preferentially infected, amplified in and lysed tumor cells and was also able to cause tumor regression in vivo without signs of toxicity. Furthermore, we demonstrated that the backbone of CAL1 can be used to engineer recombinant viruses, CAL2, that carry therapeutic genes without additionally attenuating the ability of the virus to amplify or kill tumor cells. SNV1 significantly enhanced protection of CAL1 virus from clearance by the immune system, leading to higher therapeutic efficacy. Furthermore, SNV1 provided instantly active viral particles for immediate infection and simultaneous release of therapeutic proteins in the injected tumors. Conclusions: CAL1 could be used as an oncolytic agent. We show here that a major advantage of using a cell-based platform to deliver and potentiate oncolytic vaccinia virus is the prevention of viral inactivation by the humoral immune system resulting in enhanced oncolytic viral therapy. Citation Format: Duong H. Nguyen, Thomas Herrmann, Ashley Alamillo, Forrest Neuharth, Alberto Gomez, Ivelina Minev, Barbara Härtl, Laura Schneider, Boris Minev, Dobrin Draganov, Antonio F. Santidrian. CAL1 vaccinia virus as oncolytic agent and potential use of cell-based platform to enhance its therapeutic effects [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6542.

Message in a Bottle: Upgrading Cardiac Repair into Rejuvenation.

Ischaemic cardiac disease is associated with a loss of cardiomyocytes and an intrinsic lack of myocardial renewal. Recent work has shown that the heart retains limited cardiomyocyte proliferation, which remains inefficient when facing pathological conditions. While broadly active in the neonatal mammalian heart, this mechanism becomes quiescent soon after birth, suggesting loss of regenerative potential with maturation into adulthood. A key question is whether this temporary regenerative window can be enhanced via appropriate stimulation and further extended. Recently the search for novel therapeutic approaches for heart disease has centred on stem cell biology. The “paracrine effect” has been proposed as a promising strategy to boost endogenous reparative and regenerative mechanisms from within the cardiac tissue by exploiting the modulatory potential of soluble stem cell-secreted factors. As such, growing interest has been specifically addressed towards stem/progenitor cell-secreted extracellular vesicles (EVs), which can be easily isolated in vitro from cell-conditioned medium. This review will provide a comprehensive overview of the current paradigm on cardiac repair and regeneration, with a specific focus on the role and mechanism(s) of paracrine action of EVs from cardiac stromal progenitors as compared to exogenous stem cells in order to discuss the optimal choice for future therapy. In addition, the challenges to overcoming translational EV biology from bench to bedside for future cardiac regenerative medicine will be discussed.

Possible Treatment of Neuropsychiatric Disorders by Promotion of Neuronal Differentiation through Organic Cation Transporters

Neurons differentiated from neural stem cells mature to form a neuronal network. Neuronal maturation enables neurotransmission that regulates brain function. Therefore, abnormal neuronal differentiation causes dysfunction in neurotransmission, and is involved in the onset of various neuropsychiatric disorders. Most of the drugs currently available for the treatment of neuropsychiatric disorders act on membrane receptors and reuptake transporters of neurotransmitters, and control neurotransmission. These membrane proteins have a high affinity for a specific neurotransmitter, and are highly expressed in synapses. By contrast, xenobiotic transporters have a relatively lower affinity for neurotransmitters, but widely recognize various organic compounds, and are also expressed in brain neural cells. It has remained largely unknown why such xenobiotic transporters are expressed in neural cells that play a key role in neurotransmission. We have therefore attempted to clarify the physiological roles of organic cation transporters (OCTs) in neural stem cells in order to obtain new insight into the treatment of neuropsychiatric disorders. The carnitine/organic cation transporter OCTN1/SLC22A4 is expressed at much higher levels in neural stem cells compared with other OCTs, and promotes their differentiation into neurons through the uptake of the food-derived hydrophilic antioxidant ergothioneine after oral administration. In this review, we introduce current topics on the physiological/pathophysiological roles of OCTs in neural stem cells, and discuss their possible application to the treatment of neuropsychiatric disorders.

Surface expression marker profile in colon cancer cell lines and sphere-derived cells suggests complexity in CD26+ cancer stem cells subsets.

ABSTRACTTaking advantage of eight established cell lines from colorectal cancer patients at different stages of the disease and the fact that all of them could form spheres, cell surface biomarkers of cancer stem cells and epithelial-mesenchymal transition were tested. The aim was to investigate cancer stem cells and metastatic stem cells in order to provide functional characterization of circulating tumor cells and promote the development of new anti-metastatic therapies. Our model showed an important heterogeneity in EpCAM, CD133, CD44, LGR5, CD26 and E-cadherin expression. We showed the presence of a subset of E-cadherin+ (some cells being E-cadherinhigh) expressing CD26+ (or CD26high) together with the well-known CSC markers LGR5 and EpCAMhigh, sometimes in the absence of CD44 or CD133. The already described CD26+/E-cadherinlow or negative and CD26+/EpCAM−/CD133− subsets were also present. Cell division drastically affected the expression of all markers, in particular E-cadherin, so new-born cells resembled mesenchymal cells in surface staining. CD26 and/or dipeptidyl peptidase 4 inhibitors have already shown anti-metastatic effects in pre-clinical models, and the existence of these CD26+ subsets may help further research against cancer metastasis.

