Publications by authors named "Suchitra Sumitran-Holgersson"

44 Publications

Notice of Retraction: Inappropriate Image Duplication in "Recellularization of Acellular Human Small Intestine Using Bone Marrow Stem Cells".

Stem Cells Transl Med 2019 Mar 1;8(3):315. Epub 2019 Feb 1.

STEM CELLS TRANSLATIONAL MEDICINE 2013;2:307-315; http://dx.doi.org/10.5966/sctm.2012-0108 The above-referenced article published on March 13, 2013 in Stem Cells Translational Medicine has been retracted by agreement between the Journal Editors and co-publishers, AlphaMed Press and Wiley Periodicals, Inc. The retraction has been agreed to with acknowledgment of problems with Figure 3, which we believe make some of the data unreliable.
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http://dx.doi.org/10.1002/sctm.12433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392372PMC
March 2019

Isolation and Decellularization of a Whole Porcine Pancreas.

J Vis Exp 2018 10 10(140). Epub 2018 Oct 10.

Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg;

Tissue engineering of the whole pancreas can improve current treatments for diabetes mellitus. The ultimate goal is to tissue engineer pancreas from an allogeneic or xenogeneic source with human cells. A demonstration of methods for the efficient dissection, decellularization, and recellularization of porcine pancreas might benefit the field. Akin to human pancreases, porcine pancreases have a special anatomical arrangement with three lobes (splenic, duodenal, and connection) rounded by the duodenum and small intestine. The duodenal lobe of the pancreas connects to the duodenum by several small blood vessels. Tissue engineering of the pancreas is complicated because of its exocrine and endocrine nature. In this paper, we show a detailed protocol to dissect the whole porcine pancreas and decellularize it with detergents while saving its structure and some extracellular matrix components. To achieve complete perfusion, the aorta is chosen as inlet and the portal vein as outlet. The other blood vessels (hepatic artery, splenic vein, splenic artery, mesenteric artery and vein tree) and bile duct are ligated. To prevent the formation of thrombus, the pig is heparinized and, immediately after dissection, the organ is flushed with cold heparin. To inhibit the action of exocrine enzymes, the pancreas decellularization is set at 4 °C. The decellularization is performed by perfusion of Triton X-100, sodium deoxycholate, and deoxyribonuclease, with an intermittent and final extensive washing. With a successful decellularization, the pancreas appears white, and a histological evaluation with hematoxylin and eosin shows an absence of nuclei with a preserved extracellular matrix structure. Thus, the proposed method can be used to successfully dissect and decellularize whole porcine pancreas.
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http://dx.doi.org/10.3791/58302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235501PMC
October 2018

Decellularization and Recellularization Methodology for Human Saphenous Veins.

J Vis Exp 2018 07 27(137). Epub 2018 Jul 27.

Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg.

Vascular conduits used during most vascular surgeries are allogeneic or synthetic grafts that often lead to complications caused by immunosuppression and poor patency. Tissue engineering offers a novel solution to generate personalized grafts with a natural extracellular matrix containing the recipient's cells using the method of decellularization and recellularization. We show a detailed method for performing decellularization of the human saphenous vein and recellularization by perfusion of peripheral blood. The vein was decellularized by perfusing 1% Triton X-100, 1% tri-n-butyl-phosphate (TnBP) and 2,000 Kunitz units of deoxyribonuclease (DNase). Triton X-100 and TnBP were perfused at 35 mL/min for 4 h while DNase was perfused at 10 mL/min at 37 °C for 4 h. The vein was washed in ultrapure water and PBS and then sterilized in 0.1% peracetic acid. It was washed again in PBS and preconditioned in endothelial medium. The vein was connected to a bioreactor and perfused with endothelial medium containing 50 IU/mL heparin for 1 h. Recellularization was performed by filling the bioreactor with fresh blood, diluted 1:1 in Steen solution, and adding endocrine gland-derived vascular endothelial growth factors (80 ng/mL), basic fibroblast growth factors (4 µL/mL), and acetyl salicylic acid (5 µg/mL). The bioreactor was then moved into an incubator and perfused for 48 h at 2 mL/min while maintaining glucose between 3 - 9 mmol/L. Later, the vein was washed with PBS, filled with endothelial medium and perfused for 96 h in the incubator. Treatment with Triton X-100, TnBP and DNase decellularized the saphenous vein in 5 cycles. The decellularized vein looked white in contrast to normal and recellularized veins (light red). The hematoxylin & eosin (H&E) staining showed the presence of nuclei only in normal but not in decellularized veins. In the recellularized vein, H&E-staining showed the presence of cells on the luminal surface of the vein.
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http://dx.doi.org/10.3791/57803DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6126553PMC
July 2018

Cold-perfusion decellularization of whole-organ porcine pancreas supports human fetal pancreatic cell attachment and expression of endocrine and exocrine markers.

J Tissue Eng 2017 Jan-Dec;8:2041731417738145. Epub 2017 Oct 30.

Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Despite progress in the field of decellularization and recellularization, the outcome for pancreas has not been adequate. This might be due to the challenging dual nature of pancreas with both endocrine and exocrine tissues. We aimed to develop a novel and efficient cold-perfusion method for decellularization of porcine pancreas and recellularize acellular scaffolds with human fetal pancreatic stem cells. Decellularization of whole porcine pancreas at 4°C with sodium deoxycholate, Triton X-100 and DNase efficiently removed cellular material, while preserving the extracellular matrix structure. Furthermore, recellularization of acellular pieces with human fetal pancreatic stem cells for 14 days showed attached and proliferating cells. Both endocrine (C-peptide and PDX1) and exocrine (glucagon and α-amylase) markers were expressed in recellularized tissues. Thus, cold-perfusion can successfully decellularize porcine pancreas, which when recellularized with human fetal pancreatic stem cells shows relevant endocrine and exocrine phenotypes. Decellularized pancreas is a promising biomaterial and might translate to clinical relevance for treatment of diabetes.
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http://dx.doi.org/10.1177/2041731417738145DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669317PMC
October 2017

Activation of PERK-Nrf2 oncogenic signaling promotes Mdm2-mediated Rb degradation in persistently infected HCV culture.

Sci Rep 2017 08 23;7(1):9223. Epub 2017 Aug 23.

Department of Pathology and Laboratory Medicine, New Orleans, Louisiana, USA.

