Disruption of the extracellular matrix (ECM) is frequently found in calcific aortic valve disease (CAVD), yet the role of ECM components in valvular interstitial cell (VIC) function and dysfunction remains poorly understood. This study examines the contributions of exogenous and endogenous hyaluronic acid (HA), in both two-dimensional (2D) and 3D environments, in regulating the phenotype and calcification of VICs. VIC calcification was first assessed in a 2D setting in which the cells were exposed to different molecular weights of exogenous HA presented in either an immobilized or soluble form. Delivery of HA suppressed nodule formation in a molecular weight-dependent manner, while blocking VIC recognition of HA via an antibody to CD44 abolished these nodule-suppressive effects and stimulated other hallmarks of valvular dysfunction. These 2D results were then validated in a more physiologically-relevant setting, using an approach that allowed the characterization of VIC phenotype in response to HA alterations in the native 3D environment. In this approach, leaflet organ cultures were analyzed following treatment with anti-CD44 or with hyaluronidase to specifically remove HA. Disruption of VIC-HA interactions upregulated markers of VIC disease and induced leaflet mineralization. Similarly, HA-deficient leaflets exhibited numerous hallmarks of CAVD, including increased VIC proliferation, apoptosis, increased expression of disease-related markers, and mineralization. These findings suggest that VIC-HA interactions are crucial in maintaining a healthy VIC phenotype. Identification of ECM components that can regulate VIC phenotype and function has significant implications for understanding of native valve disease, investigating possible treatments, and designing new biomaterials for valve tissue engineering.

BackgroundExtracellular matrix (ECM) disarray is found in calcific aortic valvular disease (CAVD), yet much remains to be learned about the role of individual ECM components in valvular interstitial cell (VIC) function and dysfunction. Previous clinical analyses have shown that calcification is associated with decreased collagen content, while previous in vitro work has suggested that the presence of collagen attenuates the responsiveness of VICs to pro-calcific stimuli. The current study uses whole leaflet cultures to examine the contributions of endogenous collagen in regulating the phenotype and calcification of VICs.MethodsA “top-down” approach was used to characterize changes in VIC phenotype in response to collagen alterations in the native 3D environment. Collagen-deficient leaflets were created via enzymatic treatment and cultured statically for six days in vitro. After culture, leaflets were harvested for analysis of DNA, proliferation, apoptosis, ECM composition, calcification, and gene/protein expression.ResultsIn general, disruption of collagen was associated with increased expression of disease markers by VICs in whole organ leaflet culture. Compared to intact control leaflets, collagen-deficient leaflets demonstrated increased VIC proliferation and apoptosis, increased expression of disease-related markers such as alpha-smooth muscle actin, alkaline phosphatase, and osteocalcin, and an increase in calcification as evidenced by positive von Kossa staining.ConclusionsThese results indicate that disruption of the endogenous collagen structure in aortic valves is sufficient to stimulate pathological consequences in valve leaflet cultures, thereby highlighting the importance of collagen and the valve extracellular matrix in general in maintaining homeostasis of the valve phenotype.

Background: There is a low utilization rate of donated donor lungs. Historically, transplantation of lungs from hepatitis C-viremic donors to hepatitis C (HCV) negative recipients was avoided due to concern for worse graft survival. In the past few years with the advent of direct acting antiviral (DAA) therapy, there are emerging data suggesting the safety and efficacy of transplanting thoracic organs from HCV-viremic donors.This study assessed the differences in donor characteristics and allograft-specific clinical features at the time of organ offer and investigated whether these variables differed in HCV-viremic versus HCV-negative donors and impacted recipient outcomes. Methods: We conducted a single-center, retrospective cohort study of adult patients who underwent a lung transplant at Brigham and Women's Hospital between March 2017 and October 2018. Patients were stratified based on their donor HCV status (HCV-viremic versus HCV-negative). Donor and allograftspecific characteristics and clinical features including chest imaging and bronchoscopy reports, respiratory cultures, and the donor's oxygenation as measured by the arterial partial pressure of oxygen (PaO 2 ) were collected as well as recipient baseline characteristics and transplant outcomes.Results: During the study period, 42 and 57 lung transplants were performed from HCV-viremic and HCV-negative donors, respectively. Donor age was similar in both cohorts. More HCV-viremic donors died from drug intoxication (71% versus 19%, P=0.0001) and had a history of cigarette use (83% versus 5%, P=0.0001) and drug use (76% versus 49%, P=0.007). There were differences in the baseline recipient characteristics including a lower median lung allocation score in the HCV-viremic cohort. The organspecific clinical characteristics including the terminal PaO 2 , chest imaging and bronchoscopy findings, and evidence of pulmonary infection were similar between the two cohorts. The recipient outcomes overall were excellent and did not differ significantly in both cohorts in terms of graft and patient survival at 6 and 12 months.Conclusions: Despite a greater proportion of HCV-viremic donors being increased risk with a history of drug and cigarette use and having died as a result of drug intoxication, the quality of the HCV-viremic donor organs did not differ from the HCV-negative donor organs or impact graft and recipient survival. Due to an increasing number of transplants from increased risk donors and in order to develop safe and effective protocols to perform lung transplants from HCV-infected donors, further characterization of the donor and allograft-specific clinical features and longer-term recipient outcomes is greatly needed.

Introduction Extracorporeal membrane oxygenation (ECMO) is a life‐saving technology capable of restoring perfusion but is not without significant complications that limit its realizable therapeutic benefit. ECMO‐induced hemodynamics increase cardiac afterload risking left ventricular distention and impaired cardiac recovery. To mitigate potentially harmful effects, multiple strategies to unload the left ventricle (LV) are used in clinical practice but data supporting the optimal approach is presently lacking. Materials & Methods We reviewed outcomes of our ECMO population from September 2015 through January 2019 to determine if our LV unloading strategies were associated with patient outcomes. We compared reactive (Group 1, n = 30) versus immediate (Group 2, n = 33) LV unloading and then compared patients unloaded with an Impella CP (n = 19) versus an intra‐aortic balloon pump (IABP, n = 16), analyzing survival and ECMO‐related complications. Results Survival was similar between Groups 1 and 2 (33 vs 42%, P = .426) with Group 2 experiencing more clinically‐significant hemorrhage (40 vs. 67%, P = .034). Survival and ECMO‐related complications were similar between patients unloaded with an Impella versus an IABP. However, the Impella group exhibited a higher rate of survival (37%) than predicted by their median SAVE score (18%). Discussion Based on this analysis, reactive unloading appears to be a viable strategy while venting with the Impella CP provides better than anticipated survival. Our findings correlate with recent large cohort studies and motivate further work to design clinical guidelines and future trial design.