Human Skin Xenografts Research Articles

Hedgehog costimulation during ischemia-reperfusion injury potentiates cytokine and homing responses of CD4+ T cells.

Ischemia reperfusion injury (IRI) confers worsened outcomes and is an increasing clinical problem in solid organ transplantation. Previously, we identified a "PtchHi" T-cell subset that selectively received costimulatory signals from endothelial cell-derived Hedgehog (Hh) morphogens to mediate IRI-induced vascular inflammation. Here, we used multi-omics approaches and developed a humanized mouse model to resolve functional and migratory heterogeneity within the PtchHi population. Hh-mediated costimulation induced oligoclonal and polyclonal expansion of clones within the PtchHi population, and we visualized three distinct subsets within inflamed, IRI-treated human skin xenografts exhibiting polyfunctional cytokine responses. One of these PtchHi subsets displayed features resembling recently described T peripheral helper cells, including elaboration of IFN-y and IL-21, expression of ICOS and PD-1, and upregulation of positioning molecules conferring recruitment and retention within peripheral but not lymphoid tissues. PtchHi T cells selectively homed to IRI-treated human skin xenografts to cause accelerated allograft loss, and Hh signaling was sufficient for this process to occur. Our studies define functional heterogeneity among a PtchHi T-cell population implicated in IRI.

Establishing a Xenograft Model with CD-1 Nude Mice to Study Human Skin Wound Repair.

A significant gap exists in the translatability of small-animal models to human subjects. One important factor is poor laboratory models involving human tissue. Thus, the authors have created a viable postnatal human skin xenograft model using athymic mice. Discarded human foreskins were collected following circumcision. All subcutaneous tissue was removed from these samples sterilely. Host CD-1 nude mice were then anesthetized, and dorsal skin was sterilized. A 1.2-cm-diameter, full-thickness section of dorsal skin was excised. The foreskin sample was then placed into the full-thickness defect in the host mice and sutured into place. Xenografts underwent dermal wounding using a 4-mm punch biopsy after engraftment. Xenografts were monitored for 14 days after wounding and then harvested. At 14 days postoperatively, all mice survived the procedure. Grossly, the xenograft wounds showed formation of a human scar at postoperative day 14. Hematoxylin and eosin and Masson trichome staining confirmed scar formation in the wounded human skin. Using a novel artificial intelligence algorithm using picrosirius red staining, scar formation was confirmed in human wounded skin compared with the unwounded skin. Histologically, CD31 + immunostaining confirmed vascularization of the xenograft. The xenograft exclusively showed human collagen type I, CD26 + , and human nuclear antigen in the human scar without any staining of these human markers in the murine skin. The proposed model demonstrates wound healing to be a local response from tissue resident human fibroblasts and allows for reproducible evaluation of human skin wound repair in a preclinical model. Radiation-induced fibrosis is a widely prevalent clinical phenomenon without a well-defined treatment at this time. This study will help establish a small-animal model to better understand and develop novel therapeutics to treat irradiated human skin.

Rose Bengal Induced Photothrombosis in CAM Integrated Human Split Skin Grafts—A Feasibility Study

Wound healing is a complex process requiring an adequate supply of the wound area with oxygen and nutrients by neo-vascularization, to renew tissue. Local ischemia can result in the formation of chronic wounds. Since there is a lack of wound healing models for ischemic wounds, we aimed to develop a new one, based on chick chorioallantoic membrane (CAM) integrated split skin grafts and induction of ischemia with photo-activating Rose Bengal (RB) in a two-part study: (1) investigation of the thrombotic effect of photo-activated RB in CAM vessels and (2) investigation of the influence of photo-activated RB on CAM integrated human split skin xenografts. In both study phases, we observed a typical pattern of vessel changes after RB activation with a 120 W 525/50 nm green cold light lamp in the region of interest: intravascular haemostasis and a decrease in vessel diameter within 10 min of treatment. In total, the diameter of 24 blood vessels was measured before and after 10 min of illumination. Mean relative reduction of vessel diameter after treatment was 34.8% (12.3%-71.4%; p < 0.001). The results indicate that the present CAM wound healing model can reproduce chronic wounds without inflammation due to the statistically significant reduction of blood flow in the selected area using RB. Combined with xenografted human split skin grafts, we established the set up for a new chronic wound healing model for the research of regenerative processes following ischemic damage of the tissue.

