Mark L. Barr

Immunosuppression: Evolution in practice and trends, 1993-2003

Over the last 10 years, there have been important changes in immunosuppression management and strategies for solid‐organ transplantation, characterized by the use of new immunosuppressive agents and regimens. An organ‐by‐organ review of OPTN/SRTR data showed several important trends in immunosuppression practice. There is an increasing trend toward the use of induction therapy with antibodies, which was used for most kidney, pancreas after kidney (PAK), simultaneous pancreas‐kidney (SPK) and pancreas transplant alone (PTA) recipients in 2004 (72–81%) and for approximately half of all intestine, heart and lung recipients. The highest usage of the tacrolimus/mycophenolate mofetil combination as discharge regimen was reported for SPK (72%) and PAK (64%) recipients. Maintenance of the original discharge regimen through the first 3 years following transplantation varied significantly by organ and drug. The usage of calcineurin inhibitors for maintenance therapy was characterized by a clear transition from cyclosporine to tacrolimus. Corticosteroids were administered to the majority of patients; however, steroid‐avoidance and steroid‐withdrawal protocols have become increasingly common. The percentage of patients treated for acute rejection during the first year following transplantation has continued to decline, reaching 13% for those who received a kidney in 2003, 48% of which cases were treated with antibodies.

Report of a National Conference on Donation after cardiac death.

A national conference on organ donation after cardiac death (DCD) was convened to expand the practice of DCD in the continuum of quality end‐of‐life care.

Ceramide accumulation mediates inflammation, cell death and infection susceptibility in cystic fibrosis

Microbial lung infections are the major cause of morbidity and mortality in the hereditary metabolic disorder cystic fibrosis, yet the molecular mechanisms leading from the mutation of cystic fibrosis transmembrane conductance regulator (CFTR) to lung infection are still unclear. Here, we show that ceramide age-dependently accumulates in the respiratory tract of uninfected Cftr-deficient mice owing to an alkalinization of intracellular vesicles in Cftr-deficient cells. This change in pH results in an imbalance between acid sphingomyelinase (Asm) cleavage of sphingomyelin to ceramide and acid ceramidase consumption of ceramide, resulting in the higher levels of ceramide. The accumulation of ceramide causes Cftr-deficient mice to suffer from constitutive age-dependent pulmonary inflammation, death of respiratory epithelial cells, deposits of DNA in bronchi and high susceptibility to severe Pseudomonas aeruginosa infections. Partial genetic deficiency of Asm in Cftr−/−Smpd1+/− mice or pharmacological treatment of Cftr-deficient mice with the Asm blocker amitriptyline normalizes pulmonary ceramide and prevents all pathological findings, including susceptibility to infection. These data suggest inhibition of Asm as a new treatment strategy for cystic fibrosis.

The Role of the Hyaluronan Receptor CD44 in Mesenchymal Stem Cell Migration in the Extracellular Matrix

In a previous investigation, we demonstrated that mesenchymal stem cells (MSCs) actively migrated to cardiac allografts and contributed to graft fibrosis and, to a lesser extent, to myocardial regeneration. The cellular/molecular mechanism responsible for MSC migration, however, is poorly understood. This paper examines the role of CD44‐hyaluronan interaction in MSC migration, using a rat MSC line Ap8c3 and mouse CD44−/− or CD44+/+ bone marrow stromal cells (BMSCs). Platelet‐derived growth factor (PDGF) stimulation of MSC Ap8c3 cells significantly increased the levels of cell surface CD44 detected by flow cytometry. The CD44 standard isoform was predominantly expressed by Ap8c3 cells, accounting for 90% of the CD44 mRNA determined by quantitative real‐time polymerase chain reaction. Mouse CD44−/− BMSCs bonded inefficiently to hyaluronic acid (HA), whereas CD44+/+ BMSC and MSC Ap8c3 adhered strongly to HA. Adhesions of MSC Ap8c3 cells to HA were suppressed by anti‐CD44 antibody and by CD44 small interfering RNA (siRNA). HA coating of the migration chamber significantly promoted passage of CD44+/+ BMSC or Ap8c3 cells, but not CD44−/− BMSCs, through the insert membranes (p < .01). Migration of MSC Ap8c3 was significantly inhibited by anti‐CD44 antibodies (p < .01) and to a lesser extent by CD44 siRNA (p = .05). The data indicate that MSC Ap8c3 cells, in response to PDGF stimulation, express high levels of CD44 standard (CD44s) isoform, which facilitates cell migration through interaction with extracellular HA. Such a migratory mechanism could be critical for recruitment of MSCs into wound sites for the proposition of tissue regeneration, as well as for migration of fibroblast progenitors to allografts in the development of graft fibrosis.

