Preconditioning of human umbilical cord mesenchymal stem cells with deferoxamine potentiates the capacity of the secretome released from the cells and promotes immunomodulation and beta cell regeneration in a rat model of type 1 diabetes.

This study aimed to examine the effects of the secretome released by human umbilical cord-mesenchymal stem cells (MSC) as a result of preconditioning with deferoxamine (DFX), a hypoxia mimetic agent, on type 1 diabetes (T1D), by comparing it with the secretome produced by untreated MSCs. Initially, the levels of total protein, IL4, IL10, IL17, and IFNγ in the conditioned medium (CM) obtained from MSCs subjected to preconditioning with 150 µM DFX (DFX-CM) were analyzed in comparison to CM derived from untreated MSCs (N-CM). Subsequently, the CMs were administered to rats with T1D within a specific treatment plan. Following the sacrification, immunomodulation was evaluated by measuring serum cytokine levels and assessing the regulatory T cell (Treg) ratio in spleen mononuclear cells. Additionally, ß-cell mass was determined in the islets by immunohistochemical labeling of NK6 Homeobox 1 (Nkx6.1), Pancreatic duodenal homeobox-1 (Pdx1), and insulin antibodies in pancreatic sections. In vitro findings indicated that the secretome levels of MSCs were enhanced by preconditioning with DFX. In vivo, the use of DFX-CM significantly increased the Treg population, and accordingly, the level of inflammatory cytokines decreased. In ß-cell marker labeling, D + DFX-CM showed significantly increased PDX1 and insulin immunoreactivity. In conclusion, while the factors released by MSCs without external stimulation had limited therapeutic effects, substantial improvements in immunomodulation and ß-cell regeneration were seen with DFX-preconditioned cell-derived CM.

Investigation of conditioned medium properties obtained from human umbilical cord mesenchymal stem/stromal cells preconditioned with dimethyloxalylglycine in a correlation with ultrastructural changes.

Mesenchymal stem/stromal cells (MSCs) hold significant therapeutic value due to their regeneration abilities, migration capacity, and immunosuppressive and immunomodulatory properties. These cells secrete soluble and insoluble factors, and this complex secretome contributes to their therapeutic effect. Furthermore, stimulation of cells by various external stimuli lead to secretome modifications that can increase the therapeutic efficacy. So, this study examined the effect of dimethyloxalylglycine (DMOG), a hypoxia-mimetic agent, on secretome profiles and exosome secretions of MSCs by evaluating conditioned medium (CM) and ultrastructural morphologies of the cells in comparison with unpreconditioned MSCs. The appropriate dose and duration of the use of DMOG were determined as 1000 µM and 24 h by evaluating the HIF-1α expression. DMOG-CM and N-CM were collected from MSCs incubated in serum-free medium with/without DMOG for 24 h, respectively. The content analysis of conditioned mediums (CMs) revealed that VEGF, NGF, and IL-4 levels were increased in DMOG-CM. Subsequently, exosomes were isolated from the CMs and were shown by transmission electron microscopy and Western blot analysis in both groups. The effects of CMs on proliferation and migration were determined by in vitro wound healing tests; both CMs increased the fibroblast's migratory and proliferative capacities. According to the ultrastructural evaluation, autophagosome, autolysosome, myelin figure, and microvesicular body structures were abundant in DMOG-preconditioned MSCs. Consistent with the high number of autophagic vacuoles, Beclin-1 expression was increased in those cells. These findings suggested that DMOG could alter MSCs' secretion profile, modify their ultrastructural morphology accordingly, and make the CM a more potent therapeutic tool. RESEARCH HIGHLIGHTS: Preconditioning mesenchymal stem/stromal cells with dimethyloxalylglycine, a hypoxia-mimetic agent, could modify cellular metabolism. Hypoxic mechanisms lead to alterations in the ultrastructural characteristics of mesenchymal stromal/stem cells. Preconditioning with dimethyloxalylglycine leads to ultrastructural and metabolic changes of mesenchymal stromal/stem cells along with modifications in their secretome profiles. Preconditioning of mesenchymal stromal/stem cells could render them a more potent therapeutic tool.

Therapeutic potential of conditioned medium obtained from deferoxamine preconditioned umbilical cord mesenchymal stem cells on diabetic nephropathy model.