577 The role of YAP1 in regeneration of human skin and in pathological states

To study the role of YAP1 in regeneration of human skin we have developed a unique model of a full-layer human skin xenograft, containing epidermis, dermis, adipose tissue, as well as hair follicles, sebaceous and sweat glands. On days 40, 75 and 110 after transplantation of human skin to NOD/SCID mice, biopsies were studied immunohistochemically and compared with intact skin and with biopsies of cutaneous papilloma and chronic wound. Morphometric parameters, distribution and content of markers were studied using ImageJ and Cell Profiler.

Lighting the Way for Necrosis Excision Through Indocyanine Green Fluorescence-Guided Surgery.

No objective technique exists to distinguish necrotic from viable tissue, risking over-excision in burns and loss of wound healing potential. Second window indocyanine green (SWIG) is a novel fluorescence-imaging modality being studied to identify residual solid tumors during oncological surgery. SWIG has also been shown to have avidity for necrosis in animal models, but translation of these findings to humans is lacking. The objective of this study was to evaluate SWIG in the identification of burn wound necrosis and compare it with previously published indocyanine green angiography (ICGA) techniques. This study used mouse, human skin xenograft and human patient burn models. Brightfield and SWIG near-infrared imaging were performed on macroscopic tissue samples, which were then cryopreserved, sectioned, and analyzed for microscopic fluorescence. SWIG fluorescence findings were correlated to visual assessment of the burn wound as well as histological markers of necrosis using hematoxylin and eosin and lactate dehydrogenase stains. We found that SWIG identified burn necrosis in a manner dependent on the dose and timing of indocyanine green (ICG) administration and had an inverse fluorescence signal compared with ICGA. Furthermore, SWIG fluorescence identified the interface of viable and nonviable tissue. Our study confirmed that ICGA is an inconsistent and nonstandardized modality to evaluate burn injuries. In contrast, SWIG imaging is a potential imaging modality to objectively prognosticate burn wound healing potential and guide intraoperative burn excision. Further studies are needed to define ratios of fluorescence intensity values to guide surgical decision-making in burn excision and to better define how ICG is retained in necrotic tissue to enhance utility of SWIG in other disease processes.

Robbing Peter to Pay Paul: Chlorhexidine gluconate demonstrates short-term efficacy and long-term cytotoxicity.

Wound cleansing agents are routine in wound care and preoperative preparation. Antiseptic activity intends to prevent contaminating microbes from establishing an infection while also raising concerns of cytotoxicity and delayed wound healing. We evaluated the cytotoxicity of five clinically used wound cleaning agents (saline, povidone iodine, Dove® and Dial® soaps, and chlorhexidine gluconate [CHG]) using both an ex vivo and in vivo human skin xenograft mouse model, in contrast to classical in vitro models that lack the structural and compositional heterogeneity of human skin. We further established an ex vivo wound contamination model inoculated with ~100 cells of Pseudomonas aeruginosa or Staphylococcus aureus to evaluate antimicrobial efficacy. Scanning electron microscopy and confocal microscopy were used to evaluate phenotypic and spatial characteristics of bacterial cells in wound tissue. CHG significantly reduced metabolic activity of the skin explants, while all treatments except saline affected local cellular viability. CHG cytotoxicity persisted and progressed over 14 days, impairing wound healing in vivo. Within the contamination model, CHG treatment resulted in a significant reduction of P. aeruginosa wound surface counts at 24 h post‐treatment. However, this effect was transient and serial application of CHG had no effect on both P. aeruginosa or S. aureus microbial growth. Microscopy revealed that viable cells of P. aeruginosa reside deep within wound tissue post‐CHG application, likely serving as a reservoir to re‐populate the tissue to a high bioburden. We reveal concerning cytotoxicity and limited antimicrobial activity of CHG in human skin using clinically relevant models, with the ability to resolve spatial localization and temporal dynamics of tissue viability and microbial growth.

