Fibroblast growth factor-1 (FGF-1) loaded microbeads enhance local capillary neovascularization.

BACKGROUND: Growth of new blood vessels (neovascularization) occurs naturally in the body, but the slow rate of the process may not be sufficient for survival of engineered tissues and transplanted cells, such as pancreatic islets. For transplanted islets, it is crucial that the transplantation site has sufficient vasculature to support the needs of the islets. Therefore, the specific aim of this research was quantify the effect of FGF-1 incorporation into alginate microbeads on neovascularization of such capsules in an in vivo rat transplant model. MATERIALS AND METHODS: Microbeads loaded with FGF-1 or control beads (beads without FGF-1) were implanted in the rat omental pouch model. Animals were sacrificed 7 d post-implantation. RESULTS: Microbeads loaded with FGF-1 stimulated a significant increase in vascular density compared with control rats implanted with control beads. CONCLUSIONS: These results indicate that alginate microbeads loaded with FGF-1 enhance local neovascularization around implanted microbeads. These data provide a compelling impetus for experimental pursuit of FGF-loaded alginate microcapsules for vascularization of transplanted islets.

Sustained delivery of FGF-1 increases vascular density in comparison to bolus administration.

The use of growth factors for the therapeutic stimulation of neovascularization in regenerative medicine has been extensively investigated, but the inability to control their temporal delivery may limit clinical success. A strategy that delivers continuous therapeutic concentrations of growth factors may increase the protein's efficacy. The present study investigates the ability of sustained delivery of fibroblast growth factor-1 (FGF-1), to induce neovascularization in vivo. Alginate microbeads were synthesized to release active FGF-1 for three weeks. Microbeads loaded with FGF-1 (total amount 150 ng) were implanted into a surgically created omentum pouch in rats and were compared to control empty microbead implants and a single bolus injection of 150 ng of FGF-1 with empty microbead implant. Animals were sacrificed at either 3 or 6 weeks post implantation and omenta were analyzed for vascular density and mural cell interactions. Vascular area for bolus FGF-1 and FGF-1 loaded microbeads was higher than control at 3 weeks. At 6 weeks, vascular density in the group with FGF-1 loaded microbeads was significantly higher than the group with bolus administration of FGF-1, primarily due to an increase in the number of vessels less than 20 microm in diameter. Vascular density in omenta of the group receiving the bolus FGF-1 returned to control levels by 6 weeks. Staining for smooth muscle actin showed that 50% of vessels had associated mural cells. There was a trend of increased mural cell staining at 6 weeks for the FGF-1 loaded beads compared to bolus FGF-1 and control levels. Results in these studies suggest that sustained release of FGF-1 increases the duration of the vascular response in contrast to a bolus injection of FGF-1.

Islet transplantation: the quest for an ideal source.

The progress of islet transplantation as a new therapy for patients with diabetes mellitus depends directly upon the development of efficient and practical immunoisolation methods for the supply of sufficient quantities of islet cells. Without these methods, large scale clinical application of this therapy would be impossible. Two eras of advances can be identified in the development of islet transplantation. The first was an era of experimental animal and human research that centered on islet isolation procedures and transplantation in different species as evidence that transplanted islets have the capability to reverse diabetes. The second was the era of the Edmonton protocol, when the focus became the standardization of isolation procedures and introduction of new immunosuppressive drugs to maintain human allograft transplantation. The quest for an alternative source for islets (xenographs, stem cells and cell cultures) to overcome the shortage of human islets was an important issue during these eras. This paper reviews the history of islet transplantation and the current procedures in human allotransplantation, as well as different types of immunoisolation methods. It explores novel approaches to enhancing transplantation site vascularity and islet cell function, whereby future immunoisolation technology could offer additional therapeutic advantages to human islet allotransplantation.

Immunoisolating pancreatic islets by encapsulation with selective withdrawal.

