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Species and Cell Types / Human / Bone Marrow / Stem Cell


Entecavir Promotes CD34+ Stem Cell Proliferation in the Peripheral Blood and Liver of Chronic Hepatitis B and Liver Cirrhosis Patients

Abstract: Entecavir (ETV) has been used for more than 2 decades in treating hepatitis B virus (HBV) infections. It has shown significant anti-HBV effect and has led to histological improvement in the liver of chronic hepatitis B (CHB) patients. In patients treated with ETV for over two years, reversal of cirrhosis to normal tissue has also been observed. However, the mechanisms of these tissue repairing or recovery processes are not yet clear. In order to determine the roles that bone marrow and liver stem/progenitor cells play in these processes, we evaluated the CD34+ and CD133+ stem/progenitor cells in peripheral blood from 292 patients and liver tissues from 43 patients who had received therapies with and without ETV. A significant increase in both CD34+ and CD133+ cells was found in CHB and cirrhosis patients compared to the healthy controls. In patients treated with ETV, CD34+ cells increased 2 and 4 fold in peripheral blood and liver tissues, respectively, while their CD4+ and CD8+ cells remained the same. On the other hand, CD133+ cells did not change or even slightly decreased with ETV treatment. Results from immunohistochemistry staining, real time RT-PCR, and the enzyme-linked immunosorbent assay also revealed the same level of CD34+ cell increase and CD133+ cell decrease (or no change) in ETV treated patients, compared to patients without ETV therapies. Liver functions in patients with ETV treatment improved in general, but one liver cirrhosis patient with high expression of CD133 in liver tissue developed hepatocellular carcinoma (HCC). In summary, ETV may have differential effects on various stem cell subtypes. ETV-activated stem cells in bone marrow and liver tissues may contribute to the recovery from injuries caused by HBV infection. They also contribute to the regeneration of normal tissue and the recovery of normal liver function. Meanwhile, ETV does not activate stem cells that may participate in the initiation of HCC. ... Read more

State-Of-The-Art Human Gene Therapy: Part I. Gene Delivery Technologies

Abstract: Safe and effective gene delivery is a prerequisite for successful gene therapy. In the early age of human gene therapy, setbacks due to problematic gene delivery vehicles plagued the exciting therapeutic outcome. However, gene delivery technologies rapidly evolved ever since. With the advancement of gene delivery techniques, gene therapy clinical trials surged during the past decade. As the first gene therapy product (Glybera) has obtained regulatory approval and reached clinic, human gene therapy finally realized the promise that genes can be medicines. The diverse gene delivery techniques available today have laid the foundation for gene therapy applications in treating a wide range of human diseases. Some of the most urgent unmet medical needs, such as cancer and pandemic infectious diseases, have been tackled by gene therapy strategies with promising results. Furthermore, combining gene transfer with other breakthroughs in biomedical research and novel biotechnologies opened new avenues for gene therapy. Such innovative therapeutic strategies are unthinkable until now, and are expected to be revolutionary. In part I of this review, we introduced recent development of non-viral and viral gene delivery technology platforms. As cell-based gene therapy blossomed, we also summarized the diverse types of cells and vectors employed in ex vivo gene transfer. Finally, challenges in current gene delivery technologies for human use were discussed. ... Read more

Novel Approaches and Mechanisms in Hematopoietic Stem Cell Gene Therapy

Abstract: Hematopoietic stem cell gene therapy is one of the most exciting clinical tools to emerge from the gene therapy stable. This technology combines the expansion capability of hematopoietic stem cells, capable of replacing the entire blood and immune system of an individual, with the capacity for long-term replacement of one or more gene copies using integrating gene therapy vectors. Hematopoietic stem cell gene therapy benefits significantly from the pre-existing experience of standard blood and marrow transplantation, whilst at the same time having the capacity to deliver a safer and more effective therapy to a wider range of diseases. In this review we summarize the potential of hematopoietic stem cell gene therapy to expand the scope of hematopoietic stem cell transplantation, including the evolution of vector delivery systems and the success and failures of current clinical experience with this treatment. In particular we deal with the incidence of vector mediated transformation in patients and the steps that have been taken to minimize this risk. Finally we discuss the innovations in preclinical development that are likely to drive the future of this field, including the expansion to many more genetic diseases, particularly those affecting the brain. ... Read more

