Brain Tumor Heterogeneity

Tumor heterogeneity is the concept that different tumor cells provide distinct biomorphological lesions, gene expressions, proliferation, microenvironment and graduated capacity of metastatic lesions. Brain tumor heterogeneity has been recently discussed about the interesting interaction of chronic inflammation, microenvironment, epigenetics and glioma steam cells. Brain tumors remain a challenge with regards to medication and disease, due to the lack of treatment options and unsatisfactory results. These results might be the result of the brain tumor heterogeneity and its multiple resistance mechanisms to chemo and radiotherapy.

Behavior of Mesenchymal Stem Cells Obtained From Dental Tissues: A Review of the Literature / Comportamiento de células mesenquimales obtenidas de tejidos dentales: Revisión de literatura

Abstract 20. The success of tissue engineering in combination with tissue regeneration depends on the behavior and cellular activity in the biological processes developed within a structure that functions as a support, better known as scaffolds, or directly at the site of the injury. The cell-cell and cell-biomaterial interaction are key factors for the induction of a specific cell behavior, together with the bioactive factors that allow the formation of the desired tissue. Mesenchymal Stem Cells (MSC) can be isolated from the umbilical cord and bone marrow; however, the behavior of Dental Pulp Stem Cells (DPSC) has been shown to have a high potential for the formation of bone tissue, and these cells have even been able to induce the process of angiogenesis. Advances in periodontal regeneration, dentin-pulp complex, and craniofacial bone defects through the induction of MSC obtained from tooth structures in in vitro-in vivo studies have permitted the obtaining of clinical evidence of the achievements obtained to date.

Resumen 24. El éxito de la ingeniería de tejidos en combinación con la regeneración de tejidos depende del comportamiento y la actividad celular en los procesos biológicos desarrollados dentro de una estructura que funciona como soporte mejor conocida como andamio o directamente en el sitio de la lesión. La interación célula-célula y célula-biomaterial son factores claves para la inducción a un comportamiento célular específico junto con factores bioactivos que permitan la formación del tejido deseado. Las células troncales mesenquimales (MSCs) pueden ser aisladas del cordón umbilical y de la medula ósea, sin embargo, el comportamiento de las células troncales de pulpa dental (DPSCs) han demostrado tener un alto potencial para la formación de tejido óseo e incluso han logrado inducir el proceso de angiogénesis. Avances en la regeneración periodontal, complejo dentino-pulpar y defectos óseos craneofaciales a travez de la inducción de MSCs obtenidas de estructuras de dientes en estudios in vitro-in vivo han permitido obtener evidencia clínica de los logros obtenidos hasta el momento.

Haematopoietic stem cell transplantation in South Africa: Current limitations and future perspectives

The growing need for haematopoietic stem cell transplantation (HSCT) is reflected in the increasing number of transplants performed globally each year. HSCT provides life-changing and potentially curative therapy for a range of pathologies including haematological malignancies; other indications include certain congenital and acquired disorders of the haematopoietic system, autoimmune conditions and hereditary diseases. The primary goals of HSCT are either to replace haematopoietic stem and progenitor cells (HSPC) following myeloablative chemotherapy or to cure the original pathology with allogeneic HSPCs. Success depends on optimal outcomes at various stages of the procedure including mobilisation of marrow stem/progenitor cells for harvesting from the patient or donor, long-term and sustainable engraftment of these cells in the recipient, and prevention of graft-versus-host disease in the case of allogeneic HSCT. Challenges in South Africa include high cost, limited infrastructure and lack of appropriately trained staff, as well as limitations in securing suitable haematopoietic stem cell donors. This review aims to provide an overview of HSCT and some of the challenges that are faced in the South African context

A supramolecular look at microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny / Uma visão supramolecular sobre a regulação microambiental de células tronco epiteliais limbais e a diferenciação de sua progênie

