Faculty Bibliography

Over 115 000 people are waiting for life-saving organ transplants, of whom a small fraction will receive transplants and many others will die while waiting. Existing efforts to expand the number of available organs, including increasing the number of registered donors and procuring organs in uncontrolled environments, are crucial but unlikely to address the shortage in the near future and will not improve donor/recipient compatibility or organ quality. If successful, organ bioengineering can solve the shortage and improve functional outcomes. Studying manufactured organs in animal models has produced valuable data, but is not sufficient to understand viability in humans. Before risking manufactured organ experimentation in living humans, study of bioengineered organs in recently deceased humans would facilitate evaluation of the function of engineered tissues and the complex interactions between the host and the transplanted tissue. Although such studies do not pose risk to human subjects, they pose unique ethical challenges concerning the previous wishes of the deceased, rights of surviving family members, effective operation and fair distribution of medical services, and public transparency. This article investigates the ethical, legal and social considerations in performing engineered organ research on the recently deceased.

Objective: Abdominal aortic aneurysm (AAA) is a fatal vascular disease on rupture with still limited mechanistic knowledge of the pathophysiologic process. We sought to determine the heterogeneous cell subtypes and to characterize the spectrum of transcriptome signatures in each cell population within the aneurysmal wall by unbiased single-cell RNA sequencing (scRNA-seq) of human AAA tissue.
Method(s): Aortic specimens were collected from AAA and control healthy organ donor. Samples were processed by enzymatic digestion and mechanical disruption to generate single-cell suspension. Single-cell RNA libraries were prepared after generation of single-cell beads in emulsion. Sequencing was performed on a NovaSeq 6000 platform (Illumina, San Diego, Calif). After alignment, barcode assignment, and sample de-multiplexing, data analysis was performed on t-distributed stochastic neighbor embedding charts of cell transcriptome. Cell clusters were identified by unsupervised proximity based on Euclidian distance and supervised identification of biologic markers within clusters. Pathway analysis algorithms were used to outline biologically relevant networks.
Result(s): Unbiased analysis of scRNA-seq data sets showed 19 different cell clusters with unique transcriptomic signatures in AAA. A total of 8826 significant differentially expressed genes were identified in AAA vs control. Notably, gene transcription-associated extracellular matrix remodeling (COL1A1, COL3A1, COL1A2, LUM), Wnt signaling modulation (SFRP2), and synthetic cellular phenotypes (RPS29, RPS27, RPL13A, RPL28) were among the top increased profiles in AAA tissue. Pathway enrichment analysis of AAA vs control libraries revealed significant modulation of cell proliferation, cell-extracellular matrix interaction, neoangiogenesis, and inflammation. Five novel cell clusters with distinct immune synthetic phenotypes were predominantly abundant in AAA wall compared with the healthy aorta. A robust enrichment in immune cell entities was identified in AAA but not in control tissues, including expansion of CD19⁺ B lymphocytes and a subset of CD3E⁺ T lymphocytes significantly expressing IL32 and CCL5. In contrast, smooth muscle cell (ACTA2⁺MYH11⁺) number declined in AAA but revealed increased transcription of the protease ADAMTS4 and inflammatory signals (CCL19, CCL21, IL6, CCL2). Intercluster pathway analysis revealed enrichment of eukaryotic initiation factor 2 and mechanistic target of rapamycin signaling in the AAA macrophage population along with an increased number of inflammatory and T-cell activation cascades.
Conclusion(s): To the best of our knowledge, this is the first report of scRNA-seq analysis on human AAA. This cutting-edge technique uncovered novel cell clusters and provided a comprehensive understanding of cellular spatiotemporal changes within the AAA wall. Here we provide novel interconnected mechanistic insights into this complex disease to enrich our understanding of AAA development.
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BACKGROUND:Facial transplantation introduced a paradigm shift in the reconstruction of extensive facial defects. Although the feasibility of the procedure is well established, new challenges face the field in its second decade. METHODS:The authors' team has successfully treated patients with extensive thermal and ballistic facial injuries with allotransplantation. The authors further validate facial transplantation as a reconstructive solution for irreparable facial injuries. Following informed consent and institutional review board approval, a partial face and double jaw transplantation was performed in a 25-year-old man who sustained ballistic facial trauma. Extensive team preparations, thorough patient evaluation, preoperative diagnostic imaging, three-dimensional printing technology, intraoperative surgical navigation, and the use of dual induction immunosuppression contributed to the success of the procedure. RESULTS:The procedure was performed on January 5 and 6, 2018, and lasted nearly 25 hours. The patient underwent hyoid and genioglossus advancement for floor-of-mouth dehiscence, and palate wound dehiscence repair on postoperative day 11. Open reduction and internal fixation of left mandibular nonunion were performed on postoperative day 108. Nearly 1 year postoperatively, the patient demonstrates excellent aesthetic outcomes, intelligible speech, and is tolerating an oral diet. He remains free from acute rejection. CONCLUSIONS:The authors validate facial transplantation as the modern answer to the classic reconstructive challenge imposed by extensive facial defects resulting from ballistic injury. Relying on a multidisciplinary collaborative approach, coupled with innovative emerging technologies and immunosuppression protocols, can overcome significant challenges in facial transplantation and reinforce its position as the highest rung on the reconstructive ladder. CLINICAL QUESTION/LEVEL OF EVIDENCE/METHODS:Therapeutic, V.

