Effect of Early vs Late Inguinal Hernia Repair on Serious Adverse Event Rates in Preterm Infants: A Randomized Clinical Trial

Importance

Inguinal hernia repair in preterm infants is common and is associated with considerable morbidity. Whether the inguinal hernia should be repaired prior to or after discharge from the neonatal intensive care unit is controversial.

Objective

To evaluate the safety of early vs late surgical repair for preterm infants with an inguinal hernia.

Design, Setting, and Participants

A multicenter randomized clinical trial including preterm infants with inguinal hernia diagnosed during initial hospitalization was conducted between September 2013 and April 2021 at 39 US hospitals. Follow-up was completed on January 3, 2023.

Interventions

In the early repair strategy, infants underwent inguinal hernia repair before neonatal intensive care unit discharge. In the late repair strategy, hernia repair was planned after discharge from the neonatal intensive care unit and when the infants were older than 55 weeks' postmenstrual age.

Main Outcomes and Measures

The primary outcome was occurrence of any prespecified serious adverse event during the 10-month observation period (determined by a blinded adjudication committee). The secondary outcomes included the total number of days in the hospital during the 10-month observation period.

Results

Among the 338 randomized infants (172 in the early repair group and 166 in the late repair group), 320 underwent operative repair (86% were male; 2% were Asian, 30% were Black, 16% were Hispanic, 59% were White, and race and ethnicity were unknown in 9% and 4%, respectively; the mean gestational age at birth was 26.6 weeks [SD, 2.8 weeks]; the mean postnatal age at enrollment was 12 weeks [SD, 5 weeks]). Among 308 infants (91%) with complete data (159 in the early repair group and 149 in the late repair group), 44 (28%) in the early repair group vs 27 (18%) in the late repair group had at least 1 serious adverse event (risk difference, -7.9% [95% credible interval, -16.9% to 0%]; 97% bayesian posterior probability of benefit with late repair). The median number of days in the hospital during the 10-month observation period was 19.0 days (IQR, 9.8 to 35.0 days) in the early repair group vs 16.0 days (IQR, 7.0 to 38.0 days) in the late repair group (82% posterior probability of benefit with late repair). In the prespecified subgroup analyses, the probability that late repair reduced the number of infants with at least 1 serious adverse event was higher in infants with a gestational age younger than 28 weeks and in those with bronchopulmonary dysplasia (99% probability of benefit in each subgroup).

Conclusions and Relevance

Among preterm infants with inguinal hernia, the late repair strategy resulted in fewer infants having at least 1 serious adverse event. These findings support delaying inguinal hernia repair until after initial discharge from the neonatal intensive care unit.

Trial Registration

ClinicalTrials.gov Identifier: NCT01678638.

Optimizing an Outpatient mHealth Intervention for Children with Burns: A Convergent Mixed-Methods Study

Burn injury is one of the most common traumatic injuries in childhood. Fortunately, 90% of pediatric burns may be treated in the outpatient setting after appropriate burn triage. Patients with burns face significant geographic disparities in accessing expert burn care due to regionalized care. To aid patients and their families during acute outpatient burn recovery, we developed a smartphone app, Telemedicine Optimized Burn Intervention (TOBI). With this app, we aimed to increase access to care by allowing secure, streamlined communication between patients and burn providers, including messaging and wound image transfer. The purpose of this study was to systematically evaluate user feedback to optimize the patient and provider experience. TOBI was evaluated using a convergent mixed-methods approach consisting of qualitative semi-structured interviews and quantitative measurements of app usability via the mHealth App Usability Questionnaire. Participants included 15 caregivers of pediatric patients with burns who used TOBI during treatment and ten burn providers. Users found TOBI to be a highly usable application in terms of usefulness, ease of use, satisfaction, and functionality. Qualitative data provided insight into user experience, satisfaction and preferences, difficulty navigating, usability and acceptability, and potential improvements. Although most users were highly satisfied, improvements were needed to optimize the burn app. We systematically made these improvements before we released TOBI for routine patient use. This study uncovered helpful recommendations for app improvements that can be generalized to other mobile health apps to increase their appeal and adoption.

