Recombinant Klotho Protein Ameliorates Myocardial Ischemia/Reperfusion Injury by Attenuating Sterile Inflammation.

Currently, no effective therapy and potential target have been elucidated for preventing myocardial ischemia and reperfusion injury (I/R). We hypothesized that the administration of recombinant klotho (rKL) protein could attenuate the sterile inflammation in peri-infarct regions by inhibiting the extracellular release of high mobility group box-1 (HMGB1). This hypothesis was examined using a rat coronary artery ligation model. Rats were divided into sham, sham+ rKL, I/R, and I/R+ rKL groups (n = 5/group). Administration of rKL protein reduced infarct volume and attenuated extracellular release of HMGB1 from peri-infarct tissue after myocardial I/R injury. The administration of rKL protein inhibited the expression of pro-inflammatory cytokines in the peri-infarct regions and significantly attenuated apoptosis and production of intracellular reactive oxygen species by myocardial I/R injury. Klotho treatment significantly reduced the increase in the levels of circulating HMGB1 in blood at 4 h after myocardial ischemia. rKL regulated the levels of inflammation-related proteins. This is the first study to suggest that exogenous administration of rKL exerts myocardial protection effects after I/R injury and provides new mechanistic insights into rKL that can provide the theoretical basis for clinical application of new adjunctive modality for critical care of acute myocardial infarction.

Transient Global Ischemia-Induced Brain Inflammatory Cascades Attenuated by Targeted Temperature Management.

Sudden cardiac arrest leads to a significantly increased risk of severe neurological impairment and higher mortality rates in survivors due to global brain tissue injury caused by prolonged whole-body ischemia and reperfusion. The brain undergoes various deleterious cascading events. Among these damaging mechanisms, neuroinflammation plays an especially crucial role in the exacerbation of brain damage. Clinical guidelines indicate that 33 °C and 36 °C are both beneficial for targeted temperature management (TTM) after cardiac arrest. To clarify the mechanistic relationship between TTM and inflammation in transient global ischemia (TGI) and determine whether 36 °C produces a neuroprotective effect comparable to 33 °C, we performed an experiment using a rat model. We found that TTM at 36 °C and at 33 °C attenuated neuronal cell death and apoptosis, with significant improvements in behavioral function that lasted for up to 72 h. TTM at 33 °C and 36 °C suppressed the propagation of inflammation including the release of high mobility group box 1 from damaged cells, the activation and polarization of the microglia, and the excessive release of activated microglia-induced inflammatory cytokines. There were equal neuroprotective effects for TTM at 36 °C and 33 °C. In addition, hypothermic complications and should be considered safe and effective after cardiac arrest.

In vivo near-infrared imaging for the tracking of systemically delivered mesenchymal stem cells: tropism for brain tumors and biodistribution.

Mesenchymal stem cell (MSC)-based gene therapy is a promising tool for the treatment of various neurological diseases, including brain tumors. However, the tracking of in vivo stem cell migration, distribution, and survival need to be defined for their clinical application. The systemic routes of stem cell delivery must be determined because direct intracerebral injection as a cure for brain tumors is an invasive method. In this study, we show for the first time that near-infrared (NIR) imaging can reveal the distribution and tumor tropism of intravenously injected MSCs in an intracranial xenograft glioma model. MSCs were labeled with NIR fluorescent nanoparticles, and the effects of the NIR dye on cell proliferation and migratory capacity were evaluated in vitro. We investigated the tumor-targeting properties and tissue distribution of labeled MSCs introduced by intravenous injection and followed by in vivo imaging analysis, histological analysis, and real-time quantitative polymerase chain reaction. We observed no cytotoxicity or change in the overall growth rate and characteristics of labeled MSCs compared with control MSCs. NIR fluorescent imaging showed the organ distribution and targeted tumor tropism of systemically injected human MSCs. A significant number of MSCs accumulated specifically at the tumor site in the mouse brain. These results suggest that NIR-based cell tracking is a potentially useful imaging technique to visualize cell survival, migration, and distribution for the application of MSC-mediated therapies in the treatment of malignant gliomas.

