Organ Repair Research Articles

Mechanical engineering of hair follicle regeneration by in situ bioprinting

Hair loss caused by various factors such as trauma, stress, and diseases hurts patient psychology and seriously affects patients' quality of life, but there is no effective method to control it. In situ bioprinting is a method for printing bioinks directly into defective sites according to the shape and characteristics of the defective tissue or organ to promote tissue or organ repair. In this study, we applied a 3D bioprinting machine in situ bioprinting of epidermal stem cells (Epi-SCs), skin-derived precursors (SKPs), and Matrigel into the wounds of nude mice to promote hair follicle regeneration based on their native microenvironment. The results showed successful regeneration of hair follicles and other skin appendages at 4 weeks after in situ bioprinting. Moreover, we confirmed that bioprinting only slightly decreased stem cell viability and maintained the stemness of the stem cells. These findings demonstrated a mechanical engineering method for hair follicle regeneration by in situ bioprinting which has potential in the clinic.

Liver repair of NAFLD patients following effortless exercise and the possible involvement of endogenous stem cells

Adipose tissue derived stem cells differentiate into mesenchymal stem cells (MSCs) and hepatocytes which are involved in anti-inflammatory, reparatory, and detoxification processes reinstating liver function. Aerobic, resistance and effortless workouts have been proven to be beneficial for patients with NAFLD, possibly due to stem cells released into the bloodstream from metabolized fat during exercise induced natural lipolysis. We analysed the serum levels of a number of variables such as ALT, AST, ALP, albumin, creatinine, bilirubin, triglycerides and CRP to determine if effortless exercise would demonstrate an improvement of the NAFLD condition that is substantially equivalent to liver repair documented after administering exogenous MSCs injections. We examined 10 prediabetic individuals with NAFLD, 5 males and 5 females 54-64 years of age, who received 15 treatments with an effortless exercise technology, originally invented at London University for obese individuals who have difficulty performing strenuous workouts, as well as those with limited mobility due to age or disease. The hypothesis was that the reduction of triglycerides and visceral adipose tissue (VAT) is accompanied by a natural release of adipose tissue contents into the bloodstream, supplying endogenous MSCs that differentiate into hepatocytes necessary for healthy liver functioning. Results demonstrated a statistically significant improvement of the NAFLD condition in ultrasonography reports along with optimal levels of ALT, AST, ALP, albumin, creatinine, bilirubin and CRP. Additional findings included a notable decrease in triglycerides, VLDL, BMI, VAT, and cortisol, accompanied by an increase in testosterone, BMR, and muscle mass. Our results replicated previous studies which documented a significant repair of hepatic steatosis in ultrasonography reports after using this effortless exercise regimen. The current clinical study strongly suggested the involvement of endogenous MSCs that are vital in organ repair. Reducing VLDL, VAT and triglycerides optimizes health, setting the conditions for the reparative process to commence. The possibility of endogenously released MSCs as a result of an exercise method is a new perspective with very little past research, therefore, more clinical studies focusing on this hypothesis are warranted. Demonstrating the production of endogenous MSCs via an exercise modality will introduce novel treatments for metabolic disorders without the adverse effects often observed after stem cells injections or invasive and trauma based procedures.

Kinetics of Pectin Biopolymer Facial Erosion Characterized by Fluorescent Tracer Microfluidics.

Pectin is a plant-derived heteropolysaccharide that has been implicated in drug development, tissue engineering, and visceral organ repair. Pectin demonstrates remarkable biostability in a variety of physiologic environments but is biodegradable in water. To understand the dynamics of pectin biodegradation in basic environments, we developed a microfluidics system that facilitated the quantitative comparison of pectin films exposed to facial erosion. Pectin biodegradation was assessed using fluorescein tracer embedded in pectin, trypan blue quenching of released fluorescence, and highly sensitive microfluorimetry. The microfluidic perfusate, delivered through 6 um-pore synthetic membrane interface, demonstrated nonlinear erosion of the pectin film; 75% of tracer was released in 28 h. The microfluidics system was used to identify potential modifiers of pectin erosion. The polyphenolic compound tannic acid, loaded into citrus pectin films, demonstrated a dose-dependent decrease in pectin erosion. Tannic acid had no detectable impact on the physical properties of citrus pectin including adhesivity and cohesion. In contrast, tannic acid weakened the burst strength and cohesion of pectins derived from soy bean and potato sources. We conclude that facial erosion may explain the biostability of citrus pectin on visceral organ surfaces as well as provide a useful method for identifying modifiers of citrus pectin biodegradation.

