Yunchuan Wang

The challenges and promises of allogeneic mesenchymal stem cells for use as a cell-based therapy.

Mesenchymal stem cells (MSCs) are ideal for cell-based therapy in various inflammatory diseases because of their immunosuppressive and tissue repair properties. Moreover, their immunosuppressive properties and low immunogenicity contribute to a reduced or weakened immune response elicited by the implantation of allogeneic MSCs compared with other cell types. Therefore, implantation of allogeneic MSCs may be a promising cell-based therapy. In this review, we first summarize the unique advantages of allogeneic MSCs for therapeutic applications. Second, we critically analyze the factors influencing their therapeutic effects, including administration routes, detection time-points, disease models, differentiation of MSCs in vivo, and timing and dosage of MSC administration. Finally, current approaches to allogeneic MSC application are discussed. In conclusion, allogeneic MSCs are a promising option because of their low immunogenicity and immunosuppressive and tissue repair capabilities. Further investigations are needed to enhance the consistency and efficacy of MSCs when used as a cell-based therapy in inflammatory diseases as well as for tissue repair.

Wnt/β-catenin pathway forms a negative feedback loop during TGF-β1 induced human normal skin fibroblast-to-myofibroblast transition

BACKGROUND Fibroblast-to-myofibroblast transition is a key event during wound healing and hypertrophic scar formation. Previous studies suggested Wnt/β-catenin signaling might be involved in the wound healing. However, its specific role in skin fibroblast-to-myofibroblast transition remains unclear. OBJECTIVE To investigate the specific role of β-catenin during the transforming growth factor-β1 induced normal skin myofibroblasts transition. METHODS By real-time quantitative polymerase chain reaction, Western-blot and immunocytochemistry, the activation of Wnt/β-catenin pathway in cultured human normal skin fibroblasts during TGF-β1 induced fibroblast-to-myofibroblast transition was investigated. The effects of β-catenin on myofibroblasts transition were also investigated when SB-216763, over-expression and siRNA of β-catenin were utilized. In addition, fibroblasts populated collagen lattices contraction assays were conducted to examine the effects of β-catenin on the contractility of the fibroblasts induced by TGF-β1. Furthermore, the effects of β-catenin on the expression of α-smooth muscle actin and collagen types I and III in hypertrophic scar derived fibroblasts were studied. RESULTS The expression of Wnts mRNA and β-catenin protein was up-regulated by TGF-β1 stimulation during the myofibroblasts transition. Both of SB-216763 and β-catenin over-expression was paralleled with decreased expression of α-smooth muscle actin, collagen types I and III, while siRNA targeting β-catenin leads to up-regulation of α-smooth muscle actin, collagen types I and III. The increased contractility and α-smooth muscle actin expression of the fibroblasts in the collagen lattices induced by TGF-β1 was inhibited by SB-216763. In addition, the expression levels of α-smooth muscle actin, collagen types I and III in hypertrophic scar derived fibroblasts were also down-regulated by SB-216763. CONCLUSION Specifically in normal skin fibroblasts, β-catenin might be involved in the myofibroblasts transition and negatively regulate the TGF-β1-induced myofibroblast transition.

The role of ERK and JNK signaling in connective tissue growth factor induced extracellular matrix protein production and scar formation

CCN2 plays an important role in the pathogenesis of hypertrophic scars (HTSs). Although CCN2 is involved in many fibroproliferative events, the CCN2 induction signaling pathway in HTSs is yet to be elucidated. Here, we first investigated the effect of the mitogen-activated protein kinases (MAPKs) on CCN2-induced α-smooth muscle actin (α-SMA) and collagen I expression in human HTS fibroblasts (HTSFs). Then, we established HTSs in a rabbit ear model and determined the effect of MAPKs on the pathogenesis of HTSs. MAPK pathways were activated by CCN2 in HTSFs. Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) inhibitors significantly inhibited CCN2-induced expression of α-SMA and collagen I in HTSFs. In the rabbit ear model of the HTS, JNK and ERK inhibitors significantly improved the architecture of the rabbit ear scar and reduced scar formation on the rabbit ear. Our results indicate that ERK and JNK mediate collagen I expression and scarring of the rabbit ear, and may be considered for specific drug therapy targets for HTSs.