Potential application of temozolomide in mesenchymal stem cell-based TRAIL gene therapy against malignant glioma.

Because the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively kills tumor cells, it is one of the most promising candidates for cancer treatment. TRAIL-secreting human mesenchymal stem cells (MSC-TRAIL) provide targeted and prolonged delivery of TRAIL in glioma therapy. However, acquired resistance to TRAIL of glioma cells is a major problem to be overcome. We showed a potential therapy that used MSC-TRAIL combined with the chemotherapeutic agent temozolomide (TMZ). The antitumor effects of the combination with MSC-TRAIL and TMZ on human glioma cells were determined by using an in vitro coculture system and an in vivo experimental xenografted mouse model. Intracellular signaling events that are responsible for the TMZ-mediated sensitization to TRAIL-induced apoptosis were also evaluated. Treatment of either TRAIL-sensitive or -resistant human glioma cells with TMZ and MSC-TRAIL resulted in a significant enhancement of apoptosis compared with the administration of each agent alone. We demonstrated that TMZ effectively increased the sensitivity to TRAIL-induced apoptosis via extracellular signal-regulated kinase-mediated upregulation of the death receptor 5 and downregulation of antiapoptotic proteins, such as X-linked inhibitor of apoptosis protein and cellular FLICE-inhibitory protein. Subsequently, this combined treatment resulted in a substantial increase in caspase activation. Furthermore, in vivo survival experiments and bioluminescence imaging analyses showed that treatment using MSC-TRAIL combined with TMZ had greater therapeutic efficacy than did single-agent treatments. These results suggest that the combination of clinically relevant TMZ and MSC-TRAIL is a potential therapeutic strategy for improving the treatment of malignant gliomas.

Lipoxygenase inhibitor MK886 potentiates TRAIL-induced apoptosis through CHOP- and p38 MAPK-mediated up-regulation of death receptor 5 in malignant glioma.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers specific apoptosis in tumor cells and is one of the most promising candidates for cancer gene therapy. However, resistance to TRAIL is one of the main impediments to use of TRAIL in cancer treatment. We showed previously that the lipoxygenase inhibitor MK886 in combination with TRAIL exhibits enhanced antitumor activities compared with each agent alone in human glioma cells. In this study, we elucidated the molecular mechanisms responsible for MK886-mediated sensitization to TRAIL-induced apoptosis. We found that MK886 sensitized glioma cells to TRAIL-induced apoptosis by upregulating the death receptor 5 (DR5) and that specific knockdown of DR5 attenuated cell death. The mechanisms underlying this sensitization involved activation of the MK886-induced p38 mitogen-activated protein kinase (MAPK) pathway and subsequent DR5 overexpression. However, treatment with a specific inhibitor or gene silencing of p38 MAPK abolished both the DR5 induction and the increase in apoptosis caused by TRAIL. Taken together, our findings indicate that the increased expression of DR5 in a p38 MAPK-dependent manner plays an important role in the sensitization of MK886 to TRAIL-induced apoptosis.

Effective combination therapy for malignant glioma with TRAIL-secreting mesenchymal stem cells and lipoxygenase inhibitor MK886.