BACKGROUND: The therapeutic potential of mesenchymal stem cells (MSCs)-derived conditioned media (CM) can be increased after preconditioning with various chemical agents. The aim of this study is comparative evaluation of effects of N-CM and DFS-CM which are collected from normal (N) and deferoxamine (DFS) preconditioned umbilical cord-derived MSCs on rat diabetic nephropathy (DN) model. METHODS: After incubation of the MSCs in serum-free medium with/without 150 µM DFS for 48 h, the contents of N-CM and DFS-CM were analyzed by enzyme-linked immunosorbent assay. Diabetes (D) was induced by single dose of 55 mg/kg streptozotocin. Therapeutic effects of CMs were evaluated by biochemical, physical, histopathological and immunohistochemical analysis. RESULTS: The concentrations of vascular endothelial growth factor alpha, nerve growth factor and glial-derived neurotrophic factor in DFS-CM increased, while one of brain-derived neurotrophic factor decreased in comparison with N-CM. The creatinine clearance rate increased significantly in both treatment groups, while the improvement in albumin/creatinine ratio and renal mass index values were only significant for D + DFS-CM group. Light and electron microscopic deteriorations and loss of podocytes-specific nephrin and Wilms tumor-1 (WT-1) expressions were significantly restored in both treatment groups. Tubular beclin-1 expression was significantly increased for DN group, but it decreased in both treatment groups. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cell death increased in the tubules of D group, while it was only significantly decreased for D + DFS-CM group. CONCLUSIONS: DFS-CM can be more effective in the treatment of DN by reducing podocyte damage and tubular apoptotic cell death and regulating autophagic activity with its more concentrated secretome content than N-CM.

Metformin induces mitochondrial remodeling and differentiation of pancreatic progenitor cells into beta-cells by a potential mechanism including suppression of the T1R3, PLCß2, cytoplasmic Ca+2, and AKT.

The main goal of this study was to investigate the molecular changes in pancreatic progenitor cells subject to high glucose, aspartame, and metformin in vitro. This scope of work glucose, aspartame, and metformin were exposed to pancreatic islet derived progenitor cells (PID-PCs) for 10 days. GLUT1's role in beta-cell differentiation was examined by using GLUT1 inhibitor WZB117. Insulin+ cell ratio was measured by flow cytometry; the expression of beta-cell differentiation related genes was shown by RT-PCR; mitochondrial mass, mitochondrial ROS level, cytoplasmic Ca2+, glucose uptake, and metabolite analysis were made fluorometrically and spectrophotometrically; and proteins involved in related molecular pathways were determined by western blotting. Findings showed that glucose or aspartame exposed cells had similar metabolic and gene expression profile to control PID-PCs. Furthermore, relatively few insulin+ cells in aspartame treated cells were determined. Aspartame signal is transmitted through PLCß2, CAMKK2 and LKB1 in PID-PCs. The most obvious finding of this study is that metformin significantly increased beta-cell differentiation. The mechanism involves suppression of the sweet taste signal's molecules T1R3, PLCß2, cytoplasmic Ca+2, and AKT in addition to the direct effect of metformin on mitochondria and AMPK, and the energy metabolism of PID-PCs is remodelled in the direction of oxidative phosphorylation. These findings are very important in terms of determining that metformin stimulates the mitochondrial remodeling and the differentiation of PID-PCs to beta-cells and thus it may contribute to the compensation step, which is the first stage of diabetes development.

Exendin-4 inhibits small intestinal glucose sensing and absorption through repression of T1R2/T1R3 sweet taste receptor signalling in streptozotocin diabetic mice.

The small intestine, which is the area where sugars are absorbed, should be considered in the approaches developed for the treatment of diabetes. However, studies on small intestine damage in diabetic individuals, and the effects of current treatments on the small intestine are very limited. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on small intestine injury in diabetic mice. BALB/c male mice were divided into 4 groups for this study. The first group was given citrate buffer, the second group was given exendin-4, the third group was given streptozotocin (STZ), and the fourth group was given both exendin-4, and STZ. As the results, we determined a decrease in the edema and deterioration in the integrity of the villi, disruption in continuity of the brush border, fibrosis and enterocyte apoptosis, while the TNFα level and crypt cell proliferation were increased in the small intestinal tissue of exendin-4 treated STZ diabetic mice. Furthermore, the levels of duodenal tissue glucose, SGLT1, and GLUT2 were decreased, whereas there was an increase in GIP level in diabetic mice administered with exendin-4. Moreover, we determined that the sweet taste receptors T1R2/T1R3, downstream molecules PLCß2, α-gustducin and associated secondary messengers IP3, cAMP, which were increased in the duodenal tissue of STZ-diabetic mice, decreased with exendin-4 administration. These findings were evaluated as that exendin-4 reduces glucose absorption by suppressing the T1R2/T1R3 sweet taste signal perception pathway in duodenum of STZ diabetic mice.