SIRT1 Is a Regulator in High Glucose-Induced Inflammatory Response in RAW264.7 Cells

Sepsis is defined as a systemic inflammatory response syndrome that disorders the functions of host immune system, including the imbalance between pro- and anti-inflammatory responses mediated by immune macrophages. Sepsis could also induce acute hyperglycemia. Studies have shown that the silent mating type information regulation 2 homolog 1 (SIRT1), an NAD+-dependent deacetylase, mediates NF-κb deacetylation and inhibits its function. Therefore, SIRT1 is likely to play an important role in high glucose-mediated inflammatory signalings. Here we demonstrate that high glucose significantly downregulates both the mRNA and protein levels of SIRT1 and upregulates the mRNA level and the release of two pro-inflammatory cytokines, IL-1β and TNF-α, in RAW264.7 macrophages. Interestingly, the reduced level of SIRT1 by high glucose is remarkably upregulated by SIRT1 activator SRT1720, while the level and the release of IL-1β and TNF-α significantly decrease with the use of SRT1720. However, when the function of SIRT1 is inhibited by EX527 or its expression is suppressed by RNAi, the upregulated level and release of IL-1β and TNF-α by high glucose are further increased. Taken together, these findings collectively suggest that SIRT1 is an important regulator in many high glucose-related inflammatory diseases such as sepsis.

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF‐β/Smad pathway

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars. To investigate the therapeutic effects of loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that loureirin B dose‐dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α‐smooth muscle actin (α‐SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α‐SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, loureirin B effectively inhibited TGF‐β1‐induced upregulation of ColI, ColIII and α‐SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF‐β1‐stimulated fibroblasts. Taken together, this study demonstrates that loureirin B could downregulate the expression of fibrosis‐related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF‐β1‐induced fibrosis, during which TGF‐β1/Smad2/3 pathway is likely involved. These findings suggest that loureirin B is a potential therapeutic compound for HS treatment.

Negative pressure wound therapy decreases mortality in a murine model of burn-wound sepsis involving Pseudomonas aeruginosa infection.

Background The colonization of burn wounds by Pseudomonas aeruginosa can lead to septic shock, organ injuries, and high mortality rates. We hypothesized that negative pressure wound therapy (NPWT) would decrease invasion and proliferation of P. aeruginosa within the burn wound and reduce mortality. Methods Thermal injuries were induced in anesthetized mice, and P. aeruginosa was applied to the wound surface for 24 h. After removing the burn eschar and debridement, the animals were subjected to either NPWT or wet-to-dry (WTD) treatment protocols. The bacterial loads on the wound surface were assessed during 7 d of treatment, as were the concentrations of inflammatory cytokines in the peripheral blood samples. Survival was monitored daily for 14 d after burn induction. Finally, samples of wounded skin, lung, liver, and kidney were collected and subjected to histopathological examination. Results Applying P. aeruginosa to the burn wound surface led to sepsis. During early stages of treatment, NPWT reduced the mortality of the septic animals and levels of P. aeruginosa within the burn wound compared with WTD-treated animals. Circulating levels of cytokines and cytoarchitectural abnormalities were also significantly reduced via NPWT. Conclusions Our data indicate that NPWT inhibits the invasion and proliferation of P. aeruginosa in burn-wounded tissue and decreases early mortality in a murine model of burn-wound sepsis. These therapeutic benefits likely result from the ability of NPWT to decrease bacterial proliferation on the wound surface, reduce cytokine serum concentrations, and prevent damage to internal organs.

Systemic inflammatory responses and multiple organ dysfunction syndrome following skin burn wound and Pseudomonas aeruginosa infection in mice.

ABSTRACT Burn wound–related sepsis is associated with the development of systemic inflammatory response syndrome and multiple organ dysfunction syndrome (MODS). This study is aimed at investigating the development and progression of SIS and MODS in a mouse model of skin burn sepsis. C57BL/6J mice were randomly divided into the sham, burn, Pseudomonas, and burn/Pseudomonas groups. The back skin of the sham, burn, and burn/Pseudomonas groups was burned about 10% of total area with using 37°C or 98°C water for 8 s, respectively, followed by inoculating with Pseudomonas aeruginosa. The Pseudomonas group was infected with P. aeruginosa without burn injury. Their body weights, mortality, organ histology, and function as well as systemic inflammation were measured longitudinally. The burn/Pseudomonas mice lost more body weights than did mice from the other groups and had a significantly higher mortality rate (P < 0.05). The burn/Pseudomonas mice exhibited significantly higher levels of bacterial loads in different organs and serum endotoxin, interleukin 1&bgr;, interleukin 6, tumor necrosis factor &agr;, and C-reactive protein than those in mice from the other groups (P < 0.05). The burn/Pseudomonas mice also displayed more severe liver, lung, and kidney tissue damage and impaired organ functions, particularly at 72 h after inoculation than did the burn and Pseudomonas groups of mice. Our data indicate that burn and P. aeruginosa infection induced severe sepsis and rapidly progressed into systemic inflammatory response syndrome and MODS in mice.