ABSTRACT Various approaches have been taken to improve our knowledge of the microenvironmental regulation of limbal epithelial stem cells. Researchers have extensively investigated the roles of growth factors, survival factors, cytokines, enzymes, and permeable molecules secreted by the limbal cells. However, recent evidence suggests that stem cell fate (i.e., self-renewal or differentiation) can also be influenced by biophysical and mechanical cues related to the supramolecular organization and the liquid crystalline (mesophase) nature of the stromal extracellular matrix. These cues can be sensed by stem cells and transduced into intracellular biochemical and functional responses, a process known as mechanotransduction. The objective of this review is to offer perspectives on the supramolecular microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny.

RESUMO Muitas abordagens têm sido utilizadas para ampliar entendimentos sobre a regulação microambiental das células tronco epiteliais limbais. Neste contexto, pesquisadores têm exaustivamente investigado a participação de fatores de crescimento, fatores de sobrevida, citocinas, enzimas e moléculas permeáveis secretadas pelas células limbais. Entretanto, evidências recentes sugerem que o destino (ie. autorrenovação ou recrutamento para a via de diferenciação) das células tronco também sofre influência de estímulos biofísicos ou mecânicos relacionados à organização supramolecular e à natureza liquido-cristalina (mesofases) da matriz extracelular estromal. Esses estímulos podem ser percebidos e traduzidos pelas células tronco em sinais bioquímicos que geram respostas funcionais, através de um processo designado de mecanotransdução. Objetiva-se, com a presente revisão, oferecer ao leitor perspectivas supramoleculares sobre a regulação microambiental das células tronco epiteliais limbais e a diferenciação de sua progênie.

Comparative in vitro evaluation of human dental pulp and follicle stem cell commitment

Objective: Pulp and periodontal tissues are well-known sources of mesenchymal stem cells [MSCs] that provide a promising place in tissue engineering and regenerative medicine. The molecular mechanisms underlying commitment and differentiation of dental stem cells that originate from different dental tissues are not fully understood. In this study, we have compared the expression levels of pluripotency factors along with immunological and developmentally-related markers in the culture of human dental pulp stem cells [hDPSCs], human dental follicle stem cells [hDFSCs], and human embryonic stem cells [hESCs]

Materials and Methods: In this experimental study, isolated human dental stem cells were investigated using quantitative polymerase chain reaction [qPCR], immunostaining, and fluorescence-activated cell sorting [FACS]. Additionally, we conducted gene ontology [GO] analysis of differentially expressed genes and compared them between dental stem cells and pluripotent stem cells

Results: The results demonstrated that pluripotency [OCT4 and SOX2] and immunological [IL-6 and TLR4] factors had higher expressions in hDFSCs, with the exception of the JAGGED-1/NOTCH1 ratio, c-MYC and NESTIN which expressed more in hDPSCs. Immunostaining of OCT4, SOX2 and c-MYC showed cytoplasmic and nucleus localization in both groups at similar passages. GO analysis showed that the majority of hDFSCs and hDPSCs populations were in the synthesis [S] and mitosis [M] phases of the cell cycle, respectively

Conclusion: This study showed different status of heterogeneous hDPSCs and hDFSCs in terms of stemness, differentiation fate, and cell cycle phases. Therefore, the different behaviors of dental stem cells should be considered based on clinical treatment variations