111 Optimizing an Outpatient Mhealth Intervention for Dallas with Burns: A Mixed Methods Study

Introduction

Pediatric burn injury remains one of the most common traumatic injuries in childhood. Fortunately, up to 90% of pediatric burns may be treated safely in the outpatient setting after appropriate burn triage. Patients face significant geographic disparities in access to expert burn care due to the regionalization of burn care. To aid patients and their families during acute burn recovery, a smartphone app was developed to improve patient outcomes, increase access to care, and streamline communication. The purpose of this study is to evaluate patient-derived feedback to optimize this burn app prior to subsequent efficacy testing.

Methods

The burn app was evaluated using a mixed-method approach consisting of qualitative semi-structured interviews and quantitative usability data gathered from caregivers of pediatric burn patients who utilized the app during the treatment phase of their child’s burn injury. Usability data were collected using a psychometrically validated mHealth App Usability Questionnaire (MAUQ). To analyze the interview transcriptions, we followed the Braun and Clark (2006) framework of thematic analysis. The research questions focused on caregiver perceptions of smartphone-enhanced pediatric burn care and potential app improvements, including acceptability, usability, technical preferences, and emotional perceptions.

Results

14 caregivers (93% women; M age = 36) completed the study. Overall MAUQ scores (M = 6.46; SD = .62) indicated high app usability. Ease of Use & Satisfaction (M = 6.66; SD = .42), System Information Arrangement (M = 5.93; SD = 1.07), and Usefulness (M = 6.69; SD = .61) subscales indicated an average degree of agreement above “somewhat agree” with usability statements. Furthermore, 13/14 (93%) caregivers reported a positive overall experience and agreed that the app was an acceptable method to monitor burn care. 12/14 (86%) caregivers reported that the app captured important clinical information. 53% preferred app-based burn care, 31% preferred both face-to-face and app-based care, and 15% preferred in-person only. Only 1 person preferred synchronous video-based care to asynchronous text-messaging. All study participants suggested improvements, with the most common being: (1) keeping user logged in, (2) time-stamping photos and messages, (3) consolidating text-messages and pictures, (4) adding push notifications and appointment reminders, and (5) tracking pain level.

Conclusions

Mobile health technology may be leveraged to improve outpatient burn care. The results from this study (1) demonstrate caregiver experiences using a novel mHealth platform for outpatient pediatric burn care which showed high acceptability and usability and (2) provide systematic data for app optimization.

Virtual Visits for Outpatient Burn Care during the COVID-19 Pandemic

Burn-injured patients must frequently travel long distances to regional burn centers, creating a burden on families and impairing clinical outcomes. Recent federal policies in response to the coronavirus pandemic have relaxed major barriers to conducting synchronous videoconference visits in the home. However, the efficacy and benefits of virtual visits relative to in-person visits remained unclear for burn patients. Accordingly, a clinical quality assurance database maintained during the coronavirus pandemic (3/3/2020 to 9/8/2020) for virtual and/or in-person visits at a comprehensive adult and pediatric burn center was queried for demographics, burn severity, visit quality, and distance data. A total of 143 patients were included in this study with 317 total outpatient encounters (61 virtual and 256 in-person). The savings associated with the average virtual visit were 130 ± 125 miles (mean ± standard deviation), 164 ± 134 travel minutes, &104 ± 99 driving costs, and &81 ± 66 foregone wage earnings. Virtual visit technical issues were experienced by 23% of patients and were significantly lower in pediatric (5%) than in adult patients (44%; p=0.006). This study is the first to assess the efficacy of synchronous videoconference visits in the home setting for outpatient burn care. The findings demonstrate major financial and temporal benefits for burn patients and their families. Technical issues remain an important barrier, particularly for the adult population. A clear understanding of these and other barriers may inform future studies as healthcare systems and payors move toward improving access to burn care through remote healthcare delivery services.

