Histological Signs Of Rejection Research Articles

Partial decellularization eliminates immunogenicity in tracheal allografts.

There is currently no suitable autologous tissue to bridge large tracheal defects. As a result, no standard of care exists for long-segment tracheal reconstruction. Tissue engineering has the potential to create a scaffold from allografts or xenografts that can support neotissue regeneration identical to the native trachea. Recent advances in tissue engineering have led to the idea of partial decellularization that allows for the creation of tracheal scaffolds that supports tracheal epithelial formation while preserving mechanical properties. However, the ability of partial decellularization to eliminate graft immunogenicity remains unknown, and understanding the immunogenic properties of partially decellularized tracheal grafts (PDTG) is a critical step toward clinical translation. Here, we determined that tracheal allograft immunogenicity results in epithelial cell sloughing and replacement with dysplastic columnar epithelium and that partial decellularization creates grafts that are able to support an epithelium without histologic signs of rejection. Moreover, allograft implantation elicits CD8+ T-cell infiltration, a mediator of rejection, while PDTG did not. Hence, we establish that partial decellularization eliminates allograft immunogenicity while creating a scaffold for implantation that can support spatially appropriate airway regeneration.

P12.15: Dapagliflozin for the Treatment of Post-transplant Diabetes Mellitus After Pancreas Transplantation: A Case Report With A 14-Month Follow-up

Introduction: Post-transplant diabetes mellitus (PTDM) is a common metabolic alteration after transplant. Almost all immunosuppressive (IS) drugs, reduce insulin sensitivity and express cytotoxicity against β-cell. The cause of hyperglycemia in pancreas transplant (PTX) can also be linked to rejection and type 1 diabetes (T1D) recurrence. However, mild hyperglycemia with preserved c-peptide and clear signs of insulin resistance (IR) should be treated using type 2 diabetes therapeutic recommendations, thus taking into account the extra-glycemic effects of the new antidiabetic drugs. In recent years, great attention has been paid to sodium-glucose cotransporter-2 inhibitors (SGLT-2i) for their cardio and renoprotective action. Case presentation: We report the case of a male patient who underwent PTX alone in 2007, initially on IS with tacrolimus, mycophenolate mofetil (MM) and prednisone. PTX was complicated by several episodes of acute rejection and the development of lobar pneumonia. For this reason, steroid was discontinued and MM reduced. The patient is in regular pneumological follow-up and stable. Despite radiological and histological signs of rejection, the patient remained in good glycemic control until 2016 when for the first time altered home blood glucose (BG) and glycated hemoglobin (HbA1c: 6.6%) were found. On this occasion, considering the presence of a robust c-peptide, treatment with metformin was started with beneficial effect. In February 2020, HbA1c was 6.1% with a high glycemic variability and trend for hypoglycemic events secondary to therapy with repaglinide, added by other clinician 4 months before. Fasting BG was 109 mg/dl, c-peptide 1.74 ng/ml (stable for at least 5 years). Mild diabetic nephropathy was found (eGFR: 69 ml/min; albuminuria: 94 mg/L). Considering these data and the patient’s particular condition, repaglinide was discontinued and dapagliflozin 10 mg/day was associated with metformin. On March 2021 patient showed HbA1c 6.8% with normal home BG values and an improved renal function with normalization of albuminuria. No adverse events were reported. Conclusion: Limited data in the literature describe pathophysiological mechanism and frequency of PTDM after PTX. History of T1D influences the choice of insulin as first therapeutic approach in high BG after PTX. The combination of IR and β-cell dysfunction caused by IS, T1D recurrence, and rejection contributes to the worsening of BG control. Sometimes one component prevails over the other, as in the case of our patient, who achieved BG compensation with oral agents only. The use of repaglinide as well as any other secretagogue drug is not recommended due to the rapid β-cell exhaustion after PTX. Use of SGLT-2i has allowed to maintain good glycemic control without hypoglycemia, taking advantage of renal protection and reduced CV risk. Great caution is required in this population, also considering the higher risk of adverse events as ketoacidosis and genitourinary infections.

Elevated fractional donor-derived cell-free DNA during subclinical graft injury after liver transplantation.

