Modification of a Constitutive to Glucose-Responsive Liver-Specific Promoter Resulted in Increased Efficacy of Adeno-Associated Virus Serotype 8-Insulin Gene Therapy of Diabetic Mice

We have previously used a hepatotropic adeno-associated viral (AAV) vector with a modified human insulin gene to treat diabetic mice. The HLP (hybrid liver-specific promoter) used was constitutively active and non-responsive to glucose. In this study, we examined the effects of addition of glucose responsive elements (R3G) and incorporation of a 3' albumin enhancer (3'iALB) on insulin expression. In comparison with the original promoter, glucose responsiveness was only observed in the modified promoters in vitro with a 36 h lag time before the peak expression. A 50% decrease in the number of viral particles at 5 × 10⁹ vector genome (vg)/mouse was required by AAV8-R3GHLP-hINSco to reduce the blood sugar level to near normoglycemia when compared to the original AAV8-HLP-hINSco that needed 1 × 10¹⁰ vg/mouse. The further inclusion of an 860 base-pairs 3'iALB enhancer component in the 3' untranslated region increased the in vitro gene expression significantly but this increase was not observed when the packaged virus was systemically injected in vivo. The addition of R3G to the HLP promoter in the AAV8-human insulin vector increased the insulin expression and secretion, thereby lowering the required dosage for basal insulin treatment. This in turn reduces the risk of liver toxicity and cost of vector production.

Characterization of Insulin-Secreting Porcine Bone Marrow Stromal Cells Ex Vivo and Autologous Cell Therapy in Vivo

Cell therapy could potentially meet the need for pancreas and islet transplantations in diabetes mellitus that far exceeds the number of available donors. Bone marrow stromal cells are widely used in clinical trials mainly for their immunomodulatory effects with a record of safety. However, less focus has been paid to developing these cells for insulin secretion by transfection. Although murine models of diabetes have been extensively used in gene and cell therapy research, few studies have shown efficacy in large preclinical animal models. Here we report optimized conditions for ex vivo expansion and characterization of porcine bone marrow stromal cells and their permissive expression of a transfected insulin gene. Our data show that these cells resemble human bone marrow stromal cells in surface antigen expression, are homogeneous, and can be reproducibly isolated from outbred Yorkshire–Landrace pigs. Porcine bone marrow stromal cells were efficiently expanded in vitro to >1010 cells from 20 ml of bone marrow and remained karyotypically normal during expansion. These cells were electroporated with an insulin expression plasmid vector with high efficiency and viability, and secreted human insulin and C-peptide indicating appropriate processing of proinsulin. We showed that autologous insulin-secreting bone marrow stromal cells implanted and engrafted in the liver of a streptozotocin-diabetic pig that modeled type 1 diabetes resulted in partial, but significant, improvement in hyperglycemia that could not be ascribed to regeneration of endogenous β-cells. Glucose-stimulated insulin secretion in vivo from implanted cells in the treated pig was documented by a rise in serum human C-peptide levels during intravenous glucose tolerance tests. Compared to a sham-treated control pig, this resulted in significantly reduced fasting hyperglycemia, a slower rise in serum fructosamine, and prevented weight loss. Taken together, this study suggests that bone marrow stromal cells merit further development as autologous cell therapy for diabetes.

Gene and stem cell therapy for diabetes

Gene and stem cell therapy has been on the scientific agenda in many laboratories for more than 20 years. The literature is enormous, but practical applications have been few. Recently advances in stem cell biology and gene therapy are clarifying some of the issues. I have made a few observations concerning our own studies on bone marrow mesenchymal stem cells cultured to produce a small percentage of insulin-producing cells and human insulin gene engineered into Lenti and AA viruses. The aim of clinical application would still seem to be several years away, if all goes well. The first step will be to produce enough insulin-secreting cells to be of potential value to patients. The next crucial question will be how to persuade the cells to respond to blood glucose levels swiftly and appropriately. With both stem cell and gene therapy, another important factor will be to ensure that any positive results will continue long enough to be preferable to insulin injections.

