Clarence E. Foster

A decade of experience with renal transplantation in African-Americans.

ObjectiveTo evaluate the strategies instituted by the authors’ center to decrease the time to transplantation and increase the rate of transplantation for African-Americans, consisting of a formal education program concerning the benefits of living organ donation that is oriented to minorities; a laparoscopic living donation program; use of hepatitis C-positive donors in documented positive recipients; and encouraging vaccination for hepatitis B, allowing the use of hepatitis B core Ab-positive donors. Summary Background DataThe national shortage of suitable kidney donor organs has disproportional and adverse effects on African-Americans for several reasons. Type II diabetes mellitus and hypertension, major etiologic factors for end-stage renal disease, are more prevalent in African-Americans than in the general population. Once kidney failure has developed, African-Americans are disadvantaged for the following reasons: this patient cohort has longer median waiting times on the renal transplant list; African-Americans have higher rates of acute rejection, which affects long-term allograft survival; and once they are transplanted, the long-term graft survival rates are lower in this population than in other groups. MethodsFrom March 1990 to November 2001 the authors’ center performed 2,167 renal transplants; 944 were in African-Americans (663 primary cadaver renal transplants and 253 primary Living donor renal transplants). The retransplants consisted of 83 cadaver transplants and 17 living donor transplants. Outcome measures of this retrospective analysis included median waiting time, graft and patient survival rates, and the rate of living donation in African-Americans and comparable non-African-Americans. Where applicable, data are compared to United Network for Organ Sharing national statistics. Statistical analysis employed appropriate SPSS applications. ResultsOne- and 5-year patient survival rates for living donor kidneys were 97.1% and 91.3% for non-African-Americans and 96.8% and 90.4% for African-Americans. One- and 5-year graft survival rates were 95.1% and 89.1% for non-African-Americans and 93.1% and 82.9% for African-Americans. One- and 4-year patient survival rates for cadaver donor kidneys were 91.4% and 78.7% for non-African-Americans and 92.4% and 80.2% for African-Americans. One- and 5-year graft survival rates for cadaver kidneys were 84.6% and 73.7% for non-African-Americans and 84.6% and 68.9% for African-Americans. One- and 5-year graft and patient survival rates were identical for recipients of hepatitis C virus-positive and anti-HBc positive donors, with the exception of a trend to late graft loss in the African-American hepatitis C virus group due to higher rates of noncompliance, an effect that disappears with censoring of graft loss from that cause. The cadaveric renal transplant median waiting time for non-African-Americans was 391 days compared to 734 days nationally; the waiting time for African-Americans was 647 days compared to 1,335 days nationally. When looking at all patients, living and cadaver donor, the median waiting times are 220 days for non-African-Americans and 462 days for African-Americans. ConclusionsPrograms specifically oriented to improve volunteerism in African-Americans have led to a marked improvement in overall waiting time and in rates of living donation in this patient group. The median waiting times to cadaveric renal transplantation were also significantly shorter in the authors’ center, especially for African-American patients, by taking advantage of the higher rates of hepatitis C infection and encouraging hepatitis B vaccination. These policies can markedly improve end-stage renal disease care for African-Americans by halving the overall waiting time while still achieving comparable graft and patient survival rates.

Solitary renal allografts from pediatric cadaver donors less than 2 years of age transplanted into adult recipients

Background. Transplantation of solitary pediatric renal allografts from donors 2 years of age or younger into adult recipients is controversial. Methods. Between 1998 and 2001, 15 solitary renal allografts from pediatric donors 2 years of age or younger were transplanted into adult recipients. Thirty-three en bloc renal allografts transplanted between 1994 and 2001 were used for comparison. En bloc kidneys were considered for separation if they measured greater than or equal to 6 cm in length. Renal function (creatinine clearance [CrCl]) was estimated using the Cockroft-Gault formula. Results. Two-year graft survival for the solitary and en bloc groups were 93% and 77%, respectively (P =0.405). Five grafts were lost because of arterial thrombosis (four en bloc and one solitary). Ureteral complications occurred in three grafts in the en bloc group. One-year postoperative CrCl of the surviving solitary (n=14) and en bloc (n=26) grafts were 51.4±26.2 mL/min and 55.1±27.5 mL/min (P >0.05), respectively. Donor weight and kidney length were greater in the solitary group (14.3±3.5 kg and 6.3±0.4 cm, respectively) compared with the en bloc group (10.8±2.6 kg and 5.9±0.3 cm, respectively) (P =0.001 and P <0.001). Conclusions. Separation of en bloc pairs into solitary allografts can be considered when the graft measures greater than or equal to 6 cm in length and donor weight is greater than or equal to 14 kg. The transplantation of solitary pediatric kidneys into adult recipients is successful, and the majority of pediatric en bloc allografts can be separated before transplantation.