Personalized immunosuppression (IS) promises to improve the balance of necessary control of alloreactivity and dose-dependent adverse effects of long-term IS such as kidney insufficiency, infections, and malignancies. The majority of liver transplantation (LT) recipients exhibit graft injuries (graft inflammation and/or fibrosis) that are not eligible for an IS reduction according to current Banff criteria, even when liver enzymes are normal or only marginally elevated. This cross-sectional study evaluated the noninvasive prediction of such subclinical graft injuries in surveillance liver biopsies via donor-derived cell-free DNA (dd-cfDNA). Absolute and fractional dd-cfDNA increased stepwise from patients without histological signs of rejection (n=26) over subclinical graft injury (n=61), including subclinical T cell-mediated rejection to clinical overt T cell-mediated rejection (n=21). Thus, fractional plasma dd-cfDNA was significantly elevated paired to surveillance biopsies with relevant subclinical graft injury according to 2016 Banff criteria compared with those with minimal or absent histological graft injury. In contrast, the presence of donor-specific anti-human leukocyte antigen antibodies was not associated with the amount of dd-cfDNA. The sensitivity and specificity of fractional dd-cfDNA to noninvasively predict relevant subclinical graft injury was rather limited with 73% and 52% at the cutoff value of 2.1% fractional dd-cfDNA. The positive predictive value of fractional dd-cfDNA above 2.1% was 76% to noninvasively predict subclinical graft injury, calculated on the prevalence of graft injury in our prospective surveillance biopsy program, whereas the negative predictive values was not predictive (47%). In conclusion, dd-cfDNA has a rather limited diagnostic fidelity in addition to other noninvasive markers for the assessment of subclinical graft injury in personalized IS approaches after LT in a cross-sectional setting.

A Combined microRNA and Chemokine Profile in Urine to Identify Rejection After Kidney Transplantation.

First, microRNA (miR) molecules were screened in transplant biopsies and urine sediments of patients with acute rejection and patients without rejection and stable graft function. Second, the expression of 15 selected miRs was quantified in an independent set of 115 urine sediments of patients with rejection and 55 urine sediments of patients without histological signs of rejection on protocol biopsy. Additionally, CXCL-9 and CXCL-10 protein levels were quantified in the urine supernatant. Levels of miR-155-5p (5.7-fold), miR-126-3p (4.2-fold), miR-21-5p (3.7-fold), miR-25-3p (2.5-fold), and miR-615-3p (0.4-fold) were significantly different between rejection and no-rejection urine sediments. CXCL-9 and CXCL-10 levels were significantly elevated in urine from recipients with rejection. In a multivariable model (sensitivity: 89.1%, specificity: 75.6%, area under the curve: 0.94, P < 0.001), miR-155-5p, miR-615-3p, and CXCL-9 levels were independent predictors of rejection. Stratified 10-fold cross validation of the model resulted in an area under the curve of 0.92. A combined urinary microRNA and chemokine profile discriminates kidney transplant rejection from stable graft conditions.

Biopsy findings after detection of de novo donor-specific antibodies in renal transplant recipients: a single center experience

BackgroundDe novo donor-specific antibodies (DSA) are associated with an increased risk of antibody-mediated rejection and a substantial reduction of allograft survival. We hypothesized that detection of DSA should prompt a biopsy even in the absence of proteinuria and loss of estimated glomerular filtration rate (eGFR). However, data on a population without proteinuria or loss of kidney function is scant, and this is the main novelty of our study design.MethodsSingle center retrospective analysis on biopsy findings after detection of de novo DSA. One-hundred-thirty-two kidney and pancreas-kidney transplant recipients were included. Eighty-four of these patients (63.6%) underwent allograft biopsy. At the time of biopsy n = 50 (59.5%) had a protein/creatinine ratio (PCR) > 300 mg/g creatinine and/or a loss of eGFR ≥ 10 ml/min in the previous 12 months, whereas 40.5% did not. Diagnosis of rejection was performed according to Banff criteria.ResultsSeventy-seven (91.7%) of the biopsies had signs of rejection (47.6% antibody mediated rejection (ABMR), 13.1% cellular, 20.2% combined, 10.7% borderline). Among subjects without proteinuria or loss of eGFR ≥ 10 ml/min/a (n = 34), 29 patients (85.3%) showed signs of rejection (44.1% antibody mediated (ABMR), 14.7% cellular, 11.8% combined, 14.7% borderline).ConclusionThe majority of subjects with de novo DSA have histological signs of rejection, even in the absence of proteinuria and deterioration of graft function. Thus, it appears reasonable to routinely perform an allograft biopsy after the detection of de novo DSA.Graphic abstract

Circulating mitochondrial genes detect acute cardiac allograft rejection: Role of the mitochondrial calcium uniporter complex.

