Efficacy and Safety of Viable Selective Germline Genome Edited Pigs Skin Xenotransplants in Patients with Thermal Burns

Background: Rapid closure of open wound, either temporarily or perpetually, is recognized as the standard of care in patients with thermal burns. Human cadaveric allograft and simple genetically modified porcine xenografts are not able to provide enough durable time for extensively burned patients. A selective germline genome edited pig (SGGEP) skin xenograft, Xeno X skin, would be a valuable candidate to the clinical options. Methods: In an ongoing investigator-initiated clinical trial in patients with thermal burns, the efficacy and safety of cryopreserved Xeno X skin grafts of SGGEP for burned patients were evaluated. Each patient received surgical grafting with a skin xenotransplant and wild type pig extracellular matrix (wpECM) in a side-by-side manner for in-situ comparison. The primary outcome measures of xeno-skin grafts included Xeno X skin safety and tolerability, as well as the quality and duration of temporary barrier function yielded by Xeno X skin grafts (as determined by Baux score). Seven parameters included in the analysis were vascularization, pigmentation, thickness, relief, pliability, surface area and the overall opinion, with each calculated on an independent 0-10 scale. Results: A total of 16 burned patients completed the trial. All the patients tolerated Xeno X skin grafts well and no advent events were observed. In all cases, Xeno X skin grafts were vascularized and fully adherent, they also exhibited better overall outcomes than those of wpECM. Xeno X skin grafts survived for at least 25 days without a need of any immunosuppressive drug, well consistent with our earlier preclinical studies in non- human primates. Conclusion: Xeno X skin grafts of SGGEP did not incur any signs of local and systemic safety issues, and in the meanwhile provided a high quality and long duration of temporary barrier function for burned patients. This is a major milestone in the xenotransplant field, indicating that genome-edited organ xenotransplant has become a clinical reality.

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

Background Electrostimulation (ES) therapy for wound healing is limited in clinical use due to barriers such as cumbersome equipment and intermittent delivery of therapy. Methods We 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. Results We 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. Conclusion Our 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

Innovative Burn Treatment Using Tilapia Skin as a Xenograft: A Phase II Randomized Controlled Trial

Skin substitutes are considered a useful alternative for occlusive dressings in the treatment of superficial burns as they reduce the frequency of dressing replacement. This phase II randomized controlled trial aimed to evaluate the efficacy of Nile tilapia (Oreochromis niloticus) skin as an occlusive xenograft dressing for the treatment of burn wounds in humans. In order to assess the use of tilapia skin, the following variables were evaluated: number of days for wound healing, the number of times the occlusive dressing was changed, use of anesthetics or analgesics, pain assessment using the Visual Analogue Scale, and evaluation of burn improvement on the day of dressing removal. In total, 62 participants completed the study. It was found that in participants treated with tilapia skin, complete reepithelialization occurred in significantly fewer days; reported pain intensity was lower (study arms B and C), the amount of anesthetics/analgesics required was lower (study arms B and C), and the necessity of dressing changes was significantly reduced in comparison with volunteers treated with silver sulfadiazine. In our study, the tilapia skin xenograft showed good efficacy as an occlusive biological dressing for burn wound treatment in humans.

Quantitative intravital imaging of Plasmodium falciparum sporozoites: A novel platform to test malaria intervention strategies

Malaria infection starts with the injection of motile Plasmodium sporozoites into the host’s skin during a mosquito bite. Previous studies using the rodent malaria model indicate that the dermal inoculation site may be where sporozoites are most vulnerable to antibodies, yet, functional in vivo assays with human malaria parasites are lacking. Here, we present the first characterization of P. falciparum sporozoites in the skin, comparing their motility to two rodent malaria species and investigating whether the environment of its natural host influences P. falciparum sporozoite motility using a human skin xenograft model. The combined data suggest that in contrast to the liver and blood stages, the skin is not a species-specific barrier for Plasmodium. We observe that P. falciparum sporozoites inoculated into mouse skin move with similar speed, displacement and duration, and enter blood vessels in similar numbers as the rodent parasites. Thus, interventions targeting P. falciparum sporozoite migration can be tested in the murine dermis. Importantly, to streamline quantification of sporozoite motility, we developed a toolbox allowing for automated detection and tracking of sporozoites in intravital microscopy videos. This establishes a platform to test vaccine candidates, immunization protocols, monoclonal antibodies and drug candidates for their impact on human malaria sporozoites in vivo. Screening of intervention strategies for in vivo efficacy against Pf sporozoites using this new platform will have the potential to validate targets prior to expensive clinical trials.

