Pierre Gianello

Inadequate detection of accessory spleens and splenosis with laparoscopic splenectomy. A shortcoming of the laparoscopic approach in hematologic diseases

AbstractBackground: The ultimate goal of surgery for hematological disorders is the complete removal of both the spleen and accessory spleens in order to avoid recurrence of the disease. Whereas splenectomy by open surgery provides excellent results, the validity of laparoscopic splenectomy in this regard remains unknown. Objective: The purpose of this study was to evaluate the detection of accessory spleens during laparoscopic splenectomy for hematologic diseases. Methods: We therefore evaluated the pre-, intra-, and postoperative detection of accessory spleens in a consecutive series of 18 patients treated by elective laparoscopic splenectomy for hematological diseases by using computed tomography (CT) and denatured red blood cell scintigraphy (DRBCS). Results: Preoperative CT, DRBCS, and laparoscopic exploration detected 25%, 25%, and 75% of accessory spleens, respectively. At time of laparoscopy, 16 accessory spleens were detected in seven of the 18 patients (41%). In two patients (11%), laparoscopic exploration failed to detect accessory spleens, whereas preoperative CT (one case) and DRBCS (one case) did reveal them. Postoperatively, during a mean follow-up of 28 months (median, 24; range, 12–44 months), nine patients (50%) showed persistence of splenic tissue by DRBCS, and three of them had signs of disease recurrence. Conclusions: This prospective clinical study suggests that elective laparoscopic surgery for hematological diseases does not allow complete detection of accessory spleens. Moreover, after such a laparoscopic approach, residual splenic tissue is detectable in half of the patients during the follow-up.

Low molecular weight dextran sulfate: a strong candidate drug to block IBMIR in clinical islet transplantation.

The instant blood‐mediated inflammatory reaction (IBMIR) is triggered in clinical islet transplantation when human pancreatic islets come in contact with blood and may explain the initial tissue loss associated with this procedure. Low molecular weight dextran sulfate (LMW‐DS; MM 5000), today available for clinical use, inhibits both complement and coagulation activation. In a tubing loop model, LMW‐DS at concentrations ranging from 0.01 to 1 g/L showed a dose‐dependent inhibition of IBMIR with an inhibition of coagulation and complement activation and less consumption of platelets and other blood cells. In blood or plasma APTT was demonstrated to be an excellent method for monitoring the LMW‐DS concentration both in vitro and in vivo in a nonhuman primate model. The toxicity was assessed using a glucose challenge test and the pharmacokinetics was tested in the nonhuman primate model. Here, we present a tentative protocol for using LMW‐DS in clinical islet transplantation.

Xenotransplantation of pig kidneys to nonhuman primates: I. Development of the model

Abstract: Long‐term survival of discordant xenografts will require control of both humoral and cellular aspects of the immune response. Because cellular responses to xenografts appear to be more potent than those encountered by allografts, recipients of xenogeneic tissues are likely to require more immunosuppression, with potential for unacceptably high complication rates. We have therefore directed our attention toward the induction of tolerance to some or all of the xenogeneic antigens recognized in the primate anti‐pig cellular immune response, utilizing mixed lymphohematopoietic chimerism as the means for tolerance induction. We report here our initial series of 16 animals in which the conditions for application of this treatment regimen were established. In 14 cynomolgus monkey recipients, induction therapy consisted of low dose whole body irradiation, thymic irradiation, and ATG, followed by infusion of pig bone marrow and a pig kidney transplant. Other aspects of the regimen included splenectomy and removal of monkey anti‐porcine natural antibodies by extracorporeal perfusion of the recipients blood through a pig liver. Two control animals received either no treatment or extracorporeal perfusion but no additional induction therapy. Five of the experimental animals were treated posttransplant with an anti‐IgM monoclonal antibody, five with Cyclosporin A, and two with a combination of both immunosuppressants. Both IgM and IgG natural antibodies were removed effectively by liver perfusion in all but one monkey, as determined by flow cytometry. Antibody liters remained low for 5–7 days, but increased progressively thereafter. The longest kidney survival in this series was 13 days, in an animal which maintained excellent kidney function for the first 11 days posttransplant. Peripheral chimerism was detected only transiently on day 10 in the peripheral blood of this recipient. We conclude that extracorporeal perfusion by this technique removes natural antibodies and prevents hyperacute rejection, permitting maintenance of excellent renal xenograft function for at least 11 days. Additional manipulations appear to be required to achieve mixed chimerism and tolerance of the cellular immune system in this model.

The surgical management of congenital liver cysts.