Acute rejection after heart transplantation increases the risk of chronic dysfunction. Disturbances in mitochondrial function may play a contributory role, however, the relationship between histological signs of rejection in the human transplanted heart and expression levels of circulating mitochondrial genes, such as the mitochondrial Ca2+ uniporter (MCU) complex, remains unexplored. We conducted an RNA‐sequencing analysis to identify altered mitochondrial genes in serum and to evaluate their diagnostic accuracy for rejection episodes. We included 40 consecutive samples from transplant recipients undergoing routine endomyocardial biopsies. In total, 112 mitochondrial genes were identified in the serum of posttransplant patients, of which 28 were differentially expressed in patients with acute rejection (p < .05). Considering the receiver operating characteristic analysis with an area under the curve (AUC) >0.900 to discriminate patients with moderate or severe degrees of rejection, we found that the MCU system showed a strong capability for detection: MCU (AUC = 0.944, p < .0001), MCU/MCUR1 ratio (AUC = 0.972, p < .0001), MCU/MCUB ratio (AUC = 0.970, p < .0001), and MCU/MICU1 ratio (AUC = 0.970, p < .0001). Mitochondrial alterations are reflected in peripheral blood and are capable of discriminating between patients with allograft rejection and those not experiencing rejection with excellent accuracy. The dysregulation of the MCU complex was found to be the most relevant finding.

The Helsinki Face Transplantation: Surgical aspects and 1-year outcome

Since 2005, at least 38 facial transplantations have been performed worldwide. We herein describe the surgical technique and 1-year clinical outcome in Finland's first face transplant case. A 34-year-old male who had a severe facial deformity following ballistic trauma in 1999 underwent facial transplantation at the Helsinki University Hospital on 8th February 2016. Three-dimensional (3D) technology was used to manufacture donor and recipient patient-specific osteotomy guides and a donor face mask. The facial transplant consisted of a Le Fort II maxilla, central mandible, lower ⅔ of the midface muscles, facial and neck skin, oral mucosa, anterior tongue and floor of mouth muscles, facial nerve (three bilateral branches), and bilateral hypoglossal and buccal nerves. At 1-year follow-up, there have thus far been no clinical or histological signs of rejection. The patient has a good aesthetic outcome with symmetrical restoration of the mobile central part of the face, with recovery of pain and light touch sensation to almost the entire facial skin and intraoral mucosa. Electromyography at 1 year has confirmed symmetrical muscle activity in the floor of the mouth and facial musculature, and the patient is able to produce spontaneous smile. Successful social and psychological outcome has also been observed. Postoperative complications requiring intervention included early (nasopalatinal fistula, submandibular sialocele, temporomandibular joint pain and transient type 2 diabetes) and late (intraoral wound and fungal infection, renal impairment and hypertension) complications. At 1 year, we report an overall good functional outcome in Finland's first face transplant.

THE VALUE OF EXTRACORPOREAL PHOTOCHEMOTHERAPY IN RENAL TRANSPLANT REJECTION INHIBITION

The aim of the study was to determine the value of extracorporeal photochemotherapy (EPCT) in the induction of tissue tolerance in renal transplantation. EPCT was applied to 24 renal transplant recipients in early postoperative period, the control group consisted of paired transplant recipients. In the group using EPCT over a three-year period of observation no clinical or histological signs of rejection were observed. In the control group, histologically confirmed rejection was observed in 4 cases, in 2 cases transplantectomy due to acute rejection. The reducing incidence of infectious complications in the study group compared with the control one (4 and 19 cases, respectively) and decreasing number of hospitalizations on various reasons (8 and 47 cases in the study and control groups, respectively) were also noted. Three-year graft survival was 100% and 83.3% in the study and the control groups, respectively. Using immunological tests in 30 days after transplantation the stable number of cells expressing coactivation molecules (57.7 ± 18.2 and 52.7 ± 23.2%, respectively, p &gt; 0.05) and the density of their co-expression (22.7 ± 6.0 and 19.6 ± 7.0 units, respectively, p &gt; 0.05) were demonstrated, while in the study group, the pronounced and statistically significant reduction both in the amount of cells expressing co-activation receptors (from 57.7 ± 18.2 to 34.5 ± 11.4%, p &lt; 0.05) and in the density of these receptors on naive helper T-lymphocytes (from 22.7 ± 6.0 to 16.8 ± 5.1 units, p &lt; 0.05) was revealed. Thus, it is noted that EPCT provides induction of tolerance to MHC antigens in kidney transplantation due to reducing expression of coactivation molecules which promote the second signaling pathway to T-cell receptor activation.