Normothermic liver machine perfusion as a dynamic platform for regenerative purposes: What does the future have in store for us?

Liver transplantation has become an immense success; nevertheless, far more recipients are registered on waiting lists than there are available donor livers for transplantation. High-risk, extended criteria donor livers are increasingly used to reduce the discrepancy between organ demand and supply. Especially for high-risk livers, dynamic preservation using machine perfusion can decrease post-transplantation complications and may increase donor liver utilisation by improving graft quality and enabling viability testing before transplantation. To further increase the availability of donor livers suitable for transplantation, new strategies are required that make it possible to use organs that are initially too damaged to be transplanted. With the current progress in experimental liver transplantation research, (long-term) normothermic machine perfusion may be used in the future as a dynamic platform for regenerative medicine approaches, enabling repair and regeneration of injured donor livers. Currently explored therapeutics such as defatting cocktails, RNA interference, senolytics, and stem cell therapy may assist in the repair and/or regeneration of injured livers before transplantation. This review will provide a forecast of the future utility of normothermic machine perfusion in decreasing the imbalance between donor liver demand and supply by enabling the repair and regeneration of damaged donor livers.

TGF-β1/Smad3 upregulates UCA1 to promote liver fibrosis through DKK1 and miR18a.

TGF-β1 is the strongest cytokine known to promote liver fibrosis. It has been previously demonstrated that the activation of TGF-β1 initiates a temporary collagen accumulation program, which is important for wound repair in several organs. Furthermore, temporary extracellular matrix enhancement often leads to progressive fibrosis, which is accountable for cases of severe morbidity and mortality worldwide. However, its action mechanism has not been fully explored. It was previously reported that UCA1 could promote its occurrence and development in various tumors. Importantly, it was reported that TGF-β1 could activate the expression of UCA1 in liver cancer, gastric cancer, and breast cancer. However, the role of UCA1 in organ fibrosis, including liver fibrosis, remains unreported. The present study reported for the first time that TGF-β1/Smad3 could promote liver fibrosis by upregulating UCA1, which further affected DKK1 and collagen, such as COL1A1, COL1A2, and COL3A1. Meanwhile, UCA1 could competitively bind with miR18a to stabilize Smad3 to constitute a positive feedback pathway, which played a significant role in the promotion of liver fibrosis. Altogether, the present study provides a theoretical basis for devising promising treatment strategies for liver fibrosis. KEY MESSAGES : UCA1 was found to promote the progression of liver fibrosis in vitro. UCA1 is regulated by TGF-β1 and promotes liver fibrosis through the canonical Smad pathway. UCA1 can competitively bind with miR18a, promote liver fibrosis by stabilizing Smad3, and form a UCA1-miR18a/Smad3 positive feedback. UCA1 binds EZH2 to inhibit the DKK1 expression and promote liver fibrosis.

Clinical characteristics and diagnosis and treatment strategies of patients with severe traumatic aortic injury

