Update on Bronchiolitis Obliterans Syndrome in Lung Transplantation
Abstract Lung transplantation has become an important therapeutic option for patients with end-stage organ dysfunction; however, its clinical usefulness has been limited by the relatively early onset of chronic allograft dysfunction and progressive clinical decline. Obliterative bronchiolitis is characterized histologically by luminal fibrosis of the respiratory bronchioles and clinically by bronchiolitis obliterans syndrome (BOS) which is defined by a measured decline in lung function based on forced expiratory volume (FEV1). Since its earliest description, a number of risk factors have been associated with the d...
Source: Current Transplantation Reports - September 12, 2014 Category: Transplant Surgery Source Type: research

Size and Gender Matching in Heart Transplantation – Optimizing Donor Utilization in an Era of Changing Donor and Recipient Characteristics
Abstract Heart transplantation is limited by donor organ availability. Increased use of marginal donor organs, combined with increased recipient complexity, has increased the risk of primary graft failure. These changes in donor and recipient characteristics have led to a renewed focus on modifiable donor–recipient characteristics that have historically been shown to impact on post-transplant outcomes, namely size and gender matching. Recently published analyses of large registries have found that the use of body weight to size donor organs for transplantation fails to predict post-transplant outcomes, where...
Source: Current Transplantation Reports - September 6, 2014 Category: Transplant Surgery Source Type: research

Standardizing MELD Exceptions: Current Challenges and Future Directions
Abstract Since Model for End-Stage Liver Disease (MELD)-based allocation was implemented in 2002, a system of exception points has been in place in order to award increased waitlist priority to those patients whose severity of illness or risk of complications are not captured by the MELD score. These exceptions, categorized as standardized and non-standardized, have been used with increasing frequency over time. Several challenges to the exception point system have emerged, including lack of standardization in the criteria used to approve such exceptions, geographic variability in the use and approval of such exce...
Source: Current Transplantation Reports - September 6, 2014 Category: Transplant Surgery Source Type: research

Primary Graft Dysfunction After Heart Transplantation
Abstract Primary graft dysfunction (PGD) is a life-threatening complication of heart transplantation that presents as left, right, or biventricular dysfunction occurring within the first 24 hours of transplant surgery for which there is no identifiable secondary cause. Myocardial injury caused by acute catecholamine toxicity and the release of multiple proinflammatory mediators in the donor, followed by ischaemia-reperfusion injury sustained during retrieval, have been considered the predominant pathogenetic processes leading to PGD. Donor, recipient, and procedural factors contribute to the development and s...
Source: Current Transplantation Reports - September 4, 2014 Category: Transplant Surgery Source Type: research

