Guang-Yi Wang

Accelerated Expansion of Epidermal Keratinocyte and Improved Dermal Reconstruction Achieved by Engineered Amniotic Membrane

In this study, we used human amniotic membrane (AM) to prepare a dermal scaffold with intact basement membrane (BM) and good biostability for quick expansion and transplantation of epidermal keratinocytes (EKs). Fresh AM was treated by repeated freeze–thaw cycles and DNase digestion. This new method was able to cleanse the cell components effectively and retain the BM structure with continuous distributions of laminin, collagen IV, VI, and VII. Subsequently, the acellular amniotic membrane (AAM) was cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for 5 min, 30 min, and 6 h. With the time of cross-linking prolonging, the mechanical strength and biostability of AAM increased gradually, while its cytotoxicity to EKs also increased. The 5-min cross-linked AAM (5min-AAM) had no significant cytotoxicity with good histocompatibility. The relative cell viability of EKs seeded on the 5min-AAM surface was 367 ± 33% and 631 ± 43% at 7 and 14 days of culture, respectively, both higher than 294 ± 30% and 503 ± 41% of the conventional cell culture dish (CCD) group, and the proportion of P63-positive cells was significantly higher than that of the CCD group on day 7 (54.32 ± 4.27% vs. 33.32 ± 3.18%, p < 0.05). When the 5min-AAM loaded with EKs (EK-AAM) was grafted onto full-thickness skin defects in nude mice, the cells survived well and formed an epidermis similar to normal skin. The new epidermis was thicker, and reconstruction of the dermal structure was good with an intact BM. Four weeks after transplantation, the wound contraction rate in the EK-AAM group was 43.09 ± 7.05%, significantly lower than that in the EK sheet group (57.49 ± 5.93%) and control group (69.94 ± 9.47%) (p < 0.05). In conclusion, repeated freeze–thaw treatment with appropriate EDC cross-linking offers AAM an intact BM structure with good operability and biostability. It may prove to be an ideal dermal scaffold to promote expansion of EKs in vitro and be transplanted for reconstruction of the dermal structure.

Role of inhibition of p38 mitogen-activated protein kinase in liver dysfunction after hemorrhagic shock and resuscitation

BACKGROUND The liver is one of the organs most frequently affected by trauma and hemorrhagic shock; the exact role of p38 mitogen-activated protein kinase (MAPK) activation in response to hepatic hemorrhagic shock/resuscitation (HS/R) remains unclear. MATERIALS AND METHODS C57Bl/6 mice were divided into four groups: sham-operated group, SB-only group, control group, and SB + HS/R group. Hepatocellular injury (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) and tumor necrosis factor (TNF-α) and interleukin (IL-1β) messenger ribonucleic acid (mRNA) expression in the liver were assessed 6 h after resuscitation, p38 MAPK activation in the liver was assessed at 30 min after resuscitation. RESULTS p38 MAPK activation was higher in the control group than other groups 30 min after resuscitation. p38 MAPK activation level in the SB + HS/R group did not change significantly compared with that of sham and SB-only groups, but was significantly lower than that in the control group. The TNF-α mRNA expression in the control group was significantly higher than that in the sham group. The TNF-α mRNA levels after HS/R in the SB + HS/R group were significantly lower than those in the control group and were roughly the same as those in the sham and SB-only groups. IL-1β mRNA expression showed similar changes in the four groups. Serum ALT and AST levels in the control group were significantly higher than those in the sham group. The increase in serum ALT and AST levels after HS/R in the SB + HS/R group was significantly less pronounced than that in the control group and markedly higher than that in the sham group. CONCLUSIONS p38 MAPK was phosphorylated during the HS/R process. Inhibiting the activation of p38 MAPK may attenuate HS/R injury to the liver.

Pathogenic alteration in severe burn wounds

The present study aims to define the trend of time related changes with local bacterial alteration of bacterial resistance in severe burns in our burn center during a 12-year period. Retrospective analysis of microbiological results on severely burned wounds between 1998 and 2009 was carried out. A study of 3615 microbial isolates was performed. Staphylococcus aureus was the most commonly isolated pathogen (38.2%) followed by A. baumannii (16.2%), Streptococcus viridans (11.4%), Pseudomonas aeruginosa (10.4%), coagulase-negative staphylococci (CNS, 9.2%). The species ratios of S. aureus and A. baumannii increased significantly from 1st to 8th week of hospitalization, while those of Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci decreased during the same period. Bacterial resistance rates were compared between the periods 1998-2003 and 2004-2009. Vancomycin remained as the most sensitive antibiotic in S. aureus including methicillin-resistant S. aureus (MRSA). It was very likely that the majority of infections caused by Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci occurred in the early stage of burn course and the majority of infections caused by A. baumannii occurred 4 weeks after admission. The use of different antibiotics was probably the major contributor to these trends.

