Detection of tumor stem cell markers in pancreatic carcinoma cell lines

IntroductionT he cell population of most tumors is hetero- geneous with regard to its proliferation capacity, apoptosis-resistance mechanisms, and ability to reconstitute the tumor upon xeno-transplantation. This phenomenon arises as the result of accumulation of multiple genetic and epigenetic changes. Current evidence suggests that only a few cells within the tumor, the cancer stem cells, possess unlimited proliferative capacity and give rise to tumors that phenotypically resemble their init…     

When is a stem cell really a stem cell?

While bone marrow transplantation has long been established as an effective approach to the clinical management of a variety of malignant and nonmalignant diseases, the future application of pluripotent stem cells in transplant settings promises to deliver this therapy to a much broader range of indications. In this review, I summarize the emerging field of embryonic stem cell biology in the context of potential clinical applications and regulatory issues.     

Cardiac stem cell therapy research in China

For more than two decades, the morbidity and mortality of coronary artery disease (CAD) has been increasing rapidly in China. Despite tremendous advances in treatment strate- gies of CAD, heart failure after acute myocardial infarction (AMI) continues to be one of the greatest medical chal- lenges throughout the world. In 1994, Soonpaa and col- leagues first reported the possibility of cardiomyocytes implantation and suggested that intracardiac cell grafting might provide a useful approach…     

Possible stem cell origin of human cholangiocarcinoma

MM:To investigate the expression of CD34 and c-kit(receptor of stem cell factor)in cholangiocarcinoma. METHODS:Fifteen cases of intrahepatic cholangiocarcinoma and 17 cases of extrahepatic cholangiocarcinoma were studied in this experiment.Using Envision detection system,paraffin- embedded sections of the resected cholangiocarcinoma tissue were stained with antibodies against CD34 and c- kit,respectively.The sections were counterstained with hematoxylin,and the results were examined under light microscope.Normal tonsil and mammary tissues were used as positive controls for CD34 and c-kit,respectively. RESULTS:CD34 was positive in all sections,but only in capillary endothelial cells of tumor tissue.No cholangiocarcinoma cells were positive for CD34.In one case of extrahepatic cholangiocarcinoma,a few tumor cells(about 5%)were immunoreactive with c-kit. CONCLUSION:CD34 or c-kit positive cells in liver tissue may represent liver stem cells,as they can differentiate into mature biliary cells in vitro.The expression of c-kit by some cholangiocarcinoma cells suggests that cholangiocarcinoma might originate from liver stem cells.However,other mechanisms of hepatocarcinogenesis,such as de-differentiation of mature cholangiocytes,may also exist.     

Are stem cells drugs? The regulation of stem cell research and development

Stem cell research and its clinical application have become political, social, and medical lightning rods, polarizing opinion among members of the lay community and among medical/scientific professionals. A potpourri of opinion, near-anecdotal observation, and scientifically sound data has sown confusion in ways rarely seen in the medical arts and sciences. A major issue is regulation, with different aspects of stem cell research falling within the purview of different government agencies and local offices. An overarching clearinghouse to review the field and recommend policy is lacking. In the following pages, I touch on the societal framework for regulation, the known and potential risks and benefits of cardiovascular stem cell therapies, whether stem cells should be regulated as drugs or in analogy to drugs, and if there is to be regulation, then by whom. In so doing, I refer to the stem cell literature only as it relates to the discussion of regulation because this is not a review of stem cell research; it is an opinion regarding regulation.     

Normal and leukemic hematopoiesis: are leukemias a stem cell disorder or a reacquisition of stem cell characteristics?

Leukemia can be viewed as a newly formed, abnormal hematopoietic tissue initiated by a few leukemic stem cells (LSCs) that undergo an aberrant and poorly regulated process of organogenesis analogous to that of normal hematopoietic stem cells. A hallmark of all cancers is the capacity for unlimited self-renewal, which is also a defining characteristic of normal stem cells. Given this shared attribute, it has been proposed that leukemias may be initiated by transforming events that take place in hematopoietic stem cells. Alternatively, leukemias may also arise from more committed progenitors caused by mutations and/or selective expression of genes that enhance their otherwise limited self-renewal capabilities. Identifying the LSCs for each type of leukemia is a current challenge and a critical step in understanding their respective biologies and may provide key insights into more effective treatments. Moreover, LSC identification and purification will provide a powerful diagnostic, prognostic, and therapeutic tool in the clinic.     