The mechanism of how chronic hepatitis C virus (HCV) infection leads to such a high rate of hepatocellular carcinoma (HCC) is unknown. We found that the PERK axis of endoplasmic reticulum (ER) stress elicited prominent nuclear translocation of Nrf2 in 100% of HCV infected hepatocytes. The sustained nuclear translocation of Nrf2 in chronically infected culture induces Mdm2-mediated retinoblastoma protein (Rb) degradation. Silencing PERK and Nrf2 restored Mdm2-mediated Rb degradation, suggesting that sustained activation of PERK/Nrf2 axis creates oncogenic stress in chronically infected HCV culture model. The activation of Nrf2 and its nuclear translocation were prevented by ER-stress and PERK inhibitors, suggesting that PERK axis is involved in the sustained activation of Nrf2 signaling during chronic HCV infection. Furthermore, we show that HCV clearance induced by interferon-α based antiviral normalized the ER-stress response and prevented nuclear translocation of Nrf2, whereas HCV clearance by DAAs combination does neither. In conclusion, we report here a novel mechanism for how sustained activation of PERK axis of ER-stress during chronic HCV infection activates oncogenic Nrf2 signaling that promotes hepatocyte survival and oncogenesis by inducing Mdm2-mediated Rb degradation.
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http://dx.doi.org/10.1038/s41598-017-10087-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569052PMC
August 2017

Significantly Accelerated Wound Healing of Full-Thickness Skin Using a Novel Composite Gel of Porcine Acellular Dermal Matrix and Human Peripheral Blood Cells.

Cell Transplant 2017 02 5;26(2):293-307. Epub 2016 Aug 5.

Here we report the fabrication of a novel composite gel from decellularized gal-gal-knockout porcine skin and human peripheral blood mononuclear cells (hPBMCs) for full-thickness skin wound healing. Decellularized skin extracellular matrix (ECM) powder was prepared via chemical treatment, freeze drying, and homogenization. The powder was mixed with culture medium containing hyaluronic acid to generate a pig skin gel (PSG). The effect of the gel in regeneration of full-thickness wounds was studied in nude mice. We found significantly accelerated wound closure already on day 15 in animals treated with PSG only or PSG + hPBMCs compared to untreated and hyaluronic acid-treated controls (p < 0.05). Addition of the hPBMCs to the gel resulted in marked increase of host blood vessels as well as the presence of human blood vessels. At day 25, histologically, the wounds in animals treated with PSG only or PSG + hPBMCs were completely closed compared to those of controls. Thus, the gel facilitated generation of new skin with well-arranged epidermal cells and restored bilayer structure of the epidermis and dermis. These results suggest that porcine skin ECM gel together with human cells may be a novel and promising biomaterial for medical applications especially for patients with acute and chronic skin wounds.
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http://dx.doi.org/10.3727/096368916X692690DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657757PMC
February 2017

Successful tissue engineering of competent allogeneic venous valves.

J Vasc Surg Venous Lymphat Disord 2015 Oct 7;3(4):421-430.e1. Epub 2015 Mar 7.

Department of Vascular Surgery, Oslo Vascular Centre, Oslo University Hospital, Aker, Norway; Vascular Department, University of Oslo, Oslo, Norway.

Objective: The purpose of this study was to evaluate whether tissue-engineered human allogeneic vein valves have a normal closure time (competency) and tolerate reflux pressure in vitro.

Methods: Fifteen human allogeneic femoral vein segments containing valves were harvested from cadavers. Valve closure time and resistance to reflux pressure (100 mm Hg) were assessed in an in vitro model to verify competency of the vein valves. The segments were tissue engineered using the technology of decellularization (DC) and recellularization (RC). The decellularized and recellularized vein segments were characterized biochemically, immunohistochemically, and biomechanically.

Results: Four of 15 veins with valves were found to be incompetent immediately after harvest. In total, 2 of 4 segments with incompetent valves and 10 of 11 segments with competent valves were further decellularized using detergents and DNAse. DC resulted in significant decrease in host DNA compared with controls. DC scaffolds, however, retained major extracellular matrix proteins and mechanical integrity. RC resulted in successful repopulation of the lumen and valves of the scaffold with endothelial and smooth muscle cells. Valve mechanical parameters were similar to the native tissue even after DC. Eight of 10 veins with competent valves remained competent even after DC and RC, whereas the two incompetent valves remained incompetent even after DC and RC. The valve closure time to reflux pressure of the tissue-engineered veins was <0.5 second.

Conclusions: Tissue-engineered veins with valves provide a valid template for future preclinical studies and eventual clinical applications. This technique may enable replacement of diseased incompetent or damaged deep veins to treat axial reflux and thus reduce ambulatory venous hypertension.
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http://dx.doi.org/10.1016/j.jvsv.2014.12.002DOI Listing
October 2015

In Vivo Application of Tissue-Engineered Veins Using Autologous Peripheral Whole Blood: A Proof of Concept Study.

EBioMedicine 2014 Nov 22;1(1):72-9. Epub 2014 Sep 22.

Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.

Vascular diseases are increasing health problems affecting > 25 million individuals in westernized societies. Such patients could benefit from transplantation of tissue-engineered vascular grafts using autologous cells. One challenge that has limited this development is the need for cell isolation, and risks associated with ex vivo expanded stem cells. Here we demonstrate a novel approach to generate transplantable vascular grafts using decellularized allogeneic vascular scaffolds, repopulated with peripheral whole blood (PWB) in vitro in a bioreactor. Circulating, VEGFR-2 +/CD45 + and a smaller fraction of VEGFR-2 +/CD14 + cells contributed to repopulation of the graft. SEM micrographs showed flat cells on the luminal surface of the grafts consistent with endothelial cells. For clinical validation, two autologous PWB tissue-engineered vein conduits were prepared and successfully used for by-pass procedures in two pediatric patients. These results provide a proof of principle for the generation of transplantable vascular grafts using a simple autologous blood sample, making it clinically feasible globally.
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http://dx.doi.org/10.1016/j.ebiom.2014.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457407PMC
November 2014

Chemokine-mediated robust augmentation of liver engraftment: a novel approach.

Stem Cells Transl Med 2015 Jan 3;4(1):21-30. Epub 2014 Dec 3.

