Jason A. Wertheim, MD, PhD
Northwestern University

Synopsis: This project proposes to advance the current state in development of a bioartificial kidney on the whole-organ level. Our lab has utilized a defined population of renal progenitor/stem cells, and an emphasis is placed upon their relationship to the kidney bioscaffold to re-develop the spatially complex nephron using a whole organ tissue engineering approach. Central to our hypothesis is the importance of mechanism in organ development to better understand cell differentiation and improve biological function.

Jon Odorico, MD, FACS
University of Wisconsin-Madison

William Burlingham, PhD
University of Wisconsin-Madison

Shu S. Lin, MD, PhD
Duke University

The Role of Mast Cells in Pulmonary Allograft Dysfunction

Synopsis: We have identified an apparently critical role of mast cells in pulmonary allograft failure.  Our studies show that peri-operative morbidity associated with long ischemic time affects approximately 1/3rd of the animals undergoing pulmonary allotransplantation. This morbidity is eliminated by mast cell inhibition.  Further, our studies show that mast cell inhibition effectively blocks obliterative bronchiolitis that is reproducibly observed in our transplant model. We expect to further elucidate the role of mast cells in pulmonary allograft dysfunction and to define the temporal features of that role in a matter that will facilitate translation of these results into the clinic.

Daniel Joyce, MD
Cleveland Clinic Foundation

Synopsis:

Organ transplantation has been applied for many decades, however the outcome of cellular transplants (e.g. islet cells, hepatocytes) remains disappointing.  It is thought that non-parenchymal cells may protect parenchymal cells from rejection.  We have identified that hepatic stellate cells (HSCs) have potent immunosuppressive activity.  HSCs effectively protect islet allografts in a mouse model.  This is mediated by the induction of apoptosis in effector T cells and by the generation of Treg cells and myeloid derived suppressor cells (MDSCs).    The use of HSCs to protect cell transplants from rejection is very attractive but not practical since the HSCs must be of recipient origin and the harvest of HSCs would involve a partial hepatectomy.  A solution has emerged based on our recent findings:  HSCs are potent inducers of MDSCs.  MDSCs can be produced in vitro in large quantities by the addition of HSCs into bone marrow derived dendritic cell culture; this is mediated by soluble factors, most notably iC3b.  

This project intends to determine the optimal culture conditions to generate human MDSCs in vitro and to identify the molecules that act synergistically with iC3b to promote MDSC production.  We will then characterize the immunomodulatory activity of human MDSCs in vivo and explore their utilization for protecting cell transplants in a humanized mouse model.  We will first study the immunomodulatory effect of MDSCs by footpad injection of allogeneic dendritic cells in  Hu-NOD/SCID/IL-2Ɣc mice that have been adoptively transferred with human primary bone marrow culture.  The impact of MDSCs on the T cell response will be assessed by analysis of the popliteal lymph nodes.   The ultimate goal of the study is to assess if systemic administration of MDSCs can protect islet cell allografts, this will be studied in the Hu-NOD/SCID/IL-2Ɣc mouse model, we will induce diabetes mellitus and then transplant human islet cell allografts under the renal capsule, glycemic control will then be monitored.  In the event of sustained euglycemia we will confirm that same is maintained by the transplanted islets by removing the graft bearing kidney which is expected to lead to rapid elevation in blood glucose levels.  The mice will be sacrificed and we will analyse the islet grafts, draining lymph nodes, irrelevant lymph nodes, spleen and peripheral blood.

While this project is confined to in vitro and in vivo murine studies, it is our expectation that it will provide the basis for a clinical trial in the near future.  The ability to perform allogeneic islet cell transplants without immunosuppression would represent a quantum leap in the current management of diabetes mellitus.

Sebastian Michel, MD
Massachusetts General Hospital

Synopsis: The incidence of cardiac rejection is lower in heart/kidney recipients than in isolated heart recipients. My goal is to discover the cells or cell products in the kidney that are responsible for conferring tolerance to cotransplanted hearts in a pig model. My hypothesis is that cells or cell products intrinsic to a donor kidney promote an activation of regulatory T cells. Renal tubular epithelial cells (RTECs) have the ability to inactivate effector T cells or convert them to Tregs by producing TGFβ, which is an inducer of Foxp3+.

