Ryan A. Denu

Macrophages and mesenchymal stromal cells support survival and proliferation of multiple myeloma cells

Multiple myeloma (MM) is characterized by almost exclusive tropism of malignant cells for the bone marrow (BM) milieu. The survival and proliferation of malignant plasma cells have been shown to rely on interactions with nonmalignant stromal cells, in particular mesenchymal stromal cells (MSCs), in the BM microenvironment. However, the BM microenvironment is composed of a diverse array of cell types. This study examined the role of macrophages, an abundant component of BM stroma, as a potential niche component that supports malignant plasma cells. We investigated the proliferation of MM tumour cell lines when cultured alone or together with MSCs, macrophages, or a combination of MSCs and macrophages, using the carboxyfluorescein succinimidyl ester assay. Consistently, we observed increased proliferation of MM cell lines in the presence of either MSCs or macrophages compared to cell line‐only control. Furthermore, the combined co‐culture of MSCs plus macrophages induced the greatest degree of proliferation of myeloma cells. In addition to increased proliferation, MSCs and macrophages decreased the rate of apoptosis of myeloma cells. Our in vitro studies provide evidence that highlights the role of macrophages as a key component of the BM microenvironment facilitating the growth of malignant plasma cells in MM.

Effects of Oxidative Stress on Mesenchymal Stem Cell Biology

Mesenchymal stromal/stem cells (MSCs) are multipotent stem cells present in most fetal and adult tissues. Ex vivo culture-expanded MSCs are being investigated for tissue repair and immune modulation, but their full clinical potential is far from realization. Here we review the role of oxidative stress in MSC biology, as their longevity and functions are affected by oxidative stress. In general, increased reactive oxygen species (ROS) inhibit MSC proliferation, increase senescence, enhance adipogenic but reduce osteogenic differentiation, and inhibit MSC immunomodulation. Furthermore, aging, senescence, and oxidative stress reduce their ex vivo expansion, which is critical for their clinical applications. Modulation of sirtuin expression and activity may represent a method to reduce oxidative stress in MSCs. These findings have important implications in the clinical utility of MSCs for degenerative and immunological based conditions. Further study of oxidative stress in MSCs is imperative in order to enhance MSC ex vivo expansion and in vivo engraftment, function, and longevity.

Fibroblasts and Mesenchymal Stromal/Stem Cells Are Phenotypically Indistinguishable.

Background/Aims: Human mesenchymal stromal/stem cells (MSCs), derived from many different tissues, are characterized by a fibroblast-like morphology, the expression of certain cell surface markers and their ability to differentiate into adipocytes, chondrocytes and osteoblasts. A number of studies have shown that MSCs share many characteristics with fibroblasts; however, there is no well-defined set of phenotypic characteristics that could distinguish between these 2 types of cells. Methods: We used 4 well-established human fibroblast strains from 3 different tissue sources and several human MSC strains from 2 different tissue sources to compare the phenotypic and immunological characteristics of these cells. Results: Fibroblast strains had a similar morphology to MSCs, expressed the same cell surface markers as MSCs and could also differentiate into adipocytes, chondrocytes and osteoblasts. Also, similar to MSCs, these fibroblasts were capable of suppressing T cell proliferation and modulating the immunophenotype of macrophages. We also show that MSCs deposit extracellular matrices of collagen type I and fibronectin, and express FSP1 in patterns similar to fibroblasts. Conclusions: Based on currently accepted definitions for cultured human MSCs and fibroblasts, we could not find any immunophenotypic property that could make a characteristic distinction between MSCs and fibroblasts.

