Acute Response of Engineered Cardiac Tissue to Pressure and Stretch.

The heart is a dynamic organ, and the cardiac tissue experiences changes in pressure and stretch during the cardiac cycle. Existing cell culture and animal models are limited in their capacity to decouple and tune specific hemodynamic stresses implicated in the development of physiological and pathophysiological cardiac tissue remodeling. This study focused on creating a system to subject engineered cardiac tissue to either pressure or stretch stimuli in isolation and the subsequent evaluation of acute tissue remodeling. We developed a cardiac tissue chip containing three-dimensional (3-D) cell-laden hydrogel constructs and cultured them within systems where we could expose them to either pressure changes or volume changes as seen in the left ventricle. Acute cellular remodeling with each condition was qualitatively and quantitatively assessed using histology, immunohistochemistry, gene expression studies, and soluble factor analysis. Using our unique model system, we isolated the effects of pressure and stretch on engineered cardiac tissue. Our results confirm that both pressure and stretch mediate acute stress responses in the engineered cardiac tissue. However, both experimental conditions elicited a similar acute phase injury response within this timeframe. This study demonstrates our ability to subject engineered cardiac tissue to either pressure or stretch stimuli in isolation, both of which elicited acute tissue remodeling responses.

Engineered Aging Cardiac Tissue Chip Model for Studying Cardiovascular Disease.

Due to the rapidly growing number of older people worldwide and the concomitant increase in cardiovascular complications, there is an urgent need for age-related cardiac disease modeling and drug screening platforms. In the present study, we developed a cardiac tissue chip model that incorporates hemodynamic loading and mimics essential aspects of the infarcted aging heart. We induced cellular senescence in H9c2 myoblasts using low-dose doxorubicin treatment. These senescent cells were then used to engineer cardiac tissue fibers, which were subjected to hemodynamic stresses associated with pressure-volume changes in the heart. Myocardial ischemia was modeled in the engineered cardiac tissue via hypoxic treatment. Our results clearly show that acute low-dose doxorubicin treatment-induced senescence, as evidenced by morphological and molecular markers, including enlarged and flattened nuclei, DNA damage response foci, and increased expression of cell cycle inhibitor p16INK4a, p53, and ROS. Under normal hemodynamic load, the engineered cardiac tissues demonstrated cell alignment and retained cardiac cell characteristics. Our senescent cardiac tissue model of hypoxia-induced myocardial infarction recapitulated the pathological disease hallmarks such as increased cell death and upregulated expression of ANP and BNP. In conclusion, the described methodology provides a novel approach to generate stress-induced aging cardiac cell phenotypes and engineer cardiac tissue chip models to study the cardiovascular disease pathologies associated with aging.

Locally advanced squamous cell carcinoma of the head and neck: CT texture and histogram analysis allow independent prediction of overall survival in patients treated with induction chemotherapy.

PURPOSE: To determine if computed tomographic (CT) texture and histogram analysis measurements of the primary mass are independently associated with overall survival in patients with locally advanced squamous cell carcinoma of the head and neck who were previously treated with cisplatin, 5-fluorouracil, and docetaxel (TPF) induction chemotherapy. MATERIALS AND METHODS: This institutional review board-approved retrospective study included 72 patients with locally advanced squamous cell carcinoma of the head and neck who were treated with induction TPF chemotherapy in 2004-2010. CT texture and histogram analysis of the primary mass on the pretherapy CT images were performed by using TexRAD software before and after application of spatial filters at different anatomic scales ranging from fine detail to coarse features. Cox proportional hazards models were used to examine the association between overall survival and the baseline CT imaging measurements and clinical variables. RESULTS: Primary mass entropy and skewness measurements with multiple spatial filters were associated with overall survival. Multivariate Cox regression analysis incorporating clinical and imaging variables indicated that primary mass size (hazard ratio [HR], 1.58 for each 1-cm increase; P = .018), N stage (HR, 8.77 for N3 vs N0 or N1; P = .002; HR, 4.99 for N3 vs N2; P = .001), and primary mass entropy (HR, 2.10 for each 0.5-unit increase; P = .036) and skewness (HR, 3.67 for each 1.0-unit increase; P = .009) measurements with the 1.0 spatial filter were independently associated with overall survival. CONCLUSION: Independent of tumor size, N stage, and other clinical variables, primary mass CT texture and histogram analysis parameters are associated with overall survival in patients with locally advanced squamous cell carcinoma of the head and neck who were treated with induction TPF. Online supplemental material is available for this article.

Biomimetic cardiac tissue chip and murine arteriovenous fistula models for recapitulating clinically relevant cardiac remodeling under volume overload conditions.

