Textbook Outcome: Definition and Analysis of a Novel Quality Measure in Lung Transplantation.

OBJECTIVE: To define textbook outcome (TO) for lung transplantation (LTx) using a contemporary cohort from a high-volume institution. SUMMARY BACKGROUND DATA: TO is a standardized, composite quality measure based on multiple postoperative endpoints representing the ideal "textbook" hospitalization. METHODS: Adult patients who underwent LTx at our institution between 2016 and 2019 were included. TO was defined as freedom from intraoperative complication, postoperative reintervention, 30-day intensive care unit or hospital readmission, length of stay >75th percentile of LTx patients, 90 day mortality, 30-day acute rejection, grade 3 primary graft dysfunction at 48 or 72 hours, postoperative extracorporeal membrane oxygenation, tracheostomy within 7 days, inpatient dialysis, reintubation, and extubation >48 hours post-transplant. Recipient, operative, financial characteristics, and post-transplant outcomes were recorded from institutional data and compared between TO and non-TO groups. RESULTS: Of 401 LTx recipients, 97 (24.2%) achieved TO. The most common reason for TO failure was extubation >48 hours post-transplant (N = 119, 39.1%); the least common was mortality (N = 15, 4.9%). Patient and graft survival were improved among patients who achieved versus failed TO (patient survival: log-rank P < 0.01; graft survival: log-rank P < 0.01). Rejection-free and chronic lung allograft dysfunction-free survival were similar between TO and non-TO groups (rejection-free survival: log-rank P = 0.07; chronic lung allograft dysfunction-free survival: log-rank P = 0.3). On average, patients who achieved TO incurred approximately $638,000 less in total inpatient charges compared to those who failed TO. CONCLUSIONS: TO in LTx was associated with favorable post-transplant outcomes and significant cost-savings. TO may offer providers and patients new insight into transplant center quality of care and highlight areas for improvement.

Lung transplantation after ex vivo lung perfusion versus static cold storage: An institutional cost analysis.

Ex vivo lung perfusion (EVLP) is a novel lung preservation strategy that facilitates the use of marginal allografts; however, it is more expensive than static cold storage (SCS). To understand how preservation method might affect postoperative costs, we compared outcomes and index hospitalization costs among matched EVLP and SCS preserved lung transplant (LTx) recipients at a single, high-volume institution. A total of 22 EVLP and 66 matched SCS LTx recipients were included; SCS grafts were further stratified as either standard-criteria (SCD) or extended-criteria donors (ECD). Median total preservation time was 857, 409, and 438 min for EVLP, SCD, and ECD lungs, respectively (p < .0001). EVLP patients had similar perioperative outcomes and posttransplant survival compared to SCS SCD and ECD recipients. Excluding device-specific costs, total direct variable costs were similar among EVLP, SCD, and ECD recipients (median $200,404, vs. $154,709 vs. $168,334, p =  .11). The median direct contribution margin was positive for EVLP recipients, and similar to that for SCD and ECD graft recipients (all p > .99). These findings demonstrate that the use of EVLP was profitable at an institutional level; however, further investigation is needed to better understand the financial implications of EVLP in facilitating donor pool expansion in an era of broader lung sharing.

Lung Transplantation After Ex Vivo Lung Perfusion Early Outcomes From a US National Registry.

OBJECTIVE: The objective of this study was to examine early lung transplant outcomes following EVLP using a large national transplant registry. SUMMARY OF BACKGROUND DATA: Lung transplantation in the United States continues to be constrained by a limited supply of donor organs. EVLP has the potential to significantly increase the available pool of donor lung allografts through the reconditioning of "marginal" organs. METHODS: The united network for organ sharing registry was queried for all adults (age ≥18) who underwent first-time lung transplantation between March 2018 (when united network for organ sharing began collecting confirmed donor EVLP status) and June 2019. Transplants were stratified by EVLP use. The primary outcome was short-term survival and secondary outcomes included acute rejection before discharge and need for extracorpo-real membrane oxygenation support post-transplant. RESULTS: A total of 3334 recipients met inclusion criteria including 155 (5%) and 3179 (95%) who did and did not receive allografts that had undergone EVLP, respectively. On unadjusted descriptive analysis, EVLP and non-EVLP cohorts had similar 180-day survival (92% vs 92%, P = 0.9). EVLP use was associated with a similar rate of acute rejection (13% vs 9%, P = 0.08) but increased rate of early extracorporeal membrane oxygenation use (12% vs 7%, P = 0.04). After adjustment, EVLP use was not associated with significantly increased mortality (adjusted hazard ratio 0.99, 95% confidence interval 0.62-1.58) or acute rejection (adjusted odds ratio 0.89, 95% confidence interval 0.40-1.97) compared to non-EVLP use. CONCLUSIONS: In the largest national series of EVLP lung transplant recipients, EVLP is associated with early recipient outcomes comparable to that of non-EVLP recipients with similar baseline characteristics. Longer term follow-up data is needed to further assess the impact of EVLP on post-lung transplant outcomes.