BackgroundMost series that report the results of surgical treatment for congenital liver cysts focus more on the technical aspects of the operation than on the late outcome of these patients. In this paper, we emphasize the importance of appropriate patient selection and adequate surgical technique for successful long-term outcome.MethodsTwenty-four consecutive patients with congenital liver cysts were selected for surgical treatment. According to our own classification, 13 patients had simple liver cysts, nine had multicystic liver disease, and two had type I polycystic liver disease. All of these patients were treated by the fenestration technique. An open approach was used for five patients (group 1) treated between 1984 and 1990. In 19 patients (group 2) treated since 1991, a laparoscopic approach was used. The incidence of complicated liver cysts was 40% in group 1 and 68% in group 2.ResultsThere were no treatment-related deaths in this series. The mean postoperative hospital stay was significantly shorter for patients who underwent successful laparoscopic fenestration (p < 0.05). In the open group (group 1), there were no postoperative complications, and all patients were alive and free of symptoms during a mean follow-up of 130 months, without any sign of cyst recurrence. In the laparoscopic group (group 2), four patients were converted to open surgery. One of these patients had an inaccessible posterior cyst; another had bile within the cystic cavity. A further two cases had complicated liver cysts with an uncertain diagnosis between congenital and neoplastic cysts. Four patients (21%) developed peri- or postoperative complications. During a mean follow-up time of 38.5 months, none of the patients with simple liver cysts incurred late symptoms or signs of cyst recurrence. In the six patients with multicystic liver disease, one developed disease-related cyst progression (17%) and required reoperation. One of the two patients with type I polycystic liver disease (50%) developed asymptomatic disease-related cyst progression.ConclusionsWhen patients are carefully selected and a proper surgical technique is employed, excellent long-term results with a low morbidity rate can be achieved in patients with congenital liver cysts. Patients with multicystic liver disease or type I polycystic liver disease are more prone to late cyst recurrence. A tailored approach is thus indicated for patients with congenital liver cystic disease. However, the laparoscopic approach appears to be the gold standard for the treatment of highly symptomatic or complicated simple liver cysts.

Calculation of the renal perfusion and glomerular filtration rate from the renal impulse response obtained with MRI

The aim of this study was to assess the importance of deconvolution for the calculation of renal perfusion and glomerular filtration rate (GFR) on the basis of concentration–time curves as measured with perfusion MRI. Six rabbits were scanned dynamically after injection of a gadolinium chelate. Concentration–time curves were generated by manually drawing regions of interest in the aorta and the renal cortex. To remove the dependency on the arterial input function, a regularized structured total least‐squares deconvolution algorithm was used to calculate the renal impulse response. This curve was fitted by the sum of two gamma variate functions, corresponding to the passage of the contrast agent in the glomeruli and the proximal convoluted tubules. Tracer kinetics models were applied to these two functions to obtain the renal perfusion and GFR. For comparison, these two parameters were also calculated on the basis of the renal concentration–time curve before deconvolution. The renal perfusion values correlated well (r = 0.9, P = 0.014) with the values calculated by a validated upslope method. The GFR values correlated well (r = 0.9, P = 0.014) with the values obtained from the clearance of 51Cr‐EDTA. A comparison of the values obtained with and without deconvolution demonstrated the necessity of deconvolution. Magn Reson Med 51:1017–1025, 2004.

EUK-134, a synthetic superoxide dismutase and catalase mimetic, protects rat kidneys from ischemia-reperfusion-induced damage.

The effect of a new synthetic superoxide dismutase and catalase mimetic was investigated on renal ischemia-reperfusion syndrome in rats. Synthetic salen-manganese complexes have characteristics that might facilitate their potential usefulness as therapeutic agents: (1) unlike proteinaceous antioxidant enzymes, synthetic complexes, due to their low molecular weight, have a better stability and bioavailability; (2) they have a catalytic activity enhancing their efficiency over noncatalytic reactive oxygen metabolite scavengers; and finally, (3) exhibiting combined superoxide dismutase and catalase activity, they destroy both superoxide anions and hydrogen peroxides, thereby enhancing their protective effect on ischemically injured tissues. One such compound, EUK-134, was tested in uninephrectomized rats that underwent a left renal artery clamping. After a 75-min left renal artery clamping, a single intravenous injection of EUK-134 at 0.2 mg/kg, just before unclamping, provided significantly better renal function recovery during the week after the ischemic insult compared with recovery of untreated animals. Two hours after several periods of renal ischemia (30, 45, 60, and 75 min of left renal artery clamping), EUK-134 given at a similar dose significantly improved the glomerular filtration rate after an acute ischemia of 30 and 45 min, as assessed by EDTA 51Cr. Overall, these results show that synthetic superoxide dismutase-catalase mimetics such as EUK-134 can protect ischemically injured rat kidneys from ischemia-reperfusion syndrome when administered just before reperfusion.