I. Raul Badell, MD
Emory University

Impact of Selective CD28 Blockade on Donor-Reactive T cell Programming in Transplantation

Synopsis: Increased rates of acute rejection possibly secondary to costimulation blockade-resistant CD8+ T cells highlight the need for further investigation in order to to optimize the use of costimulation blockade in the clinic. The objective of this research proposal is to determine whether mechanisms of selective CD28 blockade alter the balance of costimulatory and coinhibitory molecules engaged during CD8+ T cell activation to control alloreactivity better than less selective CD28 and CTLA4 costimulation blockade. We will investigate some of the mechanisms of selective CD28 blockade on alloreactive T cell responses in transplantation and aim to evaluate the effects of novel recombinant CD28-specific domain antibodies on donor-reactive T cell effector differentiation while promoting exhaustion and/or regulation using murine transplant models.

Zain Ahmed, BS
Massachusetts General Hospital
Synopsis: Cardiac allograft vasculopathy (CAV), a form of chronic allograft rejection that leads to stenosis of the coronary arteries and ultimately failure of the transplanted heart, remains as one of the major limiting factors to successful heart transplantation. Previous studies have demonstrated that CAV in transplanted murine hearts can be induced with passive transfer of donor specific antibodies (DSA), monoclonal antibodies to donor major histocompatibility complex (MHC) class I, in murine recipients that lack T cell and B cell function (B6.RAG1-/-). Natural killer (NK) cells were detected in the early lesions, which led to subsequent mechanistic studies that demonstrated that NK cells were necessary for antibody-mediated CAV. Because the Fc portion of the DSA was required for lesion formation, NK cells may act via their FcγRIII receptor (CD16). Based on these preliminary results, the proposed study will examine the hypothesis that the binding of DSA to FcγRIII receptors on NK cells activates effector mechanisms that can lead to endothelial cell injury and ultimately CAV.

Shannon L. Cramm, BS
University of Michigan Medical School

Failure to rescue in pediatric liver transplant patients within one year post-transplant: an analysis of data from the SPLIT registry

Synopsis: There is great variability in 1-year survival among pediatric liver transplant centers in North America, ranging from 80% to near 100%. However, the mechanisms of this variability remain unclear. Using data from the Studies of Pediatric Liver Transplantation (SPLIT) registry, we will investigate failure to rescue, defined as the rate of mortality and/or re-transplantation per complication, as a possible source of this variability. We hypothesize that an inverse correlation between a center’s failure to rescue and 1-year survival exists. We will identify the high performing centers and investigate their practices as a step towards quality improvement in the field.

Katherine Khatibi, BS
University of Illinois at Chicago, College of Medicine

Synopsis: Post-transplant inflammatory macrophage activity can contribute to enhanced scar and long-term organ dysfunction. If inflammatory macrophage activity could be rapidly converted to pro-regenerative activity, long-term outcomes of transplanted kidneys may be improved. Augmenting the action of phagocytic and pro-regenerative macrophages may be of benefit to the transplanted kidney by promoting clearance of cellular debris and enhanced endothelial and epithelial repair. Human mesenchymal stem cells (MSC) have been implicated in inducing tolerance and enhancing host defense through cross-talk with macrophages. MHC Class II complexes are well-known modulators of T regulatory cell and could also be the method of communication between the MSC and macrophage. Insights gained into the precise method of communication could be used to potentiate regenerative responses, potentially enhancing human transplant graft life.

Joshua Elias Mendoza-Elias
University of Illinois at Chicago

The role of HIF-1 upregulation hypoxia precondition and chemical induction to increase long-term resistance of microencapsulated islet to hypoxia

Synopsis: Microencapsulated islets is a promsing cell-based therapy for T1DM. One of the greatest obstacles to microencapsulation is hypoxia, which: prevents islet revascularization, increases oxygen diffusion time, and is amplified when transplanted into the peritoneum. HIF-1 is a gene that governs cell protection and regulation of: angiogenesis, cell proliferation, glucose metabolism, and increases insulin secretion. Desferrioxamine (DFO) is an iron chelator and free radical scavenger that can stabilize HIF-1a, prevents graft rejection, and increases insulin secretion. Herein, we will study hypoxia preconditioning of microencapsulated islets with DFO to induction of HIF-1a for increasing long-term resistance of microencapsulated islets to hypoxia.