A new method of wound treatment: targeted therapy of skin wounds with reactive oxygen species-responsive nanoparticles containing SDF-1α.

Objective To accelerate wound healing through promoting vascularization by using reactive oxygen species (ROS)-responsive nanoparticles loaded with stromal cell-derived factor-1α(SDF-1α). Methods The ROS-reactive nanomaterial poly-(1,4-phenyleneacetone dimethylene thioketal) was synthesized, and its physical and chemical properties were characterized. ROS-responsive nanoparticles containing SDF-1α were prepared through a multiple emulsion solvent evaporation method. The loading capacity, stability, activity of the encapsulated protein, toxicity, and in vivo distribution of these nanoparticles were determined. These nanoparticles were administered by intravenous infusion to mice with full-thickness skin defects to study their effects on the directed chemotaxis of bone marrow mesenchymal stem cells, wound vascularization, and wound healing. Results The synthesized ROS-reactive organic polymer poly-(1,4-phenyleneacetone dimethylene thioketal) possessed a molecular weight of approximately 11.5 kDa with a dispersity of 1.97. ROS-responsive nanoparticles containing SDF-1α were prepared with an average diameter of 110 nm and a drug loading capacity of 1.8%. The encapsulation process showed minimal effects on the activity of SDF-1α, and it could be effectively released from the nanoparticles in the presence of ROS. Encapsulated SDF-1α could exist for a long time in blood. In mice with full-thickness skin defects, SDF-1α was effectively released and targeted to the wounds, thus promoting the chemotaxis of bone marrow mesenchymal stem cells toward the wound and its periphery, inducing wound vascularization, and accelerating wound healing.

Reduction of CD47 on monocytes correlates with MODS in burn patients

Alternation of surface markers on monocytes is associated with the development of inflammation. The goals of the present study were to detect CD47 expression on monocytes by flow cytometry and explore its relationship with disease severity and MODS in burned patients. The results show CD47 expression on monocytes from all burned patients (n = 21) was lower than that from the healthy population (n = 21) for 24 days after burn. There was a significant difference in CD47 expression on monocytes between the patients with differing burn severity in the first 7 days after injury (P < 0.05). Considering the relationship between CD47 expression and MODS, we found the CD47 expression on monocytes from patients with MODS was lower (P < 0.05) in the first 3 days after injury than that from patients without MODS. In conclusion, diminished CD47 expression on monocytes is associated with burn severity and the occurrence of MODS in burn patients.

Deficiency of Smad3 results in enhanced inducible nitric oxide synthase–mediated hypotension in lipopolysaccharide-induced endotoxemia

BACKGROUND Smad3 is a principal intracellular mediator of signaling for transforming growth factor β, a cytokine involved in pleiotropic pathophysiological processes including inflammation and immunity. The function of Smad3 in regulating inducible nitric oxide synthase (iNOS) expression and septic shock has not been characterized. METHODS Smad3(-/-) (referred hereafter as KO) and wild-type (WT) mice were injected intraperitoneally with lipopolysaccharide (LPS) to induce the septic hypotension. Mortality, blood pressure, and plasma levels of nitrite were measured. The iNOS messenger RNA and protein levels in lung, kidney, and spleen were also analyzed. RESULTS Mice lacking functional Smad3 respond to LPS with greater mortality than their WT littermates. The high mortality of KO mice is accompanied by enhanced hypotension after intraperitoneal injection of LPS. Both KO and WT mice displayed an increase in plasma nitrite during the experimental period; however, LPS administration caused more dramatic changes in KO mice than WT mice. Likewise, the iNOS messenger RNA and protein levels in lung, kidney, and spleen were more strongly increased in KO mice than in WT mice after LPS administration. CONCLUSIONS Defects in the Smad3 gene may increase susceptibility to the development of septic hypotension because of enhanced iNOS production.

Mass chemical casualties: treatment of 41 patients with burns by anhydrous ammonia

BACKGROUND This article reports a chemical burn incident that occurred on 31 August 2013 in Shanghai. We describe situations at the scene, emergency management, triage, evacuation, and follow-up of the victims. METHOD The scene of the incident and information on the 41 victims of this industrial chemical incident were investigated. The emergency management, triage, evacuation, and hospitalization data of the patients were summarized. RESULTS At the time of the incident, 58 employees were working in a closed refrigerator workshop, 41 of whom sustained burns following the leakage of anhydrous ammonia. Ten victims died of severe inhalation injury at the scene, and another five victims died during the process of evacuation to the nearest hospital. After receiving information on the incident, a contingency plan for the burn disaster was launched immediately, and a first-aid group and an emergency and triage group were dispatched by the Changhai Hospital to the scene to aid the medical organization, emergency management, triage, and evacuation. All casualties were first rushed to the nearest hospital by ambulance. The six most serious patients with inhalation injuries were evacuated to the Changhai Hospital and admitted to the burn intensive care unit (BICU) for further treatment, one of whom died of respiratory failure and pulmonary infection. CONCLUSION This mass casualty incident of anhydrous ammonia leakage caused potential devastating effects to the society, especially to the victims and their families. Early first-aid organization, emergency management, triage, and evacuation were of paramount importance, especially rapid evaluation of the severity of inhalation injury, and subsequent corresponding medical treatment. The prognosis of ammonia burns was poor and the sequelae were severe. Management and treatment lessons were drawn from this mass casualty chemical burn incident.

