Angiogenin expression in burn blister fluid: Implications for its role in burn wound neovascularization

A human pluripotent stem cell-derived in vitro model of the blood-brain barrier in cerebral malaria

BACKGROUND

Blood-brain barrier (BBB) disruption is a central feature of cerebral malaria (CM), a severe complication of Plasmodium falciparum (Pf) infections. In CM, sequestration of Pf-infected red blood cells (Pf-iRBCs) to brain endothelial cells combined with inflammation, hemolysis, microvasculature obstruction and endothelial dysfunction mediates BBB disruption, resulting in severe neurologic symptoms including coma and seizures, potentially leading to death or long-term sequelae. In vitro models have advanced our knowledge of CM-mediated BBB disruption, but their physiological relevance remains uncertain. Using human induced pluripotent stem cell-derived brain microvascular endothelial cells (hiPSC-BMECs), we aimed to develop a novel in vitro model of the BBB in CM, exhibiting enhanced barrier properties.

METHODS

hiPSC-BMECs were co-cultured with HB3var03 strain Pf-iRBCs up to 9 h. Barrier integrity was measured using transendothelial electrical resistance (TEER) and sodium fluorescein permeability assays. Localization and expression of tight junction (TJ) proteins (occludin, zonula occludens-1, claudin-5), cellular adhesion molecules (ICAM-1, VCAM-1), and endothelial surface markers (EPCR) were determined using immunofluorescence imaging (IF) and western blotting (WB). Expression of angiogenic and cell stress markers were measured using multiplex proteome profiler arrays.

RESULTS

After 6-h of co-culture with Pf-iRBCs, hiPSC-BMECs showed reduced TEER and increased sodium fluorescein permeability compared to co-culture with uninfected RBCs, indicative of a leaky barrier. We observed disruptions in localization of occludin, zonula occludens-1, and claudin-5 by IF, but no change in protein expression by WB in Pf-iRBC co-cultures. Expression of ICAM-1 and VCAM-1 but not EPCR was elevated in hiPSC-BMECs with Pf-iRBC co-culture compared to uninfected RBC co-culture. In addition, there was an increase in expression of angiogenin, platelet factor-4, and phospho-heat shock protein-27 in the Pf-iRBCs co-culture compared to uninfected RBC co-culture.

CONCLUSION

These findings demonstrate the validity of our hiPSC-BMECs based model of the BBB, that displays enhanced barrier integrity and appropriate TJ protein localization. In the hiPSC-BMEC co-culture with Pf-iRBCs, reduced TEER, increased paracellular permeability, changes in TJ protein localization, increase in expression of adhesion molecules, and markers of angiogenesis and cellular stress all point towards a novel model with enhanced barrier properties, suitable for investigating pathogenic mechanisms underlying BBB disruption in CM.

The effect of smoking on clinical and biochemical early healing outcomes of coronally advanced flap with connective tissue graft: Prospective cohort study

BACKGROUND

This study aimed to determine the effects of smoking on early (≤3 months) clinical outcomes and relevant molecular biomarkers following root coverage surgery.

METHODS

Eighteen smokers and 18 nonsmokers, status biochemically verified, with RT1 gingival recession defects were recruited and completed study procedures. All patients received coronally advanced flap plus connective tissue graft. Baseline and 3 month recession depth (RD), recession width (RW), keratinized tissue width (KTW), clinical attachment level (CAL), and gingival phenotype (GP) were recorded. Root coverage (RC) percentage and complete root coverage (CRC) were calculated. Recipient (gingival crevicular fluid) and donor (wound fluid) site VEGF-A, HIF-1α, 8-OHdG, and ANG levels were determined.