Objective: To investigate the clinical characteristics and diagnosis and treatment strategies of patients with severe traumatic aortic injury (TAI). Methods: A total of 25 patients with TAI, who hospitalized in our hospital between August 2005 to March 2021 and underwent thoracic aortic endovascular repair (TEVAR), were included in this retrospective study. According to the time from admission to TEVAR, the patients were divided into emergency TEVAR group (14 cases, TEVAR within 24 h of admission) and elective TEVAR group (11 cases, patients underwent surgery or fracture reduction and fixation first for serious injuries and then underwent TEVAR more than 24 h after admission). The general clinical data of patients, injury severity score (ISS), time from admission to intervention, total hospital stay, the proportion of closed chest drainage and the proportion of abdominal organ repair were obtained and compared. Clinical follow-up and 1-year postoperative aortic computed tomography angiography (CTA) were performed on the patients. Death, the occurrence of aortic adverse events and injury recovery were followed up and recorded. Results: The mean age of these 25 TAI patients was (41.4±14.4) years, 20 patients were males (80.0%). 21 patients (84.0%) had persistent chest and back pain, 17 (68.0%) had pleural effusion and 5 (20.0%) had mediastinal hematoma. The injury severity score (ISS) was significantly higher in the elective TEVAR group than in the emergency TEVAR group (24.9±14.4 vs. 35.5±9.3, P=0.044). The time from admission to intervention ((1.0±0.0) d vs. (3.4±0.9) d, P<0.001], the time from admission to TEVAR ((1.0±0.0) d vs. (11.5±13.8) d, P=0.030) and total hospital stay ((6.1±2.3) d vs. (26.8±7.7) d, P<0.001) were significantly longer in elective TEVAR group than in emergency TEVAR group. The proportion of thoracic closed drainage was significantly lower in the elective TEVAR group than in the emergency TEVAR group (9 (64.3%) vs. 2 (18.2%), P=0.042). The proportion of abdominal organ repair was significantly higher than in the emergency TEVAR group (0 vs. 4 (36.4%), P=0.026). All of 25 patients were discharged alive and followed up for (84.0±30.5) months. All patients survived and completed 1-year postoperation CTA. There were no aortic adverse events occurred, and no complications after surgery, and the fractures and organ injuries healed well. Conclusions: The clinical characteristics of severe TAI are acute multi-injuries combined with persistent chest and/or back pain, pleural effusion, and mediastinal hematoma. Timely diagnosis and treatment are important factors for the outcome. The treatment strategy for multi-injuries should give priority to dealing with life-threatening injuries. TEVAR is the primary treatment strategy for severe TAI and is related to satisfactory outcomes.

Rationally Designed Anisotropic and Auxetic Hydrogel Patches for Adaptation to Dynamic Organs

AbstractCurrent hydrogel or fabric patches for organ repair are generally not designed to conform to the complex mechanics of dynamic organs such as the lung or heart. This study presents a new, biocompatible and bilayered, hydrogel‐based patch platform, consisting of a non‐fouling top layer and a cell adhesive bottom layer, that caters to the anisotropic and auxetic characteristics of dynamic organs. Integrated computational and experimental studies are used to screen over 116 unique anisotropic‐auxetic architectures to establish design rules and tailor the patches to a broad range of target organ dynamics. The patches are then validated in ex vivo and in vivo animal models, where the auxetic patches outperformed non‐auxetic patches in conforming to the volumetric dilation‐contraction of dynamic organs. To further expand the functionality of the auxetic patch platform, novel hole‐filling auxetic patches are developed. These hole‐filling patches composited with fibrin robustly reduce pulmonary air leakage in rats with surgically induced lung puncture. This is the first demonstration of a rational patch design framework that features both anisotropic and auxetic properties to cater to a wide range of organ dynamics. These studies pave the way for future clinical development of biomimetic patches.

FRaeppli: a multispectral imaging toolbox for cell tracing and dense tissue analysis in zebrafish.

Visualizing cell shapes and interactions of differentiating cells is instrumental for understanding organ development and repair. Across species, strategies for stochastic multicolour labelling have greatly facilitated in vivo cell tracking and mapping neuronal connectivity. Yet integrating multi-fluorophore information into the context of developing zebrafish tissues is challenging given their cytoplasmic localization and spectral incompatibility with common fluorescent markers. Inspired by Drosophila Raeppli, we developed FRaeppli (Fish-Raeppli) by expressing bright membrane- or nuclear-targeted fluorescent proteins for efficient cell shape analysis and tracking. High spatiotemporal activation flexibility is provided by the Gal4/UAS system together with Cre/lox and/or PhiC31 integrase. The distinct spectra of the FRaeppli fluorescent proteins allow simultaneous imaging with GFP and infrared subcellular reporters or tissue landmarks. We demonstrate the suitability of FRaeppli for live imaging of complex internal organs, such as the liver, and have tailored hyperspectral protocols for time-efficient acquisition. Combining FRaeppli with polarity markers revealed previously unknown canalicular topologies between differentiating hepatocytes, reminiscent of the mammalian liver, suggesting common developmental mechanisms. The multispectral FRaeppli toolbox thus enables the comprehensive analysis of intricate cellular morphologies, topologies and lineages at single-cell resolution in zebrafish.