Hypoxia Enhances Cell Properties of Human Mesenchymal Stem Cells

Atmospheric (in vitro) oxygen pressure is around 150 mm Hg (20% O₂), whereas physiologic (in vivo) oxygen pressure ranges between 5 and 50 mm Hg (0.7–7% O₂). The normoxic environment in cell culture does not refer to a physiological stem cell niche. The aim of this study is to investigate the effect of oxygen concentration on cell properties of human mesenchymal stem cells (MSCs). We analyzed cell proliferation rate, senescence, immunophenotype, stemness gene expression and differentiation potency with human urine stem cells (USCs), dental pulp stem cells (DPSCs), amniotic fluid stem cells (AFSCs), and bone marrow stromal cells (BMSCs). USCs, DPSCs, AFSCs and BMSCs were cultured under either 5% O₂ hypoxic or 20% O₂ normoxic conditions for 5 days. MSCs cultured under hypoxia showed significantly increased proliferation rate and high percentage of S-phase cells, compared to normoxic condition. In real-time PCR assay, the cells cultured under hypoxia expressed higher level of Oct4, C-Myc, Nanog, Nestin and HIF-1α. In immunophenotype analysis, MSCs cultured under hypoxia maintained higher level of the MSC surface markers, and lower hematopoietic markers. Senescence was inhibited under hypoxia. Hypoxia enhances osteogenic differentiation efficiency compared to normoxia. Hypoxia showed enhanced cell proliferation rate, retention of stem cell properties, inhibition of senescence, and increased differentiation ability compared to normoxia.

Endogenous Stem Cells in Homeostasis and Aging

In almost all human tissues and organs, adult stem cells or tissue stem cells are present in a unique location, the so-called stem cell niche or its equivalent, continuously replenishing functional differentiated cells. Those endogenous stem cells can be expanded for cell therapeutics using ex vivo cell culture or recalled for tissue repair in situ through cell trafficking and homing. In the aging process, inefficiency in the endogenous stem cell-mediated healing mechanism can emerge from a variety of impairments that accumulate in the processes of stem cell self-renewal, function, differentiation capacity, and trafficking through cell autonomous intrinsic pathways (such as epigenetic alterations) or systemic extrinsic pathways. This review examines the homeostasis of endogenous stem cells, particularly bone marrow stem cells, and their dysregulation in disease and aging and discusses possible intervention strategies. Several systemic pro-aging and rejuvenating factors, recognized in heterochronic parabiosis or premature aging progeroid animal models, are reviewed as possible anti-aging pharmaceutical targets from the perspective of a healthy environment for endogenous stem cells. A variety of epigenetic modifications and chromosome architectures are reviewed as an intrinsic cellular pathway for aging and senescence. A gradual increase in inflammatory burden during aging is also reviewed. Finally, the tissue repair and anti-aging effects of Substance-P, a peptide stimulating stem cell trafficking from the bone marrow and modifying the inflammatory response, are discussed as a future anti-aging target.

The Efficacy and Safety of Collagen-I and Hypoxic Conditions in Urine-Derived Stem Cell Ex Vivo Culture

Upper urinary tract-derived urine stem cells (USCs) are considered a valuable mesenchymal stem cell source for autologous cell therapy. However, the reported culture condition for USCs is not appropriate for large-quantity production, because cells can show limited replicativity, senescence, and undesirable differentiation during cultivation. These drawbacks led us to reconstitute a culture condition that mimics the natural stem cell niche. We selected extracellular matrix protein and oxygen tension to optimize the ex vivo expansion of USCs, and compared cell adhesion, proliferation, gene expression, chromosomal stability, differentiation capacity, immunity and safety. Culture on collagen type I (ColI) supported highly enhanced USC proliferation and retention of stem cell properties. In the oxygen tension analysis (with ColI), 5% O₂ hypoxia showed a higher cell proliferation rate, a greater proportion of cells in the S phase of the cell cycle, and normal stem cell properties compared to those observed in cells cultured under 20% O₂ normoxia. The established reconstituted condition (ColI/hypoxia, USCs(recon)) was compared to the control condition. The expanded USCs(recon) showed highly increased cell proliferation and colony forming ability, maintained transcription factors, chromosomal stability, and multi-lineage differentiation capacity (neuron, osteoblast, and adipocyte) compared to the control. In addition, USCs(recon) retained their immune-privileged potential and non-tumorigenicity with in vivo testing at week 8. Therefore, reconstituted condition allows for expanded uUSC cell preparations that are safe and useful for application in stem cell therapy.