A Report of the Vancouver Forum on the Care of the Live Organ Donor: Lung, Liver, Pancreas, and Intestine Data and Medical Guidelines

An international conference of transplant physicians, surgeons, and allied health professionals was held in Vancouver, Canada, on September 15 and 16, 2005 to address the care of the live lung, liver, pancreas, and intestine organ donor. The Vancouver Forum was convened under the auspices of the Ethics Committee of The Transplantation Society. Forum participants included over 100 leaders in organ transplantation, representing many countries from around the world, including participants from the following continents: Africa, Asia, Australia, Europe, North and South America. The objective of the Vancouver Forum was to develop an international standard of care for the live lung, liver, pancreas and intestinal organ donor. This Vancouver Forum followed a conference convened in Amsterdam on the care of the live kidney donor (1, 2). There were four organ specific work groups at the Vancouver Forum: lung, liver, pancreas and intestine. Each organ work group addressed the following topics in concert and reported their findings in a plenary presentation to all participants:

Photopheresis for the Prevention of Rejection in Cardiac Transplantation

BACKGROUND Photopheresis is an immunoregulatory technique in which lymphocytes are reinfused after exposure to a photoactive compound (methoxsalen) and ultraviolet A light. We performed a preliminary study to assess the safety and efficacy of photopheresis in the prevention of acute rejection of cardiac allografts. METHODS A total of 60 consecutive eligible recipients of primary cardiac transplants were randomly assigned to standard triple-drug immunosuppressive therapy (cyclosporine, azathioprine, and prednisone) alone or in conjunction with photopheresis. The photopheresis group received a total of 24 photopheresis treatments, each pair of treatments given on two consecutive days, during the first six months after transplantation. The regimen for maintenance immunosuppression, the definition and treatment of rejection episodes, the use of prophylactic antibiotics, and the schedule for cardiac biopsies were standardized among all 12 study centers. All the cardiac-biopsy samples were graded in a blinded manner at a central pathology laboratory. Plasma from the subgroup of 34 patients (57 percent) who were enrolled at the nine U.S. centers was analyzed by polymerase-chain-reaction amplification for cytomegalovirus DNA. RESULTS After six months of follow-up, the mean (+/-SD) number of episodes of acute rejection per patient was 1.44+/-1.0 in the standard-therapy group, as compared with 0.91+/-1.0 in the photopheresis group (P=0.04). Significantly more patients in the photopheresis group had one rejection episode or none (27 of 33) than in the standard-therapy group (14 of 27), and significantly fewer patients in the photopheresis group had two or more rejection episodes (6 of 33) than in the standard-therapy group (13 of 27, P=0.02). There was no significant difference in the time to a first episode of rejection, the incidence of rejection associated with hemodynamic compromise, or survival at 6 and 12 months. Although there were no significant differences in the rates or types of infection, cytomegalovirus DNA was detected significantly less frequently in the photopheresis group than in the standard-therapy group (P=0.04). CONCLUSIONS In this pilot study, the addition of photopheresis to triple-drug immunosuppressive therapy significantly decreased the risk of cardiac rejection without increasing the incidence of infection.

Angiotensin II Has Multiple Profibrotic Effects in Human Cardiac Fibroblasts

BACKGROUND Angiotensin II (Ang II) is implicated in cardiac remodeling and is increasingly recognized for its profibrotic activity. METHODS AND RESULTS Because little is known about the direct cellular effects of Ang II on human cardiac fibroblasts, we isolated fibroblasts from ventricles of explanted human hearts and added Ang II (100 nmol/L) to determine its role in growth, extracellular matrix accumulation, and adhesion. To assess which Ang II receptor is involved, Ang II was added in the presence of irbesartan (10 micromol/L), a specific AT(1) receptor antagonist; PD 123319 (10 micromol/L), a specific AT(2) receptor antagonist, or divalinil (100 nmol/L), an AT(4) receptor inhibitor. In human ventricles (n=13), message levels of atrial natriuretic peptide and AT(1) receptor were inversely correlated, which suggests a decrease in AT(1) receptor expression with progressive heart failure. Northern analysis and fluorescence-activated cell sorting demonstrated AT(1) receptor in cultured human cardiac fibroblasts. Ang II increased mitogen-activated protein kinase activity and in DNA synthesis (5-fold, P<0.01) stimulated a 2-fold increase in transforming growth factor-beta(1) (P<0.05) mRNA levels at 2 hours and a 2-fold increase in laminin (P<0.05) and fibronectin (P<0.05) mRNA levels at 24 hours. Ang II also enhanced plasminogen activator inhibitor-1 expression, which inhibits metalloproteinases that degrade the extracellular matrix. All of these effects were inhibited by irbesartan but not PD 123319 or divalinil. In addition, Ang II increased cardiac fibroblast attachment to collagens I and III, which was associated with an increase in focal adhesion kinase activity. CONCLUSIONS Activation of the AT(1) receptor in human heart promotes fibrosis. Ang II plays a novel role in stimulation of plasminogen activator inhibitor-1 expression and adhesion of cardiac fibroblasts to collagen.

