Intensive hands-on microsurgery course provides a solid foundation for performing clinical microvascular surgery.

PURPOSE: Microvascular surgery requires highly specialized and individualized training; most surgical residency training programs are not equipped with microsurgery teaching expertise and/or facilities. The aim of this manuscript was to describe the methodology and clinical effectiveness of an international microsurgery course, currently taught year-round in eight countries. METHODS: In the 5-day microsurgery course trainees perform arterial and venous end-to-end, end-to-side, one-way-up, and continuous suture anastomoses and vein graft techniques in live animals, supported by video demonstrations and hands-on guidance by a full-time instructor. To assess and monitor each trainee's progress, the course's effectiveness is evaluated using "in-course" evaluations, and participant satisfaction and clinical relevance are assessed using a "post-course" survey. RESULTS: Between 2007 and 2017, more than 600 trainees participated in the microsurgery course. "In-course" evaluations of patency rates revealed 80.3% (arterial) and 39% (venous) performed in end-to-end, 82.7% in end-to-side, 72.6% in continuous suture, and 89.5% (arterial) and 62.5% (venous) one-way-up anastomoses, and 58.1% in vein graft technique. "Post-course" survey results indicated that participants considered the most important components of the microcourse to be "practicing on live animals", followed by "the presence of a full-time instructor". In addition, almost all respondents indicated that they were more confident performing clinical microsurgery cases after completing the course. CONCLUSIONS: Microvascular surgery requires highly specialized and individualized training to achieve the competences required to perform and master the delicate fine motor skills necessary to successfully handle and anastomose very small and delicate microvascular structures. The ever-expanding clinical applications of microvascular procedures has led to an increased demand for training opportunities. By teaching time-tested basic motor skills that form the foundation of microsurgical technique this international microsurgery-teaching course is helping to meet this demand.

Rapid Lipid Modification of Endothelial Cell Membranes in Cardiac Ischemia/Reperfusion Injury: a Novel Therapeutic Strategy to Reduce Infarct Size.

PURPOSE: Plasma membranes constitute a gathering point for lipids and signaling proteins. Lipids are known to regulate the location and activity of signaling proteins under physiological and pathophysiological conditions. Membrane lipid therapies (MLTs) that gradually modify lipid content of plasma membranes have been developed to treat chronic disease; however, no MLTs have been developed to treat acute conditions such as reperfusion injury following myocardial infarction (MI) and percutaneous coronary intervention (PCI). A fusogenic nanoliposome (FNL) that rapidly incorporates exogenous unsaturated lipids into endothelial cell (EC) membranes was developed to attenuate reperfusion-induced protein signaling. We hypothesized that administration of intracoronary (IC) FNL-MLT interferes with EC membrane protein signaling, leading to reduced microvascular dysfunction and infarct size (IS). METHODS: Using a myocardial ischemia/reperfusion swine model, the efficacy of FNL-MLT in reducing IS following a 60-min coronary artery occlusion was tested. Animals were randomized to receive IC Ringer's lactate solution with or without 10 mg/mL/min of FNLs for 10 min prior to reperfusion (n = 6 per group). RESULTS: The IC FNL-MLT reduced IS (25.45 ± 16.4% vs. 49.7 ± 14.1%, P < 0.02) and enhanced regional myocardial blood flow (RMBF) in the ischemic zone at 15 min of reperfusion (2.13 ± 1.48 mL/min/g vs. 0.70 ± 0.43 mL/min/g, P < 0.001). The total cumulative plasma levels of the cardiac injury biomarker cardiac troponin I (cTnI) were trending downward but were not significant (999.3 ± 38.7 ng/mL vs. 1456.5 ± 64.8 ng/mL, P = 0.1867). However, plasma levels of heart-specific fatty acid binding protein (hFABP), another injury biomarker, were reduced at 2 h of reperfusion (70.3 ± 38.0 ng/mL vs. 137.3 ± 58.2 ng/mL, P = 0.0115).  CONCLUSION: The IC FNL-MLT reduced IS compared to vehicle in this swine model. The FNL-MLT maybe a promising adjuvant to PCI in the treatment of acute MI.

A Novel Technique for Visualizing the Intralymphatic Primo Vascular System by Using Hollow Gold Nanospheres.