RESULTS

There were no significant intergroup differences for any baseline or postoperative clinical parameters (P > 0.05), except for whole mouth gingival index (increased in nonsmokers at 3 months; P < 0.05). Compared to baseline, RD, RW, CAL, KTW, and GP significantly improved postoperatively, without significant intergroup differences. There were no significant intergroup differences for RC (smokers = 83%, nonsmokers = 91%, P = 0.069), CRC (smokers = 50%, nonsmokers = 72%, P = 0.177), and CAL gain (P = 0.193). The four biomarker levels significantly increased postoperatively (day 7; P ≤ 0.042) in both groups and returned to baseline (day 28) without significant intergroup differences (P > 0.05). Similarly, donor site parameters were not different between groups. Strong correlations, consistent over time, were found between biomarkers implicated in angiogenesis (VEGF-A, HIF-1α, and ANG).

CONCLUSIONS

The early (3 month) clinical and molecular changes after root coverage surgery utilizing a coronally advanced flap plus connective tissue graft are similar between smokers and nonsmokers.

Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

Role of Burn Blister Fluid in Wound Healing

Blisters are characteristic finding of second-degree superficial burns. Varied opinions for the management of burn blisters are available in literature. Most accepted one is to puncture it in a sterile way, keep the overlying skin as a biological cover, and over that put a moist sterile biological dressing. Fluid in the blister is ultrafiltrate of the plasma, which is rich in proteins such as immunoglobulins, various cytokines, prostaglandins, and interleukins. This fluid is pro-inflammatory, and the evidence regarding its effect on wound healing is varied. Instead of drainage, the burn blister fluid can be aspirated and immediately sprayed over the other areas of the same wound. We found this method feasible as an adjuvant therapy for second-degree superficial burn wounds. In this case report, we share our experience of the same.

Angiogenin and Copper Crossing in Wound Healing

Angiogenesis plays a key role in the wound healing process, involving the migration, growth, and differentiation of endothelial cells. Angiogenesis is controlled by a strict balance of different factors, and among these, the angiogenin protein plays a relevant role. Angiogenin is a secreted protein member of the ribonuclease superfamily that is taken up by cells and translocated to the nucleus when the process of blood vessel formation has to be promoted. However, the chemical signaling that activates the protein, normally present in the plasma, and the transport pathways through which the protein enters the cell are still largely unclear. Copper is also an angiogenic factor that regulates angiogenin expression and participates in the activation of common signaling pathways. The interaction between angiogenin and copper could be a relevant mechanism in regulating the formation of new blood vessel pathways and paving the way to the development of new drugs for chronic non-healing wounds.

Serum concentration of matrix metalloproteinases and angiogenic factors in patients with venous leg ulcers

INTRODUCTION

Leg ulcers are a frequently observed medical problem affecting 3-5% of the general population over 65 years of age. The most common factor responsible for the development of leg ulcers is chronic venous insufficiency (CVI). It is believed that during the formation of an ulcer there are two processes occurring simultaneously, extracellular matrix (ECM) degradation and angiogenesis in which several proteins including matrix metalloproteinases, angiogenic and regulatory factors are engaged.

AIM

To determine the serum concentration of matrix metalloproteinase-1 (MMP-1), -9 (MMP-9), tissue inhibitors of metalloproteinases-1 (TIMP-1), angiogenin and vascular endothelial growth factor (VEGF) in patients suffering from venous leg ulcers and in the healthy control group.

MATERIAL AND METHODS

The study group consisted of 71 Caucasians (39 patients, 32 controls). To evaluate the serum concentration of MMP-1, MMP-9, TIMP-1, VEGF and angiogenin, the ELISA technique was used.

RESULTS

Mean MMP-1 and MMP-9 concentrations in the study group were 14.16 ±2.98 and 12.45 ±3.85 ng/ml, respectively, and in controls 6.08 ±2.51 ng/ml and 6.77 ±2.41 ng/ml, respectively and both differences were statistically significant (p < 0.001). There was no significant difference between the study and the control group in TIMP-1 concentration. Mean VEGF and ANG concentrations in the study group were 589.3 ±346.2 pg/ml and 1802.0 ±415.7 pg/ml, respectively, and in controls 220.3 ±110.4 pg/ml and 1229.0 ±337.7 pg/ml, respectively and both differences were statistically significant (p < 0.001).