Stem cell therapy for diabetes

Stem cell therapy holds immense promise for the treatment of patients with diabetes mellitus. Research on the ability of human embryonic stem cells to differentiate into islet cells has defined the developmental stages and transcription factors involved in this process. However, the clinical applications of human embryonic stem cells are limited by ethical concerns, as well as the potential for teratoma formation. As a consequence, alternative forms of stem cell therapies, such as induced pluripotent stem cells, umbilical cord stem cells and bone marrow-derived mesenchymal stem cells, have become an area of intense study. Recent advances in stem cell therapy may turn this into a realistic treatment for diabetes in the near future.

Insulin-producing cells from adult human bone marrow mesenchymal stem cells control streptozotocin-induced diabetes in nude mice

Harvesting, expansion, and directed differentiation of human bone marrow-derived mesenchymal stem cells (BM-MSCs) could provide an autologous source of surrogate β-cells that would alleviate the limitations of availability and/or allogenic rejection following pancreatic or islet transplantation. Bone marrow cells were obtained from three adult type 2 diabetic volunteers and three nondiabetic donors. After 3 days in culture, adherent MSCs were expanded for two passages. At passage 3, differentiation was carried out in a three-staged procedure. Cells were cultured in a glucose-rich medium containing several activation and growth factors. Cells were evaluated in vitro by flow cytometry, immunolabeling, RT-PCR, and human insulin and c-peptide release in responses to increasing glucose concentrations. One thousand cell clusters were inserted under the renal capsule of diabetic nude mice followed by monitoring of their diabetic status. At the end of differentiation, ∼5-10% of cells were immunofluorescent for insulin, c-peptide or glucagon; insulin, and c-peptide were coexpressed. Nanogold immunolabeling for electron microscopy demonstrated the presence of c-peptide in the rough endoplasmic reticulum. Insulin-producing cells (IPCs) expressed transcription factors and genes of pancreatic hormones similar to those expressed by pancreatic islets. There was a stepwise increase in human insulin and c-peptide release by IPCs in response to increasing glucose concentrations. Transplantation of IPCs into nude diabetic mice resulted in control of their diabetic status for 3 months. The sera of IPC-transplanted mice contained human insulin and c-peptide but negligible levels of mouse insulin. When the IPC-bearing kidneys were removed, rapid return of diabetic state was noted. BM-MSCs from diabetic and nondiabetic human subjects could be differentiated without genetic manipulation to form IPCs that, when transplanted, could maintain euglycemia in diabetic mice for 3 months. Optimization of the culture conditions are required to improve the yield of IPCs and their functional performance.

Stem cell and gene therapies for diabetes mellitus

In this Perspectives article, we comment on the progress in experimental stem cell and gene therapies that might one day become a clinical reality for the treatment of patients with diabetes mellitus. Research on the ability of human embryonic stem cells to differentiate into islet cells has defined the developmental stages and transcription factors involved in this process. However, the clinical applications of human embryonic stem cells are limited by ethical concerns, as well as the potential for teratoma formation. As a consequence, alternative forms of stem cell therapies, such as induced pluripotent stem cells and bone marrow-derived mesenchymal stem cells, have become an area of intense study. Finally, gene therapy shows some promise for the generation of insulin-producing cells. Here, we discuss two of the most frequently used approaches: in vitro gene delivery into cells which are then transplanted into the recipient and direct delivery of genes in vivo.

Organ transplantation has come of age

Organ transplantation started in the mid-1950s with a kidney transplant between identical twins, demonstrating the surgical technique could provide successful therapy. The immunological barrier to be overcome, however proved to be far more difficult to deal with. The introduction of immunosuppressive agents produced some success but it was not until Cyclosporin became available in the 1980s that results became sufficiently good for widespread acceptance and rapid development of organ grafting. Now with more powerful and selective agents, although there is still much room for improvement in immunosuppression, one of the main problems in organ transplantation is a result of its success, namely a shortage of organ donors. In this review, I summarise these matters.

The role of research in transplantation

In the past 50 years, organ transplantation has developed from an improbable laboratory exercise to a major therapeutic success. The surgical problems of organ grafting have, for the most part, been solved. Rejection of grafts is now partially understood and usually controllable by powerful immunosuppressive drugs. A steady improvement in patient outcome, especially following the introduction of cyclosporin as an immunosuppressive agent has resulted in a worldwide shortage of organs for transplantation. This has provoked serious ethical dilemmas in every country. These matters are summarised in the following text.