Early Withdrawal of Calcineurin Inhibitors and Rescue Immunosuppression with Sirolimus-Based Therapy in Renal Transplant Recipients with Moderate to Severe Renal Dysfunction

Mammalian Target‐of‐Rapamycin inhibitors (mTOR inhibitors) can be used to replace the calcineurin inhibitors (CNIs) to prevent progression in chronic kidney disease (CKD) following organ transplantation. Discontinuation of tacrolimus in 136 recipients of kidney transplants with progressive renal dysfunction significantly decreased the rate of loss of estimated glomerular filtration rate (eGFR, mL/min/1.73 m2) (pre‐intervention vs. post‐intervention slopes, −0.013 vs. −0.002, p < 0.0001). Discontinuation of tacrolimus was associated with a sustained and significant improvement in graft function (pre‐eGFR vs. post‐eGFR; 26.0 ± 1.1 vs. 47.4 ± 2.1, p < 0.0001) in 74% of patients. This intervention was ineffective if the mean and (median) values of creatinine (mg/dL) and eGFR were 3.8 ± 0.2 (3.4) and 18.4 ± 1.9 (22.4), respectively, at the time of conversion therapy. During the follow‐up (range, 1.5–34.6, months), a total of 13 patients had their first acute rejection following the conversion therapy, an annual incidence of less than 10% and none of these episodes resulted in graft loss. The salutary effects of sirolimus therapy following discontinuation of tacrolimus in patients with moderate to severe graft dysfunction due to allograft nephropathy even in high‐risk patients improves kidney function and prevents acute rejection.

The impact of meeting donor management goals on the development of delayed graft function in kidney transplant recipients.

Many organ procurement organizations (OPOs) utilize preset critical care endpoints as donor management goals (DMGs) in order to standardize care and improve outcomes. The objective of this study was to determine the impact of meeting DMGs on delayed graft function (DGF) in renal transplant recipients. All eight OPOs of the United Network for Organ Sharing Region 5 prospectively implemented nine DMGs in every donor after neurologic determination of death (DNDD). “DMGs met” was defined a priori as achieving any seven of the nine DMGs and this was recorded at the time of consent for donation to reflect donor hospital ICU management, 12–18 h later, and prior to organ recovery. Multivariable analyses were performed to identify independent predictors of DGF (dialysis in the first week after transplantation) with a p < 0.05. A total of 722 transplanted kidneys from 492 DNDDs were included. A total of 28% developed DGF. DMGs were met at consent in 14%, 12–18 h in 32% and prior to recovery in 38%. DGF was less common when DMGs were met at consent (17% vs. 30%, p = 0.007). Independent predictors of DGF were age, Cr and cold ischemia time, while meeting DMGs at consent was significantly protective. The management of potential organ donors prior to consent affects outcomes and should remain a priority in the intensive care unit.

Simultaneous Heart and Kidney Transplantation in Patients with End‐stage Heart and Renal Failure