CONCLUSIONS

Lack of significant differences in the concentration of TIMP-1 between the control and the study group confirms that proteolysis is a hallmark of CVI, but increased concentration of VEGF and angiogenin in the study group compared to the control group shows that angiogenesis occurs simultaneously with ECM remodelling.

Angiogenin-A Proposed Biomarker for Cardiovascular Disease-Is Not Associated With Long-Term Survival in Patients With Peripheral Artery Disease

We evaluated angiogenin as a prospective biomarker in peripheral artery disease (PAD) patients with and without claudication symptoms. A pilot study suggested an elevation of angiogenin in critical limb ischemia. However, in PAD patients, the predictive value of angiogenin has not yet been evaluated. For this purpose, 342 patients with PAD (age: 69 ± 10 years, 34.5% women) were followed-up for 7 years in a cross-sectional study. Angiogenin was measured by enzyme-linked immunosorbent assay. All-cause and cardiovascular mortality were analyzed by Cox regression. Angiogenin levels were higher in men (P = .001) and were associated with patient waist-to-hip ratio (P < .001), fasting triglycerides (P = .011), and inversely with estimated glomerular filtration rate (P = .009). However, angiogenin showed no association with age, characteristics of diabetes, markers of lipid metabolism, or C-reactive protein. Angiogenin did not correlate with markers of angiogenesis such as vascular endothelial growth factor, angiopoietin-2, or tie-2. Furthermore, angiogenin was not associated with PAD Fontaine stages or with patient ankle-brachial index in addition to all-cause mortality (hazard ratio [HR] = 1.09 [95% CI: 0.89-1.34]) or cardiovascular morality (HR = 1.05 [0.82-1.35]). These results suggest that angiogenin does not provide further information regarding outcome prediction in patients with PAD.

Gold Nanoparticles Functionalized with Angiogenin for Wound Care Application

In this work, we aimed to develop a hybrid theranostic nano-formulation based on gold nanoparticles (AuNP)-having a known anti-angiogenic character-and the angiogenin (ANG), in order to tune the angiogenesis-related phases involved in the multifaceted process of the wound healing. To this purpose, spherical were surface "decorated" with three variants of the protein, namely, the recombinant (rANG), the wild-type, physiologically present in the human plasma (wtANG) and a new mutant with a cysteine substitution of the serine at the residue 28 (S28CANG). The hybrid biointerface between AuNP and ANG was scrutinized by a multi-technique approach based on dynamic light scattering, spectroscopic (UV-visible, circular dichroism) and microscopic (atomic force and laser scanning confocal) techniques. The analyses of optical features of plasmonic gold nanoparticles allowed for discrimination of different adsorption modes-i.e.; predominant physisorption and/or chemisorption-triggered by the ANG primary sequence. Biophysical experiments with supported lipid bilayers (SLB), an artificial model of cell membrane, were performed by means of quartz crystal microbalance with dissipation monitoring acoustic sensing technique. Cellular experiments on human umbilical vein endothelial cells (HUVEC), in the absence or presence of copper-another co-player of angiogenesis-were carried out to assay the nanotoxicity of the hybrid protein-gold nanoassemblies as well as their effect on cell migration and tubulogenesis. Results pointed to the promising potential of these nanoplatforms, especially the new hybrid Au-S28CANG obtained with the covalent grafting of the mutant on the gold surface, for the modulation of angiogenesis processes in wound care.

Current potential therapeutic strategies targeting the TGF-β/Smad signaling pathway to attenuate keloid and hypertrophic scar formation

Aberrant scar formation, which includes keloid and hypertrophic scars, is associated with a pathological disorganized wound healing process with chronic inflammation. The TGF-β/Smad signaling pathway is the most canonical pathway through which the formation of collagen in the fibroblasts and myofibroblasts is regulated. Sustained activation of the TGF-β/Smad signaling pathway results in the long-term overactivation of fibroblasts and myofibroblasts, which is necessary for the excessive collagen formation in aberrant scars. There are two categories of therapeutic strategies that aim to target the TGF-β/Smad signaling pathway in fibroblasts and myofibroblasts to interfere with their cellular functions and reduce cell proliferation. The first therapeutic strategy includes medications, and the second strategy is composed of genetic and cellular therapeutics. Therefore, the focus of this review is to critically evaluate these two main therapeutic strategies that target the TGF-β/Smad pathway to attenuate abnormal skin scar formation.