Early days of liver transplantation

The early days of liver transplantation were exciting, demanding, subject to terrible disappointments and sadness but occasional elation, and a gradual understanding of the factors necessary to achieve a satisfactory operation. In addition, care of an extremely sick patient, the management of the disease, especially if it was infectious or malignant, and the support of the relatives and the transplant team, required a group of loyal, dedicated and above all optimistic members who could see through the repeated unhappy outcomes that eventually most of the problems would be solved. This in fact has come to pass.

Alemtuzumab (Campath-1H) and tacrolimus monotherapy after renal transplantation: results of a prospective randomized trial

The lymphocyte-depleting antibody alemtuzumab was evaluated in a prospective randomized multicenter trial in deceased donor kidney transplantation. The 65 patients in the study group received induction with alemtuzumab followed by delayed tacrolimus monotherapy, while the 66 patients in the control group were started on tacrolimus in combination with mycophenolate mofetil and steroids. Tacrolimus levels of 8-12 ng/mL for the first 6 months and 5-8 ng/mL thereafter were aimed for in both groups. At 12 months the biopsy-proven rejection rate was 20% in the study group and 32% in the control group (p = 0.09). Patient survival at 1 year was 98% for both groups. Graft survival was 96% for the study group versus 90% for the control group (p = 0.18). Graft function was identical in both groups. Adverse events were similar in both groups apart for more CMV infections in the study group. At the end of the first year 82% of the patients in the study group were steroid-free and 71% continued on tacrolimus monotherapy. These results suggest that alemtuzumab induction together with tacrolimus monotherapy is at least as efficient in renal transplantation as is a tacrolimus-based triple-drug regimen with a similar safety profile but more CMV infections.

Life-threatening coagulopathy associated with use of Campath (alemtuzumab) in maintenance steroid-free renal transplant given before surgery

We report a case in which an alarming coagulopathy occurred during the operation in a patient receiving a kidney from his spouse. Campath was used for induction of immunosuppression immediately before surgery. There was catastrophic intra-abdominal bleeding associated with severe hypotension, respiratory failure, prolonged partial thrombin time (PTT), normal prothrombin time (PT) and absence of signs of disseminated intravascular coagulation. Multiple tranfusions of blood and blood products were given. Repeated explorations were carried out to secure hemostasis and removal of intra-abdominal blood clots. The coagulopathy improved after 24 h, but recurred within 3 h after the second dose of Campath, given exactly 24 h after the first dose. The coagulopathy also resulted in graft dysfunction, bilateral basal pneumonia, pleural effusions and prolonged abdominal ileus. In spite of the above, the patient went into diuresis and was discharged well after 3 weeks. He was on Prograf (tacrolimus), the sole maintenance immunosuppressor. The pathogenesis of the Campath-related coagulopathy is unclear. We wish to alert the transplant community to this unusual, but catastrophic, complication. We also advocate administering intravenous Campath following the operation, when surgical wounds are more secure and the patient is in a more stable environment.

[Allogenic islet transplantation on the rat liver after allogenic nonparenchymal cells injection in the thymus]

BACKGROUND

[corrected] The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control

AIM

We studied allogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and nonparenchymal cell group (n = 8) respectively with injection of Hanks solution and nonparenchymal cells in the thymus before islet transplantation.

MATERIAL AND METHODS

With the method of isolation and purification of the islets we obtained both in the control group 3.637 +/-783,3 islets with purity of 85 +/- 3,52% and nonparenchymal cell group 3.270 +/- 770 islets with purity of 84,25 +/- 2,76%. The nonparenchymal cells were retrieved from the liver and we obtained 2 x 106 cells. Diabetes was induced by i.v. streptozotocin

RESULTS

Control group the transplantation of 3.637 +/- 783,3 islets in the rat liver normalized glucose test, 7,21 +/- 0,57 mmol/L in the 2nd postoperative day. Acute rejection came in the 6th postoperative day with significantly increase of glucose test in nonparenchymal cell group, the transplantation of 3.270 +/- 770 islets in the rat liver, almost normalized the glucose test was 17,95 +/- 5,33 mmol/L in the 2nd postoperative day. From the 4th postoperative day to 10th postoperative day. The glucose test increase significantly showing an early acute rejection

CONCLUSION

The injection of nonparenchymal cells in the thymus before allogenic islet transplantation in the rat liver lead to an early acute rejection.