This manuscript reports the application of the selective-withdrawal coating technique to the microencapsulation of insulin-producing pancreatic islets within thin poly(ethylene glycol) coatings. These polymer coatings permit the islets to respond to changes in glucose concentration by producing insulin with a dose-response profile that is substantially similar to that of unencapsulated islets. Furthermore, the hydrogel capsules exclude the large molecules of the immune system. These results suggest that the microencapsulation technique-which combines droplet formation from a flow of two immiscible fluids with polymerization chemistries-has the characteristics required for the transplantation of islets for the treatment of Type I diabetes.

Portal Vein Thrombosis in the Setting of Newly Diagnosed Cushing's Syndrome.

The hallmark manifestations of Cushing's syndrome (CS) are well known, but hypercoagulability is perhaps least recognized. Patients with CS are at increased risk of both spontaneous and postoperative thromboembolism, with the significant majority of events occurring in the lower extremity and pulmonary venous circulations. We present a case of portal vein thrombosis (PVT) occurring in the setting of newly diagnosed CS due to a left adrenal adenoma. Factor VIII activity was approximately 2.5-fold elevated, a known mechanism by which hypercortisolemia predisposes to venous thrombosis. Acute abdominal pain and fever responded well to unfractionated heparin and parenteral antibiotics, and CS was eventually cured by left adrenalectomy. No thromboembolic events have occurred since surgery. PVT is uncommon and usually occurs as a complication of primary or secondary hepatobiliary malignancies and cirrhosis. To the best of our knowledge, this is just the second reported case of PVT due to CS and the first published in the English language literature.

Treatment of renal allograft polyoma BK virus infection with leflunomide.

BACKGROUND: Polyoma BK virus produces an aggressively destructive nephropathy in approximately 3% to 8% of renal allografts, is associated with graft loss within one year in 35% to 67% of those infected and there is no therapy of proven efficacy. Leflunomide is an immune suppressive drug with anti viral activity in vitro and in animals. METHODS: We treated twenty-six patients with biopsy proven NK virus nephropathy (BKN) with either leflunomide alone (n=17) or leflunomide plus a course of cidofovir (n=9) and followed them for six to forty months. Leflunomide was dosed to a targeted blood level of active metabolite, A77 1726, of 50 microg/ml to 100 microg/ml (150 microM to 300 microM). Response to treatment was gauged by serial determinations of viral load in blood and urine (PCR), serum creatinine, and repeat allograft biopsy. RESULTS: In the 22 patients consistently sustaining the targeted blood levels of active drug, blood and urine viral load levels uniformly decreased over time (P<.001). Mean serum creatinine levels stabilized over the first six months of treatment, and with 12 months or more of follow-up in 16 patients the mean serum creatinine has not changed significantly from base line. Four patients who did not consistently have blood levels of active drug (A77 1726) above 40 microg/ml did not clear the virus until these levels were attained or cidofovir was added. CONCLUSIONS: Leflunomide inhibits Polyoma virus replication in vitro and closely monitored leflunomide therapy with specifically targeted blood levels appears to be a safe and effective treatment for Polyoma BK nephropathy.

Outcomes of Pancreatic Islet Allotransplantation Using the Edmonton Protocol at the University of Chicago.

OBJECTIVE: The aim of this study was to assess short-term and long-term results of the pancreatic islet transplantation using the Edmonton protocol at the University of Chicago. MATERIALS AND METHODS: Nine patients underwent pancreatic islet cell transplantation using the Edmonton Protocol; they were followed up for 10 years after initial islet transplant with up to 3 separate islet infusions. They were given induction treatment using an IL-2R antibody and their maintenance immunosuppression regimen consisted of sirolimus and tacrolimus. RESULTS: Nine patients received a total of 18 islet infusions. Five patients dropped out in the early phase of the study. Greater than 50% drop-out and noncompliance rate resulted from both poor islet function and recurrent side effects of immunosuppression. The remaining 4 (44%) patients stayed insulin free with intervals for at least over 5 years (cumulative time) after the first transplant. Each of them received 3 infusions, on average 445 000 islet equivalent per transplant. Immunosuppression regimen required multiple adjustments in all patients due to recurrent side effects. In the long-term follow up, kidney function remained stable, and diabetic retinopathy and polyneuropathy did not progress in any of the patients. Patients' panel reactive antibodies remained zero and anti-glutamic acid decarboxylase 65 antibody did not rise after the transplant. Results of metabolic tests including hemoglobin A1c, arginine stimulation, and mixed meal tolerance test were correlated with clinical islet function. CONCLUSIONS: Pancreatic islet transplantation initiated according to Edmonton protocol offered durable long-term insulin-free glycemic control in only highly selected brittle diabetics providing stable control of diabetic neuropathy and retinopathy and without increased sensitization or impaired renal function. Immunosuppression adjustments and close follow-up were critical for patient retention and ultimate success.