Preliminary Assessment of Burn Depth by Paper-Based ELISA for the Detection of Angiogenin in Burn Blister Fluid-A Proof of Concept

Rapid assessment of burn depth is important for burn wound management. Superficial partial-thickness burn (SPTB) wounds heal without scars, but deep partial-thickness burn (DPTB) wounds require a longer healing time and have a higher risk of scar formation. We previously found that DPTB blister fluid displayed a higher angiogenin level than SPTB blister fluid by conventional ELISA. In this study, we developed a paper-based ELISA (P-ELISA) technique for rapid assessment of angiogenin concentration in burn blister fluid. We collected six samples of SPTB blister fluid, six samples of DPTB blister fluid, and seven normal healthy serum samples for analysis. We again chose ELISA to measure and compare angiogenin levels across all of our samples, but we developed a P-ELISA tool and compared sample results from that tool to the results from conventional ELISA. As with conventional ELISA, DPTB blister fluid displayed higher angiogenin levels than SPTB in P-ELISA. Furthermore, our P-ELISA results showed a moderate correlation with conventional ELISA results. This new diagnostic technique facilitates rapid and convenient assessment of burn depth by evaluating a key molecule in burn blister fluid. It presents a novel and easy-to-learn approach that may be suitable for clinically determining burn depth with diagnostic precision.

The Secretome of Hypoxia Conditioned hMSC Loaded in a Central Depot Induces Chemotaxis and Angiogenesis in a Biomimetic Mineralized Collagen Bone Replacement Material

The development of biomaterials with intrinsic potential to stimulate endogenous tissue regeneration at the site of injury is a main demand on future implants in regenerative medicine. For critical-sized bone defects, an in situ tissue engineering concept is devised based on biomimetic mineralized collagen scaffolds. These scaffolds are functionalized with a central depot loaded with a signaling factor cocktail, obtained from secretome of hypoxia-conditioned human mesenchymal stem cells (MSC). Therefore, hypoxia-conditioned medium (HCM)-production is standardized and adapted to achieve high signaling factor-yields; a concentration protocol based on dialysis and freeze-drying is established to enable the integration of sufficient and defined amounts into the depot. In humid milieu-as after implantation-signaling factors are released by forming a chemotactic gradient, inducing a directed migration of human bone marrow stroma cells (hBMSC) into the scaffold. Angiogenic potential, determined by coculturing human umbilical vein endothelial cells (HUVEC) with osteogenically induced hBMSC shows prevascular structures, which sprout throughout the interconnected pores in a HCM-concentration-dependent manner. Retarded release by alginate-based (1 vol%) depots, significantly improves sprouting-depth and morphology of tubular structures. With the intrinsic potential to supply attracted cells with oxygen and nutrients, this bioactive material system has great potential for clinical translation.

Angiogenin production in response to hypoxia and l-mimosine in periodontal fibroblasts

BACKGROUND

A major mediator of angiogenesis is angiogenin, which is expressed in the early phase of healing in oral tissue engineering strategies. It is unclear how angiogenin is regulated in the periodontal tissue. The objective of this study was to reveal the regulation of angiogenin in response to hypoxia and the hypoxia mimetic agent l-mimosine in periodontal fibroblasts.

METHODS

Human fibroblasts of the periodontal ligament (PDLF) and the gingiva (GF) in monolayer and spheroid cultures were exposed to hypoxia or l-mimosine. The production of angiogenin was evaluated at mRNA and protein levels with reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Echinomycin, an inhibitor of hypoxia-inducible factor (HIF)-1 activity, was used to test the involvement of HIF-1.