Loss of SIRT3 Provides Growth Advantage for B Cell Malignancies

B cell malignancies comprise a diverse group of cancers that proliferate in lymph nodes, bone marrow, and peripheral blood. SIRT3 (sirtuin 3) is the major deacetylase within the mitochondrial matrix that promotes aerobic metabolism and controls reactive oxygen species (ROS) by deacetylating and activating isocitrate dehydrogenase 2 (IDH2) and superoxide dismutase 2 (SOD2). There is controversy as to whether SIRT3 acts as an oncogene or a tumor suppressor, and here we investigated its role in B cell malignancies. In mantle cell lymphoma patient samples, we found that lower SIRT3 protein expression was associated with worse overall survival. Further, SIRT3 protein expression was reduced in chronic lymphocytic leukemia primary samples and malignant B cell lines compared to primary B cells from healthy donors. This lower level of expression correlated with hyperacetylation of IDH2 and SOD2 mitochondrial proteins, lowered enzymatic activities, and higher ROS levels. Overexpression of SIRT3 decreased proliferation and diminished the Warburg-like phenotype in SIRT3-deficient cell lines, and this effect is largely dependent on deacetylation of IDH2 and SOD2. Lastly, depletion of SIRT3 from malignant B cell lines resulted in greater susceptibility to treatment with an ROS scavenger but did not result in greater sensitivity to inhibition of the hypoxia-inducible factor-1α pathway, suggesting that loss of SIRT3 increases proliferation via ROS-dependent but hypoxia-inducible factor-1α-independent mechanisms. Our study suggests that SIRT3 acts as a tumor suppressor in B cell malignancies, and activating the SIRT3 pathway might represent a novel therapeutic approach for treating B cell malignancies.

Biologic and immunomodulatory properties of mesenchymal stromal cells derived from human pancreatic islets

BACKGROUND AIMS Mesenchymal stromal cells (MSC) have now been shown to reside in numerous tissues throughout the body, including the pancreas. Ex vivo culture-expanded MSC derived from many tissues display important interactions with different types of immune cells in vitro and potentially play a significant role in tissue homeostasis in vivo. In this study, we investigated the biologic and immunomodulatory properties of human pancreatic islet-derived MSC. METHODS We culture-expanded MSC from cadaveric human pancreatic islets and characterized them using flow cytometry, differentiation assays and nuclear magnetic resonance-based metabolomics. We also investigated the immunologic properties of pancreatic islet-derived MSC compared with bone marrow (BM) MSC. RESULTS Pancreatic islet and BM-derived MSC expressed the same cell-surface markers by flow cytometry, and both could differentiate into bone, fat and cartilage. Metabolomics analysis of MSC from BM and pancreatic islets also showed a similar set of metabolic markers but quantitative polymerase chain reactions showed that pancreatic islet MSC expressed more interleukin(IL)-1b, IL-6, STAT3 and FGF9 compared with BM MSC, and less IL-10. However, similar to BM MSC, pancreatic islet MSC were able to suppress proliferation of allogeneic T lymphocytes stimulated with anti-CD3 and anti-CD28 antibodies. CONCLUSIONS Our in vitro analysis shows pancreatic islet-derived MSC have phenotypic, biologic and immunomodulatory characteristics similar, but not identical, to BM-derived MSC. We propose that pancreatic islet-derived MSC could potentially play an important role in improving the outcome of pancreatic islet transplantation by promoting engraftment and creating a favorable immune environment for long-term survival of islet allografts.

Influence of patient, physician, and hospital characteristics on the receipt of guideline-concordant care for inflammatory breast cancer.

PURPOSE Inflammatory breast cancer (IBC) is an aggressive subtype of breast cancer for which treatments vary, so we sought to identify factors that affect the receipt of guideline-concordant care. METHODS Patients diagnosed with IBC in 2004 were identified from the Breast and Prostate Cancer Data Quality and Patterns of Care Study, containing information from cancer registries in seven states. Variation in guideline-concordant care for IBC, based on National Comprehensive Cancer Network (NCCN) guidelines, was assessed according to patient, physician, and hospital characteristics. RESULTS Of the 107 IBC patients in the study without distant metastasis at the time of diagnosis, only 25.8% received treatment concordant with guidelines. Predictors of non-concordance included patient age (≥70 years), non-white race, normal body mass index (BMI 18.5-25 kg/m(2)), patients with physicians graduating from medical school >15 years prior, and smaller hospital size (<200 beds). IBC patients survived longer if they received guideline-concordant treatment based on either 2003 (p=0.06) or 2013 (p=0.06) NCCN guidelines. CONCLUSIONS Targeting factors associated with receipt of care that is not guideline-concordant may reduce survival disparities in IBC patients. Prompt referral for neoadjuvant chemotherapy and post-operative radiation therapy is also crucial.