Laboratory for Transplantation Biology and Regenerative Medicine, Department of Surgery, and Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; The Transplant Institute, Sahlgrenska University Hospital, Gothenburg, Sweden; NovaHep AB, Stockholm, Sweden

Effective repopulation of the liver is essential for successful clinical hepatocyte transplantation. The objective was to improve repopulation of the liver with human hepatocytes using chemokines. We used flow cytometry and immunohistochemistry assays to identify commonly expressed chemokine receptors on human fetal and adult hepatocytes. The migratory capacity of the cells to various chemokines was tested. For in vivo studies, we used a nude mouse model of partial hepatectomy followed by intraparenchymal injections of chemokine ligands at various concentrations. Human fetal liver cells transformed with human telomerase reverse transcriptase were used for intrasplenic cell transplantation. Repopulation and functionality were assessed 4 weeks after transplantation. The receptor CXCR3 was commonly expressed on both fetal and adult hepatocytes. Both cell types migrated efficiently toward corresponding CXC chemokine ligands 9, 10, and 11. In vivo, animals injected with recombinant chemokines showed the highest cell engraftment compared with controls (p<.05). The engrafted cells expressed several human hepatic markers such as cytokeratin 8 and 18 and albumin as well as transferrin, UGT1A1, hepatocyte nuclear factor (1α, 1β, and 4α), cytochrome CYP3A1, CCAAT/enhancer binding protein (α and β), and human albumin compared with controls. No inflammatory cells were detected in the livers at 4 weeks after transplantation. The improved repopulation of transplanted cells is likely a function of the chemokines to mediate cell homing and retention in the injured liver and might be an attractive strategy to augment repopulation of transplanted hepatocytes in vivo.
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http://dx.doi.org/10.5966/sctm.2014-0053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4275005PMC
January 2015

An alternative approach to decellularize whole porcine heart.

Biores Open Access 2014 Dec;3(6):327-38

Transplantation Institute and Department of Surgery, Sahlgrenska Academy, University of Gothenburg , Gothenburg, Sweden .

Scaffold characteristics are decisive for repopulating the acellular tissue with cells. A method to produce such a scaffold from intact organ requires a customized decellularization protocol. Here, we have decellularized whole, intact porcine hearts by serial perfusion and agitation of hypotonic solution, an ionic detergent (4% sodium deoxycholate), and a nonionic detergent (1% Triton X-100). The resultant matrix was characterized for its degree of decellularization, morphological and functional integrity. The protocol used resulted in extensive decellularization of the cardiac tissue, but the cytoskeletal elements (contractile apparatus) of cardiomyocytes remained largely unaffected by the procedure although their membranous organelles were completely absent. Further, several residual angiogenic growth factors were found to be present in the decellularized tissue.
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http://dx.doi.org/10.1089/biores.2014.0046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4245870PMC
December 2014

TEMPORARY REMOVAL: CD271 identifies functional human hepatic stellate cells, which localize in peri-sinusoidal and portal areas in liver after partial hepatectomy.

Cytotherapy 2014 07 13;16(7):990-9. Epub 2014 May 13.

Sahlgrenska University Hospital, Laboratory for Transplantation and Regenerative Medicine, University of Gothenburg, Gothenburg, Sweden. Electronic address:

Background Aims: Hepatic stellate cells (HSCs) are liver-resident mesenchymal cells involved in essential processes in the liver. However, knowledge concerning these cells in human livers is limited because of the lack of a simple isolation method.

Methods: We isolated fetal and adult human liver cells by immunomagnetic beads coated with antibodies to a mesenchymal stromal cell marker (CD271) to enrich a population of HSCs. The cells were characterized by cell cultivation, immunocytochemistry, flow cytometry, reverse-transcription polymerase chain reaction and immunohistochemistry. Cells were injected into nude mice after partial hepatectomy to study in vivo localization of the cells.

Results: In vitro, CD271(+) cells were lipid-containing cells expressing several HSC markers: the glial fibrillary acidic protein, desmin, vimentin and α-smooth muscle actin but negative for CK8, albumin and hepatocyte antigen. The cells produced several inflammatory cytokines such as interleukin (IL)-6, IL-1A, IL-1B and IL-8 and matrix metalloproteinases MMP-1 and MMP-3 and inhibitors TIMP-1 and TIMP-2. In vivo, fetal CD271(+) cells were found in the peri-sinusoidal space and around portal vessels, whereas adult CD271(+) cells were found mainly in the portal connective tissue and in the walls of the portal vessels, which co-localized with α-smooth muscle actin or desmin. CD271(-) cells did not show this pattern of distribution in the liver parenchyma.

Conclusions: The described protocol establishes a method for isolation of mesenchymal cell precursors for hepatic stellate cells, portal fibroblasts and vascular smooth muscle cells. These cells provide a novel culture system to study human hepatic fibrogenesis, gene expression and transcription factors controlling HSC regulation.
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http://dx.doi.org/10.1016/j.jcyt.2014.03.001DOI Listing
July 2014

Phenotypic and in vivo functional characterization of immortalized human fetal liver cells.

Scand J Gastroenterol 2014 Jun 15;49(6):705-14. Epub 2014 Apr 15.

Laboratory of Transplantation and Regenerative Medicine, Sahlgrenska Academy at University of Gothenburg , Gothenburg , Sweden.

We report the establishment and characterization of immortalized human fetal liver progenitor cells by expression of the Simian virus 40 large T (SV40 LT) antigen. Well-characterized cells at various passages were transplanted into nude mice with acute liver injury and tested for functional capacity. The SV40LT antigen-immortalized fetal liver cells showed a morphology similar to primary cells. Cultured cells demonstrated stable phenotypic expression in various passages, of hepatic markers such as albumin, CK 8, CK18, transcription factors HNF-4α and HNF-1α and CYP3A/7. The cells did not stain for any of the tested cancer-associated markers. Albumin, HNF-4α and CYP3A7 expression was confirmed by reverse transcription polymerase chain reaction (RT-PCR). Flow cytometry showed expression of some progenitor cell markers. In vivo study showed that the cells expressed both fetal and differentiated hepatocytes markers. Our study suggests new approaches to expand hepatic progenitor cells, analyze their fate in animal models aiming at cell therapy of hepatic diseases.
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http://dx.doi.org/10.3109/00365521.2013.830328DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4059185PMC
June 2014

Replacement of a tracheal stenosis with a tissue-engineered human trachea using autologous stem cells: a case report.

Tissue Eng Part A 2014 Jan 12;20(1-2):389-97. Epub 2013 Oct 12.

1 Department of Otolaryngology, Head and Neck Surgery, Sahlgrenska University Hospital , University of Gothenburg, Gothenburg, Sweden .