Xenograft Skin Model to Manipulate Human Immune Responses In Vivo.

The human skin xenograft model, in which human donor skin is transplanted onto an immunodeficient mouse host, is an important option for translational research in skin immunology. Murine and human skin differ substantially in anatomy and immune cell composition. Therefore, traditional mouse models have limitations for dermatological research and drug discovery. However, successful xenotransplants are technically challenging and require optimal specimen and mouse graft site preparation for graft and host survival. The present protocol provides an optimized technique for transplanting human skin onto mice and discusses necessary considerations for downstream experimental aims. This report describes the appropriate preparation of a human donor skin sample, assembly of a surgical setup, mouse and surgical site preparation, skin transplantation, and post-surgical monitoring. Adherence to these methods allows for maintenance of xenografts for over 6 weeks post-surgery. The techniques outlined below allow maximum grafting efficiency due to the development of engineering controls, sterile technique, and pre- and post-surgical conditioning. Appropriate performance of the xenograft model results in long-lived human skin graft samples for experimental characterization of human skin and preclinical testing of compounds in vivo.

23 Chlorhexidine Delays Wound Healing in Human Skin

IntroductionChlorhexidine (CHG) is ubiquitous in surgical perioperative care. In vivo studies of CHG cytotoxicity on human skin are lacking. Given the use of CHG for daily wound cares and as a presurgical scrub, including donor site preparation, we sought to identify if CHG cytotoxicity would persist in a clinically relevant in vivo human skin xenograft model.MethodsHuman skin tissues were obtained from elective surgeries. Partial thickness wounds were created ex vivo in human skin using a 4 mm punch biopsy. 2% CHG (treatment) or PBS (control) was applied to the wounds for 30 minutes followed by rinsing the tissue +/- mechanical disruptive irrigation. Tissues were cultured at the air-liquid interface for 24 hours in culture media after treatment and tissue viability was performed using an MTT assay. For in vivo studies, athymic mice (n=4) were grafted on bilateral flanks with human skin. Eight weeks after engraftment and normalization of skin architecture, 4 mm partial thickness wounds were created on each xenograft (2 per mouse – treatment and control). 2% CHG was applied daily for 2 minutes followed by irrigation with PBS in the treatment wound. The control wound received PBS application and irrigation. The xenografts received treatment daily for 14 days to mimic daily wound cares, and digital images were obtained to document presence of infection and gross wound healing. On day 14, the xenografts were harvested and stained for lactate dehydrogenase and H&E to assess cell viability and wound re-epithelization, respectively.ResultsAn MTT assay on ex vivo human skin wounds showed that CHG treated groups (irrigation or non-irrigation) had lower cell viability compared to the PBS treated group, however irrigation mitigates the cytotoxicity of CHG on human skin. In the in vivo xenograft study, no signs of infection were identified in either PBS or CHG treated wounds throughout the study. The wound size appeared larger on gross inspection in the CHG treated group compared to the PBS group as early as day 2.Microscopically, the PBS treated wounds were fully re-epithelialized (n=2) or had significantly more re-epithelialization (n=2) than the CHG treated wounds (n=4) after 14 days of treatment. The PBS-treated wounds were viable throughout the tissue, indicating the irrigation procedure was not harmful to the cells. In the CHG-treated wounds, nonviable cells were observed in the dermis beneath the wound that was directly in contact with CHG suggesting penetration of CHG contributes to cytotoxicity in acute wounds.ConclusionsDaily CHG use is cytotoxic to human skin and impedes wound healing.