Aspartame induces cancer stem cell enrichment through p21, NICD and GLI1 in human PANC-1 pancreas adenocarcinoma cells.

This study aimed to investigate the molecular effects of the common natural sugar glucose and artificial sweetener aspartame on cancer stem cell (CSC) population and cancer aggressiveness of PANC-1 human pancreas adenocarcinoma cells. According to our findings while aspartame exposure significantly increased the CSC population, high glucose had no effect on it. The epithelial-mesenchymal transition marker N-cadherin increased only in the aspartame group. The findings indicate that a high level of glucose exposure does not effect the invasion and migration of PANC-1 cells, while aspartame increases both of these aggressiveness criteria. The findings also suggest that a high concentration of glucose maintains CSC population through induction of nuclear Oct3/4 and differentiation to parental cells via increasing cytoplasmic c-myc. Aspartame exposure to PANC-1 cells activated AKT and deactivated GSK3ß by increasing levels of ROS and cytoplasmic Ca+2, respectively, through T1R2/T1R3 stimulation. Then p-GSK3ß(Ser9) boosted the CSC population by increasing pluripotency factors Oct3/4 and c-myc via NICD, GLI1 and p21. In the aspartame group, T1R1 silencing further increased the CSC population but decreased cell viability and suppressed the p21, NICD and GLI activation. The presence and amount of T1R subunits in the membrane fraction of PANC-1 cells are demonstrated for the first time in this study, as is the regulatory effect of T1R1's on CSC population. In conclusion, the present study demonstrated that long-term aspartame exposure increases CSC population and tumor cell aggressiveness through p21, NICD, GLI1. Moreover, while aspartame had no tumorigenic effect, it could potentially advance an existing tumor.

Tub and ß-catenin play a key role in insulin and leptin resistance-induced pancreatic beta-cell differentiation.

The aim of this study was to investigate the molecular mechanism of pancreatic islet-derived mesenchymal stem cell (PID-MSC) differentiation into beta-cells in the presence of insulin and leptin resistance stimulators. We determined that beta-cell differentiation was stimulated by glucose, insulin, and leptin. Co-administration of insulin and leptin resulted in greater, at a further stage of differentiation but non-functional beta-cell formation. The levels of p-AKT(Ser473) did not change; SOCS3, PTP1B, p-IRS1(Ser307), PTEN levels increased and p-IRS1(Try) levels decreased due to insulin and leptin co-administration. These findings suggest that co-administration of insulin and leptin to PID-MSCs results in the development of both insulin and leptin resistance together. We showed that this differentiation signaling is mainly mediated by AKT/GSK-3ß/ß-catenin and Tub. Moreover, ß-catenin and Tub were linked to each other in the nucleus under this condition. Furthermore, we found that Tub and ß-catenin contributes to insulin production by increasing the expression of transcription factors by binding to the promoter regions of ins1, ins2, and pdx1 genes. In addition, Tub is also bound to the promoter region of the MafA gene. These findings demonstrate that when insulin and leptin resistance develop together in rat PID-MSCs beta-cell differentiation increases markedly via ß-catenin and Tub. New therapeutic agents that inhibit AKT/GSK-3ß/ß-catenin and in particular Tub may help prevent the development or retard the progression of type 2 diabetes.

4-Methylcatechol prevents streptozotocin-induced acute kidney injury through modulating NGF/TrkA and ROS-related Akt/GSK3ß/ß-catenin pathways.