INTRODUCTION/BACKGROUND:Online resources have become a major source of medical information for the general public. To date, there has not been an assessment of patient-oriented online resources for face and upper extremity transplantation candidates and patients. The goal of this study is to perform a comprehensive assessment of these resources. METHODS:Our analysis relied on 2 dimensions: comprehensiveness and readability. Comprehensiveness was evaluated using 14 predetermined variables. Readability was evaluated using 8 different readability scales through the Readability Studio Professional Edition Software (Oleander Software, Ltd, Vandalia, Ohio). Data were also collected from solid organ transplantation (SOT), specifically kidney and liver, programs for comparison. RESULTS:Face and upper extremity transplantation programs were significantly more likely to list exclusion criteria (73.9% vs 41.2%; P = 0.02), the need for life-long immunosuppression (87.0% vs 58.8%; P = 0.02), and benefits of transplantation (91.3% vs 61.8%; P = 0.01) compared with SOT programs. The average readability level of online resources by all face and upper extremity transplantation programs exceeded the sixth grade reading level recommended by the National Institutes of Health and the American Medical Association. The average reading grade level of online resources by these programs was also significantly higher than those of SOT with both exceeding the recommended reading level (13.95 ± 1.55 vs 12.60 ± 1.65; P = 0.003). CONCLUSIONS:Future efforts in face and upper extremity transplantation should be directed toward developing standardized, comprehensive, and intelligible resources with high-quality content and simple language.

Thoracic aortic aneurysm (TAA) is a complex life-threatening disease characterized by extensive extracellular matrix (ECM) fragmentation and persistent inflammation, culminating in a weakened aorta. Although evidence suggests defective canonical signaling pathways in TAA, the full spectrum of mechanisms contributing to TAA is poorly understood, therefore limiting the scope of drug-based treatment. Here, we used a sensitive RNA sequencing approach to profile the transcriptomic atlas of human TAA. Pathway analysis revealed upregulation of key matrix-degrading enzymes and inflammation coincident with the axonal guidance pathway. We uncovered their novel association with TAA and focused on the expression of Semaphorins and Netrins. Comprehensive analysis of this pathway showed that several members were differentially expressed in TAA compared to controls. Immunohistochemistry revealed that Semaphorin4D and its receptor PlexinB1, similar to Netrin-1 proteins were highly expressed in damaged areas of TAA tissues but faintly detected in the vessel wall of non-diseased sections. It should be considered that the current study is limited by its sample size and the use of internal thoracic artery as control for TAA for the sequencing dataset. Our data determines important neuronal regulators of vascular inflammatory events and suggest Netrins and Semaphorins as potential key contributors of ECM degradation in TAA.