Textbook surgical outcome in lung transplantation: Analysis of a US national registry.

INTRO: Textbook surgical outcome (TO) is a novel composite quality measure in lung transplantation (LTx). Compared to 1-year survival metrics, TO may better differentiate center performance, and motivate improvements in care. To understand the feasibility of implementing this metric, we defined TO in LTx using US national data, and evaluated its ability to predict post-transplant outcomes and differentiate center performance. METHODS: Adult patients who underwent isolated LTx between 2016 and 2019 were included. TO was defined as freedom from post-transplant length of stay > 30 days, 90-day mortality, intubation or extracorporeal membrane oxygenation at 72 h post-transplant, post-transplant ventilator support lasting ≥5 days, postoperative airway dehiscence, inpatient dialysis, pre-discharge acute rejection, and grade 3 primary graft dysfunction at 72 h. Recipient and donor characteristics and post-transplant outcomes were compared between patients who achieved and failed TO. RESULTS: Of 8959 lung transplant recipients, 4664 (52.1%) achieved TO. Patient and graft survival were improved among patients who achieved TO (both log-rank P < .0001). Among 62 centers, adjusted rates of TO ranged from 27.0% to 72.4% reflecting a wide variability in center-level performance. CONCLUSION: TO defined using national data may represent a novel composite metric to guide quality improvement in LTx across US transplant centers. SUMMARY: In this study we defined textbook outcome (TO) for lung transplantation (LTx) using US national data. We found that achievement of TO was associated with improved post-transplant survival, and wide variability in center-level LTx performance. These findings suggest that TO could be readily implemented to compare quality of care among US LTx centers.

A three-tier system for evaluation of organ procurement organizations' willingness to pursue and utilize nonideal donor lungs.

Lungs from "nonideal," but acceptable donors are underutilized; however, organ procurement organization (OPO) metrics do not reflect the extent to which OPO-specific practices contribute to these trends. We developed a comprehensive system to evaluate nonideal lung donor avoidance, or risk aversion among OPOs. Adult donors in the UNOS registry who donated ≥1 organ for transplantation between 2007 and 2018 were included. Nonideal donors had any of age>50, smoking history ≥20 pack-years, PaO2 /FiO2 ratio ≤350, donation after circulatory death, or increased risk status. OPO-level risk aversion in donor pursuit, consent attainment, lung recovery, and transplantation was assessed. Among 83916 donors, 70372 (83.9%) were nonideal. Unadjusted OPO-level rates of nonideal donor pursuit ranged from 81 to 100%. In a three-tier system of overall risk aversion, tier 3 OPOs (least risk-averse) had the highest rates of nonideal donor pursuit, consent attainment, lung recovery, and transplantation. Tier 1 OPOs (most risk-averse) had the lowest rates of donor pursuit, consent attainment, and lung recovery, but higher rates of transplantation compared to tier 2 OPOs (moderately risk-averse). Risk aversion varies among OPOs and across the donation process. OPO evaluations should reflect early donation process stages to best differentiate over- and underperforming OPOs and encourage optimal OPO-specific performance.

The Impact of the 2017 Kidney Allocation Policy Change on Simultaneous Liver-Kidney Utilization and Outcomes.