The bioartificial pancreas: progress and challenges.

Diabetes remains a devastating disease, with tremendous cost in terms of human suffering and healthcare expenditures. A bioartificial pancreas has the potential as a promising approach to preventing or reversing complications associated with this disease. Bioartificial pancreatic constructs are based on encapsulation of islet cells with a semipermeable membrane so that cells can be protected from the host's immune system. Encapsulation of islet cells eliminates the requirement of immunosuppressive drugs, and offers a possible solution to the shortage of donors as it may allow the use of animal islets or insulin-producing cells engineered from stem cells. During the past 2 decades, several major approaches for immunoprotection of islets have been studied. The microencapsulation approach is quite promising because of its improved diffusion capacity, and technical ease of transplantation. It has the potential for providing an effective long-term treatment or cure of Type 1 diabetes.

Reuse of a previously transplanted kidney: does success come with a price?

Longer wait times for deceased donor kidney transplant have prompted newer initiatives to expedite the process. Reuse of a previously transplanted kidney might be appropriate in certain circumstances. However, one must also consider the unique issues that may arise after such transplants. We describe our experience in one such case where the donor kidney had lesions of focal and segmental glomerulosclerosis and signs of alloreactivity (positive C4d staining) prior to transplantation and the recipient developed ganciclovir-resistant cytomegalovirus (CMV) infection, which was perhaps transmitted from the donor. Despite the challenges, the allograft function remained stable 5 years after reuse.

Improvement in outcomes of clinical islet transplantation: 1999-2010.

OBJECTIVE: To describe trends of primary efficacy and safety outcomes of islet transplantation in type 1 diabetes recipients with severe hypoglycemia from the Collaborative Islet Transplant Registry (CITR) from 1999 to 2010. RESEARCH DESIGN AND METHODS: A total of 677 islet transplant-alone or islet-after-kidney recipients with type 1 diabetes in the CITR were analyzed for five primary efficacy outcomes and overall safety to identify any differences by early (1999-2002), mid (2003-2006), or recent (2007-2010) transplant era based on annual follow-up to 5 years. RESULTS: Insulin independence at 3 years after transplant improved from 27% in the early era (1999-2002, n = 214) to 37% in the mid (2003-2006, n = 255) and to 44% in the most recent era (2007-2010, n = 208; P = 0.006 for years-by-era; P = 0.01 for era alone). C-peptide ≥0.3 ng/mL, indicative of islet graft function, was retained longer in the most recent era (P < 0.001). Reduction of HbA(1c) and resolution of severe hypoglycemia exhibited enduring long-term effects. Fasting blood glucose stabilization also showed improvements in the most recent era. There were also modest reductions in the occurrence of adverse events. The islet reinfusion rate was lower: 48% by 1 year in 2007-2010 vs. 60-65% in 1999-2006 (P < 0.01). Recipients that ever achieved insulin-independence experienced longer duration of islet graft function (P < 0.001). CONCLUSIONS: The CITR shows improvement in primary efficacy and safety outcomes of islet transplantation in recipients who received transplants in 2007-2010 compared with those in 1999-2006, with fewer islet infusions and adverse events per recipient.