61 Real-time Burn Outpatient Virtual Visits in the Home During the Era of COVID-19

Introduction

The majority of burn injured patients travel long distances to receive burn care from regional burn centers, creating a burden on families and impairing outcomes. Recent federal policies in response to the COVID-19 pandemic have relaxed some of the barriers to virtual visits in the non-health care setting. We sought to review the experience of a comprehensive burn program in managing burn patients with a virtual platform.

Methods

A clinical quality database was maintained to evaluate virtual videoconference and in-person clinic visits for a comprehensive adult and pediatric burn program during the COVID-19 pandemic (March 2020 to August 2020). Virtual visits utilized a telemedicine platform that employs real-time audio and video communication. Demographic, burn severity, and visit quality data were recorded. Zip code data was also collected and then used to calculate the following estimated savings for the patient and their family: total miles, travel hours, driving costs, and wages.

Results

A total of 145 patients were included in this study with 96 (66.2%) male and 49 (33.7%) female. 91 (62.8%) were pediatric patients with a mean age of 6.2 ± 0.5 years and 54 (37.2%) were adult patients with a mean age of 40.4 ± 2.5 years. There were 320 total burn outpatient follow-up visits with 199 pediatric visits (40 virtual and 159 in-person) and 121 adult visits (24 virtual and 97 in-person). The majority of patients (73.1%) were treated as in-person visits while 6.9% had purely virtual visits, and 20.0% of patients had both virtual and in-person visits. The following savings were associated with virtual visits: 8562.6 total miles (average 133.8 ± 42.4), $6789.29 total driving cost (average $106.08 ± 33.61), 161.5 total travel hours (average 2.5 ± 0.7), and $4758.42 total wages lost to travel (average $74.35 ± 21.43). Technical issues were only reported in 14% of total visits (2.5% of pediatric virtual visits and 33.3% of adult virtual visits).

Conclusions

Outpatient virtual visits for burn care are a new frontier, driven by improvements in technology and reduced barriers to reimbursement. This study demonstrates that virtual visits are associated with major financial and temporal benefits for patients and their families. Technical issues remain an important barrier, particularly in the adult population. A clear understanding of this and other barriers may improve implementation of this new healthcare delivery paradigm.

Islet Harvest in Carbon Monoxide-Saturated Medium for Chronic Pancreatitis Patients Undergoing Islet Autotransplantation

Stresses encountered during human islet isolation lead to unavoidable β-cell death after transplantation. This reduces the chance of insulin independence in chronic pancreatitis patients undergoing total pancreatectomy and islet autotransplantation. We tested whether harvesting islets in carbon monoxide-saturated solutions is safe and can enhance islet survival and insulin independence after total pancreatectomy and islet autotransplantation. Chronic pancreatitis patients who consented to the study were randomized into carbon monoxide (islets harvested in a carbon monoxide-saturated medium) or control (islets harvested in a normal medium) groups. Islet yield, viability, oxygen consumption rate, β-cell death (measured by unmethylated insulin DNA), and serum cytokine levels were measured during the peri-transplantation period. Adverse events, metabolic phenotypes, and islet function were measured prior and at 6 months post-transplantation. No adverse events directly related to the infusion of carbon monoxide islets were observed. Carbon monoxide islets showed significantly higher viability before transplantation. Subjects receiving carbon monoxide islets had less β-cell death, decreased CCL23, and increased CXCL12 levels at 1 or 3 days post transplantation compared with controls. Three in 10 (30%) of the carbon monoxide subjects and none of the control subjects were insulin independent. This pilot trial showed for the first time that harvesting human islets in carbon monoxide-saturated solutions is safe for total pancreatectomy and islet autotransplantation patients.

Telemedicine in pediatric surgery

IMPORTANCE

Telemedicine is an emerging strategy for healthcare delivery that has the potential to expand access, optimize efficiency, minimize cost, and enhance patient satisfaction.

OBJECTIVE

To review the current spectrum, potential strategies, and implementation process of telemedicine in pediatric surgery.

DESIGN

Review and opinion design.

SETTING

n/a.

PARTICIPANTS

n/a. MAIN OUTCOMES AND MEASURES: n/a.