Long-Duration Three-Dimensional Spheroid Culture Promotes Angiogenic Activities of Adipose-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) offer significant therapeutic promise for various regenerative therapies. However, MSC-based therapy for injury exhibits low efficacy due to the pathological environment in target tissues and the differences between in vitro and in vivo conditions. To address this issue, we developed adipose-derived MSC spheroids as a novel delivery method to preserve the stem cell microenvironment. MSC spheroids were generated by suspension culture for 3 days, and their sizes increased in a time-dependent manner. After re-attachment of MSC spheroids to the plastic dish, their adhesion capacity and morphology were not altered. MSC spheroids showed enhanced production of hypoxia-induced angiogenic cytokines such as vascular endothelial growth factor (VEGF), stromal cell derived factor (SDF), and hepatocyte growth factor (HGF). In addition, spheroid culture promoted the preservation of extracellular matrix (ECM) components, such as laminin and fibronectin, in a culture time- and spheroid size-dependent manner. Furthermore, phosphorylation of AKT, a cell survival signal, was significantly higher and the expression of pro-apoptotic molecules, poly (ADP ribose) polymerase-1 (PARP-1) and cleaved caspase-3, was markedly lower in the spheroids than in MSCs in monolayers. In the murine hindlimb ischemia model, transplanted MSC spheroids showed better proliferation than MSCs in monolayer. These findings suggest that MSC spheroids promote MSC bioactivities via secretion of angiogenic cytokines, preservation of ECM components, and regulation of apoptotic signals. Therefore, MSC spheroid-based cell therapy may serve as a simple and effective strategy for regenerative medicine.

Mesenchymal stromal cells in myeloid malignancies

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are clonal myeloid disorders characterized by hematopoietic insufficiency. As MDS and AML are considered to originate from genetic and molecular defects of hematopoietic stem and progenitor cells (HSPC), the main focus of research in this field has focused on the characterization of these cells. Recently, the contribution of BM microenvironment to the pathogenesis of myeloid malignancies, in particular MDS and AML has gained more interest. This is based on a better understanding of its physiological role in the regulation of hematopoiesis. Additionally, it was demonstrated as a ‘proof of principle’ that genetic disruption of cells of the mesenchymal or osteoblastic lineage can induce MDS, MPS or AML in mice. In this review, we summarize the current knowledge about the contribution of the BM microenvironment, in particular mesenchymal stromal cells (MSC) to the pathogenesis of AML and MDS. Furthermore, potential models integrating the BM microenvironment into the pathophysiology of these myeloid disorders are discussed. Finally, strategies to therapeutically exploit this knowledge and to interfere with the crosstalk between clonal hematopoietic cells and altered stem cell niches are introduced.

Therapeutic Options in Idiopathic Burning Mouth Syndrome: Literature Review

Introduction Burning mouth syndrome (BMS) is characterized by a burning sensation in the tongue, palate, lips, or gums of no well-defined etiology. The diagnosis and treatment for primary BMS are controversial. No specific laboratory tests or diagnostic criteria are well established, and the diagnosis is made by excluding all other possible disorders. Objective To review the literature on the main treatment options in idiopathic BMS and compare the best results of the main studies in 15 years. Data Synthesis We conducted a literature review on PubMed/MEDLINE, SciELO, and Cochrane-BIREME of work in the past 15 years, and only selected studies comparing different therapeutic options in idiopathic BMS, with preference for randomized and double-blind controlled studies. Final Comments Topical clonazepam showed good short-term results for the relief of pain, although this was not presented as a definitive cure. Similarly, α-lipoic acid showed good results, but there are few randomized controlled studies that showed the longterm results and complete remission of symptoms. On the other hand, cognitive therapy is reported as a good and lasting therapeutic option with the advantage of not having side effects, and it can be combined with pharmacologic therapy. .

