Journal of Stem Cells最新文献

Blood pharming is a recently designed concept to enable in vitro production of blood cells that are safe, effective and readily available. This approach represents an alternative to blood donation and may contribute to overcome the shortage of blood products. However, the high variability of the human leukocyte antigen (HLA) loci remains a major hurdle to the application of off-the-shelf blood products. Refractoriness to platelet (PLT) transfusion caused by alloimmunization against HLA class I antigens constitutes a relevant clinical problem. Thus, it would be desirable to generate PLT units devoid of HLA antigens. To reduce the immunogenicity of cell-based therapeutics, we have permanently reduced HLA class I expression using an RNA interference strategy. Furthermore, we demonstrated that the generation of HLA class I-silenced (HLA-universal) PLTs from CD34+ progenitor cells using an shRNA targeting β2-microglobulin transcripts is feasible. CD34+ progenitor cells derived from G-CSF mobilised donors were transduced with a lentiviral vector encoding for the β2-microglobulin-specific shRNA and differentiated into PLTs using a liquid culture system. The functionality of HLA-silenced PLTs and their ability to escape HLA antibody-mediated cytotoxicity were evaluated in vitro and in vivo. Platelet activation in response to ADP and thrombin were assessed in vitro. The immune-evasion capability of HLA-universal megakaryocytes (MKs) and PLTs was tested in lymphocytotoxicity assays using anti-HLA antibodies. To assess the functionality of HLA-universal PLTs in vivo, HLA-silenced MKs were infused into NOD/SCID/IL-2Rγc(-/-) mice with or without anti-HLA antibodies. PLT generation was evaluated by flow cytometry using anti-CD42a and CD61 antibodies. HLA-universal PLTs demonstrated to be functionally similar to blood-derived PLTs. Lymphocytotoxicity assays showed that HLA-silencing efficiently protects MKs against HLA antibody-mediated complement-dependent cytotoxicity. 80-90% of HLA-expressing MKs, but only 3% of HLA-silenced MKs were lysed. In vivo, both HLA-expressing and HLA-silenced MKs showed human PLT production (up to 0.5% within the PLT population) when anti-HLA antibodies were absent. However, in presence of anti-HLA antibodies HLA-expressing MKs were rapidly cleared from the circulation of mice, while HLA-silenced MKs escaped HLA antibody-mediated cytotoxicity and human PLT production was detectable up to 11 days. Our studies show that HLA-silenced PLTs are functional and efficiently protected against HLA antibody-mediated cytotoxicity. In this chapter, we provide a review of our most recent findings in the use of CD34+ progenitor cells for the production of HLA-universal PLTs and their potential clinical applications. Provision of HLA-universal PLT units may become an important component in the management of patients with PLT transfusion refractoriness.

Regenerative medicine with the promise of complete organ restoration could change the treatment paradigm for various degenerative disorders. In order to develop successful, safe and efficient regenerative therapies, appropriate amount of pluripotent autologous cells are desired. Pluripotent stem cell lines, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), offer a unique opportunity to derive various cell types that can be exploited for regenerative medicine. However, their application in therapies is limited due to inherent potential tumorigenesis, problems with immune-rejection, applied reprogramming methods, and ethical considerations. Recent reports on the establishment of very small embryonic-like cells (VSELs) are pointing to a way out of this dilemma, since it is proposed that these cells have similar characteristics as ESCs and could serve as basis for therapeutic applications. A careful scientific comparison of VSELs is now needed in order to make judgments about their capabilities and characteristics. In any case, the development of successful, safe and efficient regenerative therapies based on human pluripotent cells requires additional quality assessments of critical parameters that are also summarized within the review.