Until recently, the primo vascular system (PVS) has been unnoticed by most anatomists due to the small diameter and translucent features of the threadlike network. These properties make primo vessels (PVs) difficult to visualize for harvest and for further characterization. One particular PVS subtype that is located within the lymphatic vessels (LVs) is of strong interest because with a proper contrast, these long PVs can be visualized through the transparent LV wall and can be harvested to provide sufficient sample material for analysis. The most common method to visualize this PVS subtype utilizes Alcian blue as the contrast agent. This technique is effective, but tedious, and has relatively low repeatability. The purpose of this study was to develop a new technique that allows reliable visualization of the intralymphatic PVS (IL-PVS) in a user-friendly manner. The method was designed to provide optical contrast to the PVS by taking advantage of the porous nature of the PV's external wall and interstitial matrix. Turquoise-green-colored hollow gold nanospheres (HGNs) in the size range of 50-125 nm were found to provide excellent optical contrast for the IL-PVS in rats. The PVS was visualized within 10 minutes after HGN administration at a 95% success rate.

Novel cuff design to facilitate anastomosis of small vessels during cervical heterotopic heart transplantation in rats.

Cervical heterotopic heart transplantation in rodents is a useful tool for studying transplantation immunology. However, end-to-end anastomosis of small-diameter vessels by using standard microsurgical technique is technically difficult and can require prolonged graft ischemia. A novel cuff system was designed from polyethylene tubing to allow anastomosis of vessels with internal luminal diameters of 0.3 to 0.9 mm. Key features include a spring-like adjustable lumen to facilitate vessel eversion, a barb to hold vessel ends in place after eversion, and a handling system that allows easy manipulation and stabilization of cuffs by a single operator. After a training period, a single operator performed a series of 8 transplants in which the mean warm ischemic time of grafts was 8.5 ± 2.9 min. Here we provide a detailed description of how to construct and perform end-to-end vessel anastomosis by using our novel cuff system. The discussion of the technique is supplemented with tips learned during the process of developing a reliable experimental model.

Administration of exogenous adenosine triphosphate to ischemic skeletal muscle induces an energy-sparing effect: role of adenosine receptors.

BACKGROUND: Ischemia-reperfusion injury is a devastating complication that occurs in allotransplantation and replantation of limbs. Over the years, several preservation strategies have been used to conserve the critical levels of intracellular adenosine triphosphate (ATP) during ischemia to sustain the ion gradients across the membranes and thus the tissue viability. The administration of exogenous ATP to ischemic tissues is known to provide beneficial effects during reperfusion, but it is unclear whether it provides protection during ischemia. The purpose of the present study was to determine the effect of ATP administration on high-energy phosphate levels in ischemic skeletal muscle and to examine the role of purinergic and adenosine receptors in mediating the response to exogenous ATP. METHODS: The extensor digitorum longus muscles of Fischer rats were subjected to ischemia and treated with different concentrations of ATP with or without purinergic and adenosine receptor blockers. Phosphorus-31 nuclear magnetic resonance spectroscopy was used to measure the rate of decay of ATP, phosphocreatine (PCr), and the formation of adenosine monophosphate and acidification. Phosphorylated compounds were analyzed using a simple model of energy metabolism, and the PCr half-life was used as an index of internal depletion of ATP to distinguish between intracellular and extracellular ATP. RESULTS: PCr decay was rapid in all muscle groups and was followed by gradual ATP decay. The half-life of PCr was significantly longer in the ATP-treated muscles than in the vehicle controls and was maximally prolonged by treating with slow hydrolyzing adenosine 5'-O-(3-thio)triphosphate. Purinoceptor (P2X) blockade with ATP treatment significantly increased the half-life of PCr, and adenosine receptor blockers blunted the response. Administration of adenosine to ischemic muscles significantly increased the half-life of PCr compared with that in the vehicle controls. CONCLUSIONS: Exogenous ATP administration to ischemic skeletal muscles appears to spare intracellular energy by acting primarily through adenosine receptors.

Stabilizing endothelium of donor hearts with fusogenic liposomes reduces myocardial injury and dysfunction.