Accelerated telomere reduction and hepatocyte senescence in tolerated human liver allografts

BackgroundIn living donor liver transplantation, the biological organ age of the donated allograft is unknown in young patients who receive grafts from older donors. Few studies have focused on the effects of aging on allografts in the state of tolerance. The purpose of this study was to assess the biological organ age of liver grafts. MethodsIn 20 tolerated allografts over a 10-year post-transplant follow-up period, the relative telomere lengths were measured by multiplex quantitative polymerase chain reaction, and hepatocyte nuclear size and cell cycle phase markers were determined by immunohistochemistry. The results were compared with the same measurements that had been obtained prior to transplantation in the recipients' pre-implantation donor livers. Tolerance was defined strictly as a condition in which the allograft functioned normally and showed normal histology without any histological signs of rejection, fibrosis or inflammation in the absence of immunosuppression. ResultsFirst, telomere length correlated with chronological donor age (n=41). Accelerated telomere reduction was seen in tolerated grafts compared with the predicted telomere length of each allograft calculated from the regression line of donor livers. Tolerated grafts were associated with higher hepatocyte p21 expression and greater nuclear area than in the donor livers prior to transplantation. ConclusionsThese findings suggest that allografts age more rapidly than in the normal population, and that grafts may reach the limit of proliferative capacity even in the state of tolerance.

The Management of Antibody-Mediated Rejection in the First Presensitized Recipient of a Full-Face Allotransplant

We report on the management of the first full-face transplantation in a sensitized recipient with a positive preoperative crossmatch and subsequent antibody-mediated rejection (AMR). The recipient is a 45-year-old female who sustained extensive chemical burns, with residual poor function and high levels of circulating anti-HLA antibodies. With a clear immunosuppression plan and salvage options in place, a full-face allotransplant was performed using a crossmatch positive donor. Despite plasmapheresis alongside a standard induction regimen, clinical signs of rejection were noted on postoperative day 5 (POD5). Donor-specific antibody (DSA) titers rose with evidence of C4d deposits on biopsy. By POD19, biopsies showed Banff Grade III rejection. Combination therapy consisting of plasmapheresis, eculizumab, bortezomib and alemtuzumab decreased DSA levels, improved clinical exam, and by 6 months postop she had no histological signs of rejection. This case is the first to demonstrate evidence and management of AMR in face allotransplantation. Our findings lend support to the call for an update to the Banff classification of rejection in vascularized composite tissue allotransplantation (VCA) to include AMR, and for further studies to better classify the histology and mechanism of action of AMR in VCA.

Successful lung transplantation in the presence of pre-existing donor-specific cytotoxic HLA Class II antibodies

Pre-existing HLA antibodies are a well-established causal factor for rejection and graft dysfunction after solid-organ transplantation. In lung transplant recipients, the significance of HLA antibodies has not been fully established. Although rare, several cases of hyperacute rejection of the lung allograft due to pre-existing donor-specific HLA antibodies have been described. In contrast, we describe successful lung transplantation in a patient with pre-existing donor-specific HLA antibodies. Routine screening prior to lung transplantation revealed cytotoxic HLA Class II antibodies, directed against the alpha chain of HLA-DQ, induced by a previous liver transplant. Due to clinical deterioration, it was decided to accept a lung offer without virtual crossmatching for DQ compatibility. Cytotoxic antibodies against the lung donor were confirmed retrospectively, resulting in strong positive B-cell crossmatches. Interestingly, the patient showed no clinical or histologic signs of rejection. This case demonstrates that the presence of high levels of pre-existing donor-specific HLA antibodies does not necessarily lead to rejection and graft failure. Although screening for antibodies prior to transplantation remains crucial, this study shows that we are thus far not able to predict the effect of pre-existing HLA Class II antibodies on allograft survival in individual patients.