Transplantation: current developments and future directions

Organ transplantation has emerged from a few sporadic failed attempts to one of the most successful branches of surgery in the course of 50 years since the first identical twin transplant was performed in Boston. In this article I will attempt to portray the historical background and the recent shift of attitude regarding immunosuppression for solid organ transplants. Previously a culture of increasing immunosuppression and incorporating new and powerful agents into an already effective regimen has resulted in over-immunosuppression and more sepsis without an improvement in long-term graft survival. Over-immunosuppression is probably detrimental in preventing the natural control and "switching off" of the immune response as a vital function of the immune system and as a consequence any attempts to produce immunological tolerance are likely to be impaired by excessive immunosuppressive regimens. I will therefore,, explain and advocate a minimalistic approach to immunosuppression, a background on tissue typing and a summary of clinical results. Now that the procedure is perceived worldwide as an excellent therapy for previously doomed patients, there is an increasing mismatch between the number of donor organs available and patients in need of a graft. This has produced ethical dilemmas previously unknown in the medical profession. These are extremely important considerations as they can undermine the Hippocratic tradition and the high ethical standing previously enjoyed by our profession.

Gene therapy for hemophilia A

Hemophilia A is an X-linked bleeding disorder caused by defective coagulation Factor VIII (FVIII). Although the efficacies of existing treatment using purified or recombinant FVIII are good, there remain shortcomings in using this particular form of treatment. A few FVIII gene therapy clinical trials have been initiated with modest improvements recorded, but these are no longer being continued due to insufficient efficacy. However, with the progress in the development of gene delivery vectors and the availability of mouse and canine hemophilia A models, gene therapy of hemophilia A remains an area of hot pursuit.

Genetic engineering for haemophilia A

At first sight, haemophilia A would appear to be an ideal candidate for treatment by gene therapy. There is a single gene defect; cells in different parts of the body, but especially the liver, produce Factor VIII, and only 5% of normal levels of Factor VIII are necessary to prevent the serious symptoms of bleeding. This review attempts to outline the status of gene therapy at present and efforts that have been made to overcome the difficulties and remaining problems that require solving. Undoubtedly, success will be achieved, but it is likely that considerably more work will be necessary before experimental models can be introduced into the clinic with any likelihood of success. The most successful results in animals that may have clinical application were from introducing the Factor VIII gene to newborn animals before antibodies are produced, presumably inducing a state of tolerance.

Insulin-secreting cells derived from stem cells: clinical perspectives, hypes and hopes

Diabetes is a degenerative disease that results from the selective destruction of pancreatic beta-cells. These cells are responsible for insulin production and secretion in response to increases in circulating concentrations of nutrients, such as glucose, fatty acids and amino acids. This degenerative disease can be treated by the transplantation of differentiated islets obtained from cadaveric donors, according to a new surgical intervention developed as Edmonton protocol. Compared to the classical double transplant kidney-pancreas, this new protocol presents several advantages, concerning to the nature of the implant, immunosuppressive drug regime and the surgical procedure itself. However, the main problem to face in any islet transplantation program is the scarcity of donor pancreases and the low yield of islets isolated (very often around 50%) from each pancreas. Nevertheless, transplanted patients presented no adverse effects and no progression of diabetic complications. In the search of new cell sources for replacement trials, stem cells from embryonic and adult origins represent a key alternative. In order to become a realistic clinical issue transplantation of insulin-producing cells derived from stem cells, it needs to overcome multiple experimental obstacles. The first one is to develop a protocol that may allow obtaining a pure population of functional insulin-secreting cells as close as possible to the pancreatic beta-cell. The second problem should concern to the transplantation itself, considering issues related to immune rejection, tumour formation, site for implant, implant survival, and biosafety mechanisms. Although transplantation of bioengineered cells is still far in time, experience accumulated in islet transplantation protocols and in experiments with appropriate animal models will give more likely the clues to address this question in the future.