Peptide Biomaterials for Tissue Regeneration.

Expanding the toolbox of therapeutic materials for soft tissue and organ repair has become a critical component of tissue engineering. While animal- and plant-derived proteins are the foundation for developing biomimetic tissue constructs, using peptides as either constituents or frameworks for the materials has gained increasing momentum in recent years. This mini review discusses recent advances in peptide-based biomaterials’ design and application. We also discuss some of the future challenges posed and opportunities opened by peptide-based structures in the field of tissue engineering and regenerative medicine.

Obtaining a freeze-dried biomaterial for skin regeneration: Reinforcement of the microstructure through the use of crosslinkers and in vivo application

Scaffolds are one of the emerging alternatives to the traditional techniques of tissue and organ repair and regeneration. They offer the necessary support to the healthy formation of new tissues. Highly porous and interconnected scaffolds for skin regeneration were manufactured and studied with two types of crosslinking, genipin and glutaraldehyde. Two accessible biopolymers, chitosan and gelatin, were used together as matrix and were incorporated with snail mucus and aloe vera like additives. The microstructure and thermal properties analysis determined that the best crosslinker was glutaraldehyde, presenting a more homogeneous range of pore sizes, uniform distribution of the porous structure and higher denaturation temperatures showing a greater degree of crosslinking and stabilization. Thus, in vivo studies were conducted with the implantation of these scaffolds in mice after causing a burn wound. The addition of Aloe vera in the scaffolds is highlighted, apparently the large number of glycoproteins present in Aloe vera were able to integrate well into the scaffolds. Their diffusion towards the damaged tissue allowed accelerated healing and injury reduction. The material made with aloe vera crosslinked with glutaraldehyde showed promising results in accelerating the healing process in vivo studies, suggesting a great skin substitute for wound healing applications.

Cell death and ischemia-reperfusion injury in lung transplantation.

Lung transplantation is the most effective therapy for patients with end-stage lung disease. However, concern of donor lung damage and ischemia-reperfusion induced lung injury limits the use of "marginal" donor lungs. Recent transcriptomic studies have demonstrated that the enrichment of gene-clusters related to cell death and inflammation are the most profound signals during ischemia-reperfusion in human lung transplants. Herein, we focus on the relationship between inflammation and programmed cell death, especially necroptosis, mitochondrial permeability transition-initiated regulated necrosis, pyroptosis, ferroptosis, and autophagic cell death. Cell death-related molecules have been tested as potential biomarkers for donor lung assessment. Inhibitors for various types of cell death have been explored as therapeutics for ischemia reperfusion injury in lung transplantation. A deeper understanding of these mechanisms may help to improve donor management, organ preservation, prevention and treatment of primary graft dysfunction during and post transplantation. Moreover, evaluation and treatment of cell death and inflammation during ex vivo lung perfusion may be a game changer in donor organ management, assessment, repair, and reconditioning.

Supporting military maintenance and repair with additive manufacturing

Abstract The purpose of the study is to explore whether Additive Manufacturing (AM) can support the military maintenance and repair of combat troops at isolated tactical level maintenance sites. The study also sought an explanation as to how AM could be organised in military logistics. The subject was approached from a systemic perspective. A system dynamics modelling was used as an impact assessment method. When selecting the parameters used in the model, the 3D printing data of the spare parts printed on the MTLB armoured personnel carrier (APC) were utilised. With simulation, we identified several key nodes for replacing or enhancing conventional military logistics with an AM added supply chain. As a result of the study, it was identified that by adding metal AM to the mechanised battalion organic maintenance and repair at the field level, it can produce spare parts whose use will improve APC recovery in the event of failure. We found that the relatively slow production speed of AM is the most influential factor in the use of the method. This study introduces a new perspective on reviewing the potential of AM in military logistics.