Cell-based therapies involving tissue engineering represent interesting and potentially important strategies for the treatment of patients with various disorders. In this study, using a detergent-enzymatic method, we prepared an intact three-dimensional scaffold of an extracellular matrix derived from a human cadaver donor trachea, which we repopulated with autologous stem cells and implanted into a 76-year-old patient with tracheal stenosis including the lower part of the larynx. Although the graft provided the patient with an open airway, a week after the surgery, the mucous membrane of the graft was covered by a 1-2 mm thick fungal infection, which was treated with local and systemic antifungal therapy. The airway lumen was postoperatively controlled by fiber endoscopy and found stable and sufficient. However, after 23 days, the patient died due to cardiac arrest but with a patent, open, and stable tracheal transplant and intact anastomoses. Histopathological results of the transplanted tracheal graft during autopsy showed a squamous but not ciliated epithelium, neovascularization, bundles of α-sma-positive muscle cells, serous glands, and nerve fibers with S-100-positive nerve cells in the submucosa and intact chondrocytes in the cartilage. Our findings suggest that although autologous stem cells-engineered tracheal matrices may represent a tool for clinical tracheal replacement, further preclinical studies are required for generating functional airway grafts and long-term effects of such grafts.
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http://dx.doi.org/10.1089/ten.TEA.2012.0514DOI Listing
January 2014

Recellularization of acellular human small intestine using bone marrow stem cells.

Stem Cells Transl Med 2013 Apr 13;2(4):307-15. Epub 2013 Mar 13.

Laboratory for Transplantation and Regenerative Medicine, Department of Surgery, University of Gothenburg, Sweden.

We aimed to produce an acellular human tissue scaffold with a view to test the possibility of recellularization with bone marrow stem cells to produce a tissue-engineered small intestine (TESI). Human small-bowel specimens (n = 5) were obtained from cadaveric organ donors and treated sequentially with 6% dimethyl sulfoxide in hypotonic buffer, 1% Triton X-100, and DNase. Each small intestine (SI) piece (6 cm) was recellularized with EPCAM+ and CD133+ allogeneic bone marrow stem cells. Histological and molecular analysis demonstrated that after decellularization, all cellular components and nuclear material were removed. Our analysis also showed that the decellularized human SI tissue retained its histoarchitecture with intact villi and major structural proteins. Protein films of common extracellular matrix constituents (collagen I, laminin, and fibronectin) were found in abundance. Furthermore, several residual angiogenic factors were found in the decellularized SI. Following recellularization, we found viable mucin-positive goblet cells, CK18+ epithelial cells in villi adjacent to a muscularis mucosa with α-actin+ smooth muscle cells, and a high repopulation of blood vessels with CD31+ endothelial cells. Our results show that in the future, such a TESI would be ideal for clinical purposes, because it can be derived from the recipient's own immunocompatible bone marrow cells, thus avoiding the use of immunosuppression.
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http://dx.doi.org/10.5966/sctm.2012-0108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3659833PMC
April 2013

Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation.

Transplantation 2013 Jan;95(1):19-47

National Transplant Services, Australian Red Cross Blood Service, Melbourne, Victoria, Australia.

Background: The introduction of solid-phase immunoassay (SPI) technology for the detection and characterization of human leukocyte antigen (HLA) antibodies in transplantation while providing greater sensitivity than was obtainable by complement-dependent lymphocytotoxicity (CDC) assays has resulted in a new paradigm with respect to the interpretation of donor-specific antibodies (DSA). Although the SPI assay performed on the Luminex instrument (hereafter referred to as the Luminex assay), in particular, has permitted the detection of antibodies not detectable by CDC, the clinical significance of these antibodies is incompletely understood. Nevertheless, the detection of these antibodies has led to changes in the clinical management of sensitized patients. In addition, SPI testing raises technical issues that require resolution and careful consideration when interpreting antibody results.

Methods: With this background, The Transplantation Society convened a group of laboratory and clinical experts in the field of transplantation to prepare a consensus report and make recommendations on the use of this new technology based on both published evidence and expert opinion. Three working groups were formed to address (a) the technical issues with respect to the use of this technology, (b) the interpretation of pretransplantation antibody testing in the context of various clinical settings and organ transplant types (kidney, heart, lung, liver, pancreas, intestinal, and islet cells), and (c) the application of antibody testing in the posttransplantation setting. The three groups were established in November 2011 and convened for a "Consensus Conference on Antibodies in Transplantation" in Rome, Italy, in May 2012. The deliberations of the three groups meeting independently and then together are the bases for this report.

Results: A comprehensive list of recommendations was prepared by each group. A summary of the key recommendations follows. Technical Group: (a) SPI must be used for the detection of pretransplantation HLA antibodies in solid organ transplant recipients and, in particular, the use of the single-antigen bead assay to detect antibodies to HLA loci, such as Cw, DQA, DPA, and DPB, which are not readily detected by other methods. (b) The use of SPI for antibody detection should be supplemented with cell-based assays to examine the correlations between the two types of assays and to establish the likelihood of a positive crossmatch (XM). (c) There must be an awareness of the technical factors that can influence the results and their clinical interpretation when using the Luminex bead technology, such as variation in antigen density and the presence of denatured antigen on the beads. Pretransplantation Group: (a) Risk categories should be established based on the antibody and the XM results obtained. (b) DSA detected by CDC and a positive XM should be avoided due to their strong association with antibody-mediated rejection and graft loss. (c) A renal transplantation can be performed in the absence of a prospective XM if single-antigen bead screening for antibodies to all class I and II HLA loci is negative. This decision, however, needs to be taken in agreement with local clinical programs and the relevant regulatory bodies. (d) The presence of DSA HLA antibodies should be avoided in heart and lung transplantation and considered a risk factor for liver, intestinal, and islet cell transplantation. Posttransplantation Group: (a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be monitored by measurement of DSA and protocol biopsies in the first 3 months after transplantation. (b) Intermediate-risk patients (history of DSA but currently negative) should be monitored for DSA within the first month. If DSA is present, a biopsy should be performed. (c) Low-risk patients (nonsensitized first transplantation) should be screened for DSA at least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be performed. In all three categories, the recommendations for subsequent treatment are based on the biopsy results.

Conclusions: A comprehensive list of recommendations is provided covering the technical and pretransplantation and posttransplantation monitoring of HLA antibodies in solid organ transplantation. The recommendations are intended to provide state-of-the-art guidance in the use and clinical application of recently developed methods for HLA antibody detection when used in conjunction with traditional methods.
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http://dx.doi.org/10.1097/TP.0b013e31827a19ccDOI Listing
January 2013

Isolation and characterization of human primary enterocytes from small intestine using a novel method.

Scand J Gastroenterol 2012 Nov 4;47(11):1334-43. Epub 2012 Sep 4.