Prope tolerance--the future of organ transplantation from the laboratory to the clinic

This is a short review of tolerance from the point of view of the clinician. Various examples of tolerance occurring in patients and animal models that relate to the clinical experience are described. It is suggested that there may be different mechanisms by which tolerance is achieved, but, from the patient's point of view operational, tolerance is the goal whereby, after a short induction procedure, the patient will maintain good function in the grafted organ indefinitely without maintenance immunosuppression. It is pointed out that such a goal may be difficult to achieve with any given protocol due to the enormous variation between donors and recipients of organ grafts of tissue matching, innate immune reactivity, and susceptibility to disturbance of a tolerant state by infections or allergic reactions. Thus, the case is made for prope or almost tolerance in which graft acceptance is maintained by a low, nontoxic dosage of maintenance immunosuppression which may not be required indefinitely.

[Alogenic islet transplantation on the rat liver after alogenic dendritic cells injection in the thymus]

BACKGROUND

The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control.

AIM

We studied alogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and dendritic cell group (n = 9) respectively with injection of Hanks solution and dendritic cells in the thymus before islet transplantation.

MATERIAL AND METHODS

With the method of isolation and purification of the islets we obtained both in the control group 3637 +/- 783,3 islets with purity of 85 +/- 3,52% and dendritic cell group 3268 +/- 378 islets with purity of 87 +/- 4,47%. The dendritic cells were retrieved from the spleen and we obtained 3,34 x 105+/-1,16 cells. Diabetes was induced by i.v. streptozotocin.

RESULTS

Control group the transplantation of 3637 +/- 783,3 islets in the rat liver normalized glucose test, 7,21 +/- 0,57 mmol/L in the second post-operative day. Acute rejection came in the 10 postoperative day with significantly increase of glucose test. Dendritic cell group, the transplantation of 3258 +/- 378 islets in the rat liver, normalized the glucose test was 9,3 +/- 2,85 mmoL/L in the second postoperative day. From the 4th postoperative day to 10th postoperative day the glucose test increase significantly showing an early acute rejection.

CONCLUSION

The injection of dendritic cells in the thymus before alogenic islet transplantation in the rat liver lead to an early acute rejection.

Prope tolerance—the future of organ transplantation from the laboratory to the clinic

This is a short review of tolerance from the point of view of the clinician. Various examples of tolerance occurring in patients and animal models that relate to the clinical experience are described. It is suggested that there may be different mechanisms by which tolerance is achieved, but from the patient's point of view operational tolerance is the goal whereby, after a short induction procedure, the patient will maintain good function in the grafted organ indefinitely without maintenance immunosuppression. It is pointed out that such a goal may be difficult to achieve with any given protocol due to the enormous variation between donors and recipients of organ grafts of tissue matching, innate immune reactivity and susceptibility to disturbance of a tolerant state by infections or allergic reactions. Thus, the case is made for prope or almost tolerance in which graft acceptance is maintained by a low, non-toxic dosage of maintenance immunosuppression, which may not be required indefinitely.

Prope tolerance: the future of organ transplantation--from the laboratory to the clinic

This is a short review of tolerance from the point of view of the clinician. Various examples of tolerance occurring in patients and animal models that relate to the clinical experience are described. There may be different mechanisms by which tolerance is achieved, but from the patient's point of view operational tolerance is the goal whereby, after a short induction procedure, the patient will maintain good function in the grafted organ indefinitely without maintenance immunosuppression. Such a goal may be difficult to achieve with any given protocol because of the enormous variation between donors and recipients of organ grafts in tissue matching, innate immune reactivity, and susceptibility to disturbance of a tolerant state by infections or allergic reactions. Thus the case is made for prope or "almost" tolerance in which graft acceptance is maintained by a low, nontoxic dosage of maintenance immunosuppression that may not be required indefinitely.

Adult small intestinal transplantation in England and Wales

BACKGROUND

In 1996 two transplantation centres in the UK were commissioned by the National Specialist Commissioning Advisory Group for England and Wales to assess small intestinal transplantation in adults. The joint experience of the two centres is presented.