Photo-Crosslinkable Hydrogels for 3D Bioprinting in the Repair of Osteochondral Defects: A Review of Present Applications and Future Perspectives.

An osteochondral defect is a common and frequent disease in orthopedics and treatment effects are not good, which can be harmful to patients. Hydrogels have been applied in the repair of cartilage defects. Many studies have reported that hydrogels can effectively repair osteochondral defects through loaded cells or non-loaded cells. As a new type of hydrogel, photo-crosslinked hydrogel has been widely applied in more and more fields. Meanwhile, 3D bioprinting serves as an attractive platform to fabricate customized tissue-engineered substitutes from biomaterials and cells for the repair or replacement of injured tissues and organs. Although photo-crosslinkable hydrogel-based 3D bioprinting has some advantages for repairing bone cartilage defects, it also has some disadvantages. Our aim of this paper is to review the current status and prospect of photo-crosslinkable hydrogel-based 3D bioprinting for repairing osteochondral defects.

Adipose tissue in bone regeneration - stem cell source and beyond.

Adipose tissue (AT) is recognized as a complex organ involved in major home-ostatic body functions, such as food intake, energy balance, immunomodulation, development and growth, and functioning of the reproductive organs. The role of AT in tissue and organ homeostasis, repair and regeneration is increasingly recognized. Different AT compartments (white AT, brown AT and bone marrow AT) and their interrelation with bone metabolism will be presented. AT-derived stem cell populations - adipose-derived mesenchymal stem cells and pluripotent-like stem cells. Multilineage differentiating stress-enduring and dedifferentiated fat cells can be obtained in relatively high quantities compared to other sources. Their role in different strategies of bone and fracture healing tissue engineering and cell therapy will be described. The current use of AT- or AT-derived stem cell populations for fracture healing and bone regenerative strategies will be presented, as well as major challenges in furthering bone regenerative strategies to clinical settings.

Probing Notch1-Dll4 signaling in regulating osteogenic differentiation of human mesenchymal stem cells using single cell nanobiosensor

Human mesenchymal stem cells (hMSCs) have great potential in cell-based therapies for tissue engineering and regenerative medicine due to their self-renewal and multipotent properties. Recent studies indicate that Notch1-Dll4 signaling is an important pathway in regulating osteogenic differentiation of hMSCs. However, the fundamental mechanisms that govern osteogenic differentiation are poorly understood due to a lack of effective tools to detect gene expression at single cell level. Here, we established a double-stranded locked nucleic acid (LNA)/DNA (LNA/DNA) nanobiosensor for gene expression analysis in single hMSC in both 2D and 3D microenvironments. We first characterized this LNA/DNA nanobiosensor and demonstrated the Dll4 mRNA expression dynamics in hMSCs during osteogenic differentiation. By incorporating this nanobiosensor with live hMSCs imaging during osteogenic induction, we performed dynamic tracking of hMSCs differentiation and Dll4 mRNA gene expression profiles of individual hMSC during osteogenic induction. Our results showed the dynamic expression profile of Dll4 during osteogenesis, indicating the heterogeneity of hMSCs during this dynamic process. We further investigated the role of Notch1-Dll4 signaling in regulating hMSCs during osteogenic differentiation. Pharmacological perturbation is applied to disrupt Notch1-Dll4 signaling to investigate the molecular mechanisms that govern osteogenic differentiation. In addition, the effects of Notch1-Dll4 signaling on hMSCs spheroids differentiation were also investigated. Our results provide convincing evidence supporting that Notch1-Dll4 signaling is involved in regulating hMSCs osteogenic differentiation. Specifically, Notch1-Dll4 signaling is active during osteogenic differentiation. Our results also showed that Dll4 is a molecular signature of differentiated hMSCs during osteogenic induction. Notch inhibition mediated osteogenic differentiation with reduced Alkaline Phosphatase (ALP) activity. Lastly, we elucidated the role of Notch1-Dll4 signaling during osteogenic differentiation in a 3D spheroid model. Our results showed that Notch1-Dll4 signaling is required and activated during osteogenic differentiation in hMSCs spheroids. Inhibition of Notch1-Dll4 signaling mediated osteogenic differentiation and enhanced hMSCs proliferation, with increased spheroid sizes. Taken together, the capability of LNA/DNA nanobiosensor to probe gene expression dynamics during osteogenesis, combined with the engineered 2D/3D microenvironment, enables us to study in detail the role of Notch1-Dll4 signaling in regulating osteogenesis in 2D and 3D microenvironment. These findings will provide new insights to improve cell-based therapies and organ repair techniques.