BACKGROUND: Myocardial injury after heart transplantation is a consequence of pathophysiologic events initiated by local ischemia/reperfusion injury that is further aggravated by the inflammatory response due to blood exposure to the pump's artificial surfaces during cardiopulmonary bypass. The purpose of the present study was to determine the effectiveness of fusogenic lipid vesicles (FLVs) in enhancing the cardioprotective effect of St. Thomas organ preservation solution (ST). We hypothesized that donor hearts preserved with ST+FLVs will stabilize the endothelium during reperfusion, which, in turn, will reduce both endothelial barrier dysfunction and myocardial damage. METHODS: To examine the effect of ST+FLVs therapy in vitro, C3b deposition and adhesion molecule expression studies were performed on human umbilical vein endothelial cells challenged with plastic contact-activated plasma. To assess the therapy in vivo, a cervical heterotopic working heart transplantation model in rats was used. Donor hearts were preserved for 1 h at 27°C (15 min) and 4°C (45 min) and, after transplantation, were followed up for 2 h. Left ventricular function and the blood cardiac troponin I levels were quantified. RESULTS: Human umbilical vein endothelial cells treated with ST+FLVs had reduced C3b deposition and expression of adhesion molecules compared with ST alone (P < 0.05). Donor hearts receiving ST+FLVs therapy had reduced left ventricular dysfunction and cardiac troponin I compared with ST alone. CONCLUSIONS: We concluded that FLVs enhanced the cardioprotective effect of ST and reduced postischemic left ventricular dysfunction and myocardial damage. The mechanism of protection appears to be associated with the stabilization of endothelial cell membranes owing to incorporation of FLV-derived lipids.

Factors influencing microsurgical skill acquisition during a dedicated training course.

BACKGROUND: Proficient microsurgical skills are considered essential in plastic and reconstructive surgery. Specialized courses offer trainees opportunity to improve their technical skills. Trainee aptitude may play an important role in the ability of a trainee to acquire proficient skills as individuals have differing fundamental abilities. We delivered an intensive 5-day microsurgical training course. We objectively assessed the impact of the course on microsurgical skill acquisition and whether aptitudes as assessed with psychometric tests were related to surgical performance. METHODS: Sixteen surgical trainees (male = 10 and female = 6) participated in the courses. Trainees' visual spatial, perceptual, and psychomotor aptitudes were assessed on day 1 of the course. The trainees' performance of an end-to-end arterial anastomosis was assessed on days 2 and 5. Surgical performance was assessed with objective structured assessment of technical skills(OSATS) and time to complete the task. RESULTS: The trainees showed a significant improvement in OSATS scores from days 2 to 5 (P < 0.001) and the time taken to complete the anastomosis (P < 0.001). Aptitude scores correlated strongly with objectively assessed microsurgical skill performance for male trainees but not for females. CONCLUSIONS: We demonstrated that participating in a microsurgical training course results in significant improvement in objectively assessed microvascular surgical skills. The degree of skills improvement was strongly correlated with psychomotor aptitude assessments scores for male trainees.

Enhancing complement control on endothelial barrier reduces renal post-ischemia dysfunction.

BACKGROUND: Excessive complement activation is an integral part of ischemia and reperfusion (IR) injury (IRI) of organs. In kidney transplantation, the pathologic consequence of IRI and complement activation can lead to delayed graft function, which in turn is associated with acute rejection. Previous strategies to reduce complement-induced IRI required systemic administration of agents, which can lead to increased susceptibility to infections/immune diseases. The objective of this study was to determine whether an increase in complement control defenses of rat kidney endothelium reduces IRI. We hypothesized that increased complement control on the endothelial barrier reduces IR-mediated complement activation and reduces kidney dysfunction. MATERIALS AND METHODS: Fischer 344 rats underwent left kidney ischemia for 45 min and treatment with a novel fusogenic lipid vesicle (FLVs) delivery system to decorate endothelial cells with vaccinia virus complement control protein (VCP), followed by reperfusion for 24 h. Assessment included renal function by serum creatinine and urea, myeloperoxidase assay for neutrophil infiltration, histopathology, and quantification of C3 production in kidneys. RESULTS: Animals in which the kidney endothelium was bolstered by FLVs+VCP treatment had better renal function with a significant reduction in serum creatinine compared with vehicle controls (P < 0.05). Also, C3 production was significantly reduced (P < 0.05) in treated animals compared with vehicle controls. CONCLUSION: Increasing complement control at the endothelial barrier with FLVs+VCP modulates complement activation/production during the first 24 h, reducing renal dysfunction following IRI.