METHODS

Patients with irreversible small intestinal failure and complications of parenteral nutrition, and those with abdominal disease requiring extensive visceral resection, were assessed as candidates and where appropriate listed for surgery.

RESULTS

Thirty-six patients were assessed for small intestinal transplantation and, of these, 14 underwent surgery. Twelve patients survived the transplantation procedure. Of these, seven patients were alive at 1 year, five at 3 years and three at 5 years. Three patients remain alive. Patient and graft survival improved with experience; the 1-year survival rate improved in the last 4 years of this experience from 43 to 57 per cent, and the 3-year survival rate from 29 to 43 per cent.

CONCLUSION

Small intestinal transplantation is associated with a high mortality rate but may benefit carefully selected patients in whom conservative management is likely to carry a greater mortality rate.

Relapsing encephalopathy following small bowel transplantation

We report a case of a 40-year-old man presenting with relapsing encephalopathy 4 years post-intestinal transplantation. Each episode was preceded by symptoms suggestive of subacute intestinal obstruction, marked dehydration, and, on one occasion, grade 4 encephalopathy. Physical examination revealed hypertonia, clonus, and hyperreflexia. Biochemistry was consistent with renal impairment, metabolic alkalosis, hyperammonaemia, and normal liver function. Plain radiographs and abdominal computed tomography revealed dilated proximal small bowel loops, and barium radiography demonstrated a strictured distal anastomosis. Hydrogen breath testing indicated bacterial overgrowth. Following rehydration and antibiotic therapy, the patient recovered fully between episodes. Further episodes of encephalopathy did not recur following resection of the distal anastomotic stricture and resolution of bacterial overgrowth. Unfortunately, one year later the patient died of pneumonia. To the best of our knowledge, encephalopathy secondary to intestinal transplant related porto-caval shunt and bacterial overgrowth in strictured bowel has not been previously reported but might have implications for the management of future patients.

The future of organ transplantation: from the laboratory to the clinic

This is a short review of tolerance from the point of view of the clinician. Various examples of tolerance occurring in patients and animal models that relate to the clinical experience are described. It is suggested that there may be different mechanisms by which tolerance is achieved, but from the patient's point of view operational tolerance is the goal, whereby, after a short induction procedure, the patient will maintain good function in the grafted organ indefinitely without maintenance immunosuppression. It is pointed out that such a goal may be difficult to achieve with any given protocol due to the enormous variation between donors and recipients of organ grafts of tissue matching, innate immune reactivity and susceptibility to disturbance of a tolerant state by infections or allergic reactions. Thus the case is made for prope or almost tolerance in which graft acceptance is maintained by a low, non-toxic dosage of maintenance immunosuppression that may not be required indefinitely.

Combined transplantation of the heart, lung, and liver

Combined transplantation of the heart, lung, and liver may be indicated in patients with either end-stage respiratory failure complicated by advanced liver disease or end-stage liver failure complicated by advanced lung disease. A retrospective review of nine patients who underwent combined heart-lung-liver transplantation in Cambridge (1986-99) was carried out. The 1-year and 5-year actuarial survival was 56% and 42%, respectively. Combined heart-lung-liver transplantation is a feasible option for a few patients and has a 5-year survival similar to heart-lung transplantation but with a lower incidence of acute and chronic rejection.

Solitary splenic metastasis: case report and review of the literature

Solitary splenic lesion is a rare presentation of a previous or current malignancy. We describe a case of an isolated splenic lesion caused by endometrial carcinoma and summarize all the published reports on solitary splenic metastasis.

Distribution and persistence of antigen-presenting cells after intrathymic injection