Historically in the United States, kidneys for simultaneous liver-kidney transplantation (SLKT) candidates were allocated with livers, prioritizing SLKT recipients over much of the kidney waiting list. A 2017 change in policy delineated renal function criteria for SLKT and implemented a safety net for kidney-after-liver transplantation. We compared the use and outcomes of SLKT and kidney-after-liver transplant with the 2017 policy. United Network for Organ Sharing Standard Transplant Analysis and Research files were used to identify adults who received liver transplantations (LT) from August 10, 2007 to August 10, 2012; from August 11, 2012 to August 10, 2017; and from August 11, 2017 to June 12, 2019. LT recipients with end-stage renal disease (ESRD) were defined by dialysis requirement or estimated glomerular filtration rate <25. We evaluated outcomes and center-level, regional, and national practice before and after the policy change. Nonparametric cumulative incidence of kidney-after-liver listing and transplant were modeled by era. A total of 6332 patients received SLKTs during the study period; fewer patients with glomerular filtration rate (GFR) ≥50 mL/min underwent SLKT over time (5.8%, 4.8%, 3.0%; P = 0.01 ). There was also less variability in GFR at transplant after policy implementation on center and regional levels. We then evaluated LT-alone (LTA) recipients with ESRD (n = 5408 from 2012-2017; n = 2321 after the policy). Listing for a kidney within a year of LT increased from 2.9% before the policy change to 8.8% after the policy change, and the rate of kidney transplantation within 1 year increased from 0.7% to 4% (P < 0.001). After the policy change, there was no difference in patient survival rates between SLKT and LTA among patients with ESRD. Implementation of the 2017 SLKT policy change resulted in reduced variability in SLKT recipient kidney function and increased access to deceased donor kidney transplantation for LTA recipients with kidney disease without negatively affecting outcomes.

Aggressive pursuit and utilization of non-ideal donor lungs does not compromise post-lung transplant survival.

BACKGROUND: Organ procurement organizations (OPOs) vary in willingness to pursue and utilize non-ideal donor lungs; implications of these practices for lung transplant (LTx) recipients remain unclear. We examined associations between OPO-level behavior toward non-ideal donors and post-LTx outcomes. METHODS: Adult lung donors and corresponding adult first-time LTx recipients in the 2008-2019 UNOS registry were included. Non-ideal donors had any of age > 50, smoking history ≥20 pack-years, PaO2 /FiO2 ratio ≤350, donation after circulatory death, or increased risk status. OPOs were classified as least, moderately, or most aggressive based on non-ideal donor pursuit, consent attainment, lung recovery, and transplantation. Post-transplant outcomes were compared among aggressiveness strata. RESULTS: Of 22,795 recipients, 6229 (27.3%), 8256 (36.2%), and 8310 (36.5%) received lungs from least, moderately, and most aggressive OPOs, respectively. Moderately aggressive OPOs had the highest recipient rates of pre-discharge acute rejection, grade 3 primary graft dysfunction, postoperative extracorporeal membrane oxygenation, and longest lengths of stay. After adjustment, moderately and most aggressive OPOs had similar risks of recipient mortality as least aggressive OPOs. CONCLUSIONS: The most and least aggressive OPOs achieve similar patient survival and short-term post-LTx outcomes. Aggressive pursuit and utilization of non-ideal donor lungs by less aggressive OPOs would likely expand the donor pool, without compromising recipient outcomes.

Definition and Analysis of Textbook Outcome: A Novel Quality Measure in Kidney Transplantation.

BACKGROUND: "Textbook outcome" (TO) is a novel composite quality measure that encompasses multiple postoperative endpoints, representing the ideal "textbook" hospitalization for complex surgical procedures. We defined TO for kidney transplantation using a cohort from a high-volume institution. METHODS: Adult patients who underwent isolated kidney transplantation at our institution between 2016 and 2019 were included. TO was defined by clinician consensus at our institution to include freedom from intraoperative complication, postoperative reintervention, 30-day intensive care unit or hospital readmission, length of stay > 75th percentile of kidney transplant patients, 90-day mortality, 30-day acute rejection, delayed graft function, and discharge with a Foley catheter. Recipient, operative, financial characteristics, and post-transplant patient, graft, and rejection-free survival were compared between patients who achieved and failed to achieve TO. RESULTS: A total of 557 kidney transplant patients were included. Of those, 245 (44%) achieved TO. The most common reasons for TO failure were delayed graft function (N = 157, 50%) and hospital readmission within 30 days (N = 155, 50%); the least common was mortality within 90 days (N = 6, 2%). Patient, graft, and rejection-free survival were significantly improved among patients who achieved TO. On average, patients who achieved TO incurred approximately $50,000 less in total inpatient charges compared to those who failed TO. CONCLUSIONS: TO in kidney transplantation was associated with favorable post-transplant outcomes and significant cost-savings. TO may offer transplant centers a detailed performance breakdown to identify aspects of perioperative care in need of process improvement.

