Ricardo A. Dewey

Curcumin ameliorates autoimmune diabetes. Evidence in accelerated murine models of type 1 diabetes

Type 1 diabetes (T1DM) is a T cell‐mediated autoimmune disease that selectively destroys pancreatic β cells. The only possible cure for T1DM is to control autoimmunity against β cell‐specific antigens. We explored whether the natural compound curcumin, with anti‐oxidant and anti‐inflammatory activities, might down‐regulate the T cell response that destroys pancreatic β cells to improve disease outcome in autoimmune diabetes. We employed two accelerated autoimmune diabetes models: (i) cyclophosphamide (CYP) administration to non‐obese diabetic (NOD) mice and (ii) adoptive transfer of diabetogenic splenocytes into NODscid mice. Curcumin treatment led to significant delay of disease onset, and in some instances prevented autoimmune diabetes by inhibiting pancreatic leucocyte infiltration and preserving insulin‐expressing cells. To investigate the mechanisms of protection we studied the effect of curcumin on key immune cell populations involved in the pathogenesis of the disease. Curcumin modulates the T lymphocyte response impairing proliferation and interferon (IFN)‐γ production through modulation of T‐box expressed in T cells (T‐bet), a key transcription factor for proinflammatory T helper type 1 (Th1) lymphocyte differentiation, both at the transcriptional and translational levels. Also, curcumin reduces nuclear factor (NF)‐κB activation in T cell receptor (TCR)‐stimulated NOD lymphocytes. In addition, curcumin impairs the T cell stimulatory function of dendritic cells with reduced secretion of proinflammatory cytokines and nitric oxide (NO) and low surface expression of co‐stimulatory molecules, leading to an overall diminished antigen‐presenting cell activity. These in‐vitro effects correlated with ex‐vivo analysis of cells obtained from curcumin‐treated mice during the course of autoimmune diabetes. These findings reveal an effective therapeutic effect of curcumin in autoimmune diabetes by its actions on key immune cells responsible for β cell death.

Cell-based interventions to halt autoimmunity in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) results from death of insulin‐secreting β cells mediated by self‐immune cells, and the consequent inability of the body to maintain insulin levels for appropriate glucose homeostasis. Probably initiated by environmental factors, this disease takes place in genetically predisposed individuals. Given the autoimmune nature of T1DM, therapeutics targeting immune cells involved in disease progress have been explored over the last decade. Several high‐cost trials have been attempted to prevent and/or reverse T1DM. Although a definitive solution to cure T1DM is not yet available, a large amount of information about its nature and development has contributed greatly to both the improvement of patients health care and design of new treatments. In this study, we discuss the role of different types of immune cells involved in T1DM pathogenesis and their therapeutic potential as targets and/or modified tools to treat patients. Recently, encouraging results and new approaches to sustain remnant β cell mass and to increase β cell proliferation by different cell‐based means have emerged. Results coming from ongoing clinical trials employing cell therapy designed to arrest T1DM will probably proliferate in the next few years. Strategies under consideration include infusion of several types of stem cells, dendritic cells and regulatory T cells, either manipulated genetically ex vivo or non‐manipulated. Their use in combination approaches is another therapeutic alternative. Cell‐based interventions, without undesirable side effects, directed to block the uncontrollable autoimmune response may become a clinical reality in the next few years for the treatment of patients with T1DM.

Effect of TGF-β1 Stimulation on the Secretome of Human Adipose-Derived Mesenchymal Stromal Cells