Intrathymic injection of donor immune cells has been shown by previous studies to prolong survival of rat allogeneic tissues. The aim of this pilot study was to assess the distribution and the persistence of intrathymically (i.t.) injected purified antigen presenting cells (APC) over a period of time in the rat model DA-to-WAG (RT1av to RT1u) using a specific monoclonal antibody (Mab) with RT1Aa class I polymorphic specificity (R3/13 clone). Purified non-parenchymal cells (NPC) or dendritic cells (DC) were prepared from liver and spleen of DA rats with a purity of greater than 60% and 90%, respectively, shown by selected Mab staining methods. DA NPC (1 x 10(6)) or DC (5 x 10(5)) in 20 microl were injected into both lobes of the thymus of WAG rats with or without 1 ml antilymphocyte serum (ALS) intraperitoneally. Thymus tissue was removed on days 3, 5, 10, 20 and 30, and processed for frozen sections and immunohistochemical staining with R3/13. Numerous DA-positive cells were detected in the first 3-10 days post-i.t. inoculation in both NPC- and DC-treated rats, with or without ALS. After day 10, the proportion of positive cells decreased in all cases except in rats given NPC and ALS, where similar numbers of R3/13-positive cells were seen throughout. These DA-positive cells were mostly found in the medullary portion of the thymus at the corticomedullary junction in close proximity to thymic dendritic interdigitating cells. We concluded from this pilot study that the injected cells remained in the thymus for a limited period. However, the immunosuppressive effect of ALS promoted some degree of persistence of donor APC in the thymus beyond 30 days. Further studies are in progress to reveal the specificity of these cells.

Does intrathymic injection of alloantigen-presenting cells before islet allo-transplantation prolong graft survival?

Current immunosuppressive agents have potentially dangerous side-effects, are non-specific and most are also diabetogenic. We investigated tolerance induction with intrathymic injection of purified antigen-presenting cells (APC) plus a single dose of antilymphocyte serum (ALS) intraperitoneally before allogeneic islet transplantation in the rat model WAG to Lewis (RT1u to RT1l). Purified donor APC [non-parenchymal cells (NPC) or dendritic cells (DC)] were prepared from liver and spleen, respectively. Isograft function for more than 120 days proved that islet isolation, purification and transplantation procedures were adequate. A total of WAG DC (4 x 10(5)) or NPC (2 x 10(6)) in 20 microl were injected into both lobes of the thymus of 140-210 g Lewis recipients followed by a single injection of ALS. Three days later, diabetes was induced with streptozotocin (60 mg/kg). Four days later allogeneic islets were grafted into the liver by intraportal injection of 3000 WAG islets. Control animals (n = 8) received 20 microl saline intrathymically instead of APC. Graft function was assessed by blood glucose measurements with glucose levels above 15 mmol/l on 3 consecutive days defined as graft rejection. Animals given DC (n = 9) or NPC (n = 8) intrathymically plus 1 ml of ALS, rejected their grafts in an accelerated fashion with a median survival time (MST) of 3 days. However, control animals rejected their grafts with a MST of 7 days, but with two animals surviving for more than 2 months. In conclusion, intrathymic inoculation with purified APC plus a single dose of ALS did not prolong allogeneic islet graft function but induced accelerated rejection of the islet allografts.

CD4 and CD8 monoclonal antibody therapy in canine renal allografts

Therapy with CD4 and CD8 monoclonal antibodies was evaluated in dogs which received double-haplotype MHC-mismatched renal allografts. Neither CD4 nor CD8 monoclonal antibodies given alone prolonged allografts survival (creatinine > or = 300 micromol/l) beyond 7 days. However, combined therapy with CD4 and CD8 antibodies given up to day 10 did prolong allograft survival to a median of 14 days. A longer (21 day) course of CD4 and CD8 antibodies did not extend allograft survival further. The effect of prolonged antibody therapy was restricted by the occurrence of both an antiglobulin response and an anaphylactoid reaction to the monoclonal antibody preparation. When the CD4 and CD8 antibodies were combined with a pan-T-cell-depleting Thy-1 antibody, the survival of double-haplotype mismatched allografts was further prolonged (median 16 days). The median survival of single-haplotype mismatched renal allografts on this triple therapy was 21 days, with one surviving to day 36.

Life-supporting human complement regulator decay accelerating factor transgenic pig liver xenograft maintains the metabolic function and coagulation in the nonhuman primate for up to 8 days

BACKGROUND

It is not known whether the pig liver is capable of functioning efficiently when transplanted into a primate, neither is there experience in transplanting a liver from a transgenic pigs expressing the human complement regulator human complement regulator decay accelerating factor (h-DAF) into a baboon. The objective of this study was to determine whether the porcine liver would support the metabolic functions of non-human primates and to establish the effect of hDAF expression in the prevention of hyperacute rejection of porcine livers transplanted into primates.

