Effects of hydrogen-rich saline on early acute kidney injury in severely burned rats by suppressing oxidative stress induced apoptosis and inflammation.

BACKGROUND: Early acute kidney injury (AKI) in severely burned patients predicts a high mortality that is multi-factorial. Hydrogen has been reported to alleviate organ injury via selective quenching of reactive oxygen species. This study investigated the potential protective effects of hydrogen against severe burn-induced early AKI in rats. METHODS: Severe burn were induced via immersing the shaved back of rats into a 100°C bath for 15 s. Fifty-six Sprague-Dawley rats were randomly divided into Sham, Burn + saline, and Burn + hydrogen-rich saline (HS) groups, and renal function and the apoptotic index were measured. Kidney histopathology and immunofluorescence staining, quantitative real-time PCR, ELISA and western blotting were performed on the sera or renal tissues of burned rats to explore the underlying effects and mechanisms at varying time points post burn. RESULTS: Renal function and tubular apoptosis were improved by HS treatment. In addition, the oxidation-reduction potential and malondialdehyde levels were markedly reduced with HS treatment, whereas endogenous antioxidant enzyme activities were significantly increased. HS also decreased the myeloperoxidase levels and influenced the release of inflammatory mediators in the sera and renal tissues of the burned rats. The regulatory effects of HS included the inhibition of p38, JNK, ERK and NF-κB activation, and an increase in Akt phosphorylation. CONCLUSION: Hydrogen can attenuate severe burn-induced early AKI; the mechanisms of protection include the inhibition of oxidative stress induced apoptosis and inflammation, which may be mediated by regulation of the MAPKs, Akt and NF-κB signalling pathways.

Beneficial effects of hydrogen-rich saline on early burn-wound progression in rats.

INTRODUCTION: Deep burn wounds undergo a dynamic process known as wound progression that results in a deepening and extension of the initial burn area. The zone of stasis is more likely to develop more severe during wound progression in the presence of hypoperfusion. Hydrogen has been reported to alleviate injury triggered by ischaemia/reperfusion and burns in various organs by selectively quenching oxygen free radicals. The aim of this study was to investigate the possible protective effects of hydrogen against early burn-wound progression. METHODS: Deep-burn models were established through contact with a boiled, rectangular, brass comb for 20 s. Fifty-six Sprague-Dawley rats were randomly divided into sham, burn plus saline, and burn plus hydrogen-rich saline (HS) groups with sacrifice and analysis at various time windows (6 h, 24 h, 48 h) post burn. Indexes of oxidative stress, apoptosis and autophagy were measured in each group. The zone of stasis was evaluated using immunofluorescence staining, ELISA, and Western blot to explore the underlying effects and mechanisms post burn. RESULTS: The burn-induced increase in malondialdehyde was markedly reduced with HS, while the activities of endogenous antioxidant enzymes were significantly increased. Moreover, HS treatment attenuated increases in apoptosis and autophagy postburn in wounds, according to the TUNEL staining results and the expression analysis of Bax, Bcl-2, caspase-3, Beclin-1 and Atg-5 proteins. Additionally, HS lowered the level of myeloperoxidase and expression of TNF-α, IL-1ß, and IL-6 in the zone of stasis while augmenting IL-10. The elevated levels of Akt phosphorylation and NF-κB p65 expression post burn were also downregulated by HS management. CONCLUSION: Hydrogen can attenuate early wound progression following deep burn injury. The beneficial effect of hydrogen was mediated by attenuating oxidative stress, which inhibited apoptosis and inflammation, and the Akt/NF-κB signalling pathway may be involved in regulating the release of inflammatory cytokines.

Astaxanthin attenuates early acute kidney injury following severe burns in rats by ameliorating oxidative stress and mitochondrial-related apoptosis.

Early acute kidney injury (AKI) is a devastating complication in critical burn patients, and it is associated with severe morbidity and mortality. The mechanism of AKI is multifactorial. Astaxanthin (ATX) is a natural compound that is widely distributed in marine organisms; it is a strong antioxidant and exhibits other biological effects that have been well studied in various traumatic injuries and diseases. Hence, we attempted to explore the potential protection of ATX against early post burn AKI and its possible mechanisms of action. The classic severe burn rat model was utilized for the histological and biochemical assessments of the therapeutic value and mechanisms of action of ATX. Upon ATX treatment, renal tubular injury and the levels of serum creatinine and neutrophil gelatinase-associated lipocalin were improved. Furthermore, relief of oxidative stress and tubular apoptosis in rat kidneys post burn was also observed. Additionally, ATX administration increased Akt and Bad phosphorylation and further down-regulated the expression of other downstream pro-apoptotic proteins (cytochrome c and caspase-3/9); these effects were reversed by the PI3K inhibitor LY294002. Moreover, the protective effect of ATX presents a dose-dependent enhancement. The data above suggested that ATX protects against early AKI following severe burns in rats, which was attributed to its ability to ameliorate oxidative stress and inhibit apoptosis by modulating the mitochondrial-apoptotic pathway, regarded as the Akt/Bad/Caspases signalling cascade.