A novel liposome-based therapy to reduce complement-mediated injury in revascularized tissues.

BACKGROUND: Ischemia/reperfusion (IR) injury is an unavoidable consequence of tissue transplantation or replantation that often leads to inflammation and cell death. Excessive complement activation following IR induces endothelial cell injury, altering vascular and endothelial barrier function causing tissue dysfunction. To mitigate the IR response, various systemic anti-complement therapies have been tried. Recently, we developed a localized therapy that uses biotinylated fusogenic lipid vesicles (BioFLVs) to first incorporate biotin tethers onto cell membranes, which are then used to bind therapeutic fusion proteins containing streptavidin (SA) resulting in the decoration of cell membranes. The therapy is applied in two steps using solutions delivered intra-arterially. MATERIALS AND METHODS: Alteration of formulation, concentration and duration of incubation of BioFLVs were conducted to demonstrate the ability of the system to modulate biotin tether incorporation in cultured cells. Using a rat hind limb model, the ability of BioFLVs to decorate endothelium of femoral vessels with FITC-labeled SA for 48 h of reperfusion was demonstrated. The feasibility of a BioFLV-based anti-complement therapy was tested in cultured cells using SA fused with vaccinia virus complement control protein (SA-VCP), a C3 convertase inhibitor. Human ovarian carcinoma (SKOV-3) cells were incubated with BioFLVs first and then with SA-VCP. To activate complement the cells were treated with a SKOV-3-specific antibody (trastuzumab) and incubated in human serum. RESULTS: Decoration of cells with SA-VCP effectively reduced complement deposition. CONCLUSIONS: We conclude that BioFLV-mediated decoration of cell membranes with anti-complement proteins reduces complement activation and deposition in vitro and has the potential for application against inappropropriate complement activation in vivo.

Cell membrane modification for rapid display of bi-functional peptides: a novel approach to reduce complement activation.

Ischemia and reperfusion of organs is an unavoidable consequence of transplantation. Inflammatory events associated with reperfusion injury are in part attributed to excessive complement activation. Systemic administration of complement inhibitors reduces reperfusion injury but leaves patients vulnerable to infection. Here, we report a novel therapeutic strategy that decorates cells with an anti-complement peptide. An analog of the C3 convertase inhibitor Compstatin (C) was synthesized with a hexahistidine (His(6)) tag to create C-His(6). To decorate cell membranes with C-His(6), fusogenic lipid vesicles (FLVs) were used to incorporate lipids with nickel (Ni(2+)) tethers into cell membranes, and these could then couple with C-His(6). Ni(2+) tether levels to display C-His(6) were modulated by changing FLV formulation, FLV incubation time and FLV levels. SKOV-3 cells decorated with C-His(6) effectively reduced complement deposition in a classical complement activation assay. We conclude that our therapeutic approach appears promising for local ex vivo treatment of transplanted organs to reduce complement-mediated reperfusion injury.

Ethical considerations in face transplantation.

Human face transplantation is now a clinical reality. The surgical techniques necessary to perform these procedures have been used routinely in reconstructive microsurgery for many years. From an immunological standpoint since face and hand contain mostly the same tissues it is reasonable to assume that the same immunosuppressive regimen found to be effective in human hand transplants should also work in face transplantation. It is the ethical issues associated with the risks and benefits of performing facial transplantation that have posed the greatest challenges leading up to performing this new procedure. In this editorial, we will review some of the main events that have led to the recently performed human face transplants, specifically focusing on the key ethical issues at the center of this debate. We will discuss how the research and clinical experience in human hand transplantation laid the foundation for performing face transplantation and describe the research and the ethical guidelines upon which a team at the University of Louisville based their position "to move ahead" in spite of much criticism. Finally we will outline some of the key arguments against face transplantation, and conclude with a discussion on what comes next now that the first human face transplants have been performed.

