Leo Hans Buehler

Improved survival of fulminant liver failure by transplantation of microencapsulated cryopreserved porcine hepatocytes in mice.

The aim of this study was to establish hepatocyte isolation in pigs, and to evaluate function of isolated hepatocytes after encapsulation, cryopreservation, and transplantation (Tx) in a mouse model of fulminant liver failure (FLF). After isolation, porcine hepatocytes were microencapsulated with alginate-poly-L-Lysine-alginate membranes and cryopreserved. In vitro, albumin production of free and encapsulated hepatocytes were measured by enzyme linked-immunoadsorbent assay. In vivo, encapsulated hepatocytes were transplanted into different groups of mice with FLF and the following experimental groups were performed: group 1, Tx of empty capsules; group 2, Tx of free primary porcine hepatocytes; group 3, Tx of fresh encapsulated porcine hepatocytes; group 4, Tx of cryopreserved encapsulated porcine hepatocytes. In vitro, fresh or cryopreserved encapsulated porcine hepatocytes showed a continuous decreasing metabolic function over 1 week (albumin and urea synthesis, drug catabolism). In vivo, groups 1 and 2 showed similar survival (18% and 25%, respectively, p > 0.05). In groups 3 and 4, Tx of fresh or cryopreserved encapsulated porcine hepatocytes significantly increased survival rate to 75% and 68%, respectively (p < 0.05). Primary porcine hepatocytes maintained metabolic functions after encapsulation and cryopreservation. In mice with FLF, Tx of encapsulated xenogeneic hepatocytes significantly improved survival. These results indicate that porcine hepatocytes can successfully be isolated, encapsulated, stored using cryopreservation, and transplanted into xenogeneic recipients with liver failure and sustain liver metabolic functions.

Robotic single-site cholecystectomy.

Minimally invasive approaches for cholecystectomy are evolving in a surge for the best possible clinical outcome for the patients. As one of the most recent developments, a robotic set of instrumentation to be used with the da Vinci Si Surgical System has been developed to overcome some of the technical challenges of manual single incision laparoscopy.

Decomplementation with cobra venom factor prolongs survival of xenografted islets in a rat to mouse model.

Although the involvement of complement in hyperacute rejection of xenotransplants is well recognized, its role in rejection of devascularized xenografts, such as pancreatic islets, is not completely understood. In this study, we investigated whether complement participates in the immunopathology of xeno‐islet transplantation in a concordant rat to mouse model. Rat pancreatic islets were implanted under the kidney capsule of normal and cobra venom factor (CVF)‐decomplementized diabetic C57BL/6 mice. Graft survival was monitored by blood glucose levels. Deposition of IgM and C3 on grafted islets in vivo or on isolated islets in vitro (after incubation with normal and decomplementized mouse serum), as well as CD4‐ and CD8‐positive leucocyte infiltration of grafts, was checked by immunohistochemistry. In addition, complement‐mediated cytotoxicity on rat islet cells was evaluated by a 3‐(4,5‐dimethythiazolyl)‐2.5‐diphenyl‐2H‐tetrazolium‐bromide (MTT) assay. A significant C3 deposition was found on grafted islets from the first day after transplantation in vivo, as well as on isolated islets after incubation with mouse serum in vitro. By MTT assay, complement‐mediated cytotoxicity for islet cells was found. Decomplementation by CVF decreased C3 deposition on either isolated or grafted islets, delayed CD4‐ and CD8‐positive leucocyte infiltration, led to significant inhibition of complement‐mediated cytotoxicity for islet cells, and prolonged graft survival (mean survival time 21·3 versus 8·5 days; P<0·01). Our results indicate that decomplementation can prolong the survival time of devascularized xenografts across concordant species. The deposition of complement on transplanted islets may contribute to xenograft rejection by direct cytotoxicity and by promoting leucocyte infiltration.

Monitoring of CD4+CD25highIL-7Rαhigh activated T Cells in Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES In humans, circulating CD4(+)CD25(high) T cells contain mainly regulatory T cells (Treg; FoxP3(+)IL-7Rα(low)), but a small subset is represented by activated effector T cells (Tact; FoxP3(-)IL-7Rα(high)). The balance between Tact and Treg may be important after transplantation. The aim of this study was first to analyze and correlate CD4(+)CD25(high) Tact and Treg with the clinical status of kidney transplant recipients and second to study prospectively the effect of two immunosuppressive regimens on Tact/Treg during the first year after transplantation. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS CD4(+)CD25(high) Tact and Treg were analyzed by flow cytometry, either retrospectively in 90 patients greater than 1 year after kidney transplantation (cross-sectional analysis) or prospectively in 35 patients receiving two immunosuppressive regimens after kidney transplantation (prospective analysis). RESULTS A higher proportion of Tact and a lower proportion of Treg were found in the majority of kidney recipients. In chronic humoral rejection, a strikingly higher proportion of Tact was present. A subgroup of stable recipients receiving calcineurin inhibitor-free immunosuppression (mycophenolate mofetil, azathioprine, or sirolimus) had Tact values that were similar to healthy individuals. In the prospective analysis, the proportion of Tact significantly increased in both immunosuppression groups during the first year after transplantation. CONCLUSIONS These data highlight distinct patterns in the proportion of circulating Tact depending on the clinical status of kidney recipients. Moreover, the prospective analysis demonstrated an increase in the proportion of Tact, regardless of the immunosuppressive regimen. The measurement of Tact, in addition to Treg, may become a useful immune monitoring tool after kidney transplantation.