SIRT3 Enhances Mesenchymal Stem Cell Longevity and Differentiation.

Mesenchymal stem cells (MSCs) are multipotent cells that are currently being investigated in a wide variety of clinical trials for their anti-inflammatory and immunomodulatory properties as well as their osteogenic and chondrogenic capabilities. However, there are considerable interdonor variability and heterogeneity of MSC populations, making it challenging to compare different products. Furthermore, proliferation, differentiation, and immunomodulation of MSCs decrease with aging and ex vivo expansion. The sirtuins have emerged as a class of protein deacylases involved in aging, oxidative stress, and metabolism. Sirtuin 3 (SIRT3) is the major mitochondrial deacetylase involved in reducing oxidative stress while preserving oxidative metabolism, and its levels have been shown to decrease with age. This study investigated the role of SIRT3 in MSC differentiation and aging. As MSCs were expanded ex vivo, SIRT3 levels decreased. In addition, SIRT3 depletion reduced MSC differentiation into adipocytes and osteoblasts. Furthermore, overexpression of SIRT3 in later-passage MSCs reduced aging-related senescence, reduced oxidative stress, and enhanced their ability to differentiate. These data suggest that overexpressing SIRT3 might represent a strategy to increase the quality and quantity of MSCs utilized for clinical applications.

Idiopathic CD4 lymphocytopenia with giant cell arteritis and pulmonary mucormycosis.

Idiopathic CD4 lymphocytopenia (ICL) is characterized by a low CD4+ lymphocyte count in the absence of HIV or other underlying etiologies. We report a case of a 57-year old man with ICL and giant cell arteritis (GCA) who developed pulmonary mucormycosis, which, to our knowledge, is the first report of these occurring in a patient with ICL. Abnormally low total lymphocyte or CD4+ cell counts occurring in patients with autoimmune disorders should alert clinicians to the possibility of ICL. Immunosuppressive treatment should be used with caution in this context.

Potential yield of imminent death kidney donation

About 99 000 people are waiting for a kidney in the United States, and many will die waiting. The concept of “imminent death” donation, a type of living donation, has been gaining attention among physicians, patients, and ethicists. We estimated the number of potential imminent death kidney donors at the University of Wisconsin Hospital and Clinics by assessing the number of annual deaths in individuals with normal kidney function. Based on a previous survey suggesting that one‐third of patients might be willing to donate at imminent death, we estimate that between 76 and 396 people in the state of Wisconsin would be medically eligible and willing to donate each year at the time of imminent death. We extrapolated these numbers to all transplant centers in the United States, estimating that between 5925 and 31 097 people might be eligible and willing to donate each year. Our results suggest that allowing donation at imminent death and including discussions about organ donation in end‐of‐life planning could substantially reduce the nations kidney waiting list while providing many more donors the opportunity to give this gift.

Estimates of Cancer Deaths Prevented by Raising Cigarette Taxes

Estimates of Cancer Deaths Prevented by Raising Cigarette Taxes To the Editor Smoking remains one of the leading causes of preventable cancer deaths, and Lortet-Tieulent et al1 recently estimated that 28.6% of cancer deaths in 2014 can be attributed to cigarette smoking. Historically, state-based legislation and public health initiatives have been the most successful ways to reduce smoking. Some approaches include mass media antismoking advertising, smoke-free policies, smoking curricula in schools, restricting tobacco companies from marketing, raising the legal smoking age from 18 to 21, and raising the cigarette tax.2 Of these, the most promising strategy at the current time appears to be raising the cigarette tax.3,4 Each state (and the District of Columbia) sets its own cigarette tax, ranging from