Cancer stem cells: a new approach to tumor development / Células-tronco de câncer: um nova abordagem do desenvolvimento tumoral

Many theories have been proposed to explain the origins of cancer. Currently, evidences show that not every tumor cell is capable of initiating a tumor. Only a small part of the cancer cells, called cancer stem cells (CSCs), can generate a tumor identical to the original one, when removed from human tumors and transplanted into immunosuppressed mice. The name given to these cells comes from the resemblance to normal stem cells, except for the fact that their ability to divide is infinite. These cells are also affected by their microenvironment. Many of the signaling pathways, such as Wnt, Notch and Hedgehog, are altered in this tumoral subpopulation, which also contributes to abnormal proliferation. Researchers have found several markers for CSCs; however, much remains to be studied, or perhaps a universal marker does not even exist, since they vary among tumor types and even from patient to patient. It was also found that cancer stem cells are resistant to radiotherapy and chemotherapy. This may explain the re-emergence of the disease, since they are not completely eliminated and minimal amounts of CSCs can repopulate a tumor. Once the diagnosis in the early stages greatly increases the chances of curing cancer, identifying CSCs in tumors is a goal for the development of more effective treatments. The objective of this article is to discuss the origin of cancer according to the theory of stem cell cancer, as well as its markers and therapies used for treatment.

Diversas teorias buscam explicar a origem do câncer. Atualmente, há evidências de que nem todas as células tumorais têm poder de iniciar um tumor. Apenas uma pequena parte das células cancerígenas, chamadas de células-tronco de câncer (do inglês cancer stem cells - CSC), é capaz de iniciar um tumor idêntico ao original quando retirada de tumores humanos e enxertada em camundongos imunossuprimidos. Essas células foram assim denominadas por suas semelhanças com células-tronco normais, exceto pelo fato de que sua capacidade de dividir-se é infinita. Essas células também recebem influência de seu microambiente. Várias vias de sinalização, como WNT, NOTCH e Hedgehog, estão alteradas nessa subpopulação tumoral, contribuindo também para a desregulação de sua proliferação. Pesquisadores descobriram vários marcadores para as CSC, porém ainda há muito a ser pesquisado, ou talvez nem exista um marcador universal, já que eles variam entre cada tipo de tumor e até de paciente para paciente. Foi constatado também que as CSC são resistentes à radioterapia e à quimioterapia, podendo explicar o reaparecimento da doença, visto que, além de não eliminá-la completamente, quantidades mínimas das CSC podem repovoar um tumor. Como o diagnóstico em estágios iniciais aumenta muito as chances de cura do câncer, a identificação das CSC em meio a um tumor é alvo para o desenvolvimento de tratamentos mais eficazes. O objetivo deste artigo é discutir a origem do câncer segundo a teoria das CSC, bem como seus marcadores e as terapias utilizadas em seu tratamento.

Hormonal Regulation of Hematopoietic Stem Cells and Their Niche: A Focus on Estrogen

Self-renewal and differentiation are hallmarks of stem cells and controlled by various intrinsic and extrinsic factors. Increasing evidence indicates that estrogen (E2), the primary female sex hormone, is involved in regulating the proliferation and lineage commitment of adult and pluripotent stem cells as well as modulating the stem cell niche. Thus, a detailed understanding of the role of E2 in behavior of stem cells may help to improve their therapeutic potential. Recently, it has been reported that E2 promotes cell cycle activity of hematopoietic stem and progenitor cells and induces them to megakaryocyte-erythroid progenitors during pregnancy. This study paves the way towards a previously unexplored endocrine mechanism that controls stem cell behavior. In this review, we will focus on the scientific findings regarding the regulatory effects of E2 on the hematopoietic system including its microenvironment.