The apoptotic ligand TRAIL is believed to have promise as a cancer gene therapy, yet many types of cancer, including gliomas, have exhibited resistance to TRAIL-induced apoptosis. Here, we show that therapeutic combination of the lipoxygenase inhibitor MK886 and TRAIL-secreting human mesenchymal stem cells (MSC-TRAIL) provide targeted and prolonged delivery of TRAIL both in vitro and in orthotopic mouse models of glioma. Treatment of either TRAIL-sensitive or TRAIL-resistant human glioma cells with MK886 and MSC-TRAIL resulted in significantly enhanced apoptosis compared with each agent alone. MK886 effectively increased the sensitivity to TRAIL-induced apoptosis via upregulation of the death receptor 5 and downregulation of the antiapoptotic protein survivin in human glioma cell lines and in primary glioma cells. This regulation was accompanied by a substantial increase in caspase activation after combined treatment. Furthermore, in vivo survival experiments and imaging analysis in orthotopic xenografted mice showed that MSC-based TRAIL gene delivery combined with MK886 into the tumors had greater therapeutic efficacy than single-agent treatment. Together, our findings indicate that MK886 combined with MSC-based TRAIL gene delivery may represent a novel strategy for improving the treatment of malignant gliomas.

Valproic acid downregulates the expression of MGMT and sensitizes temozolomide-resistant glioma cells.

Temozolomide (TMZ) has become a key therapeutic agent in patients with malignant gliomas; however, its survival benefit remains unsatisfactory. Valproic acid (VPA) has emerged as an anticancer drug via inhibition of histone deacetylases (HDACs), but the therapeutic advantages of a combination with VPA and TMZ remain poorly understood. The main aim of the present study was to determine whether an antitumor effect could be potentiated by a combination of VPA and TMZ, especially in TMZ-resistant cell lines. A combination of VPA and TMZ had a significantly enhanced antitumor effect in TMZ-resistant malignant glioma cells (T98 and U138). This enhanced antitumor effect correlated with VPA-mediated reduced O6-methylguanine-DNA methyltransferase (MGMT) expression, which plays an important role in cellular resistance to alkylating agents. In vitro, the combination of these drugs enhanced the apoptotic and autophagic cell death, as well as suppressed the migratory activities in TMZ-resistant cell lines. Furthermore, in vivo efficacy experiment showed that treatment of combination of VPA and TMZ significantly inhibited tumor growth compared with the monotherapy groups of mice. These results suggest that the clinical efficacy of TMZ chemotherapy in TMZ-resistant malignant glioma may be improved by combination with VPA.

Valproic acid enhances anti-tumor effect of mesenchymal stem cell mediated HSV-TK gene therapy in intracranial glioma.

Suicide gene therapy of glioma based on herpes simplex virus type I thymidine kinase (HSV-TK) and prodrug ganciclovir (GCV) suffers from the lack of efficacy in clinical trials, which is mostly due to low transduction efficacy and absence of bystander effect in tumor cells. Recently, stem cells as cellular delivery vehicles of prodrug converting gene has emerged as a new treatment strategy for malignant glioma. In this study, we evaluated the anti-glioma effect of suicide gene therapy using human bone marrow mesenchymal stem cells expressing HSV-TK (MSCs-TK) combined with valproic acid (VPA), which can upregulate the gap junction proteins and may enhance the bystander effect of suicide gene therapy. Expression of HSV-TK in MSCs was confirmed by RT-PCR analysis and the sensitivity of MSCs-TK to GCV was assessed. A bystander effect was observed in co-cultures of MSCs-TK and U87 glioma cells by GCV in a dose-dependent manner. VPA induced the expression of the gap junction proteins connexin (Cx) 43 and 26 in glioma cell and thereby enhanced the bystander effect in co-culture experiment. The enhanced bystander effect was inhibited by the gap junction inhibitor 18-ß-glycyrrhetinic acid (18-GA). Moreover, the combined treatment with VPA and MSCs-TK synergistically enhanced apoptosis in glioma cells by caspase activation. In vivo efficacy experiments showed that combination treatment of MSCs-TK and VPA significantly inhibited tumor growth and prolonged the survival of glioma-bearing mice compared with single-treatment groups. In addition, TUNEL staining also demonstrated a significant increase in the number of apoptotic cells in the combination treated group compared with single-treatment groups. Taken together, these results provide the rational for designing novel experimental protocols to increase bystander killing effect against intracranial gliomas using MSCs-TK and VPA.