Micro-scaled topographies direct differentiation of human epidermal stem cells

Human epidermal stem cells initiate terminal differentiation when spreading is restricted on ECM-coated micropatterned islands, soft hydrogels or hydrogel-nanoparticle composites with high nanoparticle spacing. The effect of substrate topography, however, is incompletely understood. To explore this, primary human keratinocytes enriched for stem cells were seeded on a topographical library with over 2000 different topographies in the micrometre range. Twenty-four hours later the proportion of cells expressing the differentiation marker transglutaminase-1 was determined by high content imaging. As predicted, topographies that prevented spreading promoted differentiation. However, we also identified topographies that supported differentiation of highly spread cells. Topographies supporting differentiation of spread cells were more irregular than those supporting differentiation of round cells. Low topography coverage promoted differentiation of spread cells, whereas high coverage promoted differentiation of round cells. Based on these observations we fabricated a topography in 6-well plate format that supported differentiation of spread cells, enabling us to examine cell responses at higher resolution. We found that differentiated spread cells did not assemble significant numbers of hemidesmosomes, focal adhesions, adherens junctions, desmosomes or tight junctions. They did, however, organise the actin cytoskeleton in response to the topographies. Rho kinase inhibition and blebbistatin treatment blocked the differentiation of spread cells, whereas SRF inhibition did not. These observations suggest a potential role for actin polymerization and actomyosin contraction in the topography-induced differentiation of spread cells. Statement of SignificanceThe epidermis is the outer covering of the skin. It is formed by layers of cells called keratinocytes. The basal cell layer contains stem cells, which divide to replace cells in the outermost layers that are lost through a process known as differentiation. In this manuscript we have developed surfaces that promote the differentiation of epidermal stem cells in order to understand the signals that control differentiation. The experimental tools we have developed have the potential to help us to devise new treatments that control diseases such as psoriasis and eczema in which epidermal stem cell proliferation and differentiation are disturbed.

Ultrastructural and immunohistochemical study of phenotypic switch in gastrointestinal smooth muscle cells.

Dedifferentiation is a loss of phenotypic specialization that converts differentiated cells into adult stem cells in order to proliferate and differentiate into replacement tissue. This occurs in several tissues from various organs, such as smooth muscle cells (SMCs) of the mammalian gastrointestinal tract. The aim of this study was to describe ultrastructural and immunohistochemical changes in SMCs which could be compatible with a dedifferentiation process in human and rabbit intestinal muscles. Ultrastructural study and immunohistochemical staining (SMemb and MyoD) on human and rabbit duodenum tissue sections were performed. In both species, this dedifferentiation process is characterized by a loss of intercellular junctions, increased intercellular spaces, cytoskeletal disorganization, perinuclear accumulation of large vacuoles that tend to fuse, rupture of the vacuole membrane and release of cytoplasmic fragments. Dedifferentiated cells show the characteristic phenotype of a mesenchymal cell with scarce perinuclear cytoplasm, long cytoplasmic prolongations and finely distributed granular chromatin in the nucleus. These morphological changes are accompanied by a modulation to a less mature phenotype showing immunoreactivity for the embryonic form of the myosin heavy chain and for the myogenic regulatory factor MyoD. We suggest that SMC dedifferentiation includes the elimination of the contractile apparatus, the activation of the nucleus and the re-expression of embryonic markers. We described an ultrastructural dedifferentiation process possible in intestinal SMCs. This dedifferentiation process seems to play a key role in the homeostasis of the intestinal muscle.

On the Cooperation between Epigenetics and Transcription Factor Networks in the Specification of Tissue Stem Cells

It is generally accepted that epigenetic modifications, such as DNA and histone methylations, affect transcription and that a gene’s transcription feeds back on its epigenetic profile. Depending on the epigenetic modification, positive and negative feedback loops have been described. Here, we study whether such interrelation are mandatory and how transcription factor networks affect it. We apply self-organizing map machine learning to a published data set on the specification and differentiation of murine intestinal stem cells in order to provide an integrative view of gene transcription and DNA, as well as histone methylation during this process. We show that, although gain/loss of H3K4me3 at a gene promoter is generally considered to be associated with its increased/decreased transcriptional activity, such an interrelation is not mandatory, i.e., changes of the modification level do not necessarily affect transcription. Similar considerations hold for H3K27me3. In addition, even strong changes in the transcription of a gene do not necessarily affect its H3K4me3 and H3K27me3 modification profile. We provide a mechanistic explanation of these phenomena that is based on a model of epigenetic regulation of transcription. Thereby, the analyzed data suggest a broad variance in gene specific regulation of histone methylation and support the assumption of an independent regulation of transcription by histone methylation and transcription factor networks. The results provide insights into basic principles of the specification of tissue stem cells and highlight open questions about a mechanistic modeling of this process.

Limbal Stem Cell Transplantation: Clinical Results, Limits, and Perspectives.