Psychosocial implications of disfigurement and the future of human face transplantation.

Although the first face transplants have been attempted, the social and psychological debates concerning the ethics and desirability of the procedure continue. Critics contend that these issues have not yet been sufficiently addressed. With this in mind, the present article seeks to elaborate on key psychological and social factors that will be central for addressing the ethical and psychosocial challenges necessary to move face transplantation into mainstream medicine. The goals of this article are to (1) discuss the psychosocial sequelae of facial disfiguration and how face transplantation may relieve those problems, and (2) delineate inclusion and exclusion criteria for the selection of research subjects for face transplantation. The article uses concepts from symbolic interaction theory in sociology to articulate a theoretically coherent scheme for comprehending the psychosocial difficulties of facial disfiguration and the advantages offered by facial transplantation. The authors conclude that the psychosocial implications of disfigurement warrant surgical intervention and that research in the area of face transplantation should continue.

Electrically stimulated rectus abdominis muscle flap to achieve enterostomal continence: development of a functional canine model.

BACKGROUND: Dynamic myoplasty has many clinical applications and has proven to be a versatile surgical procedure with great promise. This procedure has been used to achieve fecal/urinary continence, as in the dynamic graciloplasty, and to augment cardiac ventricular function, as is commonly seen with dynamic latissimus cardiomyoplasty. In the present study, the authors describe a functional innovative island flap sphincter created from the rectus abdominis muscle in a large-animal model to provide stomal continence for future clinical studies. METHODS: The caudal region of the rectus abdominis muscle in eight mongrel canines (23 to 25 kg) was investigated through anatomical dissections during which the location of the neurovascular pedicles and the intersegmental muscle dimensions between the muscle inscriptions were noted. The rectus abdominis muscle was used to create functional dynamic stomal sphincters that were trained with subcutaneously implanted pulse stimulators. RESULTS: The neurovascular pedicles were consistently found in similar locations along the posterior medial aspect of the caudal portion of the canine's rectus abdominis muscle. The vertical height of the deep inferior epigastric pedicle and caudal intercostal nerve muscular mean entry points were 6.75 +/- 1.89 cm and 7.44 +/- 0.86 cm, respectively. The mean caudal intersegmental muscle length of the rectus abdominis muscle used to create the sphincter was 9.69 +/- 1.81 cm. CONCLUSIONS: The canine rectus abdominis muscle has reliable anatomical locations where the neurovascular pedicle may be found. This canine muscle may be used to create a continent island flap stomal sphincter. This large-animal sphincter model is versatile, durable, and easy to manipulate, with minimal morbidity to the animal.

Composite tissue allotransplantation of the hand and face: a new frontier in transplant and reconstructive surgery.

Each year an estimated 7-million people in the USA need composite tissue reconstruction because of surgical excision of tumors, accidents and congenital malformations. Limb amputees alone comprise over 1.2 million of these. This figure is more than double the number of solid organs needed for transplantation. Composite tissue allotransplantation in the form of hand and facial tissue transplantation are now a clinical reality. The discovery, in the late 1990s, that the same immunotherapy used routinely in kidney transplantation was also effective in preventing skin rejection made this possible. While these new treatments seem like major advancements most of the surgical, immunological and ethical methods used are not new at all and have been around and routinely used in clinical practice for some time. In this review of composite tissue allotransplantation, we: (i) outline the limitations of conventional reconstructive methods for treating severe facial disfigurement, (ii) review the history of composite tissue allotransplantation, (iii) discuss the chronological scientific advances that have made it possible, (iv) focus on the two unique clinical scenarios of hand and face transplantation, and (v) reflect on the critical issues that must be addressed as we move this new frontier toward becoming a treatment in mainstream medicine.

Risk acceptance in laryngeal transplantation.