Lycium barbarum polysaccharides reduce intestinal ischemia/reperfusion injuries in rats.

Inflammation and oxidative stress exert important roles in intestinal ischemia-reperfusion injury (IRI). Lycium barbarum polysaccharides (LBPs) have shown effective antioxidative and immunomodulatory functions in different models. The purpose of the present study was to assess the effects and potential mechanisms of LBPs in intestinal IRI. Several free radical-generating and lipid peroxidation models were used to assess the antioxidant activities of LBPs in vitro. A common IRI model was used to induce intestinal injury by clamping and unclamping the superior mesenteric artery in rats. Changes in the malondialdehyde (MDA), tumor necrosis factor (TNF)-α, activated nuclear factor (NF)-κB, intracellular adhesion molecule (ICAM)-1, E-selectin, and related antioxidant enzyme levels, polymorphonuclear neutrophil (PMN) accumulation, intestinal permeability, and intestinal histology were examined. We found that LBPs exhibited marked inhibitory action against free radicals and lipid peroxidation in vitro. LBPs increased the levels of antioxidant enzymes and reduced intestinal oxidative injury in animal models of intestinal IRI. In addition, LBPs inhibited PMN accumulation and ICAM-1 expression and ameliorated changes in the TNF-α level, NF-κB activation, intestinal permeability, and histology. Our results indicate that LBPs treatment may protect against IRI-induced intestinal damage, possibly by inhibiting IRI-induced oxidative stress and inflammation.

Bone Marrow Transplantation Combined with Mesenchymal Stem Cells Induces Immune Tolerance without Cytotoxic Conditioning

BACKGROUND Transplantation of allogeneic donor bone marrow (BM) into sufficiently conditioned recipients is an effective approach to induce immune tolerance as assessed by mixed chimerism. However, this approach is hampered by the lack of feasible protocols devoid of cytoreductive conditioning. We investigated whether mixed chimerism could be established by intra-bone marrow-bone marrow transplantation (IBM-BMT) combined with bone marrow-derived mesenchymal stem cells (BMSCs) treatment without additional cytoreductive conditioning. MATERIALS AND METHODS The recipient mice (C57BL/6) accepted BMSCs from donor mice (Balb/c) through daily tail vein injection for 4 d followed by IBM-BMT immediately. Full-thickness skin grafts from donor mice as well as from the third party mice (ICR) were transplanted to the dorsum of the recipient mice after the combined IBM-BMT with BMSCs treatment. The immune tolerance was assessed by the survival time of skin allografts. The establishment of mixed chimerism and cytokine expression profile in recipient peripheral blood were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. RESULTS IBM-BMT combined with BMSCs treatment led to stable mixed chimerism and donor-specific skin graft tolerance. The flow cytometry analysis revealed that recipient mice developed 20%-25% chimerism levels among the myeloid lineage. The skin allografts survived more than 1 y and the hair re-grew normally on the grafts. Cytokine profile showed that IBM-BMT combined with BMSCs treatment prolonged humoral tolerance in recipient chimeras. CONCLUSIONS Our results demonstrate that donor specific immune tolerance can be effectively induced by IBM-BMT combined with BMSCs treatment without any additional cytoreductive recipient treatment. This approach provides a promising allograft transplantation strategy when the donor bone marrow is available.

Up-regulation of FGFBP1 signaling contributes to miR-146a-induced angiogenesis in human umbilical vein endothelial cells

Recent microRNA expression profiling studies have documented an up-regulation of miR-146a in several angiogenesis models. However, the underlying molecular mechanism of miR-146a in the angiogenic activity of endothelial cells has not been clearly elucidated. The present study was aimed to evaluate whether miR-146a promotes angiogenesis in HUVECs by increasing FGFBP1 expression via directly targeting CREB3L1. miR-146a was over expressed in HUVECs via lentiviral-miR-146a. Expression profiling analysis found miR-146a over expression resulted in up-regulation of angiogenesis and cytokine activity associated genes including FGF2. Further a combination of bioinformatics and experimental analyses demonstrated the CREB3L1 as a bona fide functional target of miR-146a during angiogenesis. Moreover, CREB3L1 inhibited luciferase expression from FGFBP1 promoter containing only CRE elements. Furthermore, CREB3L1 inhibited FGFBP1 expression by binding to two CRE-like sites located at approximately −1780–1777 and −868–865 bp relative to the FGFBP1 transcription start site. Additionally, ectopic expression of CREB3L1 decreased miR-146a-induced FGF2 secretion. These findings indicate that the miR-146a-CREB3L1-FGFBP1 signaling axis plays an important role in the regulation of angiogenesis in HUVECs and provides a potential therapeutic target for anti-angiogenic therapeutics.