Risk Factors for Acute Kidney Injury in Patients With Burn Injury: A Meta-analysis and Systematic Review

Acute kidney injury (AKI) is a fatal complication of burn injury. Few systematic reviews to date have focused on the risk factors predisposing to AKI in patients with burn injury. The aim of this article is to identify the risk factors for the occurrence of AKI in burn patients, thus providing theoretical evidence for prevention and treatment. We performed a systematic review and meta-analysis of studies determining the prevalence, risk factors, and outcomes of AKI in patients with burn injury. An electronic search (up to April 2016) was performed using Pubmed, Embase, Web of Knowledge, and the Cochrane Library databases. Finally, a total of 18 articles (nine prospective cohort, seven retrospective cohort, two case–control) meeting the eligibility criteria were included. The pooled incidence of AKI was 39.6% (95% confidence interval = 34.7–44.4%). Significant risk factors for the occurrence of AKI included age (odds ratio [OR] = 3.78 [1.28–6.27]), TBSA (OR = 15.66 [11.01–20.31]), full-thickness TBSA (OR = 15.66 [11.01–20.31]), flame burn (OR = 1.56 [1.09–2.25]), inhalation injury (OR = 2.97 [1.80–4.89]), abbreviated burn severity index on admission (OR = 2.42 [1.87–2.98]), sequential organ failure assessment score on admission (OR = 2.69 [1.39–3.98]), baseline blood urea nitrogen (OR = 2.11 [0.72–3.51]), serum creatinine (OR = 2.69 [1.39–3.98]), and sepsis (OR = 4.42 [1.75–11.18]). In addition, burn patients with AKI are more likely to have long stay in intensive care unit and high mortality. AKI is a common complication and occurs at a remarkable rate in burn patients. We identified 10 variables as independent risk factors for the development of AKI in burn patients. Our findings may help clinicians to develop effective preventive and therapeutic strategies and provide appropriate, timely initial treatment.

Repair of Complex Abdominal Wall Defects From High-Voltage Electric Injury With Two Layers of Acellular Dermal Matrix : A Case Report

High-voltage electric burn causing full-thickness necrosis of the abdominal wall and exposure of visceral organs is a real clinical challenge. This article reports a case of high-voltage electric burn causing a giant full-thickness abdominal wall defect. Seeing that it was unable to repair the abdominal wall defect with the conventional method, we used two layers of allogenic acellular dermal matrix substitutes to reconstruct and repair the defected abdominal wall. A 1-year follow-up showed that the abdominal wall of the patient recovered strong tenacity and strength without the evidence of significant complications.

Evaluation of Dermal Substitute in a Novel Co-Transplantation Model with Autologous Epidermal Sheet

The development of more and more new dermal substitutes requires a reliable and effective animal model to evaluate their safety and efficacy. In this study we constructed a novel animal model using co-transplantation of autologous epidermal sheets with dermal substitutes to repair full-thickness skin defects. Autologous epidermal sheets were obtained by digesting the basement membrane (BM) and dermal components from rat split-thickness skins in Dispase II solution (1.2 u/ml) at 4°C for 8, 10 and 12 h. H&E, immunohistochemical and live/dead staining showed that the epidermal sheet preserved an intact epidermis without any BM or dermal components, and a high percentage of viable cells (92.10±4.19%) and P63 positive cells (67.43±4.21%) under an optimized condition. Porcine acellular dermal matrixes were co-transplanted with the autologous epidermal sheets to repair full-thickness skin defects in Sprague-Dawley rats. The epidermal sheets survived and completely re-covered the wounds within 3 weeks. Histological staining showed that the newly formed stratified epidermis attached directly onto the dermal matrix. Inflammatory cell infiltration and vascularization of the dermal matrix were not significantly different from those in the subcutaneous implantation model. Collagen IV and laminin distributed continuously at the epidermis and dermal matrix junction 4 weeks after transplantation. Transmission electron microscopy further confirmed the presence of continuous lamina densa and hemidesmosome structures. This novel animal model can be used not only to observe the biocompatibility of dermal substitutes, but also to evaluate their effects on new epidermis and BM formation. Therefore, it is a simple and reliable model for evaluating the safety and efficacy of dermal substitutes.