An acyclic phosphonate prodrug of HPMPC is effective against VZV in skin organ culture and mice

Varicella zoster virus (VZV) causes chicken pox and shingles and is prevalent worldwide. Acyclovir and penciclovir (and its prodrugs) are first-line treatments for VZV infections, but they are not highly potent against VZV and resistance may arise in immunocompromised people on long-term therapy. HPMPC (cidofovir) is active against VZV, but cidofovir is not approved for treating VZV diseases, is nephrotoxic, and is not orally bioavailable. Here, we present the synthesis and evaluation of USC-373, a phosphonate prodrug of HPMPC with activity against VZV and other DNA viruses. In cultured fibroblasts, it was potent against VZV Ellen laboratory strain and was not overtly toxic, with EC50 of 4 nM and CC50 of 0.20 μM, producing a selectivity index of 50. In ARPE-19 cells, USC-373 was effective against VZV-ORF57-Luc wild type strain and the acyclovir-resistant isogenic strain. In human skin organ culture, USC-373 formulated in cocoa butter and applied topically prevented VZV-ORF57-Luc spread without toxicity. In NuSkin mice with human skin xenografts, one daily dose of 3 mg/kg was effective by the subcutaneous route, and one daily dose of 10 mg/kg was effective by the oral route. Remarkably, a 10 mg/kg oral dose given every other day was also effective. USC-373 was well tolerated and mice did not lose weight or show signs of distress. The prodrug modifications of USC-373 increase the potency and oral bioavailability compared to its parent nucleoside analog, HPMPC.

H84T BanLec has broad spectrum antiviral activity against human herpesviruses in cells, skin, and mice

H84T BanLec is a molecularly engineered lectin cloned from bananas with broad-spectrum antiviral activity against several RNA viruses. H84T BanLec dimers bind glycoproteins containing high-mannose N-glycans on the virion envelope, blocking attachment, entry, uncoating, and spread. It was unknown whether H84T BanLec is effective against human herpesviruses varicella-zoster virus (VZV), human cytomegalovirus (HCMV), and herpes simplex virus 1 (HSV-1), which express high-mannose N-linked glycoproteins on their envelopes. We evaluated H84T BanLec against VZV-ORF57-Luc, TB40/E HCMV-fLuc-eGFP, and HSV-1 R8411 in cells, skin organ culture, and mice. The H84T BanLec EC50 was 0.025 µM for VZV (SI50 = 4000) in human foreskin fibroblasts (HFFs), 0.23 µM for HCMV (SI50 = 441) in HFFs, and 0.33 µM for HSV-1 (SI50 = 308) in Vero cells. Human skin was obtained from reduction mammoplasties and prepared for culture. Skin was infected and cultured up to 14 days. H84T BanLec prevented VZV, HCMV and HSV-1 spread in skin at 10 µM in the culture medium, and also exhibited dose-dependent antiviral effects. Additionally, H84T BanLec arrested virus spread when treatment was delayed. Histopathology of HCMV-infected skin showed no overt toxicity when H84T BanLec was present in the media. In athymic nude mice with human skin xenografts (NuSkin mice), H84T BanLec reduced VZV spread when administered subcutaneously prior to intraxenograft virus inoculation. This is the first demonstration of H84T BanLec effectiveness against DNA viruses. H84T BanLec may have additional unexplored activity against other, clinically relevant, glycosylated viruses.

New Options to Manage Epidermolysis Bullosa

RDEB is a genetic skin disorder involving COL7A1, the gene encoding C7, which is a component of the fibers anchoring the epidermis to the dermis. Affected patients (about 1.35 per million persons in the United States) experience lifelong painful itching, blistering, fibrosis, impaired healing, and scarring, with increased likelihood of infection and cancer. RCT involving those affected by RDEB are rare with limited sample sizes due to the low prevalence of this genetic disorder. Treatment with topical or systemic agents has not consistently improved patient outcomes. Therapies focused on replacing C7 using autologous bone marrow or keratinocyte grafts have been difficult, with high complication rates, and have been met with mixed success. Recent HSV-1 vector research4 led to development of HSV-1 vectors capable of transferring the COL7A1 coding sequence to keratinocytes and fibroblasts in vitro and to mice deficient in C7, as well as to RDEB human skin xenografts. This research offered new opportunities for gene therapy for patients with RDEB. In this final Evidence Corner, readers are invited to consider the implications of 2 small RCTs that suggest fruitful avenues for RDEB research and practice. The first study describes a pioneering phase 1 and 2 RCT of topical gene therapy for RDEB. The second study describes a small crossover RCT exploring the effect of topical calcipotriol (VD3) ointment on wound healing and pruritis in patients with RDEB.