Passaged Adult Chondrocytes Can Form Engineered Cartilage with Functional Mechanical Properties: A Canine Model

It was hypothesized that previously optimized serum-free culture conditions for juvenile bovine chondrocytes could be adapted to generate engineered cartilage with physiologic mechanical properties in a preclinical, adult canine model. Primary or passaged (using growth factors) adult chondrocytes from three adult dogs were encapsulated in agarose, and cultured in serum-free media with transforming growth factor-beta3. After 28 days in culture, engineered cartilage formed by primary chondrocytes exhibited only small increases in glycosaminoglycan content. However, all passaged chondrocytes on day 28 elaborated a cartilage matrix with compressive properties and glycosaminoglycan content in the range of native adult canine cartilage values. A preliminary biocompatibility study utilizing chondral and osteochondral constructs showed no gross or histological signs of rejection, with all implanted constructs showing excellent integration with surrounding cartilage and subchondral bone. This study demonstrates that adult canine chondrocytes can form a mechanically functional, biocompatible engineered cartilage tissue under optimized culture conditions. The encouraging findings of this work highlight the potential for tissue engineering strategies using adult chondrocytes in the clinical treatment of cartilage defects.

Impact of Subclinical Rejection on Kidney Graft Function During the First Year after Transplantation

Impact of Subclinical Rejection on Kidney Graft Function During the First Year after Transplantation Introduction. There is no unified opinion about the role of subclinical rejection (SR) in further kidney graft function and the necessity of its treatment. Aim of the Study. The aim of our study is to determine the impact of SR on kidney graft function during the first year after transplantation. Materials and methods. Totally 144 deceased donor kidney transplantations were performed in a single center between January 1, 2007, and March 16, 2009. The study included patients who developed the primary graft function (n=78). Protocol biopsies were performed in 28 patients. The patients were divided into 4 groups: group A - patients, who had no histological signs of rejection on their protocol biopsy; group B - patients with histological signs of rejection who were treated with steroids; group C - patients with histological signs of rejection and with no treatment; group D - patients who were not biopsied. All groups were compared for serum creatinine level, glomerular filtration rate (GFR), number of clinical rejection 1, 3, 6, 12 months after the transplantation. Results. Histological examination revealed that 18 of 28 patients who underwent the protocol biopsy had SR grade from IA to IIA (64.3%). Comparison of the group showed no statistical difference in creatinine level and GFR 12 months after the transplantation (p &gt; 0,05 for all groups). Conclusions. During the first 12 months after transplantation SR does not significantly impact the graft function. However, the graft function was slightly worse in patients with SR and without treatment, and relatively better in patients with SR who were treated by steroids than in patients from others groups. Further follow-up is needed to determine the longer-term results.

Both epithelial cells and mesenchymal stem cell–derived chondrocytes contribute to the survival of tissue-engineered airway transplants in pigs

We sought to determine the relative contributions of epithelial cells and mesenchymal stem cell-derived chondrocytes to the survival of tissue-engineered airway transplants in pigs. Nonimmunogenic tracheal matrices were obtained by using a detergent-enzymatic method. Major histocompatibility complex-unmatched animals (weighing 65 +/- 4 kg) were divided into 4 groups (each n = 5), and 6 cm of their tracheas were orthotopically replaced with decellularized matrix only (group I), decellularized matrix with autologous mesenchymal stem cell-derived chondrocytes externally (group II), decellularized matrix with autologous epithelial cells internally (group III), or decellularized matrix with both cell types (group IV). Autologous cells were recovered, cultured, and expanded. Mesenchymal stem cells were differentiated into chondrocytes by using growth factors. Both cell types were seeded simultaneously with a dual-chamber bioreactor. Animals were not immunosuppressed during the entire study. Biopsy specimens and blood samples were taken from recipients continuously, and animals were observed for a maximum of 60 days. Matrices were completely covered with both cell types within 72 hours. Survival of the pigs was significantly affected by group (P < .05; group I, 11 +/- 2 days; group II, 29 +/- 4 days; group III, 34 +/- 4 days; and group IV, 60 +/- 1 days). Cause of death was a combination of airway obstruction and infection (group I), mainly infection (group II), or primarily stenosis (group III). However, pigs in group IV were alive, with no signs of airway collapse or ischemia and healthy epithelium. There were no clinical, immunologic, or histologic signs of rejection despite the lack of immunosuppression. We confirm the clinical potential of autologous cell- and tissue-engineered tracheal grafts, and suggest that the seeding of both epithelial and mesenchymal stem cell-derived chondrocytes is necessary for optimal graft survival.