Has allogeneic stem cell cryopreservation been given the 'cold shoulder'? An analysis of the pros and cons of using frozen versus fresh stem cell products in allogeneic stem cell transplantation

Donor stem cells for allogeneic transplant traditionally are collected and transfused 'fresh' into the recipient on the day of transplant; alternatively such cells can be collected in advance and cryopreserved until needed. Most centers favor the former approach based on theoretical concerns that cryopreservation and thawing may worsen clinical outcomes. Limited published data from single institution retrospective studies show no significant impairment of engraftment or reduced day 100 survival for cryopreserved bone marrow recipients. There are no reported outcomes for recipients of cryopreserved peripheral blood allografts. Use of cryopreserved stem cells is associated with a higher incidence of adverse events (transfusion reactions, bacterial graft contamination and collection of grafts which are not utilized). Conversely, use of cryopreserved grafts introduces a greater flexibility into a stressed healthcare system and results in a more streamlined experience for the donor. Some data suggest that transplantation with a cryopreserved product may lower the incidence of acute graft-versus-host disease. We compare the pros and cons of using 'fresh' versus cryopreserved stem cell products for allogeneic transplantation and suggest that the current standard of using 'fresh' products may not be warranted. We also suggest future areas of exploration to better elucidate this issue.     

Guillain-Barré syndrome after allogeneic hematopoietic stem cell transplantation

Guillain-Barré syndrome is a rare complication in the setting of hematopoietic stem cell transplantation. We report three children with T cell lymphoma/leukemia in whom this syndrome developed soon after they received unrelated donor transplants. The rapid onset of symptoms raises the concern that the bone marrow transplant conditioning regimen (ie, total body irradiation, cyclophosphamide and cytosine arabinoside) might have precipitated the clinical syndrome of ascending polyneuropathy. Although central nervous system toxicity has been well described with high-dose cytosine arabinoside therapy, peripheral neuropathy of the Guillain-Barré type has been reported only infrequently. We review possible factors contributing to the development of this syndrome in these three patients.     

Adult stem cell maintenance and tissue regeneration around the clock: do impaired stem cell clocks drive age-associated tissue degeneration?

Human adult stem cell research is a highly prolific area in modern tissue engineering as these cells have significant potential to provide future cellular therapies for the world’s increasingly aged population. Cellular therapies require a smart biomaterial to deliver and localise the cell population; protecting and guiding the stem cells toward predetermined lineage-specific pathways. The cells, in turn, can provide protection to biomaterials and increase its longevity. The right combination of stem cells and biomaterials can significantly increase the therapeutic efficacy. Adult stem cells are utilised to target many changes that negatively impact tissue functions with age. Understanding the underlying mechanisms that lead to changes brought about by the ageing process is imperative as ageing leads to many detrimental effects on stem cell activation, maintenance and differentiation. The circadian clock is an evolutionarily conserved timing mechanism that coordinates physiology, metabolism and behavior with the 24 h solar day to provide temporal tissue homeostasis with the external environment. Circadian rhythms deteriorate with age at both the behavioural and molecular levels, leading to age-associated changes in downstream rhythmic tissue physiology in humans and rodent models. In this review, we highlight recent advances in our knowledge of the role of circadian clocks in adult stem cell maintenance, driven by both cell-autonomous and tissue-specific factors, and the mechanisms by which they co-opt various cellular signaling pathways to impose temporal control on stem cell function. Future research investigating pharmacological and lifestyle interventions by which circadian rhythms within adult stem niches can be manipulated will provide avenues for temporally guided cellular therapies and smart biomaterials to ameliorate age-related tissue deterioration and reduce the burden of chronic disease.     

Progeroid syndromes: models for stem cell aging?

Stem cells are responsible for tissue repair and maintenance and it is assumed that changes observed in the stem cell compartment with age underlie the concomitant decline in tissue function. Studies in murine models have highlighted the importance of intrinsic changes occurring in stem cells with age. They have also drawn the attention to other factors, such as changes in the local or systemic environment as the primary cause of stem cell dysfunction. Whilst knowledge in murine models has been advancing rapidly there has been little translation of these data to human aging. This is most likely due to the difficulties of testing the regenerative capacity of human stem cells in vivo and to substantial differences in the aging phenotype within humans. Here we summarize evidence to show how progeroid syndromes, integrated with other models, can be valuable tools in addressing questions about the role of stem cell aging in human degenerative diseases of older age and the molecular pathways involved.     

HLA-identical stem cell transplantation: is there an optimal CD34 cell dose?

A review of the published literature, supplemented with a recent analysis of Fred Hutchinson data, has been undertaken to investigate the association of infused CD34 cell dose with various clinical outcomes after HLA-identical transplantation. Separate assessments for unrelated vs related donors and the use of bone marrow or mobilized G-PBMC have been incorporated. The three primary findings are: (1) higher CD34 dose results in better neutrophil and platelet recovery in all settings; (2) high CD34 doses (>8 x 10(6)/kg) are associated with the development of more chronic GVHD when using related G-PBMC; (3) higher CD34 dose is correlated with improved survival after bone marrow transplantation, especially with unrelated donors. This is not seen when using G-PBMC. The data suggest that the CD34 content of the graft can have a significant impact on clinical outcome after allogeneic transplantation, but optimal dose is dependent on both donor type and stem cell source.     