RESULTS

Our data show that hypoxia and l-mimosine can increase angiogenin mRNA and protein levels in PDLF monolayer cultures. In GF monolayer cultures, we found an increase of angiogenin at the mRNA level in response to hypoxia. The increase of angiogenin can be blocked by inhibition of HIF-1 signaling via echinomycin. In PDLF and GF spheroid cultures, the impact of hypoxia and l-mimosine did not reach the level of significance.

CONCLUSION

Hypoxia and the hypoxia mimetic agent l-mimosine can increase the production of angiogenin via HIF-1 signaling in PDLF monolayer cultures but not in spheroid cultures. GF were less sensitive to the impact of hypoxia and l-mimosine. Overall, these results suggest a link between hypoxia, HIF-1 signaling and angiogenin in the periodontium.

Characterization of the Blister Fluid Proteome for Pediatric Burn Classification

Blister fluid (BF) is a novel and viable research matrix for burn injury study, which can reflect both systemic and local microenvironmental responses. The protein abundance in BF from different burn severities were initially observed using a 2D SDS-PAGE approach. Subsequently, a quantitative data independent acquisition (DIA) method, SWATH, was employed to characterize the proteome of pediatric burn blister fluid. More than 600 proteins were quantitatively profiled in 87 BF samples from different pediatric burn patients. These data were correlated with clinically assessed burn depth and time until complete wound re-epithelialization through several different statistical analyses. Several proteins from these analyses exhibited significant abundance change between different burn depth or re-epithelialization groups, and can be considered as potential biomarker candidates. Further gene ontology (GO) enrichment analysis of the significant proteins revealed the most significant burn related biological processes (BP) that are altered with burn depth, including homeostasis and oxygen transport. However, for wounds with re-epithelialization times more or less than 21 days, the significant GO annotations were related to enzyme activity. This quantitative proteomics investigation of burn BF may enable objective classification of burn wound severity and assist with clinical decision-making. Data are available via ProteomeXchange with identifier PXD011102.

Predominance of CD14+ Cells in Burn Blister Fluids

BACKGROUND

Burn blister fluid contains several angiogenic factors to promote wound neovascularization. In our previous study, we found that deep partial-thickness burn (DPTB) wounds showed higher expression levels of angiogenin to enhance vascularization compared with superficial partial-thickness burn wounds. Neovascularization is a complex process that involves an interaction between circulating angiogenic cells and mediators. We hypothesized that in addition to angiogenic factors burn blisters may contain specific cell types. The aim of the present study was to characterize the specific cells present in burn blisters.

METHODS

Twenty-four burn blister fluid samples were obtained with informed consent from patients with superficial partial-thickness burn (n = 16) or DPTB (n = 8) wounds. Blister cells were isolated from individual intact blisters and characterized with flow cytometry analysis using CD14, CD34, vascular endothelial growth factor receptor 2, and CD133 markers. CD14 and CD34 blister cells were also isolated using a magnetic-activated cell sorting system to examine their potential for endothelial differentiation. Angiogenin levels in the burn blister fluids were evaluated with enzyme-linked immunosorbent assay.

RESULTS

CD14 cells were the most highly represented cell type in the burn fluids of both groups, although a significantly greater percentage of CD14 cells were observed in DPTB fluids. CD14 blister cells had a higher potency to differentiate into functional endothelial cells as compared with CD34 cells. The proportion of CD14 cells gradually increased after burn injury. In contrast to CD14 cells, angiogenin showed the highest expression levels at day 1 postburn. With regard to burn wound neovascularization, angiogenin expression was partially correlated with CD14 blister cells in the burn fluids.

CONCLUSIONS

We provide the first report on the characterization of blister cells in burn fluids. Our data suggest that CD14 blister cells may play a role in burn wound neovascularization. Measurement of CD14 blister cells serves as a possible tool for assessing burn wound status.