Combined simultaneous organ transplantation has become more common as selection criteria for transplantation have broadened. Broadening selection criteria is secondary to improved immunosuppression and surgical techniques. The kidney is the most common extrathoracic organ to be simultaneously transplanted with the heart. A series of 13 patients suffering from both end‐stage heart and renal failure underwent 14 simultaneous heart and kidney transplantations at Temple University Hospital between 1990 and 1999. This is the largest series reported from a single center. Three patients died during the initial hospitalization for an in‐hospital mortality of 21%. Of 10 patients who left the hospital, 1‐year survival was 100% and 2‐year survival 75%. One patient required retransplant for rejection within the first year. Overall mortality at 1 and 2 years was 25 and 41%, respectively. Four out of nine (44%) patients greater than 5 years post‐transplant were alive. Of the 10 patients who left the hospital, 66% were alive at 5 years. One patient succumbed to primary nonfunction of the cardiac allograft, while the four other deaths were secondary to bacterial or fungal sepsis. The patients racial backgrounds were equally divided between African‐American and white. These results are similar to those reported in a United Network of Organ Sharing Database (UNOS) registry analysis of 84 simultaneous heart and kidney transplants that found 1‐ and 2‐year survival to be 76 and 67%, respectively. Simultaneous heart and kidney transplantation continues to be a viable option for patients suffering from failure of these two organ systems, although the results do not match those of heart transplant alone.

In Vitro Maturation of Viable Islets From Partially Digested Young Pig Pancreas

Isolation of islets from market-sized pigs is costly, with considerable islet losses from fragmentation occurring during isolation and tissue culture. Fetal and neonatal pigs yield insulin unresponsive islet-like cell clusters that become glucose-responsive after extended periods of time. Both issues impact clinical applicability and commercial scale-up. We have focused our efforts on a cost-effective scalable method of isolating viable insulin-responsive islets. Young Yorkshire pigs (mean age 20 days, range 4–30 days) underwent rapid pancreatectomy (<5 min) and partial digestion using low-dose collagenase, followed by in vitro culture at 37°C and 5% CO2 for up to 14 days. Islet viability was assessed using FDA/PI or Newport Green, and function was assessed using a glucose-stimulated insulin release (GSIR) assay. Islet yield was performed using enumeration of dithizonestained aliquots. The young porcine (YP) islet yield at dissociation was 12.6 ± 2.1 × 103 IEQ (mean ± SEM) per organ and increased to 33.3 ± 6.4 × 103 IEQ after 7 days of in vitro culture. Viability was 97.3 ± 7% at dissociation and remained over 90% viable after 11 days in tissue culture (n = ns). Glucose responsiveness increased throughout maturation in culture. The stimulation index (SI) of the islets increased from 1.7 ± 2 on culture day 3 to 2.58 ± 0.5 on culture day 7. These results suggest that this method is both efficient and scalable for isolating and maturing insulin-responsive porcine islets in culture.

The Effect of Nrf2 Pathway Activation on Human Pancreatic Islet Cells

Background Pancreatic islets are known to contain low level of antioxidants that renders them vulnerable to oxidative stress. Nrf2 is the master regulator of numerous genes, encoding antioxidant, detoxifying, and cytoprotective molecules. Activation of Nrf2 pathway induces up-regulation of numerous genes encoding antioxidant and phase II detoxifying enzymes and related proteins. However, little is known regarding the role of this pathway in human islet cells. The aim was to investigate the effect of Nrf2 activator (dh404, CDDO-9,11-dihydro-trifluoroethyl amide) on human islet cells. Methods Human islets were obtained from cadaveric donors. After dh404 treatment, Nrf2 translocation, mRNA expression, and protein abundance of its key target gene products were examined. The proportion of dh404-treated or non-treated viable islet beta cells was analyzed using flowcytemetry. The cytoprotective effects against oxidative stress and production of inflammatory mediators, and in vivo islet function after transplantation were determined. Results Nrf2 nuclear translocation was confirmed by con-focal microscope within 2 hours after treatment, which was associated with a dose-dependent increase in mRNA expression of anti-oxidants, including NQO1, HO-1, and GCLC. Enhanced HO-1 expression in dh404 treated islets was confirmed by Western Blot assay. Islet function after transplantation (2000 IEQ/mouse) to diabetic nude mice was not affected with or without dh404 treatment. After induction of oxidative stress with hydrogen peroxide (200 μM) the proportion of dh404-treated viable islet cells was significantly higher in the dh404-treated than untreated islets (74% vs.57%; P<0.05). Dh404 significantly decreased production of cytokines/chemokines including IL-1β, IL-6, IFN-γ and MCP-1. Conclusion Treatment of human pancreatic islets with the potent synthetic Nrf2 activator, dh404, significantly increased expression of the key anti-oxidants enzymes, decreased inflammatory mediators in islets and conferred protection against oxidative stress in beta cells.