Abstract 5838: Successful Replacement of Aortic Valves by Decellularized Allografts in the Sheep: First Long-Term Results

Immunogenicity of human allografts leads to gradual valve degeneration. Pulmonal cell-free valvular scaffolds obtained by methods of tissue engineering have proved to induce in-vivo guided tissue regeneration and represent a promising valve substitute especially for children. Here we describe the successful orthotopic implantation of decellularized aortic valves in the systemic circulation in sheep. Allogenic detergent decellularized (0.5% sodium deoxycholate/0.5% SDS) aortic valve (AV) conduits (n = 12) were implanted orthotopically as root replacement in lambs (35–45 kg). Fresh native AV conduits served as controls (n = 6). After three and nine months follow-up the valves were investigated for functionality by echocardiography, for morphology and histological appearance. Decellularization resulted in complete loss of cells in AV wall, cusp and myocardial cuff, no influence on scaffold microarchitecture was observed. During 9 months follow-up no signs of conduit dilatation, aortic stenosis (transvalvular gradient max. 6.1 ± 5.1mmHg) or reduction of cusp mobility were observed in the decellularized group. Regurgitation in these valves was trivial in all cases. The grafts showed no histological signs of rejection and partial repopulation of the valvular scaffolds with autologous cells. In contrast, control animals developed mild to severe AV insufficiency. Histological investigation revealed significant calcific degeneration and massive rejection of these valves. Decellularized AV conduits may represent a durable AV substitute resistant to high systemic pressure. Furthermore, cell-removal prevents the allograft valve from immunologic deterioration and early graft degeneration.

The Effect of Immunosuppression on Peritoneal Adhesions Formation After Small Bowel Transplantation in Rats

The reported incidence of adhesion related small bowel obstruction after abdominal organ transplantation is considerably lower than other abdominal procedures. The purpose of the study was to investigate the influence of immunosuppression on peritoneal adhesion formation after intestinal transplantation in rats. Four groups of rats (n = 6) underwent small bowel intestinal transplantation in syngeneic (Groups A, B) and allogeneic (Groups C, D) combinations. Groups B and D received tacrolimus immunosuppression 1 mg/kg/d. Animals were euthanized on postoperative day 7, and the total adhesion score (TAS), tissue hydroxyproline content (HPC), TGF-beta mRNA expression levels and histology were examined. All of the animals in Group C showed severe histological (Grade III) acute cellular rejection. There were no histological signs of rejection in Group D. A significant reduction in TAS was observed in tacrolimus treated animals in both syngeneic and allogeneic combinations (Groups B and D), compared with controls (Groups A and C) (P < 0.001 and P < 0.01, respectively). TAS results correlated with the differences in TGF-beta levels that showed significant reduction when each immunosuppressed group was compared with its nontreated counterpart, i.e., (Groups B versus A, P < 0.05, and Groups D versus C, P < 0.01). TGF-beta levels were significantly high in the rejection group (C) and correlated with the intense adhesion formation that was demonstrated in that group. Group C was also the only group in which a significant elevation in HPC was demonstrated (P < 0.001). Intense adhesion formation occurs during early posttransplant acute rejection. Postsurgical adhesion formation is significantly reduced in immunosuppressed rats after intestinal transplantation.

Delayed administration of FK 506 is sufficient to suppress acute rejection changes after aortal transplantation in rats

Arterial allografts are used now-a-days as a modality in the treatment of vascular prosthesis infections. Prolonged administration of immunosuppressive drugs seemed to be essential for long-time patency rates of alloarterial vascular reconstructions. Nevertheless, the use of immunosuppressives if there exist an acute infection is controversial. The experimental work described herein studied effects of a delayed low-dose FK 506 administration on the development of acute rejection changes 30 days after aortal transplantation in rats. The response of the recipient's immune system to aortal wall antigens of the donor in the field of no immunosuppression resulted in an intimal proliferation and its infiltration by immunocompetent cells of the recipient, necrosis of medial smooth muscle cells, including deposition of immunoglobulins, and a massive adventitial infiltration of CD4 and CD8 positive cells. On the other hand, all the principal histological signs of rejection listed above were suppressed by FK 506 administration, no matter whether the immunosuppressive was administered on day 0 or day 7 after the transplantation.