Intragraft vascular occlusive sickle crisis with early renal allograft loss in occult sickle cell trait.

Early renal allograft failure due to sickle cell trait is rare. We present clinical and pathologic findings in 2 cases of early renal allograft failure associated with renal vein thrombosis and extensive erythrocyte sickling. Hemoglobin AS was identified in retrospect. In case 1, a 41-year-old female recipient of a deceased donor renal transplant developed abdominal pain and acute allograft failure on day 16, necessitating immediate nephrectomy. In case 2, the transplanted kidney in a 58-year-old female recipient was noted to be mottled blue within minutes of reperfusion. At 24 hours, the patient was oliguric; and the graft was removed. Transplant nephrectomies had diffuse enlargement with diffuse, nonhemorrhagic, cortical, and medullary necrosis. Extensive sickle vascular occlusion was evident in renal vein branches; interlobar, interlobular, and arcuate veins; vasa recta; and peritubular capillaries. The renal arteries had sickle vascular occlusion in case 1. Glomeruli had only focal sickle vascular occlusion. The erythrocytes in sickle vascular occlusion had abundant cytoplasmic filaments by electron microscopy. Acute rejection was not identified in either case. Protein C and S levels, factor V Leiden, and lupus anticoagulant assays were within normal limits. Hemoglobin analysis revealed hemoglobin S of 21.8% and 25.6%, respectively. Renal allograft necrosis with intragraft sickle crisis, characterized by extensive vascular occlusive erythrocyte sickling and prominent renal vein thrombosis, was observed in 2 patients with sickle cell trait. Occult sickle cell trait may be a risk factor for early renal allograft loss.

Biocompatibility investigation of polyethylene glycol and alginate-poly-L-lysine for islet encapsulation.

The use of microencapsulation with alginate-poly-l-lysine (PLL) as the encapsulation material has been hampered by overgrowth of collagen around implanted capsules. Studies have shown that poly(ethylene glycol) (PEG) has higher biocompatibility than PLL. In this project, we examined the biocompatibility of PEG in comparison with PLL in the Lewis rat model. Capsules made from either PEG or PLL were implanted into Lewis rats in three anatomical sites: subcutaneous (SC), intramuscular (IM), and intra-epididymis (IE). After 2 or 4 weeks, capsules were retrieved, sectioned, and stained with Sirius Red for analysis of fibrotic overgrowth with ImageJ software. The results were statistically analyzed using either unpaired t test or analysis of variance (ANOVA). PEG demonstrated significantly better biocompatibility in SC, at both 2 and 4 weeks, and IE at 2 weeks (p < 0.0001). No significant differences were found in IM implantation at either time point (p = 0.36) between the two materials. However, there was significantly heavier fibrotic overgrowth around PEG capsules in IE than PLL capsules at 4 weeks (p < 0.01). When compared among the anatomical sites, IM implantation demonstrated significantly less fibrotic overgrowth than other sites for both materials (p < 0.01). In conclusion, PLL and PEG may induce different levels of fibrosis based on anatomical location and duration of implantation.

Bariatric surgery: a history of empiricism, a future in science.

BACKGROUND: The observation that obesity can be successfully treated by gastrointestinal surgery is a tribute to the innovative efforts by determined surgeons and the ever improving safety of general anesthesia. Yet as the body of knowledge and discovery on the root causes of human obesity accumulate, surgical approaches to treat morbid obesity are likely to change dramatically. While there is little doubt that dramatic weight loss can be achieved by surgically creating volume and absorption limitation to the reservoir and digestive functions of the gastrointestinal tract, human progress to more processed foods, less physical activity, and the pervasive public opinion that obesity is self-imposed are major obstacles to more widespread application of this approach. DISCUSSION: Here we provide a mechanico-physiologic analysis of current operations, their rationale and limitations, as well as a glimpse of how future interventions might develop as a result of current knowledge in the field. The future of bariatric surgery is discussed in the context of these emerging technologies and in the context of the politics of obesity.