Burn Eschar Stimulates Fibroblast and Adipose Mesenchymal Stromal Cell Proliferation and Migration but Inhibits Endothelial Cell Sprouting

The majority of full-thickness burn wounds heal with hypertrophic scar formation. Burn eschar most probably influences early burn wound healing, since granulation tissue only forms after escharotomy. In order to investigate the effect of burn eschar on delayed granulation tissue formation, burn wound extract (BWE) was isolated from the interface between non-viable eschar and viable tissue. The influence of BWE on the activity of endothelial cells derived from dermis and adipose tissue, dermal fibroblasts and adipose tissue-derived mesenchymal stromal cells (ASC) was determined. It was found that BWE stimulated endothelial cell inflammatory cytokine (CXCL8, IL-6 and CCL2) secretion and migration. However, BWE had no effect on endothelial cell proliferation or angiogenic sprouting. Indeed, BWE inhibited basic Fibroblast Growth Factor (bFGF) induced endothelial cell proliferation and sprouting. In contrast, BWE stimulated fibroblast and ASC proliferation and migration. No difference was observed between cells isolated from dermis or adipose tissue. The inhibitory effect of BWE on bFGF-induced endothelial proliferation and sprouting would explain why excessive granulation tissue formation is prevented in full-thickness burn wounds as long as the eschar is still present. Identifying the eschar factors responsible for this might give indications for therapeutic targets aimed at reducing hypertrophic scar formation which is initiated by excessive granulation tissue formation once eschar is removed.

L-mimosine and hypoxia can increase angiogenin production in dental pulp-derived cells

Background

Angiogenin is a key molecule in the healing process which has been successfully applied in the field of regenerative medicine. The role of angiogenin in dental pulp regeneration is unclear. Here we aimed to reveal the impact of the hypoxia mimetic agent L-mimosine (L-MIM) and hypoxia on angiogenin in the dental pulp.

Methods

Human dental pulp-derived cells (DPC) were cultured in monolayer and spheroid cultures and treated with L-MIM or hypoxia. In addition, tooth slice organ cultures were applied to mimic the pulp-dentin complex. We measured angiogenin mRNA and protein levels using qPCR and ELISA, respectively. Inhibitor studies with echinomycin were performed to reveal the role of hypoxia-inducible factor (HIF)-1 signaling.

Results

Both, L-MIM and hypoxia increased the production of angiogenin at the protein level in monolayer cultures of DPC, while the increase at the mRNA level did not reach the level of significance. The increase of angiogenin in response to treatment with L-MIM or hypoxia was reduced by echinomycin. In spheroid cultures, L-MIM increased angiogenin at protein levels while the effect of hypoxia was not significant. Angiogenin was also expressed and released in tooth slice organ cultures under normoxic and hypoxic conditions and in the presence of L-MIM.

Conclusions

L-MIM and hypoxia modulate production of angiogenin via HIF-1 differentially and the response depends on the culture model. Given the role of angiogenin in regeneration the here presented results are of high relevance for pre-conditioning approaches for cell therapy and tissue engineering in the field of regenerative endodontics.

Three decades of research on angiogenin: a review and perspective

As a member of the vertebrate-specific secreted ribonucleases, angiogenin (ANG) was first isolated and identified solely by its ability to induce new blood vessel formation, and now, it has been recognized to play important roles in various physiological and pathological processes through regulating cell proliferation, survival, migration, invasion, and/or differentiation. ANG exhibits very weak ribonucleolytic activity that is critical for its biological functions, and exerts its functions through activating different signaling transduction pathways in different target cells. A series of recent studies have indicated that ANG contributes to cellular nucleic acid metabolism. Here, we comprehensively review the results of studies regarding the structure, mechanism, and function of ANG over the past three decades. Moreover, current problems and future research directions of ANG are discussed. The understanding of the function and mechanism of ANG in a wide context will help to better delineate its roles in diseases, especially in cancer and neurodegenerative diseases.