Nerve growth factor (NGF) has been shown to protect the viability of kidney cells in acute phase of renal damage. However, since the half-life of NGF is very short, it is too large to pass the blood-brain barrier and rapidly transported to the liver for catabolizing its use in therapy is limited. 4-Methylcatechol (4MC) is a substance that increases NGF synthesis in many tissues. This study aimed to investigate the protective effects of 4MC against acute renal injury induced by streptozotocin (STZ). We have investigated the profibrotic, proinflammatory, oxidative changes in STZ-induced acute renal damage and the possible role of the NGF/TrkA system and Akt/GSK3ß/ß-catenin pathway in this mechanism. Experiment was designed as to be started with injection of 4MC for 10 days as a single dose (10 µg/kg) per day and to be terminated after 4 h of a single dose (75 mg/kg) STZ injection. As the result, 4MC pre-treatment decreased kidney damage, ROS production, the renal levels of TGFß1, CD68, tumor necrosis factor-α and interleukin 1ß. Moreover, 4MC pre-treatment increased levels of NGF and its receptor TrkA, p-Akt (Thr308), p-GSK3ß (Ser9) and nuclear ß-catenin. These data suggest that 4MC prevents the development of STZ-induced renal damage by suppressing ROS production and inflammation via Akt/GSK3ß/ß-catenin pathway which may be stimulated by NGF/TrkA signaling. Therefore, 4MC can be suggested as a potential agent for the prevention of acute renal injury.

Exendin-4 partly ameliorates - hyperglycemia-mediated tissue damage in lungs of streptozotocin-induced diabetic mice.

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion, - plays anti-inflammatory role in atherosclerosis, and has surfactant-releasing effects in lungs. GLP-1 analogues are used in diabetes therapy. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on lung injury in diabetic mice. BALB/c male mice were divided into four groups. The first group was given only citrate buffer, the second group was given only exendin-4, the third group was given only streptozotocin (STZ), and the fourth group was given both exendin-4 and STZ. Exendin-4 (3µg/kg) was administered daily by subcutaneous injection for 30days after mice were rendered diabetic with a single dose of STZ (200mg/kg). Structural alterations, oxidative stress, apoptosis, insulin signaling and expressions of prosurfactant-C, alpha-smooth muscle actin, collagen-I and fibronectin were evaluated in lung tissue. Diabetic mice lungs were characterized by induced oxidative stress, apoptosis, edema, and cell proliferation. They had honeycomb-like alveoli, thicker alveolar walls, and hypertrophic pneumocytes. Although exendin-4 treatment improved pulmonary edema, apoptosis, oxidative stress, and lung injury, it led to the disrupted insulin signaling and interstitial collagen accumulation in the lungs of diabetic mice. Exendin-4 ameliorates hyperglycemia-mediated lung damage by reducing glucose, -oxidative stress and stimulating cell proliferation. However, exendin-4 led to increased lung injury partly by reducing insulin signaling - and collagen accumulation around pulmonary vasculature in diabetic mice.

Vitamin U has a protective effect on valproic acid-induced renal damage due to its anti-oxidant, anti-inflammatory, and anti-fibrotic properties.

The aim of present study was to investigate the effect of vitamin U (vit U, S-methylmethionine) on oxidative stress, inflammation, and fibrosis within the context of valproic acid (VPA)-induced renal damage. In this study, female Sprague Dawley rats were randomly divided into four groups: Group I consisted of intact animals, group II was given vit U (50 mg/kg/day, by gavage), group III was given VPA (500 mg/kg/day, intraperitonally), and group IV was given VPA + vit U. The animals were treated by vit U 1 h prior to treatment with VPA every day for 15 days. The following results were obtained in vit U + VPA-treated rats: (i) the protective effect of vit U on renal damage was shown by a significant decrease in histopathological changes and an increase in Na(+)/K(+)-ATPase activity; (ii) anti-oxidant property of vit U was demonstrated by a decrease in malondialdehyde levels and xanthine oxidase activity and an increase in glutathione levels, catalase and superoxide dismutase activities; (iii) anti-inflammatory property of vit U was demonstrated by a decrease in tumor necrosis factor-α, interleukin-1ß, monocyte chemoattractant protein-1 levels, and adenosine deaminase activity; (iv) anti-fibrotic effect of vit U was shown by a decrease in transforming growth factor-ß, collagen-1 levels, and arginase activity. Collectively, these data show that VPA is a promoter of inflammation, oxidative stress, and fibrosis which resulted in renal damage. Vit U can be proposed as a potential candidate for preventing renal damage which arose during the therapeutic usage of VPA.