Search

Background: Diabetic foot ulcer (DFU) is an intractable diabetic complication. Patients suffering from diabetes mellitus (DM) frequently present with infected DFUs. In this study, a wound healing model on diabetic rat foot was established to mimic the pathophysiology of clinical patients who suffer from DFUs. Our study aimed to explore the localization of human adipose-derived stem cells (hADSCs) and the role of these cells in the repair of foot ulcerated tissue in diabetic rats, and thus to estimate the possibilities of adipose-derived stem cells for diabetic wound therapy. Method: Sprague-Dawley rats were used to establish diabetic models by streptozotocin injection. A full-thickness foot dorsal skin wound was created by a 5 mm skin biopsy punch and a Westcott scissor. These rats were randomly divided into two groups: the hADSC-treated group and the phosphate-buffered saline (PBS) control group. The hADSC or PBS treatment was delivered through the left femoral vein of rats. We evaluated the localization of hADSCs with fluorescence immunohistochemistry and the ulcer area and ulcerative histology were detected dynamically. Result: The hADSCs had a positive effect on the full-thickness foot dorsal skin wound in diabetic rats with a significantly reduced ulcer area at day 15. More granulation tissue formation, angiogenesis, cellular proliferation, and higher levels of growth factors expression were also detected in wound beds. Conclusions: Our data suggest that hADSC transplantation has the potential to promote foot wound healing in diabetic rats, and transplantation of exogenous stem cells may be suitable for clinical application in the treatment of DFU. [ABSTRACT FROM AUTHOR]

Background: Celastrol is a promising anti-tumor agent, yet it also elevates heat shock proteins (HSPs), especially HSP70, this effect believed to reduce its anti-tumor effects. Concurrent use of siRNA to increase celastrol's antitumor effects through HSP70 interference has been reported, but because siRNA technology is difficult to clinically apply, an alternative way to curb unwanted HSP70 elevation caused by celastrol treatment is worth exploring. Methods: In this work, we explore three alternative strategies to control HSP70 elevation: (1) Searching for cancer cell types that show no HSP70 elevation in the presence of celastrol (thus recommending themselves as suitable targets); (2) Modifying HSP70-inducing chemical groups, i.e.: the carboxyl group in celastrol; and (3) Using signaling molecule inhibitors to specifically block HSP70 elevation while protecting and/or enhancing anti-tumor effects. Results: The first strategy was unsuccessful since celastrol treatment increased HSP70 in all 7 of the cancer cell types tested, this result related to HSF1 activation. The ubiquity of HSF1 expression in different cancer cells might explain why celastrol has no cell-type limitation for HSP70 induction. The second strategy revealed that modification of celastrol's carboxyl group abolished its ability to elevate HSP70, but also abolished celastrol's tumor inhibition effects. In the third strategy, 11 inhibitors for 10 signaling proteins reportedly related to celastrol action were tested, and five of these could reduce celastrol-caused HSP70 elevation. Among these, the peptide deformylase (PDF) inhibitor, actinonin, could synergize celastrol's proliferation inhibition. Conclusions: Concurrent use of the chemical agent actinonin could reduce celastrol's HSP70 elevation and also enhance proliferation inhibition by celastrol. This combination presents a novel alternative to siRNA technology and is worth further investigation for its potentially effective anti-tumor action. [ABSTRACT FROM AUTHOR]

Background: In several neuropathological conditions, microglia can become overactivated and cause neurotoxicity by initiating neuronal damage in response to pro-inflammatory stimuli. Our previous studies have shown that exposure to electromagnetic fields (EMF) activates cultured microglia to produce tumor necrosis factor (TNF)-α and nitric oxide (NO) through signal transduction involving the activator of transcription STAT3. Here, we investigated the role of STAT3 signaling in EMF-induced microglial activation and pro-inflammatory responses in more detail than the previous study. Methods: N9 microglial cells were treated with EMF exposure or a sham treatment, with or without pretreatment with an inhibitor (Pyridone 6, P6) of the Janus family of tyrosine kinases (JAK). The activation state of microglia was assessed via immunoreaction using the microglial marker CD11b. Levels of inducible nitric oxide synthase (iNOS), TNF-α and NO were measured using real-time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and the nitrate reductase method. Activation of JAKs and STAT3 proteins was evaluated by western blotting for specific tyrosine phosphorylation. The ability of STAT3 to bind to DNA was detected with an electrophoresis mobility shift assay (EMSA). Results: EMF was found to significantly induce phosphorylation of JAK2 and STAT3, and DNA-binding ability of STAT3 in N9 microglia. In addition, EMF dramatically increased the expression of CD11b, TNF-α and iNOS, and the production of NO. P6 strongly suppressed the phosphorylation of JAK2 and STAT3 and diminished STAT3 activity in EMF-stimulated microglia. Interestingly, expression of CD11b as well as gene expression and production of TNF-α and iNOS were suppressed by P6 at 12 h, but not at 3 h, after EMF exposure. Conclusions: EMF exposure directly triggers initial activation of microglia and produces a significant pro-inflammatory response. Our findings confirm that the JAK2-STAT3 pathway may not mediate this initial microglial activation but does promote pro-inflammatory responses in EMF-stimulated microglial cells. Thus, the JAK2-STAT3 pathway might be a therapeutic target for reducing pro-inflammatory responses in EMF-activated microglia. [ABSTRACT FROM AUTHOR]