First update of the International Xenotransplantation Association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes--Chapter 4: pre-clinical efficacy and complication data required to justify a clinical trial.

In 2009, the International Xenotransplantation Association (IXA) published a consensus document that provided guidelines and “recommendations” (not regulations) for those contemplating clinical trials of porcine islet transplantation. These guidelines included the IXAs opinion on what constituted “rigorous pre‐clinical studies using the most relevant animal models” and were based on “non‐human primate testing.” We now report our discussion following a careful review of the 2009 guidelines as they relate to pre‐clinical testing. In summary, we do not believe there is a need to greatly modify the conclusions and recommendations of the original consensus document. Pre‐clinical studies should be sufficiently rigorous to provide optimism that a clinical trial is likely to be safe and has a realistic chance of success, but need not be so demanding that success might only be achieved by very prolonged experimentation, as this would not be in the interests of patients whose quality of life might benefit immensely from a successful islet xenotransplant. We believe these guidelines will be of benefit to both investigators planning a clinical trial and to institutions and regulatory authorities considering a proposal for a clinical trial. In addition, we suggest consideration should be given to establishing an IXA Clinical Trial Advisory Committee that would be available to advise (but not regulate) researchers considering initiating a clinical trial of xenotransplantation.

Macro- or microencapsulation of pig islets to cure type 1 diabetes.

Although allogeneic islet transplantation can successfully cure type 1 diabetes, it has limited applicability. For example, organs are in short supply; several human pancreas donors are often needed to treat one diabetic recipient; the intrahepatic site may not be the most appropriate site for islet implantation; and immunosuppressive regimens, which are associated with side effects, are often required to prolong survival of the islet graft. An alternative source of insulin-producing cells would therefore be of major interest. Pigs represent a possible alternative source of beta cells. Grafting of pig islets may appear difficult because of the immunologic species barrier, but pig islets have been shown to function in primates for at least 6 mo with clinically incompatible immunosuppression. Therefore, a bioartificial pancreas made of encapsulated pig islets may resolve issues associated with islet allotransplantation. Although several groups have shown that encapsulated pig islets are functional in small-animal models, less is known about the use of bioartificial pancreases in large-animal models. In this review, we summarize current knowledge of encapsulated pig islets, to determine obstacles to implantation in humans and possible solutions to overcome these obstacles.

The importance of large animal models in transplantation.

Animal models have been extensively used in transplantation research. However, animal experimentation is contentious and subject to legal and ethical restrictions. Most experiments are carried out on rodents, but crucial prerequisites for the development of safe pre-clinical protocols in biomedical research are needed through suitable large animal models. In transplantation particularly, large animal models have developed dramatically. This article provides an overview of the large animal models commonly used to evaluate organ transplant experiments and analyzes the specificity of several models in various situations such as induction of allospecific tolerance and xenotransplantation. The key determination that remains be addressed is the most appropriate species and strains to model human immune and physiological systems. Because of their phylogenetic and physiologic similarities to man, non-human primates play an increasingly important role in pre-clinical testing. Nevertheless, a number of studies have shown the pig to be a reliable large animal model for transplantation research, and the availability of genetically defined or modified pigs establishes a stronger position for pigs as a large animal model.

Tolerance to class I-disparate renal allografts in miniature swine. Maintenance of tolerance despite induction of specific antidonor CTL responses.

Miniature swine that become tolerant to renal allografts across an MHC class I barrier following a short course of cyclosporine are unresponsive to donor class I antigens in cell-mediated lymphocytotoxicity. However, skin grafts bearing donor class I plus third-party class II antigens are promptly rejected, and the animals then develop marked cell-mediated lymphocytoxic reactivity to donor class I antigens in vitro, but do not reject the kidney transplants. We show here that CTL generation is directed toward the same donor class I antigens as are expressed by the kidney donor, and is not the result of recognition in vitro of the tolerated class I antigen plus peptides of minor antigens shared between the skin graft donor and the stimulator/target cells. We also show that detection by CTLs of peptides expressed by skin but not by kidney is also not a sufficient explantation of the results, since the survival of skin grafts from the kidney donor is also prolonged, even after precursor CTL can be detected in vitro. The data are most consistent with suppression in vivo in tolerant animals of the helper pathways necessary for activation of precursor CTLs. Differences in patterns of cytokine expression by graft infiltrating cells may provide a mechanism for local suppression of help in this model. Finally, we have examined antibody production after sensitizing by skin grafts in long-term tolerant animals and have found that anti-donor class I antibodies are not produced, even though the same animals produce both anti-class II and anti-third-party class I antibodies.