Mapeamento de potencial nicho neurogênico no lobo temporal humano / Mapping of potential neurogenic niche in the human temporal lobe

No final do século 19, o neurônio foi descrito como a unidade funcional básica do sistema nervoso e sua formação era considerada inexistente na fase adulta, explicando a ausência de recuperação significativa em doenças neurológicas. Evidências de geração de neurônios em mamíferos adultos surgiram na década de 1960 e foram confirmadas três décadas depois. Atualmente, predomina a visão de que mamíferos adultos possuem dois nichos neurogênicos independentes: a zona subventricular (ZSV) e a zona subgranular (ZSG) do giro denteado. No entanto, a existência de nichos neurogênicos em humanos adultos é controversa. Nossa hipótese foi de que o mapeamento de nichos neurogênicos no lobo temporal humano poderia esclarecer aspectos sobre a neurogênese adulta. A detecção destes nichos foi buscada em 28 lobos temporais através de imuno-histoquímica para nestina, o marcador mais comum de células-tronco neurais, que são aquelas capazes de se autorrenovar e de gerar novas células neurais. A neurogênese foi pesquisada no hipocampo pelo uso de DCX (do inglês "doublecortin"), o principal marcador de neuroblastos e neurônios imaturos. Nestina foi observada em uma camada contínua formada pela ZSV, zona subpial do lobo temporal medial e ZSG, terminando no subículo. A partir do subículo, uma intensa expressão de DCX ocorreu através da principal via eferente do hipocampo até a fímbria. A visão panorâmica das marcações por nestina e DCX mostrava em conjunto uma linha que circundava as estruturas límbicas do lobo temporal. Por isto, foi denominada linha externa de células do sistema límbico (LECEL). Uma possível explicação para os resultados é que a LECEL seja um nicho neurogênico no qual a ZSV, a zona subpial do lobo temporal medial e a ZSG formam uma unidade contendo células-tronco neurais que se diferenciam em neurônios no subículo. Curiosamente, a área identificada previamente como sendo a corrente migratória rostral humana (formada por células neurais imaturas migrando a partir da...

At the end of the 19th century, the neuron was described as the basic functional unit of the nervous system. The formation of neurons was thought to be absent in adulthood, thus explaining the lack of significant recovery from neurological diseases. Evidence for the generation of neurons in adult mammals was reported in the 1960s and confirmed three decades later. Currently, the prevailing view is that adult mammals harbour two neurogenic niches: the subgranular zone (SGZ) of the dentate gyrus and the subventricular zone (SVZ). Nonetheless, the existence of these niches in adult humans is controversial. We hypothesised that mapping neurogenic niches in the human temporal lobe could clarify this issue. The presence of neurogenic niches was examined in 28 temporal lobes via immunostaining for nestin, the most common marker for neural stem cells, which are cells with the capacities of self-renewal and the generation of neural cells. The presence of neurogenesis was examined in the hippocampus with doublecortin (DCX), a prominent marker for neuroblasts and immature neurons. Nestin was observed in a continuous layer that was formed by the SVZ, the subpial zone of the medial temporal lobe and the SGZ, terminating in the subiculum. In the subiculum, remarkable DCX expression was observed through the principal efferent pathway of the hippocampus to the fimbria. A panoramic view of nestin and DCX staining collectively displayed a line that surrounded the limbic structures of the temporal lobe. Hence, we termed it the external line of cells of the limbic system (EXCEL). A possible explanation for the results is that the EXCEL is a neurogenic niche, in which the SVZ, the subpial zone of the medial temporal lobe and the SGZ form a unit containing neural stem cells that differentiate into neurons in the subiculum. Curiously, the area previously identified as the human rostral migratory stream (formed by immature neural cells that migrate from the SVZ of the frontal horn)...

Roles of osteoblasts in hematopoietic stem cell niche and relationship between osteoblasts and hematopoietic diseases / 中国实验血液学杂志

Hemopoietic stem cells(HSCs) are regulated by two niches: osteoblastic niche and vascular niche. Osteoblasts are the critical constitutive regulators of the osteoblastic niche. The significance of osteoblasts for hematopoietic disease has not escaped attention. This review attempts to capture the discoveries of the last few years regarding the role of osteoblasts in hematopoietic stem cell niche and relationship between osteoblasts and hematopoietic diseases.