Adipose tissue is an attractive source of mesenchymal stromal cells (MSCs) owing to the relative ease of obtaining large volumes with more MSC abundance compared with other sources. Increasing evidence supports the fact that trophic factors secreted by MSCs play a pivotal therapeutic role. Several strategies in regenerative medicine use MSCs, mainly exploiting their immunosuppressive effect and homing capacity to sites of damage. Transforming growth factor‐β1 (TGF‐β1) is a pleiotropic cytokine that, depending on the cell niche, can display either anti‐inflammatory or proinflammatory effects. TGF‐β1 expression increases in various tissues with damage, especially when accompanied by inflammation. Thus, we analyzed the effect of TGF‐β1 on the secretion by adipose‐derived mesenchymal stromal cells (ASCs) of a panel of 80 cytokines/chemokines using an antibody array. To avoid a possible effect of fetal bovine serum (FBS) on ASCs secretion, we performed our analysis by culturing cells in FBS‐free conditions, only supplemented with 0.1% of bovine serum albumin. We report the cytokine profile secreted by ASCs. We also found that TGF‐β1 exposure modulates 8 chemokines and 18 cytokines, including TGF‐β1 and ‐β2, and other important cytokines involved in immunosuppression, allergic responses, and bone resorption.

Pluripotent Nontumorigenic Adipose Tissue-Derived Muse Cells Have Immunomodulatory Capacity Mediated by Transforming Growth Factor-β1.

Adult mesenchymal stromal cell‐based interventions have shown promising results in a broad range of diseases. However, their use has faced limited effectiveness owing to the low survival rates and susceptibility to environmental stress on transplantation. We describe the cellular and molecular characteristics of multilineage‐differentiating stress‐enduring (Muse) cells derived from adipose tissue (AT), a subpopulation of pluripotent stem cells isolated from human lipoaspirates. Muse‐AT cells were efficiently obtained using a simple, fast, and affordable procedure, avoiding cell sorting and genetic manipulation methods. Muse‐AT cells isolated under severe cellular stress, expressed pluripotency stem cell markers and spontaneously differentiated into the three germ lineages. Muse‐AT cells grown as spheroids have a limited proliferation rate, a diameter of ∼15 µm, and ultrastructural organization similar to that of embryonic stem cells. Muse‐AT cells evidenced high stage‐specific embryonic antigen‐3 (SSEA‐3) expression (∼60% of cells) after 7–10 days growing in suspension and did not form teratomas when injected into immunodeficient mice. SSEA‐3+‐Muse‐AT cells expressed CD105, CD29, CD73, human leukocyte antigen (HLA) class I, CD44, and CD90 and low levels of HLA class II, CD45, and CD34. Using lipopolysaccharide‐stimulated macrophages and antigen‐challenged T‐cell assays, we have shown that Muse‐AT cells have anti‐inflammatory activities downregulating the secretion of proinflammatory cytokines, such as interferon‐γ and tumor necrosis factor‐α. Muse‐AT cells spontaneously gained transforming growth factor‐β1 expression that, in a phosphorylated SMAD2‐dependent manner, might prove pivotal in their observed immunoregulatory activity through decreased expression of T‐box transcription factor in T cells. Collectively, the present study has demonstrated the feasibility and efficiency of obtaining Muse‐AT cells that can potentially be harnessed as immunoregulators to treat immune‐related disorders. Stem Cells Translational Medicine 2017;6:161–173

Disease-Modifying Immunotherapy for the Management of Autoimmune Diabetes

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease that destroys the insulin-secreting β-cells of the pancreas. It is now possible to predict those candidates that will progress to T1D before the full onset of the disease. Prevention of uncontrollable autoimmunity against β-cells in therapies for T1D is mandatory to preserve the β-cell mass. Therefore, immunomodulatory strategies directed to inhibiting the activity of self-reactive T cell clones as well as induction of regulatory T cells would be beneficial for prevention of T1D or recurrence of β-cell autoimmunity against islet cell allografts.

Aligned ovine diaphragmatic myoblasts overexpressing human connexin-43 seeded on poly (l-lactic acid) scaffolds for potential use in cardiac regeneration