PURPOSE: Advancements in the fields of head and neck surgery and immunology have paved the way for new quality of life-improving procedures such as larynx transplantation. To quantitatively assess the risks versus benefits in larynx transplantation, we used a questionnaire-based survey (Louisville Instrument For Transplantation [LIFT]) to measure the degree of risk individuals are willing to accept to receive different types of transplantation procedures. METHODS: The LIFT contains 237 standardized questions incorporating standard gamble and time tradeoff outcome measures as well as questions assessing body image perception, depression, self-esteem, optimism, socially desirable responding, and demographics. Respondents were questioned on the extent to which they would trade off specific numbers of life-years, or sustain other costs, in exchange for receiving seven different types of transplant procedures. For this study, we questioned 243 individuals in three study populations with differing life experiences: healthy individuals, organ transplant recipients, and laryngectomees. RESULTS: All populations questioned perceived risks differently based on their varied life experiences and would accept differing degrees of risk for the different transplant procedures. Organ transplant recipients were the most risk-tolerant group, whereas laryngectomees were the least risk-tolerant. CONCLUSIONS: By questioning individuals with life experiences directly relevant to the risks and benefits associated with larynx transplantation, this study provides an empiric basis for assessing risk versus benefit in this new quality of life-improving procedure.

Neuroregeneration in composite tissue allografts: effect of low-dose FK506 and mycophenolate mofetil immunotherapy.

BACKGROUND: The immunosuppressant FK506 has been reported to increase the rate of peripheral nerve regeneration in nerve crush injury and nerve allograft models. The purpose of this study was to determine whether low doses of FK506 and mycophenolate mofetil had a neuroregenerative effect in revascularized peripheral nerve allografts in a rat hind limb transplantation model. METHODS: Wistar Furth rat recipients received limbs from syngeneic Wistar Furth donors (group 1, n = 4) or from allogeneic August X Copenhagen Irish rat donors (group 2, n = 6). Wistar Furth recipients received limbs from August X Copenhagen Irish donors and were treated with FK506/mycophenolate mofetil for 5 months (group 3, n = 7). At the end of the follow-up period, histomorphometric analysis of sciatic and tibial nerves from transplanted and intact hind limbs was conducted. Sciatic and tibial nerves were examined at the level of coaptation and near the neuromuscular junction, respectively. RESULTS: Transplanted limbs in groups 1 and 3 completed the study without rejection, while the limbs in group 2 were rejected within a few days. Sciatic and tibial nerve analysis in groups 1 and 3 limbs showed myelinated axons of various diameters but in significantly fewer numbers than in nontransplanted contralateral nerves. The number and size of myelinated axons of transplanted nerves at corresponding levels were not significantly different between syngeneic and allogeneic (FK506/mycophenolate mofetil-treated) transplants. CONCLUSIONS: The authors conclude that long-term neuroregeneration of revascularized peripheral nerves using low-dose FK506/mycophenolate mofetil was similar to that of syngeneic transplants. The occurrence of acute rejection episodes with low-dose FK506/mycophenolate mofetil did not appear to benefit nor impair neuroregeneration.

Investigation of risk acceptance in facial transplantation.

BACKGROUND: The surgical techniques necessary to transplant a human face are well established, and the early success of human hand transplants suggests that the immunological hurdles of transplanting human facial tissues have largely been overcome. Therefore, it is the ethical barriers that pose the greatest challenge to performing facial transplantation. At the center of the ethical debate is the question, "Do the risks posed by the life-long immunosuppression that a recipient would have to take justify the benefits of receiving a face transplant?" In this study, the authors answer this question by assessing the degree of risk individuals would be willing to accept to receive a face transplant. METHODS: To quantitatively assess risks versus benefits in facial transplantation, the authors developed the Louisville Instrument for Transplantation, or LIFT, which contains 237 standardized questions. Respondents in three study populations (healthy individuals, n = 150; organ transplant recipients, n = 42; and individuals with facial disfigurement, n = 34) were questioned about the extent to which they would trade off specific numbers of life-years, or sustain other costs, in exchange for receiving seven different transplant procedures. RESULTS: The authors found that the three populations would accept differing degrees of risk for the seven transplant procedures. Organ transplant recipients were the most risk-tolerant group, while facially disfigured individuals were the least risk tolerant. All groups questioned would accept the highest degree of risk to receive a face transplant compared with the six other procedures. CONCLUSIONS: This study presents an empirical basis for assessing risk versus benefit in facial transplantation. In doing so, it provides a more solid foundation upon which to introduce this exciting new reconstructive modality into the clinical arena.

Vascularized lymph node transplantation induces graft-versus-host disease in chimeric hosts.