New treatment strategies targeting cancer stem cells / 中国医学科学院学报

Cancer stem cells represent a subpopulation of cells within tumor mass, endowed with self-renewal, survival, proliferation, and tumorigenic capacity. These cell populations are potentially associated with cancer prognosis. However, these cells do not play a part in isolation; instead, they are dependent on a variety of signals from their microenvironments. Cancer stem cells have two microenvironment niches: the first one is perivascular niche and the second is hypoxic regions where tumor stem cells locate. Bidirectional signal transduction is found between cancer stem cells and cancer stem cell niches. As a cancer stem cell-specific surface marker, CD133 plays a role in key molecular signaling pathways and high levels of drug-or radiation-resistance. Other molecules closely related to cancer stem cell signaling pathways include Wnt and Hh, which are also associated with cancer drug resistance. Further understanding the molecular mechanisms of pathological basis of cancer stem cells will facilitate the development of new therapeutic targets and new strategies for eradicating cancers. This paper summarizes the molecular mechanisms, and the possibilities and limitations of therapies targeting cancer stem cell.

Research progress on visual observations of hematopoietic stem cell homing / 中国实验血液学杂志

Hematopoietic stem cell transplantation (HSCT) is an important mean for clinical treatment to many of hematological diseases, malignant diseases, hereditary diseases and autoimmune diseases. Whether the implanted hematopoietic stem cells (HSC) can home to bone marrow (BM) smoothly and reconstitute the hematopoiesis is the key to successful HSCT. With the cognition of HSC homing mechanism, the visual observation of HSC homing to BM is attracting more and more attention and helps to clarify the micro-dialogue between HSC and BM microenvironment. In recent years, with the development of imaging technology, confocal laser scanning microscope (CLSM) and two-photon microscope are able to make 3D reconstruction and real-time observation of the tissue or cells. Researches on HSC homing process visibly become reality. In this article the methods of visual research and their application in HSC homing observation are reviewed.

Tracking the Fate of Muscle-derived Stem Cells: an Insight into the Distribution and Mode of Action

PURPOSE: To examine the fate of muscle-derived stem cells (MDSC) after injection into different host conditions and provide an insight for their mechanism of action. MATERIALS AND METHODS: MDSCs differentiated in vitro towards the endothelial lineage and transfected with lentivirus tagged with green fluorescent protein (GFP) were injected into two animal models mimicking vascular diseases: hindlimb ischemia and carotid injury models. Injected cells were tracked at the site of injection and in remote organs by harvesting the respective tissues at different time intervals and performing immunofluorescent histological analyses. Stem cell survival was quantified at the site of injection for up to 4 weeks. RESULTS: MDSCs were successfully tagged with fluorescent material GFP and showed successful implantation into the respective injection sites. These cells showed a higher affinity to implant in blood vessel walls as shown by double fluorescent co-stain with CD31. Quantification of stem cell survival showed a time-dependent decrease from day 3 to 4 weeks (survival rate normalized against day 3 was 72.0% at 1 week, 26.8% at 2 weeks and 2.4% at 4 weeks). Stem cells were also fo und in distant organs, especially the kidneys and liver, which survived up to 4 weeks. CONCLUSION: MDSCs were successfully tracked in different vascular disease models, and their fate was assessed in terms of cell survival and distribution. Better understanding of the donor cell properties, including their interaction with the host conditions and their mechanism of action, are needed to enhance cell survival and achieve improved outcomes.