Lung transplantation during the COVID-19 pandemic: Safely navigating the new "normal".

In the United States, an overall national decline in organ transplants has accompanied the substantial burden of COVID-19. Amidst significant regional variations in COVID-19, lung transplantation (LTx) remains a critical life-saving operation. Our LTx practice during the early pandemic may provide a blueprint for managing LTx in an era of continued community prevalence. Patients who underwent LTx at our institution between March 1 and May 20, 2020 were included. Recipient, operative, and donor characteristics were compared to those from our program in 2019, and COVID-19 testing practices were evaluated for March, April, and May to understand how our practice adapted to the pandemic. Our program performed 36 LTx, 33% more than the same period in 2019. Recipient, operative, and donor characteristics during COVID-19 were similar to those in 2019. By April 1, all donors and recipients underwent pretransplant COVID-19 testing, all returning negative results. To date, no recipients have developed posttransplant COVID-19. At our institution, pretransplant COVID-19 testing, use of local donor lungs, and avoidance of donors from areas of increased community penetration supported a safe and effective LTx practice during the early COVID-19 pandemic. Continued follow-up is required to ensure the long-term safety of these newly transplanted patients.

Long-term renal function in living kidney donors with simple renal cysts: A retrospective cohort study.

Simple (Bosniak I) renal cysts are considered acceptable in living kidney donor selection in terms of cancer risk. However, they tend to increase in number and size over time and might compromise renal function in donors. To clarify their implications for long-term renal function, we characterized the prevalence of renal cysts in 454 individuals who donated at our center from 2000 to 2007. We estimated the association between the presence of cysts in the kidney remaining after nephrectomy (ie, retained cysts) and postdonation eGFR trajectory using mixed-effects linear regression. Donors with retained cysts (N = 86) were older (P < .001) and had slightly lower predonation eGFR (median 94 vs 98 mL/min/1.73 m2 , P < .01) than those without cysts. Over a median 7.8 years, donors with retained cysts had lower baseline eGFR (-8.7 -5.6 -2.3  mL/min/1.73 m2 , P < .01) but similar yearly change in eGFR (-0.4 0.02 0.4  mL/min/1.73 m2 , P = .2) compared to those without retained cysts. Adjusting for predonation characteristics, there was no difference in baseline eGFR (P = .6) or yearly change in eGFR (P > .9). There continued to be no evidence of an association when we considered retained cyst(s) ≥10 mm or multiple retained cysts (all P > .05). These findings reaffirm current practices of accepting candidates with simple renal cysts for donor nephrectomy.

Liver transplantation and waitlist mortality for HCC and non-HCC candidates following the 2015 HCC exception policy change.

Historically, exception points for hepatocellular carcinoma (HCC) led to higher transplant rates and lower waitlist mortality for HCC candidates compared to non-HCC candidates. As of October 2015, HCC candidates must wait 6 months after initial application to obtain exception points; the impact of this policy remains unstudied. Using 2013-2017 SRTR data, we identified 39  350 adult, first-time, active waitlist candidates and compared deceased donor liver transplant (DDLT) rates and waitlist mortality/dropout for HCC versus non-HCC candidates before (October 8, 2013-October 7, 2015, prepolicy) and after (October 8, 2015-October 7, 2017, postpolicy) the policy change using Cox and competing risks regression, respectively. Compared to non-HCC candidates with the same calculated MELD, HCC candidates had a 3.6-fold higher rate of DDLT prepolicy (aHR = 3.49 3.69 3.89 ) and a 2.2-fold higher rate of DDLT postpolicy (aHR = 2.09 2.21 2.34 ). Compared to non-HCC candidates with the same allocation priority, HCC candidates had a 37% lower risk of waitlist mortality/dropout prepolicy (asHR = 0.54 0.63 0.73 ) and a comparable risk of mortality/dropout postpolicy (asHR = 0.81 0.95 1.11 ). Following the policy change, the DDLT advantage for HCC candidates remained, albeit dramatically attenuated, without any substantial increase in waitlist mortality/dropout. In the context of sickest-first liver allocation, the revised policy seems to have established allocation equity for HCC and non-HCC candidates.

Organs from deceased donors with false-positive HIV screening tests: An unexpected benefit of the HOPE act.