RESULTS

n/a.

CONCLUSIONS AND RELEVANCE

Telemedicine is an emerging approach with the potential to facilitate efficient, cost-effective delivery of pediatric surgical services.

BRIEF ABSTRACT

Telemedicine is an emerging strategy for healthcare delivery that has the potential to expand access, optimize efficiency, minimize cost, and enhance patient satisfaction. The objectives of this review are to explore common terms in telemedicine, provide an overview of current legislative and billing guidelines, review the current state of telemedicine in surgery and pediatric surgery, and provide basic themes for successful implementation of a pediatric surgical telemedicine program.

TYPE OF STUDY

Review.

LEVEL OF EVIDENCE

Level V.

Minimally invasive repair of pectus excavatum

Pectus excavatum, an acquired or congenital depression of the anterior chest wall, is the most commonly occurring chest wall deformity. Patients with pectus excavatum experience psychosocial and physiologic consequences such as impaired social development and pulmonary and/or cardiac dysfunction as a result of the deformity. Traditionally, repair of the defect was performed with a major open operation, the most common being based on modifications of the Ravitch procedure. In the late 1990's, the operative approach was challenged with a new minimally invasive technique described by Dr. Donald Nuss. This approach utilizes thoracoscopic visualization with small incisions and placement of a temporary metal bar positioned behind the sternum for support it while the costal cartilages remodel. Since introduction, the minimally invasive repair of pectus excavatum (MIRPE) has become accepted in many centers as the procedure of choice for repair of pectus excavatum. In experienced hands, the procedure has excellent outcomes, shorter procedural length, and outstanding cosmetic results. However, proper patient selection and attention to technical details are essential to achieve optimal outcomes and prevent significant complications. In the following, we describe our perspective on pectus excavatum deformities, operative planning, and technical details of the MIRPE procedure.

Pancreatic and Duodenal Trauma in Children

Trauma is the leading cause of death in children of all ages. The most common site of injury in pediatric patients is the head followed by the extremities and the abdomen. Though less than 10% of admissions to the hospital are secondary to intra-abdominal injuries, mortality related to these injuries is not insignificant. Pancreatic and duodenal trauma occurs in 3 to 12% of the patients with abdominal injuries and can be associated with significant morbidity. The management of pancreatic and duodenal trauma in children is based mostly on adult data, but there is an increasing volume of research on the subject.

TCR transduced CD4+ T cells exhibit a TH1 phenotype while inhibiting priming of naïve CD8+ T cells by peptide-loaded mature dendritic cells (48.19)

Adoptive immunotherapy is a promising new treatment modality for patients with advanced malignancies. A key limitation to adoptive T cell transfer is generating sufficient numbers of tumor reactive T cells for patient treatment. We have developed the ability to engineer T cells with TCR genes to redirect the specificity of PBL-derived T cells. A novel population we can produce are MHC class I restricted CD4+ T cells. CD4+ T cells have been implicated in the priming and maintenance of the CD8+ T cell response, in addition to having cytolytic properties in experimental models. In this study, tyrosinase-reactive human CD4+ T cells were created by retroviral transduction using a CD8-independent T cell receptor. Tyrosinase-reactive gene-modifed CD4+ cells produced IFN-γ, GM-CSF, and IL-2 in an HLA-A2 restricted, antigen-specific manner. Following tumor antigen recognition in vitro, TCR-transduced CD4+ T cells upregulated secondary costimulatory molecules, including OX-40 and 4-1BB. Despite their type I phenotype, priming of CD8+ cells by MART-1-loaded dendritic cells was impaired by these TCR-transduced CD4+ cells. Therefore, simultaneous engraftment of genetically-engineered CD4+ and CD8+ effector T cells may inhibit tumor killing by suppressing both CD8+ T cell induction and maintenance.