Accelerated complete human skin architecture restoration after wounding by nanogenerator-driven electrostimulation

BackgroundElectrostimulation (ES) therapy for wound healing is limited in clinical use due to barriers such as cumbersome equipment and intermittent delivery of therapy.MethodsWe adapted a human skin xenograft model that can be used to directly examine the nanogenerator-driven ES (NG-ES) effects on human skin in vivo—an essential translational step toward clinical application of the NG-ES technique for wound healing.ResultsWe show that NG-ES leads to rapid wound closure with complete restoration of normal skin architecture within 7 days compared to more than 30 days in the literature. NG-ES accelerates the inflammatory phase of wound healing with more rapid resolution of neutrophils and macrophages and enhances wound bed perfusion with more robust neovascularization.ConclusionOur results support the translational evaluation and optimization of the NG-ES technology to deliver convenient, efficient wound healing therapy for use in human wounds.Graphic abstract

Efficacy of CRISPR-Cas9 CAR T-Cell Therapy vs. Blinatumomab in the Treatment of Acute Lymphoblastic Leukemia

Introduction: With immunotherapy drugs such as Blinatumomab (Blincyto), the current overall survival rate of relapsed/refractory B Lymphocyte Acute Lymphoblastic Leukemia (B-ALL) is 7.8 months in adults. However, with CRISPR-Cas9 gene editing, CAR T-cell therapy may extend survival. By knocking out T-cell receptors (TCRs) and HLA class I receptors on T-cells, CRISPR-Cas9 edited CAR T-cells could become a universal treatment alternative for B-ALL. This study compares the efficacy of CRISPR-Cas9 edited CAR T-cell therapy, a new era of CAR T-cell therapy, to the treatment of relapsed/ refractory B-ALL with Blinatumomab in mice. Methods: A cohort of 30 NSG mice receiving xenografts from an 18-24 year old patient with relapsed B-ALL will be randomly assigned to one of three groups, where they will receive treatment with: (1) mock transduced T-cells, (2) Blincyto, or (3) CRISPR-Cas9 edited TRAC- and B2M- knockout CAR T-cells. Another cohort of 30 NSG mice, receiving human skin xenografts from a healthy donor, will also be assigned to one of the groups and treated accordingly. Tumour shrinkage will be analyzed through in vivo antibody fluorescent imaging in the first cohort. Graft Vs Host Disease (GvHD) development will be assessed in the second cohort. Results: It is expected that mice treated with CRISPR-Cas9 edited CAR T-cells will be more effective at eliminating tumours. Compared to mice treated with Blincyto or mock-transfused T-cells, these mice will exhibit the highest overall response rates, complete response rates and tumour shrinkage rates, and the lowest relapse rates. It is also expected that these mice will not develop GvHD. Discussion: The use of CRISPR-Cas9 edited CAR T-cells in the treatment of B-ALL reveals a new facet to cancer therapeutics. The efficacy of this treatment will be demonstrated through greater tumour shrinkage rates and higher overall response rates than treatment with Blincyto, the current standard treatment drug for B-ALL. Conclusion: Current treatments involving Blinatumomab or conventional CAR T-cell therapy are expensive and therefore inaccessible to many. These results could demonstrate that CRISPR-Cas9 edited CAR T-cell therapy is viable as a safe, universal and more affordable alternative for relapsed/refractory B-ALL treatment.