METHODS

Five orthotopic liver xenotransplants from pig to baboon were carried out: three from unmodified pigs and two using livers from h-DAF transgenic pigs.

FINDINGS

The three control animals transplanted with livers from unmodified pigs survived for less than 12 hr. Baboons transplanted with livers from h-DAF transgenic pigs survived for 4 and 8 days. Hyperacute rejection was not detected in the baboons transplanted with hDAF transgenic pig livers; however, it was demonstrated in the three transplants from unmodified pigs. Baboons transplanted with livers from h-DAF transgenic pigs were extubated at postoperative day 1 and were awake and able to eat and drink. In the recipients of hDAF transgenic pig livers the clotting parameters reached nearly normal levels at day 2 after transplantation and remained normal up to the end of the experiments. In these hDAF liver recipients, porcine fibrinogen was first detected in the baboon plasma 2 hr postreperfusion, and was present up to the end of the experiments. One animal was euthanized at day 8 after development of sepsis and coagulopathy, the other animal arrested at day 4, after an episode of vomiting and aspiration. The postmortem examination of the hDAF transgenic liver xenografts did not demonstrate rejection.

INTERPRETATION

The livers from h-DAF transgenic pigs did not undergo hyperacute rejection after orthotopic xenotransplantation in baboons. When HAR is abrogated, the porcine liver maintains sufficient coagulation and protein levels in the baboon up to 8 days after OLT.

Historic landmarks in clinical transplantation: conclusions from the consensus conference at the University of California, Los Angeles

The transplantation of organs, cells, and tissues has burgeoned during the last quarter century, with the development of multiple new specialty fields. However, the basic principles that made this possible were established over a three-decade period, beginning during World War II and ending in 1974. At the historical consensus conference held at UCLA in March 1999, 11 early workers in the basic science or clinical practice of transplantation (or both) reached agreement on the most significant contributions of this era that ultimately made transplantation the robust clinical discipline it is today. These discoveries and achievements are summarized here in six tables and annotated with references.

Prope tolerance: a step in the search for tolerance in the clinic

Following the demonstration by Knechtle and colleagues that profound T cell depletion in rhesus monkeys treated with a CD3 diphtheria immunotoxin resulted in tolerance to renal allografting, we have used a similarly depleting protocol that, in addition, depletes B cells in recipients of a cadaveric renal transplant. The humanized antiCD52 monoclonal antibody had a rapid depleting effect when given intravenously, 20 mg on days 0 and 1 after-renal transplantation, to 31 patients. At 48 hours after the second dose of low dose monotherapy cyclosporine (Neoral) was given to maintain blood levels averaging 100 ng/ml. Initially no other immunosuppression was given. With an average follow-up of 24 months all but one of the patients are alive, 29 with intact functioning grafts. There have been five rejection episodes, which responded to pulsed steroid treatment. One patient had a recurrence of her original disease. Two patients developed opportunistic infections, which responded to therapy; and one patient with severe heart failure at the time of surgery died from this condition after 11 months. Currently 29 patients are still on the original low dose cyclosporine monotherapy. The outcome in this cohort of patients has been encouraging, with efficacy that compares favorably to our conventional triple therapy but in most cases allows the patients to be steroid-free on low dose immunosuppressive monotherapy. The maintenance treatment is inexpensive and should be beneficial in the context of tight budgetary constraints worldwide. The patients who avoided steroids are pleased with this aspect of the protocol. A randomized trial comparing this treatment with standard therapy is planned.

Immunological tolerance--the liver effect

The developing immune system in the embryo is programmed to accept all its own tissues as self-products and not react against them. It has been the aim of transplantation research for the past 40 years to try and manipulate the developed immune system temporarily to a similar status to that in the embryo at the time of an organ graft, so that the organ graft is accepted but immunity generally is not interfered with. Such a state is known as immunological tolerance and can be produced in the laboratory by a number of special techniques, none of which is appropriate for clinical use in organ grafting. In pigs and rats, an allografted liver can sometimes survive permanently without any immunosuppressive treatment in immunologically mature animals.