Caenorhabditis elegans: A Model System for Anti-Cancer Drug Discovery and Therapeutic Target Identification

The nematode Caenorhabditis elegans (C. elegans) offers a unique opportunity for biological and basic medical researches due to its genetic tractability and well-defined developmental lineage. It also provides an exceptional model for genetic, molecular, and cellular analysis of human disease-related genes. Recently, C. elegans has been used as an ideal model for the identification and functional analysis of drugs (or small-molecules) in vivo. In this review, we describe conserved oncogenic signaling pathways (Wnt, Notch, and Ras) and their potential roles in the development of cancer stem cells. During C. elegans germline development, these signaling pathways regulate multiple cellular processes such as germline stem cell niche specification, germline stem cell maintenance, and germ cell fate specification. Therefore, the aberrant regulations of these signaling pathways can cause either loss of germline stem cells or overproliferation of a specific cell type, resulting in sterility. This sterility phenotype allows us to identify drugs that can modulate the oncogenic signaling pathways directly or indirectly through a high-throughput screening. Current in vivo or in vitro screening methods are largely focused on the specific core signaling components. However, this phenotype-based screening will identify drugs that possibly target upstream or downstream of core signaling pathways as well as exclude toxic effects. Although phenotype-based drug screening is ideal, the identification of drug targets is a major challenge. We here introduce a new technique, called Drug Affinity Responsive Target Stability (DARTS). This innovative method is able to identify the target of the identified drug. Importantly, signaling pathways and their regulators in C. elegans are highly conserved in most vertebrates, including humans. Therefore, C. elegans will provide a great opportunity to identify therapeutic drugs and their targets, as well as to understand mechanisms underlying the formation of cancer.

La translocación in vitro citoplasma/núcleo del factor de transcripción embrionario oct-4 en células perivasculares propone a la aorta como un nicho quiescente de células madres adultas / In vitro translocation cytoplasm/nucleus of embryonic transcription factor oct-4 in perivascular cells suggests that aorta as a niche of quiescent adult stem cells

Las células perivasculares tienen un origen común en las células madre embrionarias y en los vasos sanguíneos que proporcionan un nicho para la mantención de su troncalidad. La expresión de marcadores embrionarios y de células indiferenciadas, como también la gran variedad de fenotipos celulares generados desde los pericitos, podrían ser explicados por la capacidad de estas células de ser inducidas a un estado "stemness" cuando son tratadas con factores adecuados. Nuestros resultados describen la expresión de células con OCT-4 citoplasmático en una ubicación anatómica perivascular donde de su nicho se encuentra en la región intima de la aorta en rata. In vitro las células aisladas por el método de explante que promueve el aislamiento de células migratorias desde los tejidos muestran un fenotipo con un citoplasma alargado y que expresan aSMA, PDGFRa y b, siendo estos dos últimos marcadores específicos de pericitos. En estas células se presenta una tranlocación a la variante nuclear de OCT-4 que ha sido descrito como el principal regulador de los procesos de autorrenovación y pluripotencia. La expresión de OCT-4 confirma y amplía aún más las observaciones obtenidas en nuestras investigaciones anteriores y demuestra que células madre se encuentran en los vasos sanguíneos en un microambiente que, probablemente, les permite que sobrevivan y permanezcan en reposo como un tipo de célula troncal quiescente.

Perivascular cells have a common origin from embryonic stem cells and blood vessels provide a niche for the maintenance of their stemness. Embryonic markers expression of undifferentiated cells, as well as, the wide variety of cellular phenotypes generated from pericytes, could be explained by the ability of these cells to be induced to a state of "stemness" when treated with appropriate factors. Our findings describe the expression of cells with cytoplasmic OCT-4 in perivascular anatomical location where their niche region is in the intima of the aorta in rats. In vitro isolated cells by explant method that promotes the isolation of migratory cells from tissues show an elongated cytoplasm phenotype, expressing aSMA, PDGFRa & b where the last two are specific markers of pericytes. These cells present a translocated nuclear variant of OCT-4 that has been described as the master regulator of self-renewal processes and pluripotency. The expression of OCT-4 further confirms and extends the observations obtained in our previous research and proves that stem cells found in the blood vessels in a microenvironment that probably allows them to survive and remain at rest as a type of quiescent stem cell.