The biochemistry of blister fluid from pediatric burn injuries: proteomics and metabolomics aspects

Burn injury is a prevalent and traumatic event for pediatric patients. At present, the diagnosis of burn injury severity is subjective and lacks a clinically relevant quantitative measure. This is due in part to a lack of knowledge surrounding the biochemistry of burn injuries and that of blister fluid. A more complete understanding of the blister fluid biochemistry may open new avenues for diagnostic and prognostic development. Burn insult induces a highly complex network of signaling processes and numerous changes within various biochemical systems, which can ultimately be examined using proteome and metabolome measurements. This review reports on the current understanding of burn wound biochemistry and outlines a technical approach for 'omics' profiling of blister fluid from burn wounds of differing severity.

Adiponectin fine-tuning of liver regeneration dynamics revealed through cellular network modelling

Following partial hepatectomy, the liver initiates a regenerative programme involving hepatocyte priming and replication driven by the coordinated actions of cytokine and growth factors. We investigated the mechanisms underlying adiponectin's (Adn) regulation of liver regeneration through modulation of these mediators. Adn(-/-) mice showed delayed onset of hepatocyte replication, but accelerated cell cycle progression relative to wild-type mice, suggesting Adn has multiple effects fine-tuning the kinetics of liver regeneration. We developed a computational model describing the molecular and physiological kinetics of liver regeneration in Adn(-/-) mice. We employed this computational model to evaluate the underlying regulatory mechanisms. Our analysis predicted that Adn is required for an efficient early cytokine response to partial hepatectomy, but is inhibitory to later growth factor actions. Consistent with this prediction, Adn knockout reduced hepatocyte responses to interleukin-6 during the priming phase, but enhanced growth factor levels through peak hepatocyte replication. By contrast, supraphysiological concentrations of Adn resulting from rosiglitazone treatment suppressed regeneration by reducing growth factor levels during S phase, consistent with computational predictions. Together, these results revealed that Adn fine-tunes the progression of liver regeneration through dynamically modulating molecular mediator networks and cellular interactions within the liver.

Characterization of sulfur mustard resistant keratinocyte cell line HaCaT/SM

BACKGROUND

The cell line HaCaT/SM was derived from the human keratinocyte cell line HaCaT. HaCaT/SM cells display a high resistance against sulfur mustard (SM). Intention of the presented study was to determine the cellular and molecular differences between HaCaT/SM and HaCaT so as to evaluate which changes might be responsible for being resistant against SM.

METHODS

Both cell lines HaCaT and HaCaT/SM were analyzed with respect to their cell growth, nuclei perimeter, clonogenicity and secretion profile. Moreover DNA alkylation pattern under presence of SM was investigated.

RESULTS

In comparison to HaCaT, the HaCaT/SM showed a significant smaller nuclei perimeter. For DNA alkylation a significant difference was observed over time. The clonogenicity of HaCaT/SM was increased to 150%. The secretion profile of these cells demonstrated a strong increase of ANG, PDGF-AA, TIMP1, TIMP2, and a decrease of AREG, CCL5, CXC1, CXC2/3, CXCL6, CXCL7, CXCL8, CXCL10, MIF, Trappin-1.

CONCLUSION

The sulfur mustard (SM) resistant cell line HaCaT/SM demonstrates a wide range of significant differences to their origin cell line HaCaT. These differences might be responsible to provide resistance against SM and might also be useful to establish treatment concepts for humans after SM exposure.

Evaluation of haemoglobin in blister fluid as an indicator of paediatric burn wound depth

The early and accurate assessment of burns is essential to inform patient treatment regimens; however, this first critical step in clinical practice remains a challenge for specialist burns clinicians worldwide. In this regard, protein biomarkers are a potential adjunct diagnostic tool to assist experienced clinical judgement. Free circulating haemoglobin has previously shown some promise as an indicator of burn depth in a murine animal model. Using blister fluid collected from paediatric burn patients, haemoglobin abundance was measured using semi-quantitative Western blot and immunoassays. Although a trend was observed in which haemoglobin abundance increased with burn wound severity, several patient samples deviated significantly from this trend. Further, it was found that haemoglobin concentration decreased significantly when whole cells, cell debris and fibrinous matrix was removed from the blister fluid by centrifugation; although the relationship to depth was still present. Statistical analyses showed that haemoglobin abundance in the fluid was more strongly related to the time between injury and sample collection and the time taken for spontaneous re-epithelialisation. We hypothesise that prolonged exposure to the blister fluid microenvironment may result in an increased haemoglobin abundance due to erythrocyte lysis, and delayed wound healing.