Organs from deceased donors with suspected false-positive HIV screening tests were generally discarded due to the chance that the test was truly positive. However, the HIV Organ Policy Equity (HOPE) Act now facilitates use of such organs for transplantation to HIV-infected (HIV+) individuals. In the HOPE in Action trial, donors without a known HIV infection who unexpectedly tested positive for anti-HIV antibody (Ab) or HIV nucleic acid test (NAT) were classified as suspected false-positive donors. Between March 2016 and March 2018, 10 suspected false-positive donors had organs recovered for transplant for 21 HIV + recipients (14 single-kidney, 1 double-kidney, 5 liver, 1 simultaneous liver-kidney). Median donor age was 24 years; cause of death was trauma (n = 5), stroke (n = 4), and anoxia (n = 1); three donors were labeled Public Health Service increased infectious risk. Median kidney donor profile index was 30.5 (IQR 22-58). Eight donors were HIV Ab+/NAT-; two were HIV Ab-/NAT+. All 10 suspected false-positive donors were confirmed to be HIV-noninfected. Given the false-positive rates of approved assays used to screen > 20 000 deceased donors annually, we estimate 50-100 HIV false-positive donors per year. Organ transplantation from suspected HIV false-positive donors is an unexpected benefit of the HOPE Act that provides another novel organ source.

Patterns of primary care utilization before and after living kidney donation.

BACKGROUND: Annual visits with a primary care provider (PCP) are recommended for living kidney donors to monitor long-term health postdonation, yet adherence to this recommendation is unknown. METHODS: We surveyed 1170 living donors from our center from 1970 to 2012 to ascertain frequency of PCP visits pre- and postdonation. Interviews occurred median (IQR) 6.6 (3.8-11.0) years post-transplant. We used multivariate logistic regression to examine associations between donor characteristics and PCP visit frequency. RESULTS: Overall, only 18.6% had less-than-annual PCP follow-up postdonation. The strongest predictor of postdonation PCP visit frequency was predonation PCP visit frequency. Donors who had less-than-annual PCP visits before donation were substantially more likely to report less-than-annual PCP visits postdonation (OR=9.8 14.421.0, P<.001). Men were more likely to report less-than-annual PCP visits postdonation (adjusted OR=1.2 1.62.3, P<.01); this association was amplified in unmarried/noncohabiting men (aOR=2.4 3.96.3, P<.001). Donors without college education were also more likely to report less-than-annual PCP visits postdonation (aOR=1.3 1.82.5 , P=.001). CONCLUSIONS: The importance of annual PCP visits should be emphasized to all living donors, especially those with less education, men (particularly single men), and donors who did not see their PCP annually before donation.

Implications of the Composite Allocation Score System for Lung Transplantation in the United States: Review of the New System.

Due to criticism regarding undue adherence to fixed geographic boundaries, the Lung Allocation Score system was recently replaced by the more holistic allocation via continuous distribution. This review highlights the historical evolution of US lung allocation paradigms, outlines rationale for continuous distribution under the Composite Allocation Score system and discusses expected implications of this new system.

The cost of lung transplantation in the United States: How high is too high?

Objectives: To identify patient and process factors that contribute to the high cost of lung transplantation (LTx) in the perioperative period, which may allow transplant centers to evaluate situations in which transplantation is most cost-effective to inform judicious resource allocation, avoid futile care, and reduce costs. Methods: The MarketScan Research databases were used to identify 582 privately insured patients undergoing single or bilateral LTx between 2013 and 2019. The patients were subdivided into groups by disease etiology using the United Network of Organ Sharing classification system. Multivariable generalized linear models using a gamma distribution with a log link were fit to examine the associations between the etiology of lung disease and costs during the index admission, 3 months before admission, and 3 months after discharge. Results: Our results indicate that the index admission contributed the most to the total transplantation costs compared to the 3 months before admission and after discharge. The regression-adjusted mean index hospitalization cost was 35% higher for patients with pulmonary vascular disease compared to those with obstructive lung disease ($527,156 vs $389,055). The use of extracorporeal membrane oxygenation, mechanical ventilation, and surgical complications in the post-transplantation period were associated with higher costs during the index admission. Surprisingly, age ≥55 was associated with lower costs during the index admission. Conclusions: This analysis identifies pivotal factors influencing the high cost of LTx, emphasizing the significant impact of the index admission, particularly for patients with pulmonary vascular disease. These insights offer transplant centers an opportunity to enhance cost-effectiveness through judicious resource allocation and service bundling, ultimately reducing overall transplantation costs.