Laboratory for Transplantation and Regenerative Medicine at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Cell culture studies of enterocytes are important in many fields. However, there are difficulties in obtaining cell lines from adult human intestine, such as microbial contamination of cultures from the tissue samples, short life span of enterocytes, overgrowth of mesenchymal cells, etc. Various model used to obtain adult intestinal cell lines are very complex requiring use of feeder layer or gel matrices. The aim of this study was to establish a novel method for the simple and reproducible isolation of human enterocytes. Enterocytes were isolated from SI samples (n = 5) obtained from cadaveric donors using a mechanical procedure, and separation with immunomagnetic beads coated with anti-EpCAM antibodies. Light and electron microscopy, flow cytometry and immunocytochemistry techniques were used to characterize the isolated cells. Immunohistochemical staining of normal SB biopsies confirmed that the cell cultures maintained an in vivo phenotype as reflected in cytokeratin expression CK18, CK20 and expression of intestine-specific markers such as sucrase isomaltase and maltase glucoamylase. Furthermore, the cells strongly expressed TLR-5, 6, 7, 8 and 10 and several molecules such as CD40, CD86, CD44, ICAM-1 and HLA-DR which are important in triggering cell-mediated immune responses. This novel technique provides a unique in vitro system to study the biology of enterocytes in normal conditions as well as to study inflammatory processes in various small bowel disorders.
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http://dx.doi.org/10.3109/00365521.2012.708940DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3490477PMC
November 2012

Transplantation of an allogeneic vein bioengineered with autologous stem cells: a proof-of-concept study.

Lancet 2012 Jul 14;380(9838):230-7. Epub 2012 Jun 14.

Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital, Sweden.

Background: Extrahepatic portal vein obstruction can have severe health consequences. Variceal bleeding associated with this disorder causes upper gastrointestinal bleeding, leading to substantial morbidity and mortality. We report the clinical transplantation of a deceased donor iliac vein graft repopulated with recipient autologous stem cells in a patient with extrahepatic portal vein obstruction.

Methods: A 10 year old girl with extrahepatic portal vein obstruction was admitted to the Sahlgrenska University Hospital in Gothenburg, Sweden, for a bypass procedure between the superior mesenteric vein and the intrahepatic left portal vein (meso Rex bypass). A 9 cm segment of allogeneic donor iliac vein was decellularised and subsequently recellularised with endothelial and smooth muscle cells differentiated from stem cells obtained from the bone marrow of the recipient. This graft was used because the patient's umbilical vein was not suitable and other strategies (eg, liver transplantation) require lifelong immunosuppression.

Findings: The graft immediately provided the recipient with a functional blood supply (25-30 cm/s in the portal vein and 40 mL/s in the artery was measured intraoperatively and confirmed with ultrasound). The patient had normal laboratory values for 9 months. However, at 1 year the blood flow was low and, on exploration, the shunt was patent but too narrow due to mechanical obstruction of tissue in the mesocolon. Once the tissue causing the compression was removed the graft dilated. We therefore used a second stem-cell populated vein graft to lengthen the previous graft. After this second operation, the portal pressure was reduced from 20 mm Hg to 13 mm Hg and blood flow was 25-40 cm/s in the portal vein. With restored portal circulation the patient has substantially improved physical and mental function and growth. The patient has no anti-endothelial cell antibodies and is receiving no immunosuppressive drugs.

Interpretation: An acellularised deceased donor vein graft recellularised with autologous stem cells can be considered for patients in need of vascular vein shunts without the need for immunosuppression.

Funding: Swedish Government.
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http://dx.doi.org/10.1016/S0140-6736(12)60633-3DOI Listing
July 2012

Fetal liver-derived mesenchymal stromal cells augment engraftment of transplanted hepatocytes.

Cytotherapy 2012 Jul 16;14(6):657-69. Epub 2012 Mar 16.

Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.

Background Aims: One important problem commonly encountered after hepatocyte transplantation is the low numbers of transplanted cells found in the graft. If hepatocyte transplantation is to be a viable therapeutic approach, significant liver parenchyma repopulation is required. Mesenchymal stromal cells (MSC) produce high levels of various growth factors, cytokines and metalloproteinases, and have immunomodulatory effects. We therefore hypothesized that co-transplantation of MSC with human fetal hepatocytes (hFH) could augment in vivo expansion after transplantation. We investigated the ability of human fetal liver MSC (hFLMSC) to augment expansion of phenotypically and functionally well-characterized hFH.

Methods: Two million hFH (passage 6) were either transplanted alone or together (1:1 ratio) with green fluorescence protein-expressing hFLMSC into the spleen of C57BL/6 nude mice with retrorsine-induced liver injury.

Results: After 4 weeks, engraftment of cells was detected by fluorescence in situ hybridization using a human-specific DNA probe. Significantly higher numbers of cells expressing human cytokeratin (CK)8, CK18, CK19, Cysteine-rich MNNG HOS Transforming gene (c-Met), alpha-fetoprotein (AFP), human nuclear antigen, mitochondrial antigen, hepatocyte-specific antigen and albumin (ALB) were present in the livers of recipient animals co-transplanted with hFLMSC compared with those without. Furthermore, expression of human hepatocyte nuclear factor (HNF)-4α and HNF-1β, and cytochrome P450 (CYP) 3A7 mRNA was demonstrated by reverse transcriptase-polymerase chain reaction (RT-PCR) in these animals. In addition, significantly increased amounts of human ALB were detected. Importantly, hFLMSC did not transdifferentiate into hepatocytes.

Conclusions: Our study reports the use of a novel strategy for enhanced liver repopulation and thereby advances this experimental procedure closer to clinical liver cell therapy.
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http://dx.doi.org/10.3109/14653249.2012.663526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3411318PMC
July 2012

Antibodies to kidney endothelial cells contribute to a "leaky" glomerular barrier in patients with chronic kidney diseases.

Am J Physiol Renal Physiol 2012 Apr 21;302(7):F884-94. Epub 2011 Dec 21.

Dept. of Transplantation Surgery, Laboratory for Transplantation and Regenerative Medicine, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska Science Park, Medicinaregatan 8A, Gothenburg, Sweden.