Human CD4+CD103+ cutaneous resident memory T cells are found in the circulation of healthy individuals

Tissue-resident memory T cells (TRM) persist locally in nonlymphoid tissues where they provide frontline defense against recurring insults. TRM at barrier surfaces express the markers CD103 and/or CD69, which function to retain them in epithelial tissues. In humans, neither the long-term migratory behavior of TRM nor their ability to reenter the circulation and potentially migrate to distant tissue sites has been investigated. Using tissue explant cultures, we found that CD4+CD69+CD103+ TRM in human skin can down-regulate CD69 and exit the tissue. In addition, we identified a skin-tropic CD4+CD69−CD103+ population in human lymph and blood that is transcriptionally, functionally, and clonally related to the CD4+CD69+CD103+ TRM population in the skin. Using a skin xenograft model, we confirmed that a fraction of the human cutaneous CD4+CD103+ TRM population can reenter circulation and migrate to secondary human skin sites where they reassume a TRM phenotype. Thus, our data challenge current concepts regarding the strict tissue compartmentalization of CD4+ T cell memory in humans.

Deoxypodophyllotoxin Exerts Anti-Cancer Effects on Colorectal Cancer Cells Through Induction of Apoptosis and Suppression of Tumorigenesis

Deoxypodophyllotoxin (DPT) is a cyclolignan compound that exerts anti-cancer effects against various types of cancers. DPT induces apoptosis and inhibits the growth of breast, brain, prostate, gastric, lung, and cervical tumors. In this study, we sought to determine the effect of DPT on cell proliferation, apoptosis, motility, and tumorigenesis of three colorectal cancer (CRC) cell lines: HT29, DLD1, and Caco2. DPT inhibited the proliferation of these cells. Specifically, the compound-induced mitotic arrest in CRC cells by destabilizing microtubules and activating the mitochondrial apoptotic pathway via regulation of B-cell lymphoma 2 (Bcl-2) family proteins (increasing Bcl-2 associated X (BAX) and decreasing B-cell lymphoma-extra-large (Bcl-xL)) ultimately led to caspase-mediated apoptosis. In addition, DPT inhibited tumorigenesis in vitro, and in vivo skin xenograft experiments revealed that DPT significantly decreased tumor size and tumor weight. Taken together, our results suggest DPT to be a potent compound that is suitable for further exploration as a novel chemotherapeutic for human CRC.

Human CD4+CD103+ cutaneous resident memory T cells are found in the circulation of healthy subjects

Tissue-resident memory T cells (TRM) persist locally in non-lymphoid tissues where they provide front-line defense against recurring insults. TRM at barrier surfaces express the markers CD103 and/or CD69 which function to retain them in epithelial tissues. In humans, neither the long-term migratory behavior of TRM nor their ability to re-enter the circulation and potentially migrate to distant tissue sites have been investigated. Using tissue explant cultures, we found that CD4+CD69+CD103+ TRM in human skin can downregulate CD69 and exit the tissue.Additionally, we identified a skin-tropic CD4+CD69−CD103+ population in human lymph and blood that is transcriptionally, functionally and clonally related to the CD4+CD69+CD103+ TRM population in the skin. Using a skin xenograft model, we confirmed that a fraction of the human cutaneous CD4+CD103+ TRM population can re-enter circulation, and migrate to secondary human skin sites where they re-assume a TRM phenotype. Thus, our data challenge current concepts regarding the strict tissue compartmentalization of CD4+ T cell memory in humans.One Sentence SummaryHuman CD4+CD103+ cutaneous resident memory T cells are found in the circulation of healthy subjects, and these cells can seed distant skin sites.