Mesenchymal Stem Cell-Based Therapy for Type 1 Diabetes

Abstract: Diabetes has increasingly become a worldwide health problem, causing huge burden on healthcare system and economy. Type 1 diabetes (T1D), traditionally termed "juvenile diabetes" because of an early onset age, is affecting 5~10% of total diabetic population. Insulin injection, the predominant treatment for T1D, is effective to ameliorate the hyperglycemia but incompetent to relieve the autoimmunity and to regenerate lost islets. Islet transplantation, an experimental treatment for T1D, also suffers from limited supply of human islets and poor immunosuppression. The recent progress in regenerative medicine, especially stem cell therapy, has suggested several novel and potential cures for T1D. Mesenchymal stem cell (MSC) based cell therapy is among one of them. MSCs are a type of adult stem cells residing in bone marrow, adipose tissue, umbilical cord blood, and many other tissues. MSCs, with self-renewal potential and transdifferentiation capability, can be expanded in vitro and directed to various cell lineages with relatively less efforts. MSCs have well-characterized hypoimmunogenicity and immunomodulatory effect. All these features make MSCs attractive for treating T1D. Here, we review the properties of MSCs and some of the recent progress using MSCs as a new therapeutic in the treatment of T1D. We also discuss the strength and limitations of using MSC therapy in human trials. ... Read more

Advances in Cellular Therapy for the Treatment of Leukemia

Abstract: Adoptive immunotherapy in the form of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a treatment modality for acute and chronic leukemias that has been in practice for several decades. Drawbacks to transplantation include toxicity from chemotherapy/radiation conditioning regimens, additional toxicity from graft versus host disease, and reliance on appropriate human leukocyte antigen matched donors. Newer modalities with increased specificity of donor cells to tumor cells in addition to therapies that do not require engraftment for anti-tumor effect reduce the risk of graft versus host disease and may create a more robust graft versus leukemia response. Without the need for engraftment, or at the very least in the absence of a 100% engraftment requirement, conditioning regimens may be minimized. Three methods of adoptive immunotherapy that may offer some of these advantages over traditional transplantation are donor lymphocyte infusions (DLI), chimeric antigen receptor modified T cells (CAR T cells), and cellular immunotherapy. DLIs and cellular therapy consist of transfusing T lymphocytes from the donor to recipient in an unmanipulated form. Alternatively, donor T lymphocytes can be modified with addition of chimeric antigen receptors for specific antigen directed killing of tumor cells. Significant responses and survival benefit have been reported with these modalities. Herein, we review the mechanisms for these newer adoptive immune therapies, clinical indications for their use, and potential future directions. ... Read more

Adipose Tissue-derived Stem Cells in Stroke Treatment: From Bench to Bedside

Abstract: More recently, growing interests have brought cell therapy to the forefront of promising new approaches towards efficacious treatment for stroke. Of all cell-types, adipose tissue-derived mesenchymal stem cells (AD-MSC) are considered good candidates for stroke treatment because of their abundance and easy harvesting without invasive surgery from healthy donors. A wide number of experimental studies have demonstrated the potential of AD-MSC administration for improving functional deficits and have led to the first clinical trials in stroke patients. Trophic factor release and paracrine interactions, transdifferentiation potential, and immunomodulatory effects have all been cited as the main functional mechanisms involved in AD-MSC therapy. These properties make AD-MSC therapy of special interest in fomenting the enhancement of natural brain repair mechanisms such as neurogenesis, gliagenesis, oligodendrogenesis, axonal sprouting, nerve repair, and angiogenesis. This review will focus on studies showing promising results of AD-MSC in stroke treatment. ... Read more