Tyrosinase reactive T cells can eliminate large established human melanoma tumors in vivo (48.23)

Objective clinical responses of melanoma can be achieved by infusion of tumor infiltrating lymphocytes or T cell receptor (TCR) gene transduced T cells. To evaluate the therapeutic efficacy of T cells expressing a high affinity TCR specific for the tyrosinase melanoma antigen (epitope Tyr368-376), we have developed a xenogenic model of human melanoma. Established human melanoma tumors (624 MEL) were rejected by administering low numbers of TIL 1383I TCR transgenic (h3T) splenocytes in an antigen specific, HLA-A2 restricted manner. Importantly, this therapeutic effect was observed with both small (30mm3) and large (100mm3) tumors. However, many of the mice that rejected their tumors recurred in time and the recurrent tumor cells were no longer recognized by h3T cells in vitro or in vivo. Phenotypic analysis revealed that all recurrent tumors from mice bearing 624 MEL had specifically lost HLA-A2, but not other MHC class I alleles, and this was not restored by IFN-γ treatment. Interestingly, mice bearing a HLA-A2 positive clone of 624 MEL (624-38 MEL) did not exhibit any tumor recurrences when treated with h3T cells. These results highlight the limitations of using a monoclonal therapeutic approach for melanoma. They also stress the need of models that enable us to evaluate combinatory therapies targeting heterogeneous tumors to develop improved immunotherapeutic strategies.

CD34-based enrichment of genetically engineered human T cells for clinical use results in dramatically enhanced tumor targeting

Objective clinical responses can be achieved in melanoma patients by infusion of T cell receptor (TCR) gene transduced T cells. Although promising, the therapy is still largely ineffective, as most patients did not benefit from treatment. That only a minority of the infused T cells were genetically modified and that these were extensively expanded ex vivo may have prevented their efficacy. We developed novel and generally applicable retroviral vectors that allow rapid and efficient selection of T cells transduced with human TCRs. These vectors encode two TCR chains and a truncated CD34 molecule (CD34t) in a single mRNA transcript. Transduced T cells were characterized and the effects of CD34-based enrichment of redirected T cells were evaluated. Both CD8(+) and CD4(+) T cells could be transduced and efficiently co-expressed all introduced transgenes on their surface. Importantly, more than fivefold enrichment of both the frequency of transduced cells and the specific anti-tumor reactivity of the effector population could be achieved by magnetic beads-based enrichment procedures readily available for clinical grade hematopoietic stem cell isolation. This CD34-based enrichment technology will improve the feasibility of adoptive transfer of clinically relevant effectors. In addition to their enhanced tumor recognition, the enriched redirected T cells may also show superior reactivity and persistence in vivo due to the high purity of transduced cells and the shortened ex vivo culture.

Inhibition of superoxide generation upon T-cell receptor engagement rescues Mart-1(27-35)-reactive T cells from activation-induced cell death

Cytotoxic T lymphocytes (CTL) may undergo massive expansion upon appropriate antigenic stimulation. Homeostasis is maintained by a subsequent "contraction" of these cells. Activation-induced cell death (AICD) and programmed cell death prevent the untoward side effects, arising from excessive numbers and prolonged persistence of activated CTL, that occur upon uncontrolled and/or continued expansion. However, effector cell persistence has been identified as a hallmark of successful T-cell-mediated adoptive immunotherapy. Thus, prevention of AICD may be critical to achieve more successful clinical results. We have previously shown that treatment with the c-Jun NH(2)-terminal kinase (JNK) inhibitor SP600125 protects human melanoma epitope Mart-1(27-35)-reactive CTL from apoptotic death upon their reencounter with cognate antigen. However, inhibition of JNK also interferes with the functional ability of the CTL to secrete IFN-gamma. Here, we show that reactive oxygen species (ROS) inhibitors, such as the superoxide dismutase mimetic Mn (III) tetrakis (5, 10, 15, 20-benzoic acid) porphyrin (MnTBAP), efficiently protected Mart-1(27-35)-reactive primary CTL from AICD without impairing their functional capability. MnTBAP prevented the increase in intracellular ROS, mitochondrial membrane collapse, and DNA fragmentation observed in control-treated cells upon cognate antigen encounter. Furthermore, the mechanism of AICD prevention in primary CTL included blockade of JNK activation. Finally, tumor-reactive in vitro expanded tumor infiltrating lymphocytes, which are used clinically in cancer immunotherapy, also benefit from MnTBAP-mediated antioxidant treatment. Thus, modulation of the redox pathway might improve CTL persistence and lead to better clinical results for T cell-based immunotherapies.