We have since the 1970's embarked on the development of biologically derived fluorophore-protein complexes that will find applications in the communicable and non-communicable disease etiology processes and their cures. We have since then become largely successful in these endeavors along with interspersed contributions also from investigators who have generally restricted to working in confined disciplines. Their encompassment with our works as this investigator has traversed his definitely chosen and not merely a circumstantial, coincidental, or accidental step-wise multi-disciplinary scientific path from biophysics to regenerative medicine spanning these lines of investigations for last four decades have finally yielded the much necessitated disease related applied biological interventions for human benefits. Taking a cue from our early investigations and findings on which we call attention to the identification and characterization of the use of the primary light-emitting lumazine precursor of riboflavin which is 6,7-dimethyl-8-ribityl lumazine-protein complex which we had derived from the bioluminescence bacterium (Photobacterium phosphoreum) wherein it functions as a naturally occurring fluorescence light emitter (LumP). These in vivo phenomena have been a precursor to the subsequent developments in vitro. This in vivo to in vitro investigation path of ours has been also comprised among others of binding of photosynthetic light-harvesting marine dinoflagellate algae (Glenodinium sp.) derived peridinin-chlorophyll a-protein (PerCP) complex-labeled monoclonal antibodies useful in the development of flow cytometry. These fluorescence labeled antibodies bound antigens which include those of communicable infectious diseases (HIV/AIDS - env-gp160, gag-p24), non-communicable but also potential hereditary and malignant disorders (Cancer/Tumor Markers - Melan-A/Mart-1 of melanoma), normal immune response cells (Human/Mouse/species cellular MHC/TCR/CD45/CD33/CD56/CD19/CD41), and of types of stem cells (CD34/CD38/c-Mpl/Oct4/Neuropilin-1/SOX17). Such antigens have been analyzed by us and other investigators by fluorescence-activated cell sorting (FACS - cell surface and intracellular binding), confocal fluorescence microscopy, or/and immunohistochemistry, to determine qualitative and quantitative antigen expression levels and their mechanistic implications. We have followed stem cell differentiation patterns and signaling mechanisms through marker antigen-antibody binding wherein the antibodies are labeled with covalently linked fluorophore-protein complexes or fluorescence emitting chromophores. These complexes among others also have included PerCP. We are also now in the process of developing flow cytometry applications of additional visible light emitting chromophore-protein complexes through industrial collaborations. The United States Navy has long been known for interest in the estimation of changes in illumination intensity in and under th

Breast cancer is a leading cause of deaths in humans. Mesenchymal stem cells (MSC) have been identified to possess powerful therapeutic properties in humans. The capability of MSC to migrate toward injured tissue suggests their potential in new clinical applications. The aim of this study was to investigate the potential role of adipose stem cells (ADSCs) for recovering cellular potential and delaying or treating breast cancer in an animals model of human breast cancer. Cellular adoptive immunotherapy using adipose derived mesenchymal stem cells tailored made for Breast Cancer patients would offer a new effective less invasive treatment method. ADSCs injected into the cancer tumor did not affect tumor growth and the cancer kept growing. ADSCs injected so that they surrounded the tumor decreased growth and the tumor had disappeared after 3 to 8 weeks and total recovery was maintained throughout the 6 months of study. The adipose stem cells are the "active" and "regenerative" part of fat. ADSCs may appear promising for their use as "secretor" of the supernatant substance against breast cancer cells.

Aim: Clonospheres formed due to modified culture conditions are often studied for their stem cell like behaviour. The main objective of the current study is to compare the stem cell markers and link it to hTERT levels by monitoring their quantitative gene expression as they are potential targets for new generation combination therapeutics.

Method: In the present study we created stable colonospheres of Human colon cancer cell line HCT-116 long term culture conditions of Serum deprivation. Clonospheres formed after 15 days were collected by gentle and enzymatic dissociation was performed. Single cell suspension was obtained by mechanically dissociating the cells through a 22G needle. Single cells were replanted at a density 1200 cells/ml in Serum Free Medium in the 6 well plates for further passage. Passaging of cells was done at an interval of 8 days. The spheres formed were cyto-spun in special slides for Immunocytochemistry (ICC) studies for β-catenin protein and hTERT. The colonospheres were also processed for real time PCR expression studies for the same genes to confirm.