Vascularized Composite Allografts: Procurement, Allocation, and Implementation
Abstract Vascularized composite allotransplantation is a continuously evolving area of modern transplant medicine. Recently, vascularized composite allografts (VCAs) have been formally classified as ‘organs’. In this review, key aspects of VCA procurement are discussed, with a special focus on interaction with the procurement of classical solid organs. In addition, options for a matching and allocation system that ensures VCA donor organs are allocated to the best-suited recipients are looked at. Finally, the different steps needed to promote VCA transplantation in society in general and in the medica...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Memory T Cells in Transplantation
Abstract Following infections and other environmental exposures, the resulting primary immune response generates memory T cells that provide long-term protective immunity. Compared to their naïve T cell counterparts, memory T cells possess unique characteristics that endow them with the ability to quickly and robustly respond to foreign antigens. While such memory T cells are beneficial in protecting hosts from recurrent infection, memory cells reactive to donor antigens pose a major barrier to successful transplantation and tolerance induction. Significant progress has been made over the past decade contrib...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Ischemia/Reperfusion Injury and its Consequences on Immunity and Inflammation
Abstract Ischemia/reperfusion injury (IRI), an inherent component of transplantation, affects organ quality and transplant outcomes. Although the complexity of the pathophysiology is recognized, detailed mechanisms remain unclear, and strategies preventing the consequences of IRI have been challenging. Of critical significance appears to be the link between IRI, the initiation of innate immune responses, and the (potential) augmentation of adaptive immunity. An improved understanding of those complex mechanisms and interactions may pave the way for more effective treatment strategies. (Source: Current Transplantation Reports)
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Non-Antibody Mediated Roles of B Cells in Allograft Survival
Abstract Antibody production is unquestionably a key effector function of B cells that remains a formidable barrier against long-term graft survival. However, emerging evidence indicates that B cells play a key role in shaping the effector responses by mechanisms that extend beyond their function as antibody producing cells. B cell depletion in transplant recipients has resulted in paradoxical outcomes of increased graft rejection versus improved graft function, implying that B cells function as both enhancers and regulators of the alloimmune response. Based on findings from animal and human studies, we address m...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Evolving Concepts of Skin and Mucosal Biopsy in Facial Vascularized Composite Allotransplantation
Abstract Facial vascularized composite allotransplantation has ushered in a new era in treating complex facial injuries that cannot be reconstructed using traditional techniques. Multiple teams have reported their experiences in monitoring for allograft rejection using skin and mucosal biopsies. The association of biopsy findings and clinical observations are poorly understood and are continuously being redefined. We review the world’s experience in monitoring skin and mucosal histological findings in facial transplantation, review acute rejection, antibody-mediated rejection, chronic rejection, and describ...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Measuring Outcome in Upper-Extremity Transplantation
Abstract Measuring the outcome in upper-extremity transplantation is important to understand the potential of the procedure and to assist the patient and surgeon in decision making. The outcome of replantation varies with the anatomic level and mechanism of amputation; factors which inform the indications for replantation. We review the outcome measures used in upper-extremity transplantation and advocate for a combination of patient-answered outcomes, physical measurements, preference-based measurement, and cost analysis. Since this procedure is not common, and there is significant risk associated with immunosup...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Postoperative Monitoring: Biomarkers and Alloimmune Responses and Their Relevance to Vascularized Composite Allotransplantation
Abstract Vascularized composite allotransplantation (VCA) is an evolving area of transplantation. Postoperative monitoring and immunosuppression strategies draw experience from solid organ transplantation, but VCA provides unique challenges as grafts incorporate histologically heterogenous tissues with differing degrees of antigenicity. In addition, such procedures are often life-improving rather than life-saving; therefore, minimizing the risks of immunosuppression is an important clinical priority. To this end, the identification of biomarkers to monitor the health of the transplanted tissues, assess alloimmune...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Mouse Models of Experimental Vascularized Composite Allotransplantation
Abstract The clinical practice of vascularized composite allotransplantation (VCA) has been limited by the potential side effects of chronic immunosuppression. Studies using rodent models have been useful for dissecting mechanisms underlying immunological events induced by VCA and for developing protocols such as mixed chimerism for tolerance induction. Mouse models of VCA have great advantages over rat and other rodents with regard to dissection of immunologic mechanisms; however, the microsurgical revascularization procedures that are required are much more difficult. Here we review recent advances in surgical ...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Large Animal Models for Vascularized Composite Allotransplantation
Abstract Large animal models have served as the foundation for clinical trials in all solid organ transplantation. Likewise, pre-clinical studies in vascularized composite allotransplantation (VCA) have provided a foundation for initial human applications in VCA. The growth of clinical VCA correspondingly benefits from large animal studies investigating the unique immunobiology, improved immunosuppressive regimens, and the potential induction of immunologic tolerance. VCA studies in large animal models of nonhuman primates, swine, and canines have and continue to build knowledge towards improved clinical outcomes...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

T Follicular Helper Cells in Transplantation: The Target to Attenuate Antibody-Mediated Allogeneic Responses?
Abstract Antibody-mediated, humoral rejection has been recognized as a common cause of transplant dysfunction and is responsible for 30–50 % of failed allografts. The production of antibody is dependent on instructions from memory CD4+ T helper cells that interact with antigen-specific B cells. Recently, a specialized T-cell subset has been identified—T follicular helper (Tfh) cells—which support activated B cells via interleukin (IL)-21 after binding to the IL-21 receptor expressed by these B cells. Therefore, neutralizing the IL-21 pathway will selectively inhibit the allogeneic IL-21-dri...
Source: Current Transplantation Reports - September 1, 2014 Category: Transplant Surgery Source Type: research

Program Specific Reports: Friend or Foe? —The Intended and Unintended Consequences of Scientific Registry of Transplant Recipient Program Specific Reports
Abstract Both the OPTN and CMS evaluate transplant center performance status. Since 2000, publicly available SRTR generated program specific reports (PSRs) are used to identify, or flag, programs that may be performing below expectations. The intended use of PSRs is to focus attention on centers requiring greater scrutiny to aid in the efforts to identify those programs where transplant outcomes can be improved, ultimately optimizing national transplant outcomes. However, the consequences to a transplant program of being flagged, even when the program is not found to be underperforming upon further review, are si...
Source: Current Transplantation Reports - June 1, 2014 Category: Transplant Surgery Source Type: research

Repeat Pancreas Transplant Procedures: Recipient Selection and Surgical Techniques
This article highlights the existing literature on pancreas retransplant, and outlines key points regarding recipient selection and technical considerations that may be useful when offering pancreas retransplantation. (Source: Current Transplantation Reports)
Source: Current Transplantation Reports - June 1, 2014 Category: Transplant Surgery Source Type: research