Limbal stem cell deficiency (LSCD) is a clinical condition characterized by damage of cornea limbal stem cells, which results in an impairment of corneal epithelium turnover and in an invasion of the cornea by the conjunctival epithelium. In these patients, the conjunctivalization of the cornea is associated with visual impairment and cornea transplantation has poor prognosis for recurrence of the conjunctivalization. Current treatments of LSCD are aimed at replacing the damaged corneal stem cells in order to restore a healthy corneal epithelium. The autotransplantation of limbal tissue from the healthy, fellow eye is effective in unilateral LSCD but leads to depauperation of the stem cell reservoir. In the last decades, novel techniques such as cultivated limbal epithelial transplantation (CLET) have been proposed in order to reduce the damage of the healthy fellow eye. Clinical and experimental evidence showed that CLET is effective in inducing long-term regeneration of a healthy corneal epithelium in patients with LSCD with a success rate of 70%–80%. Current limitations for the treatment of LSCD are represented by the lack of a marker able to unequivocally identify limbal stem cells and the treatment of total, bilateral LSCD which requires other sources of stem cells for ocular surface reconstruction.

Construction of High Sensitive CD133 Immune PLGA Magnetic Spheres Platform for Lung Cancer Stem Cells Isolation and Its Property Evaluation.

High sensitive immune CD133 PLGA magnetic spheres platform is constructed to isolate and enrich lung cancer stem cells in order to study their biological characteristics, such as their proliferation, self-renewal and invasion and metastasis in vitro. The expression of the specific transcription factors Oct 4 and Nanog genes of stem cells were detected by immunofluorescence and RT-PCR. The tumorigenic capacity of lung cancer cells were studied using the tumorigenesis experiment in nude mice in vivo. The results indicated that the CD133 immune PLGA magnetic beads (with diameter 356.25 ± 0.64 nm) can effectively separate more lung cancer stem cells under the serum-free suspension culture compared with MACS CD133 MicroBead Kit. Some A549 cells sorted magnetically could form stable tumor suspended spheres that were able to undergo passage stably after 3 to 6 days. The self-renewal, clonal formation and invasion and metastasis capacities of the suspended spheres were higher than those of the parent cells (P < 0.05). The expressions of Oct 4 and Nanog mRNA in stem cells were significantly elevated (P < 0.05), and the A549 suspended spheres could significantly improve the in vivo tumorigenic capacity of nude mice. Among the peripheral blood of 20 patients with lung adenocarcinoma, CD133+ cells were isolated from the peripheral blood of 14 (70%), and CD133+ cells sorted from 11 (55%) patients were cultured into spheres.

HPV-Induced Field Cancerisation: Transformation of Adult Tissue Stem Cell Into Cancer Stem Cell.

Field cancerisation was originally described as a basis for multiple head and neck squamous cell carcinoma (HNSCC) and is a pre-malignant phenomenon that is frequently attributable to oncogenic human papillomavirus (HPV) infection. Our work on β-HPV-induced cutaneous squamous cell carcinomas identified a novel Lrig1+ hair follicle junctional zone keratinocyte stem cell population as the basis for field cancerisation. Herein, we describe the ability for HPV to infect adult tissue stem cells in order to establish persistent infection and induce their proliferation and displacement resulting in field cancerisation. By review of the HPV literature, we reveal how this mechanism is conserved as the basis of field cancerisation across many tissues. New insights have identified the capacity for HPV early region genes to dysregulate adult tissue stem cell self-renewal pathways ensuring that the expanded population preserve its stem cell characteristics beyond the stem cell niche. HPV-infected cells acquire additional transforming mutations that can give rise to intraepithelial neoplasia (IEN), from environmental factors such as sunlight or tobacco induced mutations in skin and oral cavity, respectively. With establishment of IEN, HPV viral replication is sacrificed with loss of the episome, and the tissue is predisposed to multiple cancer stem cell-driven carcinomas.

Immune ligands for cytotoxic T Lymphocytes (CTLS) in cancer stem cells (CSCS).

The immune system has come to the forefront of cancer therapeutics in recent years with the success of immune blockade inhibitors in a variety of cancers whose list is increasing with a quick pace. Despite the efficacy of these drugs across a significant part of the cancer spectrum, responses are still seen only in a minority of patients, that implies that most patients are refractory or promptly develop resistance to these agents. Mechanisms of this resistance are important to decipher as this knowledge may lead to the introduction of additional therapies or manipulations to modulate resistance. The cancer stem cell theory stipulates that a minority of cancer cells in a given tumor are responsible for self-renewal and bulk tumor propagation. These cells, in most instances, are rare and less proliferative but give rise to highly proliferative progeny. In addition, they are, in general, resistant to therapies and endowed with metastatic potential through a process called EMT (Epithelial to Mesenchymal Transition). Cancer stem cells resistance to treatments may relate to inherent insensitivity to external apoptotic stimuli and, thus, may extend to immune therapies by inhibiting the actions of Cytotoxic T Lymphocytes (CTLs) in the tumor micro-environment. This paper examines available data on expression and regulation of immune co-modulatory (co-stimulatory and co-inhibitory) ligands on cancer stem cells in order to devise strategies to circumvent resistance.