BACKGROUND: The role of lymph nodes (LNs) in adaptive immune responses has been the subject of extensive research. In previous studies, the surgical removal of lymph nodes from rat hind limbs prevented the development of lethal graft-versus-host disease (GVHD) after allogeneic hind limb transplantation to chimeric recipient rats. The purpose of this study was to establish the role of the cellular fraction versus the microenvironment of LNs in the development of GVHD in this model. METHODS: A rat model for vascularized LN transplantation was developed and graft-versus-host responses were compared after: 1) naive ACI LN cells were infused into Wistar-Furth (WF) rats as chimeric recipients (e.g. [ACI-->WF]); 2) vascularized WF lymph nodes were transplanted to syngeneic WF recipients; 3) nonvascularized ACI lymph nodes were transplanted to [ACI-->WF] chimeric recipients; 4) vascularized ACI lymph nodes were transplanted to [ACI-->WF] chimeric recipients. RESULTS: Transplantation of vascularized ACI lymph nodes to [ACI-->WF] chimeric recipient rats resulted in severe and sometimes lethal GVHD. In contrast, neither the infusion of purified ACI LN cells nor the transplantation of nonvascularized LNs led to GVHD in chimeric recipients. CONCLUSIONS: When introducing allogeneic cells into chimeric recipients, concomitant transplantation of the vascularized LN microenvironment makes a manifest difference between induction and absence of GVHD. This illustrates the important role of the LN microenvironment in adaptive immune responses.

Risk acceptance in composite-tissue allotransplantation reconstructive procedures.

Composite-tissue allotransplantation (CTA) is a new therapeutic modality to reconstruct major tissue defects of the face, larynx, and extremities. Unlike most life-saving organ-transplantation procedures, CTA is considered to improve quality of life. Therefore, the question arises, do the risks posed by the immunosuppression drugs that patients must take to prevent rejection justify the benefits of these procedures? The purpose of this study was to assess the relative risk that individuals are willing to accept in order to receive the benefits of CTA procedures. We used a psychometrically reliable and valid instrument to question two primary populations of individuals: those who live with the risks of immunosuppression, and healthy individuals. The level of risk acceptance for the seven transplant procedures tested (foot, single hand, double hand, larynx, kidney, hemiface, and full face) showed significant differences in research participants' risk acceptance for the different transplant procedures, but no significant differences between groups. Based on these findings, we conclude that certain CTA procedures convey benefits to recipients that are perceived by subjects, including individuals who live with the risks of immunosuppression, to warrant the risks of these procedures.

Bone quality in swine composite tissue allografts: effects of combination immunotherapy.

BACKGROUND: Tacrolimus (FK506)/mycophenolate mofetil (MMF)/prednisone combination immunosuppression therapy has been found to effectively prevent composite tissue allograft (CTA) rejection with minimal toxicity in a preclinical porcine model. These findings have been reproduced in 24 human hands transplanted in 18 patients. In CTAs containing bone, adequate bone quality and healing are essential for long-term functional success. The purpose of this study was to determine the effect FK506/MMF/prednisone immunotherapy has on bone quality and healing. METHODS: Forelimb CTA-flaps were transplanted in nine pigs. Recipient animals received FK506/MMF/prednisone therapy for 3 months. Bone quality was studied pre- and posttransplant by measuring acoustic velocity and density and by calculating elastic coefficients. Additional bone quality analyses were performed on unoperated limbs, and in bone grafts from two pigs that had autograft procedures performed. Bone healing was assessed using radiographic analysis. RESULTS: Three animals were lost to immunosuppression-related complications before the endpoint of the study. The bone component of all six CTA-flaps showed normal healing. Although results of the bone density measurements were not significantly different when comparing pre- to posttransplant values, acoustic velocity and elastic coefficient measurements showed a significant decrease posttransplant indicating a decrease in bone quality. CONCLUSIONS: FK506/MMF/prednisone combination therapy prevented rejection, did not adversely affect bone quality, and showed normal bone healing. The transplant procedure itself decreased bone quality more than the immunosuppression regimen did over the observation period in this study. Based on these findings, we conclude to prevent CTA failure it is important to monitor bone quality posttransplant.