Anti-endothelial cell antibodies (AECA) have been reported to cause endothelial dysfunction, but their clinical importance for tissue-specific endothelial cells is not clear. We hypothesized that AECA reactive with human kidney endothelial cells (HKEC) may cause renal endothelial dysfunction in patients with chronic kidney diseases. We report that a higher fraction (56%) of end-stage renal disease (ESRD) patients than healthy controls (5%) have AECA reactive against kidney endothelial cells (P <0.001). The presence of antibodies was associated with female gender (P < 0.001), systolic hypertension (P < 0.01), and elevated TNF-α (P < 0.05). These antibodies markedly decrease expression of both adherens and tight junction proteins VE-cadherin, claudin-1, and zonula occludens-1 and provoked a rapid increase in cytosolic free Ca(2+) and rearrangement of actin filaments in HKEC compared with controls. This was followed by an enhancement in protein flux and phosphorylation of VE-cadherin, events associated with augmented endothelial cell permeability. Additionally, kidney biopsies from ESRD patients with AECA but not controls demonstrated a marked decrease in adherens and tight junctions in glomerular endothelium, confirming our in vitro data. In summary, our data demonstrate a causal link between AECA and their capacity to induce alterations in glomerular vascular permeability.
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http://dx.doi.org/10.1152/ajprenal.00250.2011DOI Listing
April 2012

Characterization and engraftment of long-term serum-free human fetal liver cell cultures.

Cytotherapy 2010 Apr;12(2):201-11

Department of Transplantation Surgery, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden.

Background Aims: Cultured human hepatocytes have extensive diagnostic and clinical applications. However, the setting-up of new in vitro culture techniques allowing the long-term survival and functional maintenance of adult human hepatocytes represents a formidable challenge. Fetal liver cells (FLC) are attractive candidate donor cells because of their high proliferative capacity.

Methods: Using cell culture and molecular techniques, we studied the in vitro and in vivo characteristics of FLC grown long-term in serum-free conditions.

Results: Serum-free FLC obtained from 6-10-week-old human fetal livers grew as multiple clusters in suspension and could be subcultured for at least six passages. These cells maintained stable hepatocyte phenotypes and gene expression patterns in culture for up to 6 months. When a cluster of these cells in various passages was placed on collagen-coated plates, they formed a monolayer and morphologically resembled hepatocytes. The cells expressed alpha -fetoprotein, cytokeratin (CK) 8, CK18 and CK19 and albumin (ALB). Hepatocyte nuclear factor 4alpha and 1beta and cytochrome P450 (CYP) 3A4 and CYP3A7 mRNA expression was demonstrated by reverse transcriptase-polymerase chain reaction (RT-PCR). Cells at different passages, when transplanted into nude mice with liver injury, engrafted successfully, as detected by in situ hybridization using a human-specific DNA probe. Colonies of human-specific CK8, CK18, c-Met nuclear antigen (Ag), mitochondrial Ag, hepatocyte-specific Ag and ALB-expressing cells were present in the livers of recipient animals.

Conclusions: Primary human FLC can be kept in culture consistently over a long time period and are potential candidates for cell therapy and in vitro diagnostics.
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http://dx.doi.org/10.3109/14653240903398053DOI Listing
April 2010

Generation of hepatocyte-like cells from in vitro transdifferentiated human fetal pancreas.

Cell Transplant 2009 ;18(2):183-93

Division of Transplantation Surgery, Karolinska University Hospital-Huddinge, Karolinska Institutet, Stockholm, Sweden.

Although the appearance of hepatic foci in the pancreas has been described in animal experiments and in human pathology, evidence for the conversion of human pancreatic cells to liver cells is still lacking. We therefore investigated the developmental plasticity between human embryonic pancreatic cells and liver cells. Cells were isolated and expanded from 7-8-week-old human fetal pancreata (HFP) and were characterized for the absence and presence of pancreatic and hepatic markers. In vitro expanded HFP were treated with fibroblast growth factor 2 (FGF2) and dexamethasone (DX) to induce a liver phenotye in the cells. These treated cells in various passages were further studied for their capacity to be functional in hepatic parenchyma following retrorsine-induced injury in nude C57 black mice. Amylase- and EPCAM-positive-enriched cells isolated from HFP and treated with FGF2 and DX lost expression of pancreatic markers and gained a liver phenotype. Hepatic differentiation was based on the expression (both at the mRNA and protein level) of liver markers albumin and cytokeratin 19. When transplanted in vivo into nude mice treated with retrorsine, both cell types successfully engrafted and functionally differentiated into hepatic cells expressing human albumin, glycogen, dipeptidyl peptidase, and gamma-glutamyltranspeptidase. These data indicate that human fetal pancreatic cells have a capacity to alter their gene expression profile in response to exogenous treatment with FGF2 and DX. It may be possible to generate an unlimited supply of hepatocytes in vitro for cell therapy.
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http://dx.doi.org/10.3727/096368909788341333DOI Listing
August 2009

Multicenter evaluation of a novel endothelial cell crossmatch test in kidney transplantation.

Transplantation 2009 Feb;87(4):549-56

Department of Surgery, Sahlgrenska Academy at Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden.

Background: Despite their clinical importance, clinical routine tests to detect anti-endothelial cell antibodies (AECA) in organ transplantation have not been readily available. This multicenter prospective kidney transplantation trial evaluates the efficacy of a novel endothelial cell crossmatch (ECXM) test to detect donor-reactive AECA associated with kidney allograft rejection.

Methods: Pretransplant serum samples from 147 patients were tested for AECA by a novel flow cytometric crossmatch technique (XM-ONE) using peripheral blood endothelial progenitor cells as targets. Patient enrolment was based on acceptance for transplantation determined by donor lymphocyte crossmatch results.

Results: Donor-reactive AECA were found in 35 of 147 (24%) patients. A significantly higher proportion of patients with a positive ECXM had rejections (16 of 35, 46%) during the follow-up of at least 3 months compared with those without AECA (13 of 112, 12%; P<0.00005). Both IgG and IgM AECAs were associated with graft rejections. Mean serum creatinine levels were significantly higher in patients with a positive ECXM test at 3 and 6 months posttransplant.

Conclusions: XM-ONE is quick, easy to perform on whole blood samples and identifies patients at risk for rejection and reduced graft function not identified by conventional lymphocyte crossmatches.
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http://dx.doi.org/10.1097/TP.0b013e3181949d4eDOI Listing
February 2009

Evidence for no relevance of anti-major histocompatibility complex class I-related chain a antibodies in liver transplantation.

Liver Transpl 2008 Dec;14(12):1793-802

Division of Clinical Immunology, Huddinge University Hospital, Karolinska Institutet, Stockholm, Sweden.