Angiotensin II Receptor Expression Following Intestinal Transplantation in Mice

To further improve the success rate of intestinal transplantation there is a need to find early appearing indicators of rejection. The specific aim of this study was to compare Angiotensin (Ang) II type 1 receptor and Ang II type 2 receptor expression in relation to histological signs of rejection. Mice of the C57BL6 strain with syngeneic intestinal grafts were compared to mice subjected to allogeneic intestinal transplantation with BalbC strain as donors. Local expression of Ang II type 1 and 2 receptor was evaluated using rt-PCR and Western blot and compared to histological picture in grafts and native intestine. The Ang II type 2 receptor protein expression was markedly up-regulated in the allogeneically transplanted graft from day 1 postoperatively. Histological signs of rejection were not seen until day 6. Intestinal allograft transplantation in mice is associated with a marked up-regulation of the Ang II type 2 receptor. However, the detailed role of the renin-angiotensin system in the immune rejection following intestinal transplantation remains to be clarified.

Prediction of renal allograft rejection by urinary protein analysis using ProteinChip Arrays (surface-enhanced laser desorption/ionization time-of-flight mass spectrometry)

Objectives To develop a noninvasive method for the detection of renal transplant rejection using ProteinChip Arrays (surface-enhanced laser desorption/ionization time-of-flight mass spectrometry). Methods A total of 23 urine samples were collected from 13 patients showing biopsy-proven renal allograft rejection and from 10 patients without histologic signs of rejection. All 23 patients had clinical symptoms and signs of acute allograft rejection and underwent renal biopsy. Samples were centrifuged, and supernatants were directly spotted onto the ProteinChip arrays with different chromatographic surfaces. The obtained spectra in a range from 2 to 200 kDa were subjected to bioinformatic analysis using the method of Fuzzy c-means, followed by the establishment of rule bases and evaluation using the relevance index according to Kiendl. Results Several protein peaks were identified allowing differentiation between rejection and no rejection. Using two different ProteinChip surfaces, we found two biomarkers at 25.71 kDa and 28.13 kDa that gave a diagnostic sensitivity of 90% and 93% and a specificity of 80% (SAX2) and 85% (CM10), respectively. Conclusions Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry appears to be a promising new diagnostic tool for distinguishing renal transplant patients with no rejection from those with acute rejection.

Tacrolimus versus cyclosporine induction therapy in pulmonary transplantation in miniature swine

Tacrolimus has been shown to provide superior immunosuppression in various solid organ transplant settings. The purpose of our study was to compare the survival of porcine lung allografts after induction with either cyclosporine A (CsA) or tacrolimus. Single lung transplantation from MHC mismatched donors was performed in 10 minipigs. Immunosuppression included 1.5 mg/kg per day methylprednisolone and 1.0 mg/kg per day azathioprine. CsA (n=5) was adjusted to trough levels of 300-500 ng/ml, tacrolimus (n=5) was adjusted to 16-26 ng/ml. All immunosuppressive drugs were discontinued on postoperative day (POD) 28. Allograft survival was monitored by sequential chest radiographs, bronchoscopy and transbronchial biopsy histology. Peripheral blood leukocytes were scanned for donor chimerism and CD3, CD4, CD8 and CD25 expression. The animals survived a 4-week course of immunosuppression without radiological or histological signs of rejection on POD 28. Median allograft survival in CsA-treated animals was 55+/-15 days and all animals rejected their grafts within 42 days after withdrawal of immunosuppression. In tacrolimus-treated animals, median survival was 152+/-65 days with the longest survivor being electively sacrificed on POD 390 (P=0.0064). The degree of donor leukocyte chimerism and the frequency of CD4+CD25+ T-cells were higher in the tacrolimus group, however, these differences were not statistically significant. The results of our study show that primary immunosuppression with tacrolimus is superior to cyclosporine after pulmonary allotransplantation in a large animal model.