Noninvasive evaluation of the vascular response to transplantation of alginate encapsulated islets using the dorsal skin-fold model

Alginate encapsulation reduces the risk of transplant rejection by evading immune-mediated cell injury and rejection; however, poor vascular perfusion results in graft failure. Since existing imaging models are incapable of quantifying the vascular response to biomaterial implants after transplantation, in this study, we demonstrate the use of in vivo laser speckle imaging (LSI) and wide-field functional imaging (WiFI) to monitor the microvascular environment surrounding biomaterial implants. The vascular response to two islet-containing biomaterial encapsulation devices, alginate microcapsules and a high-guluronate alginate sheet, was studied and compared after implantation into the mouse dorsal window chamber (N = 4 per implant group). Images obtained over a 14-day period using LSI and WiFI were analyzed using algorithms to quantify blood flow, hemoglobin oxygen saturation and vascular density. Using our method, we were able to monitor the changes in the peri-implant microvasculature noninvasively without the use of fluorescent dyes. Significant changes in blood flow, hemoglobin oxygen saturation and vascular density were noted as early as the first week post-transplant. The dorsal window chamber model enables comparison of host responses to transplanted biomaterials. Future experiments will study the effect of changes in alginate composition on the vascular and immune responses.

Function and Viability of Human Islets Encapsulated in Alginate Sheets: In Vitro and in Vivo Culture

Islet encapsulation offers an immune system barrier for islet transplantation, and encapsulation within an alginate sheetlike structure offers the ability to be retrievable after transplanted. This study aims to show that human islets encapsulated into islet sheets remain functional and viable after 8 weeks in culture or when transplanted into the subcutaneous space of rats. Human islets were isolated from cadaveric organs. Dissociation and purification were done using enzymatic digestion and a continuous Ficoll-UWD gradient. Purified human islets were encapsulated in alginate sheets. Human Islet sheets were either kept in culture, at 37°C and 5% CO(2), or transplanted subcutaneously into Lewis rats. After 1, 2, 4, and 8 weeks, the human islet sheets were retrieved from the rats and assessed. The viability of the sheets was measured using fluorescein diacetate (FDA)/propidium iodide (PI), and function was measured through glucose-stimulated insulin release, in which the sheets were incubated for an hour in low-glucose concentration (2.8 mmol/L) and then high (28 mmol/L), then high (28 mmol/L) plus 3-isobutyl-1-methylxanthine (50 μm). Human islet sheets remained both viable, above 70%, and functional, with a stimulation index (insulin secretion in high glucose divided by insulin secretion in low glucose) above 1.5, over 8 weeks of culture or subcutaneous transplantation. Islet transplantation continues to make advances in the treatment of type 1 diabetes. These preliminary results suggest that encapsulated islets sheets can survive and maintain islet viability and function in vivo, within the subcutaneous region.

FTY720 and everolimus in de novo renal transplant patients at risk for delayed graft function: results of an exploratory one-yr multicenter study.

Abstract:  This exploratory, multicenter, open‐label study evaluated the efficacy and safety of FTY720, as a part of an immunosuppressive regimen, in combination with everolimus and steroids in de novo renal transplant recipients at increased risk of delayed graft function (DGF). Patients received FTY720 (5 mg) and everolimus (4 mg) 2–12 h pre‐transplantation, followed by 2.5 mg/d FTY720 and concentration‐controlled everolimus (4–8 ng/mL) post‐transplant for 12 months. Induction therapy was prohibited. After enrollment of 56 of the planned 200 patients between 2000 and 2002, the recruitment was terminated. The primary endpoint, rate of graft loss, or death at three months was 15.4% and the biopsy‐confirmed acute rejection was 42.3%. Death or graft loss at 12 months in the DGF and non‐DGF arms was 36.0% and 25.9%, respectively. The mean estimated creatinine clearance at three months was 63 and 55 mL/min in the non‐DGF and DGF groups, respectively, while at 12 months it was 56 mL/min in both the groups. Although there was no comparator arm, the results from this exploratory study (compared with data from other phases II and III trials) indicated no apparent benefits of FTY720‐based regimens for prevention of acute rejection and preservation of renal function in renal transplant recipients at high risk of DGF.