Comparative intravital imaging of human and rodent malaria sporozoites reveals the skin is not a species‐specific barrier

Malaria infection starts with the injection of Plasmodium sporozoites into the host’s skin. Sporozoites are motile and move in the skin to find and enter blood vessels to be carried to the liver. Here, we present the first characterization of P. falciparum sporozoites in vivo, analyzing their motility in mouse skin and human skin xenografts and comparing their motility to two rodent malaria species. These data suggest that in contrast to the liver and blood stages, the skin is not a species‐specific barrier for Plasmodium. Indeed, P. falciparum sporozoites enter blood vessels in mouse skin at similar rates to the rodent malaria parasites. Furthermore, we demonstrate that antibodies targeting sporozoites significantly impact the motility of P. falciparum sporozoites in mouse skin. Though the sporozoite stage is a validated vaccine target, vaccine trials have been hampered by the lack of good animal models for human malaria parasites. Pre‐clinical screening of next‐generation vaccines would be significantly aided by the in vivo platform we describe here, expediting down‐selection of candidates prior to human vaccine trials.

The latency-associated transcript locus of herpes simplex virus 1 is a virulence determinant in human skin

Herpes simplex virus 1 (HSV-1) infects skin and mucosal epithelial cells and then travels along axons to establish latency in the neurones of sensory ganglia. Although viral gene expression is restricted during latency, the latency-associated transcript (LAT) locus encodes many RNAs, including a 2 kb intron known as the hallmark of HSV-1 latency. Here, we studied HSV-1 infection and the role of the LAT locus in human skin xenografts in vivo and in cultured explants. We sequenced the genomes of our stock of HSV-1 strain 17syn+ and seven derived viruses and found nonsynonymous mutations in many viral proteins that had no impact on skin infection. In contrast, deletions in the LAT locus severely impaired HSV-1 replication and lesion formation in skin. However, skin replication was not affected by impaired intron splicing. Moreover, although the LAT locus has been implicated in regulating gene expression in neurones, we observed only small changes in transcript levels that were unrelated to the growth defect in skin, suggesting that its functions in skin may be different from those in neurones. Thus, although the LAT locus was previously thought to be dispensable for lytic infection, we show that it is a determinant of HSV-1 virulence during lytic infection of human skin.

Research Techniques Made Simple: Mouse Bacterial Skin Infection Models for Immunity Research

Bacterial skin infections are a major societal health burden and are increasingly difficult to treat owing to the emergence of antibiotic-resistant strains such as community-acquired methicillin-resistant Staphylococcus aureus. Understanding the immunologic mechanisms that provide durable protection against skin infections has the potential to guide the development of immunotherapies and vaccines to engage the host immune response to combat these antibiotic-resistant strains. To this end, mouse skin infection models allow researchers to examine host immunity by investigating the timing, inoculum, route of infection and the causative bacterial species in different wild-type mouse backgrounds as well as in knockout, transgenic, and other types of genetically engineered mouse strains. To recapitulate the various types of human skin infections, many different mouse models have been developed. For example, four models frequently used in dermatological research are based on the route of infection, including (i) subcutaneous infection models, (ii) intradermal infection models, (iii) wound infection models, and (iv) epicutaneous infection models. In this article, we will describe these skin infection models in detail along with their advantages and limitations. In addition, we will discuss how humanized mouse models such as the human skin xenograft on immunocompromised mice might be used in bacterial skin infection research.

Human resident memory T cells hit the road

T Cells Skin and other barrier tissues are home to long-lived tissue-resident memory T cells (TRM) that function as sentries capable of rapidly responding to previously encountered antigens. Klicznik et al. investigated the relationship between human skin CD4+ TRM and human blood CD4+ memory T cells expressing skin-homing markers by comparing immunophenotypes, gene expression, and T cell receptor sequences. Shared phenotype, function, and clonotypes between blood and skin CLA+CD103+CD4+ T cells indicated that blood CD4+CLA+CD103+ T cells were previously skin resident. Analysis of immunodeficient mice bearing human skin xenografts revealed that human skin CD4+ TRM can exit the skin, reenter the circulation, and home to secondary human skin sites. Sci. Immunol. 4 , eaav8995 (2019).

Survival of human cadaver skin on severe combined immune deficiency pigs: Proof of concept.