The polymorphic major histocompatibility complex class I-related chain A (MICA) antigen is being increasingly recognized as a potential target molecule for immune cells during allograft rejection. Here we studied whether MICA is a target antigen for antibodies in liver transplant patients. Eighty-four patients were investigated for the presence of MICA antibodies before and after liver transplantation with MICA-transfected cells and flow cytometry. MICA typing was performed by polymerase chain reaction. Expression of MICA in liver cells was determined by reverse-transcription polymerase chain reaction, Western blotting, and flow cytometry. Liver biopsy specimens from liver transplant patients were examined for MICA expression. A total of 22 of 84 (26%) patients had MICA antibodies either pre-transplant (8/84, 9.5%) or post-transplant (14/84, 17%). No correlation between rejection frequencies (14/22, 63%) or other clinical parameters was observed in patients with MICA antibody versus those without MICA antibody (29/62, 47% P = not significant). We found weak messenger RNA expression for MICA in liver cells but no protein or cell surface expression. In addition, no MICA expression in liver biopsy sections from liver transplant patients was observed at any time point, including rejections. Thus, our preliminary results demonstrate no causal relationship between the presence of MICA antibodies and liver allograft rejections. Therefore, it is likely that MICA may not be an important target antigen during liver allograft rejections.
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http://dx.doi.org/10.1002/lt.21620DOI Listing
December 2008

Novel antibodies to the donor stem cell population CD34+/VEGFR-2+ are associated with rejection after hematopoietic stem cell transplantation.

Transplantation 2008 Sep;86(5):686-96

Center for allogenic stem cell transplantation, Karolinska University Hospital-Huddinge, Stockholm, Sweden.

Background: Reconstitution of hematopoiesis after hematopoietic stem cell transplantation (HSCT) occurs through a reservoir of donor CD34+ HSC. CD34+/VEGFR-2+ is a primitive, quiescent subpopulation of HSC known to generate hematopoietic or endothelial progeny in vitro and in vivo. We hypothesized that donor-specific antibodies to the CD34+/VEGFR-2+ stem cells may be associated with rejection after HSCT.

Methods: We studied 30 patients without and 11 with rejections after HSCT and 20 nontransplanted healthy individuals. Ninety-three sera taken pre and posttransplantation from patients receiving HSCT were studied for the presence of donor CD34+/VEGFR-2+ cell-specific antibodies.

Results: We provide evidence that significantly higher numbers of patients with rejections 9/11 (81%), whereas 1/30 (3%) (P=0.001) without rejections had antibodies against donor CD34+/VEGFR-2+ cells, but not CD34-/VEGFR-2- cells. In eight transplantations, antibodies against donor CD34+/VEGFR-2+ cells were detected already before transplantation. Purified IgG fractions from patients with rejections but not controls significantly decreased the ability of these cells to form hematopoietic and endothelial colonies. In multivariate analysis, antibodies against CD34+/VEGFR-2+ cells proved to be the most significant risk factor for rejection.

Conclusions: These novel findings document a high rate of rejections in patients with donor-specific antibodies to CD34+/VEGFR-2+ HSC. These antibodies may significantly and commonly contribute to HSCT rejections.
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http://dx.doi.org/10.1097/TP.0b013e3181820333DOI Listing
September 2008

Beyond ABO and human histocompatibility antigen: other histocompatibility antigens with a role in transplantation.

Curr Opin Organ Transplant 2008 Aug;13(4):425-9

Division of Transplantation Surgery, Karolinska University Hospital-Huddinge, Stockholm, Sweden.

Purpose Of Review: In the past few years, there has been an increasing interest in nonhuman histocompatibility antigens as targets of injury in organ-transplant recipients. This increased interest has been spurred by the fact that human-histocompatibility-antigen-identical kidney transplants also undergo immunological rejections.

Recent Findings: Polymorphisms within nonhuman histocompatibility antigen genes associated with evoking an immune response to alloantigens are currently being studied for their association with transplant outcome. Studies identify the polymorphic major histocompatibility complex class I-related chain A as one of the important nonhuman histocompatibility antigen antibody targets in kidney allograft rejections. Use of endothelial cells as targets may clarify the specificities of other clinically relevant nonhuman histocompatibility antigen antibodies in graft rejections.

Summary: This review summarizes current knowledge of the specificities and associations of nonhuman histocompatibility antigens with graft outcome after transplantation. The aims of current research into the role of nonhuman histocompatibility antigens and their genetics in predicting outcome are to develop an improved insight into the basic science of transplantation and to develop a risk or prognostic index for use in the clinical setting. Undoubtedly, this will continue to be an area of interest in terms of fully understanding the role of nonhuman histocompatibility antigens as targets of immune-mediated injury and the potential for clinical intervention.
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http://dx.doi.org/10.1097/MOT.0b013e328307ebd7DOI Listing
August 2008

Relevance of MICA and other non-HLA antibodies in clinical transplantation.

Curr Opin Immunol 2008 Oct 12;20(5):607-13. Epub 2008 Aug 12.

Division of Transplantation Surgery, Karolinska University Hospital, Huddinge, S-141 86 Stockholm, Sweden.

The clinical importance of HLA-specific antibodies for organ allograft outcome is well established. In the past few years, there has been an increasing interest in non-HLA antigens as targets of injury in organ transplant recipients. This increased interest has been spurred by the fact that HLA-identical kidney transplants also undergo immunological rejections. Polymorphisms within non-HLA genes associated with evoking an immune response to alloantigens are currently being studied for their association with transplant outcome. Non-HLA antigens, such as the polymorphic MHC class I-related chain A (MICA), expressed on endothelial cells have been implicated in the pathogenesis of hyperacute, acute and chronic organ allograft rejections. Use of endothelial cells as targets may clarify the specificities of other clinically relevant non-HLA antibodies in graft rejections. This review summarizes past and current knowledge of the clinical importance and specificities of non-HLA antibodies, and mechanisms by which these antibodies may contribute to graft destruction in clinical transplantation. The aims of current research into the role of non-HLA antigens and their genetics in predicting outcome are to develop an improved insight into the basic science of transplantation and to develop a risk or prognostic index for use in the clinical setting. Non-HLA antibody responses are receiving increasing interest in acute and chronic rejection and specificity, affinity, and pathogenicity need to be investigated to estimate their contribution. Undoubtedly, this will continue to be an area of interest in terms of fully understanding the role of non-HLA antigens as targets of immune-mediated injury and the potential for clinical intervention.
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http://dx.doi.org/10.1016/j.coi.2008.07.005DOI Listing
October 2008

A case of acute vascular rejection caused by endothelial-reactive non-HLA antibodies.

Clin Transpl 2006 :535-8

Division of Clinical Immunology, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden.