Secondary hypertension due to a juxtaglomerular cell tumor

Juxtaglomerular cell tumors are rare, generally benign, and they are one of the secondary surgically treatable causes of arterial hypertension. There are about 100 reported cases on literature, and the diagnosis is usually carried out based on a high clinic suspicion index, mostly in patients with hypokalemia and arterial hypertension. The diagnosis involves blood tests and imaging studies, but it is only definite with histopathological exam after surgical treatment. We present a case of a 22-year-old woman with resistant arterial hypertension and renal and cardiovascular target-organ lesions. High plasmatic renin and a nodular renal mass on magnetic resonance imaging were present. A tumorectomy was performed and the histological exam confirmed a reninoma. After surgery, blood pressure and serum renin values returned to normal without medication. This work focuses on the need to exclude rare secondary causes of hypertension in young patients with resistant forms of this disease.     

Anti-tumor × anti-lymphocyte heteroconjugates augment colon tumor cell lysisin Vitro and prevent tumor growthin Vivo

Cross-linking an anti-tumor antibody, specific for tumor cell surface antigens, and an anti-lymphocyte antibody, specific for the T lymphocyte receptor complex (TCR/ CD3), produces a heteroconjugate that can direct T cells to lyse tumor cells. We tested the ability of anti-tumor × anti-lymphocyte (CD3) heteroconjugates to redirect human peripheral blood lymphocytes (PBLs) to lyse human colon cancer cells in cytotoxicity assays and in a murine colon tumor model. We demonstrated in vitro,that cultured human PBLs alone produced low levels of tumor lysis, but PBLs treated with anti-tumor × anti-CD3 heteroconjugates produced significantly greater tumor cell lysis (P<0.0025). Similarly, nude mice injected with LS174T human colon cancer cells and treated with cultured human PBLs and anti-tumor × anti-CD3 heteroconjugates survived significantly longer than saline control mice (P<0.01), or mice treated with PBLs alone (P<0.01), or heteroconjugates alone (P<0.05). F(ab) ₂ heteroconjugates were equally as effective in prolonging animal survival, but irrelevant heteroconjugates and monoclonal anti-tumor antibodies showed no therapeutic benefit. Anti-tumor × anti-CD3 heteroconjugates may represent an effective approach to tumor-specific cellular immunotherapy.Read at the meeting of The American Society of Colon and Rectal Surgeons, St. Louis, Missouri, April 29–May 4, 1990. Dr. Nelson was supported by the Leon Hirsch Traveling Scholarship, awarded by the Research Foundation of The American Society of Colon and Rectal Surgeons. This material was acknowledged with a research award from the New England Society of Colon and Rectal Surgeons. Dr. Donohue is the recipient of a Cancer Development Award from the American Cancer Society.     

Curative options for sickle cell disease: haploidentical stem cell transplantation or gene therapy?

Haematopoietic stem cell transplantation (HSCT) is curative in sickle cell disease (SCD); however, the lack of available matched donors makes this therapy out of reach for the majority of patients with SCD. Alternative donor sources such as haploidentical HSCT expand the donor pool to nearly all patients with SCD, with recent data showing high overall survival, limited toxicities, and effective reduction in acute and chronic graft-versus-host disease (GVHD). Simultaneously, multiple gene therapy strategies are entering clinical trials with preliminary data showing their success, theoretically offering all patients yet another curative strategy without the morbidity and mortality of GVHD. As improvements are made for alternative donors in the allogeneic setting and as data emerge from gene therapy trials, the optimal curative strategy for any individual patient with SCD will be determined by many critical factors including efficacy, transplant morbidity and mortality, safety, patient disease status and preference, cost and applicability. Haploidentical may be the preferred choice now based mostly on availability of data; however, gene therapy is closing the gap and may ultimately prove to be the better option. Progress in both strategies, however, makes cure more attainable for the individual with SCD.     

Has stem cell transplantation come of age in the treatment of sickle cell disease?

Currently, hematopoietic SCT (HCT) is the only intervention that can restore normal hematopoiesis to provide a 'cure' in sickle cell disease. Yet, this treatment modality is used sparsely-a total of less than 400 transplants are reported in the Center for International Blood and Marrow Transplant Research database despite 70,000 afflicted in the United States; 88% of transplants are from HLA-matched sibling donors and 84% are <16 years of age at transplant. Overall survival at 3 years is over 90% after HCT in the young but 62% in adult HCT recipients due to increased disease and transplant-related morbidity. The decision and timing of HCT is a dilemma for physicians and families due to the need to consider HCT before severe organ damage in a disease that is generally not fatal in children with adequate supportive care. From the transplant physician's perspective, however, advances in the ability to identify well-matched donors, supportive care and promising conditioning regimens with low toxicity and transplant complications support the development of new HCT trials for sickle cell disease as the risk/benefit ratio can be balanced better. With the recognition of new predictors of early mortality, the anticipation of extensive and expensive life-long medical support, and the poor quality of life despite medical care, the scales tip in favor of HCT. This is prime time for the development of careful unrelated donor HCT trials for sickle cell disease. Research efforts targeting HCT will need to be directed at seeking safe and effective transplant methods applicable to all patients who might derive benefit.