Pediatric Lung Allocation: The Rest of the Story

In their article ‘‘The Equitable Allocation of Deceased Donor Lungs for Transplant in Children in the United States,’’ Snyder et al (1) provide an objective analysis of the waiting list mortality and transplant rate for children under 12 years of age before and after the implementation of the US lung allocation system. The primary conclusion from their article is that there is no significant difference between either metric for pediatric lung transplant candidates in the 6to 11-year-old age group compared to older children and adults. Although the authors acknowledge the fact that children under 12 continue to receive organs based on waiting time creates significantly different listing practices in comparison to older candidates (likely underestimating waiting list mortality for children under 12), the tacit implication is that the widely publicized case advanced by the parents of SarahMurnaghan, the child in Philadelphia, is without merit.

Living-donor lobar lung transplantation experience: Intermediate results

OBJECTIVE Living-donor lobar lung transplantation offers an alternative for patients with a life expectancy of less than a few months. We report on our intermediate results with respect to recipient survival, complications, pulmonary function, and hemodynamic reserve. METHODS Thirty-eight living-donor lobar lung transplants were performed in 27 adult and 10 pediatric patients for cystic fibrosis (32), pulmonary hypertension (two), pulmonary fibrosis (one), viral bronchiolitis (one), bronchopulmonary dysplasia (one), and posttransplantation obliterative bronchiolitis (one). Seventy-six donors underwent donor lobectomies. RESULTS There were 14 deaths among the 37 patients, with an average follow-up of 14 months. Predominant cause of death was infection, consistent with the large percentage of patients with cystic fibrosis in our population. The overall incidence of rejection was 0.07 episodes/patient-month, representing 0.8 episodes/patient. Postoperative pulmonary function testing generally showed a steady improvement that plateaued by postoperative months 9 to 12. Fourteen patients who were followed up for at least 1 year underwent right heart catheterization; pressures and pulmonary vascular resistances were within normal ranges. Bronchiolitis obliterans was definitively diagnosed in three patients. Among the 76 donors, complications in the postoperative period included postpericardiotomy syndrome (three), atrial fibrillation (one), and surgical reexploration (three). CONCLUSIONS We believe that these data support an expanded role for living-donor lobar lung transplantation. Our intermediate data are encouraging with respect to the functional outcome and survival of these critically ill patients, who would have died without this option.

Lobar transplantation: Indications, technique, and outcome

Lobar transplantation represents a therapeutic option for children and some adults with severe end-stage pulmonary disease. Six patients including two neonates, three children, and one adult underwent lobar transplantation. Ages ranged from 17 days to 21 years. Transplant procedures were unilateral in the neonates and two of the children and bilateral in the child and adult who had cystic fibrosis. The donor lobes were from cadavers in the two neonates and living related donors in the children and the adult. Unilateral grafts involved use of the right upper lobe in the 12-year-old patient with bronchopulmonary dysplasia; right middle lobe with a ventricular septal defect repair in the 4-year-old patient with Eisenmengers syndrome, left upper lobe in the 28-day-old patient with primary pulmonary hypertension, and the right upper and middle lobes in the 17-day-old patient with diaphragmatic hernia. Bilateral lobar transplantations were performed with the right lower and left lower lobes in the two patients with cystic fibrosis (aged 13 and 21 years). The two neonates underwent emergency transplantation with the use of extracorporeal membrane oxygenation as a bridge. Perioperative survival was 83%, with only the 4-year-old patient with ventricular septal defect/Eisenmengers syndrome dying early. No airway complications were observed. The unilateral grafts received most of the blood flow as shown by perfusion scanning (range 74% to 99%). Living related donor complications included prolonged air leaks (> 6 days) in two patients. In urgent situations, such as an infant requiring extracorporeal membrane oxygenation, and in the existing milieu of donor shortage, lobar transplantation (living related or cadaveric) is a surgically feasible procedure and can provide a donor source in the limited time frame of these clinical situations. Bilateral lobe transplantation may be a viable option for patients with cystic fibrosis and life-threatening respiratory decompensation.