Diaphragmatic myoblasts (DMs) are precursors of type-1 muscle cells displaying high exhaustion threshold on account that they contract and relax 20 times/min over a lifespan, making them potentially useful in cardiac regeneration strategies. Besides, it has been shown that biomaterials for stem cell delivery improve cell retention and viability in the target organ. In the present study, we aimed at developing a novel approach based on the use of poly (L-lactic acid) (PLLA) scaffolds seeded with DMs overexpressing connexin-43 (cx43), a gap junction protein that promotes inter-cell connectivity. DMs isolated from ovine diaphragm biopsies were characterized by immunohistochemistry and ability to differentiate into myotubes (MTs) and transduced with a lentiviral vector encoding cx43. After confirming cx43 expression (RT-qPCR and Western blot) and its effect on inter-cell connectivity (fluorescence recovery after photobleaching), DMs were grown on fiber-aligned or random PLLA scaffolds. DMs were successfully isolated and characterized. Cx43 mRNA and protein were overexpressed and favored inter-cell connectivity. Alignment of the scaffold fibers not only aligned but also elongated the cells, increasing the contact surface between them. This novel approach is feasible and combines the advantages of bioresorbable scaffolds as delivery method and a cell type that on account of its features may be suitable for cardiac regeneration. Future studies on animal models of myocardial infarction are needed to establish its usefulness on scar reduction and cardiac function.

Human Adipose-Derived Mesenchymal Stem/Stromal Cells Handling Protocols. Lipid Droplets and Proteins Double-Staining

Human Adipose-derived mesenchymal stem/stromal cells (hASCs) are of great interest because of their potential for therapeutic approaches. The method described here covers every single step necessary for hASCs isolation from subcutaneous abdominal adipose tissue, multicolor phenotyping by flow cytometry, and quantitative determination of adipogenic differentiation status by means of lipid droplets (LDs) accumulation, and Western blot analysis. Moreover, to simultaneously analyze both LDs accumulation and cellular proteins localization by fluorescence microscopy, we combined Oil Red O (ORO) staining with immunofluorescence detection. For LDs quantification we wrote a program for automatic ORO-stained digital image processing implemented in Octave, a freely available software package. Our method is based on the use of the traditional low cost neutral lipids dye ORO, which can be imaged both by bright-field and fluorescence microscopy. The utilization of ORO instead of other more expensive lipid-specific dyes, together with the fact that the whole method has been designed employing cost-effective culture reagents (standard culture medium and serum), makes it affordable for tight-budget research laboratories. These may be replaced, if necessary or desired, by defined xeno-free reagents for clinical research and applications.

Effect of poly (l-lactic acid) scaffolds seeded with aligned diaphragmatic myoblasts overexpressing connexin-43 on infarct size and ventricular function in sheep with acute coronary occlusion

Abstract Diaphragmatic myoblasts (DM) are stem cells of the diaphragm, a muscle displaying high resistance to stress and exhaustion. We hypothesized that DM modified to overexpress connexin-43 (cx43), seeded on aligned poly (l-lactic acid) (PLLA) sheets would decrease infarct size and improve ventricular function in sheep with acute myocardial infarction (AMI). Sheep with AMI received PLLA sheets without DM (PLLA group), sheets with DM (PLLA-DM group), sheets with DM overexpressing cx43 (PLLA-DMcx43) or no treatment (control group, n = 6 per group). Infarct size (cardiac magnetic resonance) decreased ∼25% in PLLA-DMcx43 [from 8.2 ± 0.6 ml (day 2) to 6.5 ± 0.7 ml (day 45), p < .01, ANOVA-Bonferroni] but not in the other groups. Ejection fraction (EF%) (echocardiography) at 3 days post-AMI fell significantly in all groups. At 45 days, PLLA-DM y PLLA-DMcx43 recovered their EF% to pre-AMI values (PLLA-DM: 61.1 ± 0.5% vs. 58.9 ± 3.3%, p = NS; PLLA-DMcx43: 64.6 ± 2.9% vs. 56.9 ± 2.4%, p = NS), but not in control (56.8 ± 2.0% vs. 43.8 ± 1.1%, p < .01) and PLLA (65.7 ± 2.1% vs. 56.6 ± 4.8%, p < .01). Capillary density was higher (p < .05) in PLLA-DMcx43 group than in the remaining groups. In conclusion, PLLA-DMcx43 reduces infarct size in sheep with AMI. PLLA-DMcx43 and PLLA-DM improve ventricular function similarly. Given its safety and feasibility, this novel approach may prove beneficial in the clinic.