Marching Towards Regenerative Cardiac Therapy with Human Pluripotent Stem Cells

Abstract: Damage in cardiac tissues from ischemia or other pathological conditions leads to heart failure; and cell loss or dysfunction in pacemaker tissues due to congenital heart defects, aging, and acquired diseases can cause severe arrhythmias. The promise of successful therapies with stem cells to treat these conditions has remained elusive to the scientific community. However, recent advances in this field have opened new opportunities for regenerative cardiac therapy. Transplantation of cardiomyocytes derived from human pluripotent stem cells has the potential to alleviate heart disease. Since the initial derivation of human embryonic stem cells, significant progress has been made in the generation and characterization of enriched cardiomyocytes and the demonstration of the ability of these cardiomyocytes to survive, integrate, and function in animal models. The scope of therapeutic potential from pluripotent stem cell-derived cardiomyocytes has been further expanded with the invention of induced pluripotent stem cells, which can be induced to generate functional cardiomyocytes for regenerative cardiac therapy in a patient specific manner. The reprogramming technology has also inspired the recent discovery of direct conversion of fibroblasts into cardiomyocyte-like cells, which may allow endogenous cardiac repair. Regenerative cardiac therapy with human pluripotent stem cells is now moving closer to clinic testing. ... Read more

Novel Therapeutic Approaches for Corneal Disease

Abstract: Congenital and acquired corneal opacities, and diseases of the ocular surface, are blinding conditions that impose physical, psychological, and financial constraints upon the sufferer. In the past, corneal and corneal epithelial stem cell transplantation have been the major treatment for severe corneal and ocular surface disease, respectively, but the sequelae of neovascularization and inflammatory eye disease cause many grafts to undergo irreversible immunological rejection. Furthermore, in the case of corneal dystrophies, the original disease may recur in the graft. New therapeutic options for diseases of the cornea and ocular surface are now being actively explored in experimental animals and in clinical trials. Antibody-based biologics are being tested for their ability to reduce blood and lymphatic vessel ingrowth into the cornea, and to reduce inflammation. Many new biomaterials are being examined for their capacity to transfer drugs and corneal epithelial cell progenitor cells to the ocular surface and anterior segment of the eye. New component-cell corneal transplantation procedures that may reduce the risk of immunological rejection have been developed and are already in clinical practice. Finally, gene therapy is being tested in experimental animals to improve the outcomes of corneal transplantation, and to halt or reverse the pathophysiology of some corneal dystrophies. ... Read more

Tolerance Induction in Hemophilia A Animal Models: Battling Inhibitors with Antigen-specific Immunotherapies

Abstract: Hemophilia A is an X-linked recessive bleeding disorder due to either a lack of or greatly reduced activity in the blood coagulation protein factor VIII (FVIII), due to mutations in the F8 gene. This poses significant challenges for FVIII replacement therapy since hemophilic patients are not immunologically tolerant to the protein. Thus, a proportion of patients who receive plasma-derived or recombinant FVIII replacement therapy develop anti FVIII neutralizing antibodies, known as "inhibitors." These patients require long-term regimens of high dose FVIII administration, which has varying success rates and prohibitive costs. Therefore, therapeutics for tolerance induction in such patients with inhibitors are desired. In this review, we address the current progress of immunotherapies for inducing FVIII specific tolerance in animal models of hemophilia A. Specifically we discuss the beneficial effects of B-cell depletion on immune tolerance induction (ITI), B-cell mediated gene therapy, antigen-coupled lymphocyte therapy, and regulatory T-cell epitopes (Tregitopes). ... Read more

Tumor Heterogeneity, Clonal Evolution, and Therapy Resistance: An Opportunity for Multitargeting Therapy

Abstract: Heterogeneity within the cell population is a feature of many tumors. This lack of cellular homogeneity may originate from a number of sources, including differential nutrient status due to the de novo microcirculations of tumors, to infiltration of normal cells into the tumor, and to the hierarchical natures of the cell populations from which cancers arise. Tumors are thought to arise from one or more tumor initiating cells (TIC) within the population and to found hierarchies of progenitors and more differentiated cancer cells. TIC are often derived from tissue stem cells and these cancer stem cells are characterized by resistance to most cytotoxic treatments and by a high metastatic rate. Many of the properties of tumor populations, including the ability to express mutated oncogenes and to evolve new features such as treatment resistance and invasive and metastatic potential appear to depend on the molecular chaperone Hsp90. We discuss the potential of targeting the heterogeneous cell population with Hsp90 inhibitory drugs and its potential ability to inactivate TIC and to block the evolution of new phenotypes in cancer. ... Read more

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