Short-term outcomes after third-time lung transplantation: A single institution experience.

BACKGROUND: Reoperative lung transplantation (LTx) survival has improved over time such that a growing number of patients may present for third-time LTx (L3Tx). To understand the safety of L3Tx, we evaluated perioperative outcomes and 3-year survival after L3Tx at a high-volume US LTx center. METHODS: This retrospective study included all patients who underwent bilateral L3Tx at our institution. Using an optimal matching technique, a primary LTx (L1Tx) cohort was matched 1:2 and a second-time LTx (L2Tx) cohort 1:1. Recipient, operative, and donor characteristics, perioperative outcomes, and 3-year survival were compared among L1Tx, L2Tx, and L3Tx groups. RESULTS: Eleven L3Tx, 11 L2Tx, and 22 L1Tx recipients were included. Among L3Tx recipients, median age at transplant was 37 years and most (73%) had cystic fibrosis. L3Tx was performed median 6.0 and 10.6 years after L2Tx and L1Tx, respectively. Compared to L1Tx and L2Tx recipients, L3Tx recipients had greater intraoperative transfusion requirements, a higher incidence of postoperative complications, and a higher rate of unplanned reoperation. Rates of grade 3 primary graft dysfunction at 72 hours, extracorporeal membrane oxygenation at 72 hours, reintubation, and in-hospital mortality were similar among groups. There were no differences in 3-year patient (log-rank p = 0.61) or rejection-free survival (log-rank p = 0.34) after L1Tx, L2Tx, and L3Tx. CONCLUSIONS: At our institution, L3Tx was associated with similar perioperative outcomes and 3-year patient survival compared to L1Tx and L2Tx. L3Tx represents the only safe treatment option for patients with allograft failure after L2Tx; however, further investigation is needed to understand the long-term survival and durability of L3Tx.

Same-teams versus different-teams for long distance lung procurement: A cost analysis.

OBJECTIVE: In an era of broader lung sharing, different-team transplantation (DT, procuring team from nonrecipient center) may streamline procurement logistics; however, safety and cost implications of DT remain unclear. To understand whether DT represents a safe means to reduce lung transplant (LTx) costs, we compared posttransplant outcomes and lung procurement and index hospitalization costs among matched DT and same-team transplantation (ST, procuring team from recipient center) cohorts at a single, high-volume institution. We hypothesized that DT reduces costs without compromising outcomes after LTx. METHODS: Patients who underwent DT between January 2016 to May 2020 were included. A cohort of patients who underwent ST was matched 1:3 (nearest neighbor) based on recipient age, disease group, lung allocation score, history of previous LTx, and bilateral versus single LTx. Posttransplant outcomes and costs were compared between groups. RESULTS: In total, 23 DT and 69 matched ST recipients were included. Perioperative outcomes and posttransplant survival were similar between groups. Compared with ST, DT was associated with similar lung procurement and index hospitalization costs (DT vs ST, procurement: median $65,991 vs $58,847, P = .16; index hospitalization: median $294,346 vs $322,189, P = .7). On average, procurement costs increased $3263 less per 100 nautical miles for DT versus ST; DT offered cost-savings when travel distances exceeded approximately 363 nautical miles. CONCLUSIONS: At our institution, DT and ST were associated with similar post-LTx outcomes; DT offered cost-savings with increasing procurement travel distance. These findings suggest that DT may mitigate logistical and financial burdens of lung procurement; however, further investigation in a multi-institutional cohort is warranted.

Adeno-associated virus mediates gene transduction after static cold storage treatment in rodent lung transplantation.