The burn wound exudate-an under-utilized resource

INTRODUCTION

The burn wound exudate represents the burn tissue microenvironment. Extracting information from the exudate relating to cellular components, signaling mediators and protein content can provide much needed data relating to the local tissue damage, depth of the wound and probable systemic complications. This review examines the scientific data extracted from burn wound exudates over the years and proposes new investigations that will provide useful information from this underutilized resource.

METHOD

A literature review was conducted using the electronic database PubMed to search for literature pertaining to burn wound or blister fluid analysis. Key words included burn exudate, blister fluid, wound exudate, cytokine burn fluid, subeschar fluid, cytokine burns, serum cytokines. 32 relevant articles were examined and 29 selected as relevant to the review. 3 papers were discarded due to questionable methodology or conclusions. The reports were assessed for their affect on management decisions and diagnostics. Furthermore, traditional blood level analysis of these mediators was made to compare the accuracy of blood versus exudate in burn wound management. Extrapolations are made for new possibilities of burn wound exudate analysis.

RESULTS

Studies pertaining to burn wound exudate, subeschar fluid and blister fluid analyses may have contributed to burn wound management decisions particularly related to escharectomies and early burn wound excision. In addition, information from these studies has the potential to impact on areas such as healing, scarring, burn wound conversion and burn wound depth analysis.

CONCLUSION

Burn wound exudate analysis has proven useful in burn wound management decisions. It appears to offer a far more accurate reflection of the burn wound pathophysiology than the traditional blood/serum investigations undertaken in the past. New approaches to diagnostics and treatment efficacy assessment are possible utilizing data from this fluid. Burn wound exudate is a useful, currently under-utilized resource that is likely to take a more prominent role in burn wound management.

Burn blister fluids in the neovascularization stage of burn wound healing: A comparison between superficial and deep partial-thickness burn wounds

Burn wound healing is a complex and dynamic process that involves the interaction between different cell types and mediators. Neovascularization is an imperative stage of wound healing and consists of not only angiogenesis but also adult vasculogenesis. A superficial partial-thickness burn (SPTB) heals within 2 weeks without scarring. A deep partial-thickness burn (DPTB), conversely, requires 2 weeks or longer to heal and requires an aggressive treatment to prevent hypertrophic scarring. Burn blisters on the skin are a hallmark of not only SPTB but also DPTB; however, the effect of burn blister fluids on the neovascularization in these types of burns has not been fully explored. To verify this effect, the role of different burn fluids and the angiogenic factors that modulate this process are currently under investigation.

Molecular Mechanisms in Amyotrophic Lateral Sclerosis: The Role of Angiogenin, a Secreted RNase

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease caused by the loss of motoneurons. The precise molecular and cellular basis for neuronal death is not yet well established, but the contemporary view is that it is a culmination of multiple aberrant biological processes. Among the proposed mechanisms of motoneuron degeneration, alterations in the homeostasis of RNA binding proteins (RBP) and the consequent changes in RNA metabolism have received attention recently. The ribonuclease, angiogenin was one of the first RBPs associated with familial and sporadic ALS. It is enriched in motoneurons under physiological conditions, and is required for motoneuron survival under stress conditions. Furthermore, delivery of angiogenin protects cultured motoneurons against stress-induced injury, and significantly increases the survival of motoneurons in SOD^G93A mice. In this overview on the role of angiogenin in RNA metabolism and in the control of motoneuron survival, we discuss potential pathogenic mechanisms of angiogenin dysfunction relevant to ALS and other neurodegenerative disorders. We also discuss recent evidence demonstrating that angiogenin secreted from stressed motoneurons may alter RNA metabolism in astrocytes.