Results: In this present study, immunofluorescence studies revealed high β-catenin expression in the nucleus in colonospheres as compared to that of differentiated cancer cell line HCT-116 where the signal was localized mostly in the membranous and non-nuclear regions. Also increased TRF2 signal in colonospheres indicated higher activity of hTERT gene as TRF2 is the direct activator of hTERT to protect the telomere. Quantitative PCR studies showed that there was a significant over expression (p<0.05) at the mRNA level of the hTERT, TRF2, Rap1 genes along with the β-catenin over expression. Immunofluorescence analysis also revealed higher expression of CSC marker CD44 and ALDH1in colonospheres compared to the parental population.

Conclusion: Clonospheres sub-population is showing higher degree of hTERT gene expression along with β-catenin when compared to the parental HCT-116 cancer cells. We also checked the co expression of other telomere maintenance genes mainly TRF 2 and Rap1 which also showed similar results. Therefore, we conclude that not only hTERT but possibly other Sheltrin proteins are regulated by β-catenin which is co expressed.

Cancer stem cells (CSCs) are defined by their innate stem cell like properties and can be identified by specific markers that include antigens, molecules and signaling pathways. Like stem cells, CSC divide indefinitely giving rise to both more CSCs and differentiated cell progeny. CSCs can give rise to tumors that phenotypically resemble their origin, either morphologically or by expression of tissue specific genes. Tumors arise from a single cell, the CSC, but the cells that constitute the tumor are not identical to each other. Evidence of heterogeneous populations within a tumor has led to an investigation of the cellular hierarchy of cancers. This review gives an overview of cancer stem cells, from breast, cervical, lung, prostate, head and neck, glioblastoma, pancreatic and colorectal cancers and mechanisms implicated in tumor development and therapeutic interventions.

With the cementing of the cancer stem cell (CSC) concept, cancer biology and cancer drug discovery have attained a new avenue to target cancer. Studying the hierarchy of tumor tissue organization and how to inhibit the cell that resides at the very top of this hierarchy has opened up a new branch of tumor biology and given the opportunity to develop novel cancer-targeting strategies. With the discovery of CSCs in majority of cancer indications there seems to be a universal applicability of the concept. However, the CSC field is still at an early fledgling state and a lot more needs to be done in terms of understanding their emergence, maintenance, role in metastasis and their function in shaping the tumor architecture. CSCs are considered to be responsible for tumor initiation, metastasis and resistance to conventional radio and chemotherapy. Therefore, different approaches to targeting these tumorigenic and rare cells are urgently needed in order to improve the efficacy of anti-cancer therapy. We outline here the cancer stem cell concept and its relevance as well as biotherapeutic approaches to CSC targeting, including oncolytic viruses, monoclonal antibodies, cytokines and cytotoxic T lymphocytes.

Hematopoietic homeostasis is maintained throughout the lifetime of an individual through self-renewal of hematopoietic stem cells. Defects in the self - renewal and differentiation lead to hematopoietic insufficiency and development of malignancies. Leukemic stem cells (LSCs), which are considered to originate from hematopoietic stem or progenitor cells, not only adopt the regulatory machinery operating in normal HSCs but establish their own mechanisms against apoptosis and senescence. Hematopoietic malignancies are of Lymphoid origin with CLL and ALL and myeloid malignancies with AML and CML and in addition there are disease of the plasma multiple myelomas. One of the major therapeutic strategies for hematological malignancies is hematopoietic stem cell transplantation along with combination of chemotherapy. The review gives an insight of different hematological malignancies, the mechanism and therapeutic strategies available at present.

Blastocyst activation, a process for the blastocyst to achieve implantation competency is equally important as attainment of uterine receptivity for the success of embryo implantation. While a wide range of regulatory molecules have been identified as essential players in conferring uterine receptivity in both laboratory animal models and humans, it remains largely unknown how blastocysts achieve implantation competency. This chapter will highlight our current knowledge about the mechanisms governing the process of blastocyst activation. A better understanding of this periimplantation event is hoped to alleviate female infertility and help to develop novel contraceptives and new strategies for accessing embryo quality in clinical practice.