Biomarkers of heatstroke-induced organ injury and repair.

What is the topic of this review? The status and potential role of novel biological markers (biomarkers) that can help identify the patients at risk of organ injury or long-term complications following heatstroke. What advances does it highlight? Numerous biomarkers were identified related to many aspects of generalized heatstroke-induced cellular injury and tissue damage, and heatstroke-provoked cardiovascular, renal, cerebral, intestinal and skeletal muscle injury. No novel biomarkers were identified for liver or lung injury. Classic and exertional heatstroke cause acute injury and damage across numerous organ systems. Moreover, heatstroke survivors may sustain long-term neurological, cardiovascular and renal complications with a persistent risk of death. In this context, biomarkers, defined as biological samples obtained from heatstroke patients, are needed to detect early organ injury, and predict outcomes to develop novel organ preservation therapeutic strategies. This narrative review provides preliminary insights that will guide the development and future utilization of these biomarkers. To this end, we have identified numerous biomarkers of widespread heatstroke-associated cellular injury, tissue damage and repair (extracellular heat shock proteins 72 and 60, high mobility group box protein 1, histone H3, and interleukin-1α), and other organ-specific biomarkers including those related to the cardiovascular system (cardiac troponin I, endothelium-derived factors, circulation endothelial cells, adhesion molecules, thrombomodulin and von Willebrand factor antigen), the kidneys (plasma and urinary neutrophil gelatinase-associated lipocalin), the intestines (intestinal fatty acid-binding protein 2), the brain (serum S100β and neuron-specific enolase) and skeletal muscle (creatine kinase, myoglobin). No specific biomarkers have been identified so far for liver or lung injury in heatstroke. Before translating the identified biomarkers into clinical practice, additional preclinical and clinical prospective studies are required to further understand their clinical utility, particularly for the biomarkers related to long-term post-heatstroke health outcomes.

Self-Sustained Regulation or Self-Perpetuating Dysregulation: ROS-dependent HIF-YAP-Notch Signaling as a Double-Edged Sword on Stem Cell Physiology and Tumorigenesis.

Organ development, homeostasis, and repair often rely on bidirectional, self-organized cell-niche interactions, through which cells select cell fate, such as stem cell self-renewal and differentiation. The niche contains multiplexed chemical and mechanical factors. How cells interpret niche structural information such as the 3D topology of organs and integrate with multiplexed mechano-chemical signals is an open and active research field. Among all the niche factors, reactive oxygen species (ROS) have recently gained growing interest. Once considered harmful, ROS are now recognized as an important niche factor in the regulation of tissue mechanics and topology through, for example, the HIF-YAP-Notch signaling pathways. These pathways are not only involved in the regulation of stem cell physiology but also associated with inflammation, neurological disorder, aging, tumorigenesis, and the regulation of the immune checkpoint molecule PD-L1. Positive feedback circuits have been identified in the interplay of ROS and HIF-YAP-Notch signaling, leading to the possibility that under aberrant conditions, self-organized, ROS-dependent physiological regulations can be switched to self-perpetuating dysregulation, making ROS a double-edged sword at the interface of stem cell physiology and tumorigenesis. In this review, we discuss the recent findings on how ROS and tissue mechanics affect YAP-HIF-Notch-PD-L1 signaling, hoping that the knowledge can be used to design strategies for stem cell-based and ROS-targeting therapy and tissue engineering.