Increased levels of IgE and autoreactive, polyreactive IgG in wild rodents: implications for the hygiene hypothesis

To probe the potential role of Th1 versus Th2 reactivity underlying the hygiene hypothesis, intrinsic levels of Th1-associated and Th2-associated antibodies in the serum of wild rodents were compared with that in various strains of laboratory rodents. Studies using rat lung antigens as a target indicated that wild rats have substantially greater levels of autoreactive, polyreactive immunoglobulin G (IgG), but not autoreactive, polyreactive IgM than do laboratory rats, both on a quantitative and qualitative basis. Increased levels of serum IgG and IgE were observed in both wild rats and wild mice relative to their laboratory-raised counterparts, with the effect being most pronounced for IgE levels. Further, wild rats had greater intrinsic levels of both Th1- and Th2-associated IgG subclasses than did lab rats. The habitat (wild versus laboratory raised) had a more substantial impact on immunoglobulin concentration than did age, strain or gender in the animals studied. The presence in wild rodents of increased intrinsic, presumably protective, non-pathogenic responses similar to both autoimmune (autoreactive IgG, Th1-associated) and allergic (IgE, Th2-associated) reactions as well as increased levels of Th1-associated and Th2-associated IgG subclasses points toward a generally increased stimulation of the immune system in these animals rather than a shift in the nature of the immunoreactivity. It is concluded that, at least to the extent that feedback inhibition is a controlling element of immunoreactivity, an overly hygienic environment may affect the threshold of both types of immune responses more so than the balance between the different responses.

Increased IL‐4 production and attenuated proliferative and pro‐inflammatory responses of splenocytes from wild‐caught rats ( Rattus norvegicus )

Wild animals, unlike their laboratory counterparts, live amidst an abundance of pathogens and parasites. The presence of such immune stimulation from the time of birth likely has a profound effect on the development and stasis of the immune system. To probe potential differences between the immune systems of wild and laboratory animals, the response to mitogen (Con A) of splenocytes from wild rats was evaluated in vitro and compared with results from lab-rat-derived splenocytes. Although the response to mitogen is ubiquitous in splenocytes from laboratory animals regardless of strain or even species, splenocytes derived from wild rats were unresponsive to mitogen as judged by upregulation of activation markers and proliferation. Further, splenocytes from wild rats produced almost 10-fold less IL-2 and TNF-alpha in response to mitogen than did splenocytes from laboratory rats. In addition, mitogen stimulation resulted in an almost 100-fold greater production of IL-4 in wild-rat-derived splenocytes than in lab-rat-derived splenocytes. Perhaps surprisingly, these differences were observed in the absence of differences between wild and laboratory animals in the ratio of CD4+/CD8+ T cells or in the relative numbers of T cells, B cells and monocytes in the splenocyte population. These observations may have substantial implications for the hygiene hypothesis and provide considerable insight into the roles played by the environment during immune system development and modulation.

Effect of an anti-C5a monoclonal antibody indicates a prominent role for anaphylatoxin in pulmonary xenograft dysfunction

BACKGROUND

In contrast to renal or cardiac xenografts, the inhibition of complement using cobra venom factor (CVF) accelerates pulmonary xenograft failure. By activating C3/C5 convertase, CVF depletes complement while additionally generating C5a and other anaphylatoxins, to which pulmonary xenografts may be uniquely susceptible. The current study investigates the role of C5a in pulmonary xenograft failure in baboons.

METHODS

Left orthotopic pulmonary xenografts using swine lungs expressing human CD46 were performed in baboons receiving: I) no other treatment (n=4), II) immunodepletion (n=5), and III) immunodepletion plus a single dose of mouse anti-human C5a monoclonal antibody (anti-C5a, 0.6 mg/kg administered intravenously) (n=3). The extent to which anti-C5a inhibits baboon C5a was assessed in vitro using a hemolytic reaction involving baboon serum and porcine red blood cells and by ELISA.