OBJECTIVE: Adeno-associated virus is a clinically used gene therapy vector but has not been studied in lung transplantation. We sought to determine the efficacy of adeno-associated virus delivery during static cold storage via the airway versus the pulmonary artery before lung transplantation in a rodent model. METHODS: Lewis rat lung grafts were treated with a dose of 8e8 or 4e9 viral genome/µL recombinant adeno-associated virus subtype-9 vectors containing firefly luciferase genomes administered via the pulmonary artery or airway during cold storage. A control group did not receive adeno-associated virus. Recipient syngeneic rats then underwent single left lung transplantation. Animals underwent bioluminescence imaging on postoperative days 7, 14, 28, and 56. Explanted tissues were prepared as lysates to quantify luciferase activity. Immunohistochemistry was performed to evaluate cellular transgene expression patterns. RESULTS: Control animals with no luminescent signal produced a background radiance of 6.1e4 p/s/cm2/sr. In the airway delivery group, mean radiance was greater than the control at 4e9 viral genome/µL postoperative day 7 radiance 6.9e4 p/s/cm2/sr (P = .04). In the pulmonary artery delivery group, we observed greater in vivo luminescence in animals receiving 4e9 viral genome/µL compared with all other groups. However, analysis of tissue lysate revealed greater luminescence in the airway delivery group and suggested off-target expression in heart and liver tissue in the pulmonary artery delivery group. Immunohistochemistry demonstrated transgene staining in distal airway epithelium and alveoli but sparing of the vasculature in the airway delivery group. CONCLUSIONS: Adeno-associated virus mediates gene transduction during static cold storage in rat lung isografts when administered via the airway and pulmonary artery. Airway administration leads to robust transgene expression in respiratory epithelial cells, whereas pulmonary artery administration targets alternative cell types and increases extrapulmonary transgene expression.

AAV9-mediated gene delivery to liver grafts during static cold storage in a rat liver transplant model.

Introduction: Recombinant adeno-associated virus (rAAV) is a novel strategy used clinically for gene delivery, but has not been characterized in the context of organ transplantation. We sought to determine the efficacy of rAAV-mediated gene delivery during static cold storage (SCS) prior to liver transplantation. Methods: A triple-plasmid transfection protocol was used to produce rAAV subtype-9 vectors containing firefly luciferase genomes in HEK293 cells. Lewis rat liver grafts were flushed and stored in cold HTK solution. Three experimental groups received rAAV at different doses, administered via the portal vein as a bolus during SCS. A control group did not receive rAAV (N = 2). Recipients then underwent syngeneic liver transplantation. Bioluminescence imaging to quantify in vivo luciferase expression was performed on post-operative days 7, 14, 28, and 56. Results: Control animals demonstrated no bioluminescent activity, while animals receiving rAAV-treated livers had increasing bioluminescence, peaking at four weeks but sustained to the eight-week endpoint. This result was confirmed by experimental endpoint tissue luciferase activity assay. Discussion: rAAV mediates gene transduction in liver grafts when administered during SCS and has potential for gene therapy applications in solid organ transplantation.

Textbook outcome in lung transplantation: Planned venoarterial extracorporeal membrane oxygenation versus off-pump support for patients without pulmonary hypertension.

BACKGROUND: Planned venoarterial extracorporeal membrane oxygenation (VA ECMO) is increasingly used during bilateral orthotopic lung transplantation (BOLT) and may be superior to off-pump support for patients without pulmonary hypertension. In this single-institution study, we compared rates of textbook outcome between BOLTs performed with planned VA ECMO or off-pump support for recipients with no or mild pulmonary hypertension. METHODS: Patients with no or mild pulmonary hypertension who underwent isolated BOLT between 1/2017 and 2/2021 with planned off-pump or VA ECMO support were included. Textbook outcome was defined as freedom from intraoperative complication, 30-day reintervention, 30-day readmission, post-transplant length of stay >30 days, 90-day mortality, 30-day acute rejection, grade 3 primary graft dysfunction at 48 or 72 hours, post-transplant ECMO, tracheostomy within 7 days, inpatient dialysis, reintubation, and extubation >48 hours post-transplant. Textbook outcome achievement was compared between groups using multivariable logistic regression. RESULTS: Two hundred thirty-seven BOLTs were included: 68 planned VA ECMO and 169 planned off-pump. 14 (20.6%) planned VA ECMO and 27 (16.0%) planned off-pump patients achieved textbook outcome. After adjustment for prior BOLT, lung allocation score, ischemic time, and intraoperative transfusions, planned VA ECMO was associated with higher odds of textbook outcome than planned off-pump support (odds ratio 3.89, 95% confidence interval 1.58-9.90, p = 0.004). CONCLUSIONS: At our institution, planned VA ECMO for isolated BOLT was associated with higher odds of textbook outcome than planned off-pump support among patients without pulmonary hypertension. Further investigation in a multi-institutional cohort is warranted to better elucidate the utility of this strategy.