Robotic general surgery: current practice, evidence, and perspective

BackgroundRobotic technology commenced to be adopted for the field of general surgery in the 1990s. Since then, the da Vinci surgical system (Intuitive Surgical Inc, Sunnyvale, CA, USA) has remained by far the most commonly used system in this domain. The da Vinci surgical system is a master–slave machine that offers three-dimensional vision, articulated instruments with seven degrees of freedom, and additional software features such as motion scaling and tremor filtration. The specific design allows hand–eye alignment with intuitive control of the minimally invasive instruments. As such, robotic surgery appears technologically superior when compared with laparoscopy by overcoming some of the technical limitations that are imposed on the surgeon by the conventional approach.PurposeThis article reviews the current literature and the perspective of robotic general surgery.ConclusionsWhile robotics has been applied to a wide range of general surgery procedures, its precise role in this field remains a subject of further research. Until now, only limited clinical evidence that could establish the use of robotics as the gold standard for procedures of general surgery has been created. While surgical robotics is still in its infancy with multiple novel systems currently under development and clinical trials in progress, the opportunities for this technology appear endless, and robotics should have a lasting impact to the field of general surgery.

Robotic versus open liver resections: A case-matched comparison

Most hepatic resections are currently performed using an open approach. Robotic surgery might enable the transition of these procedures to minimally invasive surgery.

Human islet allotransplantation with Basiliximab in type I diabetic patients with end-stage renal failure

ISLET allotransplantation is still an experimental procedure for treatment of type I diabetic patients with end-stage renal failure. There are a variety of immunologic and nonimmunologic factors determining the fate of an islet allograft. An analysis of the results reported to the International Islet Transplant Registry shows a benefit for anti–T-cell induction therapy in human islet allotransplantation. However, in the cyclosporine era, the routine use of antilymphocyte sera in renal allotransplantation has been abandoned by most centers. In light of the rather modest results presently obtained in type I diabetic patients with end-stage renal disease, it is questionable whether the increased risk for infectious and malignant disease secondary to administration of depleting antilymphocyte sera can be justified for a pancreatic islet allograft. Furthermore, new monoclonal anti–interleukin-2 receptor antibodies have shown efficacy in the prevention of acute kidney allograft rejection and seem to have fewer side effects than antilymphocyte sera. Moreover, results reported recently by the Edmonton group on islet transplantation alone in nonuremic type I diabetic patients suggest that depleting anti–T-cell induction therapy is not necessary. In this study, we tested whether the results of treatment with the monoclonal anti–interleukin-2 receptor antibody Basiliximab (Simulect, Novartis) are comparable to those obtained using a depleting antilymphocyte antibody for induction therapy in end-stage kidney disease patients receiving human islet allotransplantation for type I diabetes. PATIENTS AND METHODS

Robotic bariatric surgery: A general review of the current status

While conventional laparoscopy is the gold standard for almost all bariatric procedures, robotic assistance holds promise for facilitating complex surgeries and improving clinical outcomes. Since the report of the first robotic‐assisted bariatric procedure in 1999, numerous publications, including those reporting comparative trials and meta‐analyses across bariatric procedures with a focus on robotic assistance, can be found.

Models of xenotransplantation tolerance

Induction of tolerance is likely to be necessary for the achievement of successful xenotransplantation, because immune responses against xenogeneic tissues or organs are vigorous. Currently, protocols that allow prolongation of xenogeneic grafts in preclinical large animal models are not clinically applicable, because the immunosuppressive regimens induce significant morbidity and mortality. This review focuses on the progress that has been made in the strategies that aim to induce donor-specific xenogeneic tolerance, which are largely based on the transplantation of thymic tissue, the induction of molecular chimerism, and the induction of mixed hematopoietic cell chimerism.

Xenotransplantation: back to the future?

The field of xenotransplantation has fluctuated between great optimism and doubts over the last 50 years. The initial clinical attempts were extremely ambitious but faced technical and ethical issues that prompted the research community to go back to preclinical studies. Important players left the field due to perceived xenozoonotic risks and the lack of progress in pig‐to‐nonhuman‐primate transplant models. Initial apparently unsurmountable issues appear now to be possible to overcome due to progress of genetic engineering, allowing the generation of multiple‐xenoantigen knockout pigs that express human transgenes and the genomewide inactivation of porcine endogenous retroviruses. These important steps forward were made possible by new genome editing technologies, such as CRISPR/Cas9, allowing researchers to precisely remove or insert genes anywhere in the genome. An additional emerging perspective is the possibility of growing humanized organs in pigs using blastocyst complementation. This article summarizes the current advances in xenotransplantation research in nonhuman primates, and it describes the newly developed genome editing technology tools and interspecific organ generation.