Transplantation of human xenografts onto immunocompromised mice is a powerful research tool for studying wound healing. However, differences in healing between humans and mice and their small size limit this model. We determined whether human cadaver skin xenografts transplanted onto pigs with severe combined immune deficiency (SCID) would survive and not be rejected. Meshed (1:1.5), cryopreserved human cadaver skin was transplanted onto 10 partial thickness dermatome wounds in each of two normal domestic pigs and two SCID pigs. Autografts (n = 2/animal) from the four animals were used as controls. In normal pigs, all autografts were engrafted and healed with a minimal, if any, inflammation and scarring. All human xenografts were rejected by the normal pigs within 5-11 days and associated with an intense T-cell inflammatory response. In contrast, both autografts and xenografts were engrafted and survived the 28-day study in the SCID pigs with a minimal inflammation and no gross scarring.

AS2762900-00, a potent anti-human IL-23 receptor monoclonal antibody, prevents epidermal hyperplasia in a psoriatic human skin xenograft model

Interleukin (IL)-23 is thought to be critical in the pathogenesis of psoriasis, and anti-IL-23 monoclonal antibodies (mAbs) have been approved for the treatment of psoriasis. We speculated that an anti-IL-23 receptor mAb might have greater efficacy than an anti-IL-23 mAb in the treatment of local inflamed lesions with high IL-23 levels. We previously generated an anti-human IL-23 receptor mAb, AS2762900-00, which potently blocked IL-23-induced cell proliferation, regardless of the concentration of IL-23. Here, we evaluated the therapeutic potential of AS2762900-00 in the treatment of psoriasis. Compared with untreated control, AS2762900-00 significantly reduced the epidermal thickness of lesions in a clinically relevant psoriatic human skin xenograft model. The expression of inflammatory genes including genes downstream of IL-23 signaling in the lesion tended to be lower in the AS2762900-00 group than the untreated group, suggesting that the inhibitory effects of AS2762900-00 in the psoriatic human skin xenograft model might occur via blockade of IL-23 signaling pathways. Further, AS2762900-00 showed an inhibitory effect on signal transducer and activator of transcription 3 (STAT3) phosphorylation as a downstream signal of IL-23 receptor activation in whole blood from patients with psoriasis. We also confirmed that AS2762900-00 inhibited IL-23-induced STAT3 phosphorylation in a concentration-dependent manner using whole blood from healthy donors. These data suggest that AS2762900-00 is a promising drug candidate for the treatment of psoriasis. In addition, STAT3 phosphorylation in whole blood may be a useful biomarker for the evaluation of the pharmacodynamic effects of AS2762900-00 in healthy volunteers in clinical development.

Photobiomodulation (PBM) promotes angiogenesis in-vitro and in chick embryo chorioallantoic membrane model

The application of light in various therapeutic settings known as Photobiomodulation (PBM) is well established. Indications are the improvement of wound healing and tissue regeneration, scarring, and perfusion as well as pain therapy. Tissue perfusion is mandatory for successful wound healing. Nevertheless, there is a lack of mechanistic studies. We investigate the potential effect of PBM from light emitting diodes (LED) at 635 nm, 80 mW/cm2, 24 J/cm2 on angiogenesis in a two-part study: 1.) Investigation of the effect of PBM on the proliferation of endothelial cells and on vasculogenesis in a co-culture model of endothelial cells and stem cells. 2.) Investigation of the influence of PBM at chick egg chorioallantoic membrane (CAM) assays with fresh human skin xenografts. In both study phases, we observed a stimulating effect of PBM at 635 nm; in part 1: for proliferation of HUVEC (human umbilical vein endothelial cells) (25833 ± 12859 versus 63002 ± 35760 cells/well, p < 0.05, for cellular network formation (2.1 ± 2.1 versus 4.6 ± 3.5, p < 0.05) and for less cell compactness p = 0.01; in part 2: for the increase of number of vessel junctions per ROI (region of interest) (15.9 ± 2.6 versus 20.8 ± 5.4, p < 0.05). Our results suggest significant promotion of angiogenesis by PBM at 635 nm in vitro and in vivo.