Background/UNASSIGNED:Perioperative cardiovascular outcomes of transplant surgery are not well defined. We evaluated the incidence of perioperative major cardiovascular and cerebrovascular events (MACCE) after non-cardiac transplant surgery from a large database of hospital admissions from the United States. Methods/UNASSIGNED:Patients ≥18 years of age undergoing non-cardiac solid organ transplant surgery from 2004 to 2014 were identified from the Healthcare Cost and Utilization Project's (HCUP) National Inpatient Sample (NIS). The primary outcome was perioperative MACCE, defined as in-hospital death, myocardial infarction (MI), or ischemic stroke. Results/UNASSIGNED:A total of 49,978 hospitalizations for transplant surgery were identified. Renal (67.3%), liver (21.6%), and lung (6.7%) transplantation were the most common surgeries. Perioperative MACCE occurred in 1,539 transplant surgeries (3.1%). Recipients of organ transplantation were more likely to have perioperative MACCE in comparison to non-transplant, non-cardiac surgery (3.1% vs. 2.0%, p < 0.001; adjusted OR [aOR] 1.29, 95% CI 1.22-1.36). MACCE after transplant surgery were driven by increased mortality (1.7% vs. 1.1%, p < 0.001; aOR 1.15, 95% CI 1.07-1.23) and MI (1.2% vs. 0.6%, p < 0.001; aOR 2.26, 95% CI 2.09-2.46) versus non-transplant surgery, with lower rates of stroke (0.3% vs. 0.5%, p < 0.001; aOR 0.56, 95% CI 0.47-0.65). Among patients hospitalized for renal, liver, and lung transplantation, MACCE occurred in 1.7%, 5.6%, and 7.5%, respectively, with no difference in the frequency of MI by surgery type. Conclusions/UNASSIGNED:Cardiovascular outcomes of transplant surgery vary by surgical subtype and are largely driven by increased perioperative death and MI. Efforts to reduce cardiovascular risks of non-cardiac organ transplant surgery are necessary.

Background: Inheritance of two APOL1 risk variants accounts for the excess risk of non-diabetic ESRD in African Americans when compared to Caucasian, Hispanic and Asian Americans. African American living donors have a higher risk of ESRD than matched non-black donors. APOL1 genotyping in potential kidney donors of African descent may identify individuals at risk for progressive CKD following donation.
Method(s): We report the retrospective analysis of APOL1 genotyping in a cohort of African American potential kidney donors. In July 2016, we initiated targeted genotyping of all African American kidney donor candidates. African American candidates with two APOL1 risk variants were excluded from kidney donation.
Result(s): A total of 28 African American kidney donor candidates were evaluated between July 2016 and April 2018. 2 (7%) were found to have two APOL1 risk variants (high risk genotype). Low risk genotype was identified in 10 (36%) candidates who had one risk variant and 16 (57%) candidates who had none. To date, 15 candidates have completed their donor work-up. Of these, 7 (47%) have already undergone donor nephrectomy, and 4 (27%) were cleared for surgery and are awaiting operation. 4 (27%) of the candidates did not meet our center specific criteria for donation. 2 out these 4 candidates who were excluded from donation were ruled out expressly for having been found to have two APOL1 risk variants.
Conclusion(s): APOL1 genotyping led to the exclusion of two donors who might have previously been allowed to donate, possibly mitigating their risk of CKD/ESRD and suboptimal graft outcomes in recipients. (Table Presented)

Kidneys from donors with blood type A2 can be successfully transplanted into blood type B and O recipients without the need for desensitization if the recipient's starting anti-A hemagglutinin titer is within an acceptable range. National kidney allocation policy now offers priority for eligible B recipients to receive A2 or A2B deceased donor kidneys, and therefore, the frequency with which A2 or A2B to B transplants will occur is expected to increase. The precise mechanisms by which antibody-mediated rejection is averted in these cases despite the presence of both circulating anti-A antibody and expression of the A2 antigen on the graft endothelium are not known. Whether this process mirrors proposed mechanisms of accommodation, which can occur in recipients of ABO incompatible transplants, is also not known. Repeated exposure to mismatched antigens after retransplantation could elicit memory responses resulting in antibody rebound and accelerated antibody-mediated rejection. Whether this would occur in the setting of repeated A2 donor exposure was uncertain. Here we report the case of a patient with history of a prior A2 to B transplant which failed owing to nonimmunologic reasons; the patient successfully underwent a repeat A2 to B transplant. Neither rebound in anti-A2 antibody nor clinical evidence of antibody-mediated rejection were observed after the transplant. Current kidney allocation will likely enable more such transplants in the future, and this may provide a unique patient population in whom the molecular mechanisms of incompatible graft accommodation may be investigated.