Human amnion-derived mesenchymal stem cells attenuate xenogeneic graft-versus-host disease by preventing T cell activation and proliferation.

Acute graft-versus-host disease (GVHD) is characterized by severe tissue damage that is a life-threatening complication of allogeneic hematopoietic stem cell transplantation. Due to their immunosuppressive properties, mesenchymal stem cells (MSC) have been increasingly examined for the treatment of immune-related diseases. We aimed to assess the immunosuppressive effects of human amnion-derived MSC (AMSC) in a xenogeneic GVHD NOD/Shi-scid IL2rγnull mouse model using human peripheral blood mononuclear cells (PBMC). Additionally, we used human bone marrow-derived MSC (BMSC) as comparative controls to determine differences in immunomodulatory functions depending on the MSC origin. Administration of AMSC significantly prolonged survival, and reduced human tumor necrosis factor-α (TNF-α) concentration and percentage of programmed cell death protein-1 receptor (PD-1)+CD8+ T cell populations compared with in GVHD control mice. Furthermore, colonic inflammation score and percentage of human CD8+ T cell populations in AMSC-treated mice were significantly lower than in GVHD control and BMSC-treated mice. Interestingly, gene expression and protein secretion of the PD-1 ligands were higher in AMSC than in BMSC. These findings are the first to demonstrate that AMSC exhibit marked immunosuppression and delay acute GVHD progression by preventing T cell activation and proliferation via the PD-1 pathway.

Genotoxicity and subacute toxicity studies of a new astaxanthin-containing Phaffia rhodozyma extract.

Experimental and clinical studies demonstrate that astaxanthin (AXN), a xanthophyll carotenoid, has protective effects against oxidative damage. Because most of these studies assessed AXN derived from Haematococcus pluvialis that were cultivated at industrial scales, few studies have examined the toxicity of AXN derived from Phaffia rhodozyma. To evaluate the safety of astaxanthin-containing P. rhodozymaextract (AXN-PRE), genotoxicity was assessed in bacterial reverse mutation test and mouse bone marrow micronucleus test, and general toxicity was assessed in 4-week repeated oral toxicity study in rats. AXN-PRE did not induce reverse mutations in the Salmonella typhimurium strains TA98 or TA100 at concentrations of 5,000 µg/plate with or without S9 mix, and no chromosome damage was observed at a dose of 2,000 mg/kg in mouse micronucleus test. In the subacute toxicity study, male and female Sprague-Dawley rats were given AXN-PRE at doses of 0, 500, and 1,000 mg/kg by gavage for 4 weeks. Body weights, urinalysis, hematology, serum biochemistry, organ weights, or histopathological lesions indicated no distinct toxicity. In conclusion, AXN-PRE had no effect in bacterial reverse mutation test and mouse bone marrow micronucleus test. The no-observed-adverse-effect level for AXN-PRE in 4-week repeated oral toxicity study in rats was determined to be greater than 1,000 mg/kg (corresponding to dose of 50 mg/kg AXN) regardless of gender.

Possible tumor development from double positive foci for TGF-alpha and GST-P observed in early stages on rat hepatocarcinogenesis.

Expression of TGF-alpha during promotion of neoplastic development from GST-P-positive foci in rat chemical hepatocarcinogenesis was investigated. One-hundred male F344 rats were given a single intraperitoneal injection of DEN (200 mg/kg bodyweight) and subjected to two-thirds partial hepatectomy at week 3. Commencing 2 weeks from the start, PB at doses of 0 or 500 p.p.m. was fed to the rats for 46 weeks. Groups of 10 rats were killed at weeks 4, 8, 16, 32, 48 and their livers were immunohistochemically examined for expression of GST-P and TGF-alpha. TGF-alpha-positive foci and single positive cells were observed from week 4, partially overlapping with GST-P-positive foci but being much fewer. Numbers of TGF-alpha-positive lesions did not increase from weeks 4-48, but their areas showed increment at weeks 32 and 48, especially with PB administration. Almost all of the tumors observed at weeks 16, 32 and 48 were positive for TGF-alpha (98%). In addition, epidermal growth factor receptor overexpression was observed in most TGF-alpha-positive lesions (foci and tumors). The proliferating cell nuclear antigen labeling index in double positive foci for GST-P and TGF-alpha was significantly higher than that in TGF-alpha-negative foci. In conclusion, TGF-alpha may be closely related with promotion from altered foci to neoplasms in rat hepatocarcinogenesis. Our data suggest that double positive foci for GST-P and TGF-alpha in the early stages of rat hepatocarcinogenesis may develop into tumors with promotion.

Effects of a new extracorporeal system using CTR on mortality and inflammatory responses to bacterial toxin-induced multiple organ dysfunction syndrome in rabbits.

BACKGROUND/AIMS: In the pathogenesis of multiple organ dysfunction syndrome (MODS) caused by bacterial infection, a complex series of systemically secreted bacterial toxins and cytokines are intensely associated. Our previous study demonstrated that a new adsorbent, CTR, was capable of removing cytokines and toxic shock syndrome toxin-1 (TSST-1) in vitro. Moreover, extracorporeal treatment with CTR reduced the high mortality rate and inhibited inflammatory responses in endotoxin-induced shock in rats. However, it is unclear whether CTR treatment will be an effective therapy for MODS. Here, we demonstrated the efficacy of a new extracorporeal system using CTR on MODS induced by bacterial toxins in rabbits. METHODS: Direct hemoperfusion (DHP) apheresis with or without CTR for 120 min was performed in rabbits that had been intravenously infused with endotoxin and TSST-1. The mean arterial pressure was recorded and the plasma toxin and cytokine concentrations were measured during the treatment period. Mortality was assessed up to 7 days after exposure to the toxins. In addition, tissues specimens were examined using microscopy. RESULTS: The mortality rates at 7 days after the injection of the toxins were 90 and 10% for the control and CTR groups, respectively. The plasma concentrations of TSST-1, tumor necrosis factor and interleukin-1 beta in the CTR group were significantly lower than those in the control group. Histopathological examination revealed that tissue damage, such as necrosis and depletion of lymphocytes in the spleen and mesenteric lymph node, was reduced in the CTR group, compared with that in the control group, at 24 h after toxin infusion. CONCLUSION: The new adsorbent CTR improved the mortality rate in a MODS rabbit model by adsorbing TSST-1 and cytokines. Further development of CTR may expand the scope of extracorporeal therapies for patients with MODS.