[Vascularization of poly-lactic-co-glycolic acid knitted mesh/collagen-chitosan hybrid scaffold].

OBJECTIVE: To investigate the effects of poly-lactic-co-glycolic acid (PLGA) knitted mesh/collagen-chitosan hybrid scaffold (PCCS) on angiogenesis, and to explore the relative mechanisms. METHODS: PLGA knitted mesh was integrated into collagen-chitosan scaffold (CCS) to construct PCCS with freeze-lyophilizing method, and CCS was made with the same method. The characteristics of morphology and water absorbing capacity among PCCS, PLGA knitted mesh, and CCS were compared in vitro. PCCS and CCS was respectively implanted into subcutaneous tissue of back on both sides in 24 SD rats, and the tissue specimens were harvested at post operation week (POW) 1, 2, and 4 according to the random number table to evaluate the level of angiogenesis by histopathological and immunohistochemical examinations. The expression levels of alpha smooth muscle actin (alpha-SMA) and vascular endothelial growth factor (VEGF) mRNA were examined by real-time quantitative RT-PCR. Data were processed with t test. RESULTS: (1) PLGA knitted mesh was closely integrated with sponge of collagen-chitosan in PCCS, and the porous structure of PCCS was similar to that of CCS. (2) Compared with that of PCCS [(506 +/- 15)%], the water absorbing rate of CCS and PLGA knitted mesh was respectively increased and decreased [(627 +/- 21)%, (195 +/- 15)%, with t value respectively 3.8, 11.9, P < 0.05 or P < 0.001]. (3) The scaffolds were filled with newly formed tissue in CCS at POW 4, while those in PCCS were observed at POW 2 with more homogeneous and abundant collagen. (4) Blood vessels could be induced, and they grew into scaffolds along with prolongation of implantation time in PCCS and CCS. The number of mature blood vessels in PCCS at POW 1, 2, 4 [(10.7 +/- 3.2), (18.6 +/- 2.1), and (30.3 +/- 4.5) branches per square centimeter] was respectively higher than that in CCS [(5.4 +/- 0.9), (10.8 +/- 4.2), and (23.6 +/- 1.7) branches per square centimeter, with t value respectively 4.6, 4.4, 4.5, P values all below 0.01]. (5) The expression levels of alpha-SMA and VEGF mRNA in PCCS at POW 1, 2, 4 were significantly higher than those in the CCS (with t(alpha-SMA) value respectively 1.26, 1.63, 2.17, with t(VEGF) value respectively 5.52, 2.07, 1.78, P values all below 0.01). CONCLUSIONS: PCCS is able to induce the ingrowth of blood vessels rapidly and promote their maturity. The mechanical properties and microstructures of scaffolds play synergistic role in the process of angiogenesis.

[Design and biological evaluation of poly-lactic-co-glycolic acid (PLGA) mesh/collagen-chitosan hybrid scaffold (CCS) as a dermal substitute].

OBJECTIVE: To design and construct a kind of dermal regeneration template with mesh, and to preliminarily evaluate its biological characteristics. METHODS: PLGA mesh was integrated into CCS with freeze-drying method for constructing PLGA mesh/CCS composite (PCCS). The micromorphologies and mechanical properties among PLGA mesh, CCS, and PCCS were compared. PCCS and CCS was respectively implanted into subcutaneous tissue of SD rats (PCCS and CCS groups, 9 rats in each group). The tissue samples were collected at post operation week (POW) 1, 2, and 4 for histopathological and immunohistochemical observation. Protein levels of CD68, MPO, IL-1beta, IL-10 were examined by Western blot, with expression of gray value. Data were processed with one-way analysis of variance and t test. RESULTS: Three-dimensional porous structure of PCCS was similar to that of CCS. Mechanical property of PLGA mesh and PCCS was respectively (3.07 +/- 0.10), (3.26 +/- 0.15) MPa, and they were higher than that of CCS [(0.42 +/- 0.21) MPa, F = 592.3, P < 0.0001)]. The scaffolds were filled with newly formed tissue in PCCS group at POW 2, while those in CCS group were observed at POW 4. A large accumulation of macrophages was observed in both groups, especially at POW 2, and more macrophage infiltration was observed in CCS group. The protein level of IL-10 in PCCS group at POW 2 was obviously higher than that in CCS group, while the protein levels of CD68, MPO, IL-1beta were significantly decreased as compared with those in CCS group (with t value from -4.06 to 2.89, P < 0.05 or P < 0.01). CONCLUSIONS: PCCS has excellent mechanical property with appropriate three-dimensional porous structure. Meanwhile, it can rapidly induce formation of new tissue and vascularization, and it has a prospect of serving as a dermal substitute.