RESULTS

Baboons in Group III exhibited significantly prolonged xenograft survival (mean=722+/-121 min, P=0.02) compared to baboons in Group I (mean=202+/-24 min) and Group II (mean=276+/-79 min). Furthermore, baboons in Groups I and II experienced pronounced hemodynamic compromise requiring inotropic support whereas those in Group III remained hemodynamically stable throughout experimentation without the need for additional pharmacologic intervention.

CONCLUSIONS

These findings indicate that C5a exacerbates pulmonary xenograft injury and compromises recipient hemodynamic status. Moreover, blockade of anaphylatoxins, such as C5a, offers a promising approach for future investigations aimed at preventing pulmonary xenograft injury in baboons.

The role of the porcine von Willebrand factor: baboon platelet interactions in pulmonary xenotransplantation

BACKGROUND

Porcine von Willebrand factor (pvWF) has been shown to bind to human glycoprotein Ib (GPIb) and cause activation of human (or primate) platelets in the absence of shear stress. Pulmonary xenografts develop disseminated intravascular coagulation (DIC) and microvascular thrombosis within hours of reperfusion, and the aberrant interaction between pvWF and human platelets may be a possible cause of xenograft-associated DIC.

METHODS

Experimental baboons (n=3) received mouse anti-human GPIb monoclonal antibody before undergoing orthotopic pulmonary xenotransplantation with porcine lungs expressing human membrane cofactor protein (CD46).

RESULTS

Blocking the pvWF-GPIb interaction with a monoclonal antibody to GPIb prevented the agglutination of human and baboon platelets by pvWF in vitro. In vivo, the anti-GPIb antibody prevented platelet deposition and prevented the increases in D-Dimers (P=0.011) seen in control xenograft recipients (n=5). However, there was no difference in elevations of prothrombin times (PT) or improvement in the vasoconstriction associated with the loss of xenograft function.

CONCLUSIONS

This study indicates that the DIC associated with the hyperacute dysfunction of pulmonary xenografts is a complex phenomenon that is affected by, but not solely dependent on, activation of platelets. Aberrant interactions between pvWF and GPIb play a significant role in DIC associated with pulmonary xenotransplantation.

Disseminated intravascular coagulation in association with pig-to-primate pulmonary xenotransplantation

BACKGROUND

Profound coagulopathy has been proposed as a barrier to xenotransplantation. Disseminated intravascular coagulation (DIC) has been observed with the rejection of renal and bone marrow xenografts but has not yet been described in pulmonary xenografts.

METHODS

This study examined the coagulation parameters in five baboons that received pulmonary xenografts and one baboon that was exposed to porcine lung during an extracorporeal perfusion. Platelet counts, prothrombin times (PT), and levels of fibrinogen, D-dimers, and thrombin-antithrombin III complex (TAT) were analyzed. In addition, serum levels of plasminogen activator inhibitor-1 (PAI-1), thrombomodulin (TM), tissue plasminogen activator (tPA), and tissue factor (TF) were determined.

RESULTS

Hyperacute pulmonary xenograft dysfunction, which occurred within 0-9 hr of graft reperfusion, was associated with clinically evident DIC. This coagulopathy was characterized by thrombocytopenia, decreased fibrinogen levels, elevations in PT, and increases in D-dimers and TAT. Furthermore, transient increases in PAI-1, increases in TM, and increases in tPA were observed in the serum of some but not all recipients. None of the baboons demonstrated measurable increases in soluble TF.

CONCLUSIONS

Although DIC in renal or bone marrow xenotransplantation develops over a period of days, DIC associated with hyperacute pulmonary xenograft dysfunction develops within hours of graft reperfusion. Thus, the DIC in pulmonary xenotransplantation may represent a unique and/or accelerated version of the coagulopathy observed with renal and bone marrow xenotransplantation.