We describe a female patient who, despite negative conventional cross-matches, lost her first kidney graft in an acute humoral rejection. Prior to the second, AB0-incompatible (A1B to A1) living-donor kidney transplant, the patient had negative T- and B-cell cross-matches but had a positive donor-reactive endothelial cell cross-match. Following pre-transplant protein A and GlycoSorb-ABO immunoadsorptions to remove blood group B and anti-endothelial cell antibodies, Mabthera, and IVIG administrations, she was successfully transplanted. By the second post-operative day, creatinine levels were down to 96 micromol/L from 611 micromol/L pre-operatively. On day 9 creatinine rose again, and on the same day the endothelial cell crossmatch became positive for IgG, whereas the T-cell cross-match remained negative and the anti-A1B titers remained low. A kidney biopsy taken on day 10 post-transplant showed a picture of an acute vascular, antibody-mediated rejection. Following rejection treatment and repeated protein A and Glyco-Sorb-ABO immunoadsorptions, the patient's kidney function was again normalized. The use of a recently developed kit (XM-ONE) for the detection of anti-endothelial cell antibodies allowed us to identify a patient at risk for developing acute antibody-mediated rejection as well as to monitor treatment efficacy and post-transplant complications.
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May 2008

Liver sinusoidal endothelial cell function in rejected and spontaneously accepted rat liver allografts.

Transpl Int 2008 Jan 10;21(1):49-56. Epub 2007 Oct 10.

Division of Transplantation Surgery, Karolinska University Hospital-Huddinge, Karolinska Institute, Stockholm, Sweden.

Studies have suggested that liver sinusoidal endothelial cells (LSEC) may play an important role in tolerance induction. In this study, we evaluated the functional difference of LSEC in rejection and spontaneous acceptance of liver allografts by using rat liver transplant model. LSEC function was determined by circulating hyaluronic acid (HA) levels and fluorescein isothiocyanate-labeled formaldehyde-treated serum albumin (FITC-FSA) uptake. Additional parameters include the number of circulating lymphocytes and LSEC apoptosis. In spontaneously accepted group, we found (i) significantly lower serum HA levels (P = 0.002), (ii) a more rapid uptake of FITC-FSA, and (iii) a reduced number of circulating CD8a+ cells when compared with the rejection group. Strikingly, HA levels in spontaneously accepted group are even lower than syngeneic control group. Further investigation revealed that interleukin-1beta, a cytokine that promotes LSEC function, was higher in DA than in Lewis rats. In summary, our study demonstrates that LSEC function is better preserved in spontaneously accepted rat liver allografts than in those which are rejected. These findings warrant further studies to verify if LSEC actively contributes to liver transplant outcome or just a target of different immunologic responses.
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http://dx.doi.org/10.1111/j.1432-2277.2007.00569.xDOI Listing
January 2008

Anti endothelial cell autoantibodies selectively activate SAPK/JNK signalling in Wegener's granulomatosis.

J Am Soc Nephrol 2007 Sep 15;18(9):2497-508. Epub 2007 Aug 15.

Division of Clinical Immunology, Karolinska University Hospital at Huddinge, Karolinska Institutet, Stockholm, Sweden.

The pathogenic role of anti-endothelial cell antibodies (AECA) in vascular injury is debated. It was previously shown that many patients with Wegener's granulomatosis (WG) have AECA that react with human kidney microvascular endothelial cells (EC). In addition, during active disease, renal endothelium strongly expresses the inflammatory molecules vascular adhesion protein-1 (VAP-1) and MHC class I-related antigen A (MICA). This study sought to determine whether AECA mediates this upregulation of VAP-1 and MICA and to define better the signaling pathways that are activated by these autoantibodies upon binding to EC in the kidney. Stimulation of human kidney microvascular EC with AECA IgG upregulated surface expression of MICA and VAP-1, elicited a rapid Ca2+ flux, induced high levels of the chemokines monocyte chemoattractant protein-1 and granulocyte chemotactic protein-2, induced specific phosphorylation of stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and the transcription factors c-Jun and activating transcription factor-2, and activated NF-kappaB. Specific inhibitors of SAPK/JNK significantly reduced AECA-induced chemokine production and phosphorylation of c-Jun and activating transcription factor-2 and abrogated protein expression of MICA but not VAP-1. In kidney sections from patients with WG, infiltrating cells that expressed the ligand for MICA (NKG2D+) were identified, as were CD8+ and 32 gamma delta+ T cells. In conclusion, AECA may be involved in the pathogenesis of WG, and the SAPK/JNK pathway and the endothelial inflammatory protein VAP-1 may be novel therapeutic targets for vasculitis.
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http://dx.doi.org/10.1681/ASN.2006111286DOI Listing
September 2007

Biliary epithelial cell antibodies link adaptive and innate immune responses in primary sclerosing cholangitis.

Gastroenterology 2007 Apr 25;132(4):1504-14. Epub 2007 Jan 25.

Division of Transplantation Surgery, Division of Clinical Immunology, Karolinska University Hospital-Huddinge, Stockholm, Sweden.

Background & Aims: Primary sclerosing cholangitis (PSC) is an autoimmune liver disease with destruction of hepatic bile ducts. A high frequency of biliary epithelial cell antibodies (BEC-Ab) is present in PSC. Here, we studied the mechanisms and signaling pathways used by these Ab in causing BEC dysfunction.

Methods: Immunoassays were performed using freshly isolated BECs to study the signaling capacity of purified immunoglobulin (Ig) G and F(ab)'(2) fractions from 33 patients with PSC with anti-BEC-Ab.

Results: We provide evidence that stimulation of BECs with PSC IgG, but not control IgG, induced expression of Toll-like receptor (TLR) 4 and TLR9 and specific phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 as well as the transcription factors ELK-1 and nuclear factor kappaB. A specific inhibitor of ERK1/2 abrogated phosphorylation of ELK-1 and protein expression of TLR4 but not TLR9 on BECs. TLR-expressing BECs, when further stimulated with lipopolysaccharide and CpG DNA, produced high levels of interleukin-1beta, interleukin-8, interferon gamma, tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, and transforming growth factor beta. Bile ducts stained positively for TLR4 and TLR9 in 58% of liver specimens taken from patients with PSC with BEC-Ab, as compared with 14% in those without BEC-Ab and also less frequently in diseased control livers.

Conclusions: Our data show that binding of PSC BEC-Ab initiates ERK1/2 signaling and up-regulation of TLR, which upon ligation induces BECs to produce cytokines/chemokines, leading to the possible recruitment of inflammatory cells. Thus, in PSC, BECs are not only targets of the immune attack but may also be active participants and mediators of their own destruction. BEC-Ab may be critical regulators of cholangitis in PSC.
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http://dx.doi.org/10.1053/j.gastro.2007.01.039DOI Listing
April 2007