Recent Development of Conductive Hydrogels for Tissue Engineering: Review and Perspective.

In recent years, tissue engineering techniques have been rapidly developed and offer a new therapeutic approach to organ or tissue damage repair. However, most of tissue engineering scaffolds are nonconductive and cannot establish effective electrical coupling with tissue for the electroactive tissues. Electroconductive hydrogels (ECHs) have received increasing attention in tissue engineering owing to their electroconductivity, biocompatibility, and high water content. In vitro, ECHs can not only promote the communication of electrical signals between cells, but also mediate the adhesion, proliferation, migration, and differentiation of different kinds of cells. In vivo, ECHs can transmit the electric signal to electroactive tissues and activate bioelectrical signaling pathways to promote tissue repair. As a result, implanting ECHs into damaged tissues can effectively reconstruct physiological functions related to electrical conduction. In this review, an overview about the classifications and the fabrication methods of ECHs is first presented. And then, the applications of ECHs in tissue engineering, including cardiac, nerve, skin, and skeletal muscle tissue, are highlighted. At last, some rational guidelines for designing ECHs toward clinical applications are provided.

Normothermic ex situ pancreas perfusion for the preservation of porcine pancreas grafts

Pancreas transplantation improves and extends the life of patients with insulin-dependent diabetes. Pancreata from extended criteria donors have been increasingly used due to the scarcity of available grafts. Normothermic ex situ pancreas perfusion (NESPP) can keep grafts metabolically active, potentially allowing for assessment and organ repair, and could improve outcomes of marginal grafts. A novel NESPP technique was developed and tested. Porcine pancreata were removed after a short period of warm ischemia and subjected to 6 h of NESPP. Perfusion parameters, potential graft assessment markers and graft injury were measured. Next, pancreata subjected to 3 h of NESPP were transplanted and animals were followed for up to 3 days. Graft function and injury post-transplantation were evaluated. Using this novel system of perfusion, pancreata were perfused for an extended period of time with minimal edema. Histology at the end of perfusion showed intact islet cells with only mild signs of tissue injury. NESPP transplanted grafts showed immediate function after transplantation, with glucose levels in normal range. NESPP maintains a physiologic environment and excellent graft function without causing significant graft injury. Porcine pancreas transplantation is feasible and allows for in vivo graft assessment of pancreas function and injury after NESPP.

Obesity in Angiogenesis and Lung Regeneration

Obesity is associated with impairment of wound healing and tissue regeneration. Angiogenesis, the formation of new blood capillaries, plays a key role in organ regeneration and repair. We and other groups have reported that inhibition of angiogenesis attenuates lung growth after unilateral pneumonectomy (PNX) and that obesity is accompanied by endothelial cell dysfunction. The aim of this project is to investigate the effects of obesity on post‐PNX lung vascular and alveolar morphogenesis. We have found that post‐PNX regenerative lung growth is inhibited in Lepob/ob obese mice compared to Lepob/+ mice. The levels of the major angiogenic factor, vascular endothelial growth factor (VEGF) are higher in the serum and the lung tissue collected from post‐PNX mice compared to those from sham‐operated control mice, while these effects are attenuated in post‐PNX Lepob/ob mice. The levels of adiponectin, one of the adipokines that exhibits pro‐angiogenic and vascular protective properties, increase in the remaining mouse lungs after unilateral PNX, while these effects are attenuated in Lepob/ob obese mice. Regenerative lung growth, vascular and alveolar morphogenesis, and VEGF levels in the post‐PNX mouse lungs are inhibited in adiponectin knockout mice. These results suggest that obesity inhibits post‐PNX regenerative lung growth through adiponectin‐VEGF signaling. Modulation of adiponectin‐VEGF signaling may be the efficient strategy to restore lung regeneration and repair in obese people.