Cardiovascular events are the primary cause of death among dialysis patients. While arteriovenous fistulas (AVFs) are the access of choice for hemodialysis patients, AVF creation can lead to a volume overload (VO) state in the heart. We developed a three-dimensional (3D) cardiac tissue chip (CTC) with tunable pressure and stretch to model the acute hemodynamic changes associated with AVF creation to complement our murine AVF model of VO. In this study, we aimed to replicate the hemodynamics of murine AVF models in vitro and hypothesized that if 3D cardiac tissue constructs were subjected to "volume overload" conditions, they would display fibrosis and key gene expression changes seen in AVF mice. Mice underwent either an AVF or sham procedure and were sacrificed at 28 days. Cardiac tissue constructs composed of h9c2 rat cardiac myoblasts and normal adult human dermal fibroblasts in hydrogel were seeded into devices and exposed to 100 mg/10 mmHg pressure (0.4 s/0.6 s) at 1 Hz for 96 h. Controls were exposed to "normal" stretch and experimental group exposed to "volume overload". RT-PCR and histology were performed on the tissue constructs and mice left ventricles (LVs), and transcriptomics of mice LVs were also performed. Our tissue constructs and mice LV both demonstrated cardiac fibrosis as compared to control tissue constructs and sham-operated mice, respectively. Gene expression studies in our tissue constructs and mice LV demonstrated increased expression of genes associated with extracellular matrix production, oxidative stress, inflammation, and fibrosis in the VO conditions vs. control conditions. Our transcriptomics studies demonstrated activated upstream regulators related to fibrosis, inflammation, and oxidative stress such as collagen type 1 complex, TGFB1, CCR2, and VEGFA and inactivated regulators related to mitochondrial biogenesis in LV from mice AVF. In summary, our CTC model yields similar fibrosis-related histology and gene expression profiles as our murine AVF model. Thus, the CTC could potentially play a critical role in understanding cardiac pathobiology of VO states similar to what is present after AVF creation and may prove useful in evaluating therapies.

The Risk of Hemorrhagic Complications After Anticoagulation Therapy in Trauma Patients: A Multicenter Evaluation.

BACKGROUND: The use of anticoagulation therapy (ACT) in trauma patients during the post-injury period presents a challenge given the increased risk of hemorrhage. Guidelines regarding whether and when to initiate ACT are lacking, and as a result, practice patterns vary widely. The purpose of this study is to describe the incidence of hemorrhagic complications in patients who received ACT during their hospitalization, identify risk factors, and characterize the required interventions. METHODS: In this retrospective cohort study, all trauma admissions at two Level 1 trauma centers between January 2015 and December 2020 were reviewed. Patients with pre-existing ACT use or those who developed a new indication for ACT were included for analysis. Demographic and outcome data were collected for those who received ACT during their admission. Comparisons were then made between the complications and no complications groups. A subgroup analysis was performed for all patients started on ACT within 14 days of injury. RESULTS: A total of 812 patients were identified as having an indication for ACT, and 442 patients received ACT during the post-injury period. The overall incidence of hemorrhagic complications was 12.7%. Of those who sustained hemorrhagic complications, 18 required procedural intervention. On regression analysis, male sex, severe injuries, and the need for hemorrhage control surgery on arrival were all found to be associated with hemorrhagic complications after the initiation of ACT. Waiting 7-14 days from the time of injury to initiate ACT reduced the odds of complications by 46% and 71%, respectively. CONCLUSIONS: The use of ACT in trauma during the post-injury period is not without risk. Waiting 7-14 days post-injury might greatly reduce the risk of hemorrhagic complications. STUDY TYPE/LEVEL OF EVIDENCE: Therapeutic/care management study: Level IV.

Tissue Chips and Microphysiological Systems for Disease Modeling and Drug Testing.

Tissue chips (TCs) and microphysiological systems (MPSs) that incorporate human cells are novel platforms to model disease and screen drugs and provide an alternative to traditional animal studies. This review highlights the basic definitions of TCs and MPSs, examines four major organs/tissues, identifies critical parameters for organization and function (tissue organization, blood flow, and physical stresses), reviews current microfluidic approaches to recreate tissues, and discusses current shortcomings and future directions for the development and application of these technologies. The organs emphasized are those involved in the metabolism or excretion of drugs (hepatic and renal systems) and organs sensitive to drug toxicity (cardiovascular system). This article examines the microfluidic/microfabrication approaches for each organ individually and identifies specific examples of TCs. This review will provide an excellent starting point for understanding, designing, and constructing novel TCs for possible integration within MPS.

Ionizing radiation sensitizes tumors to PD-L1 immune checkpoint blockade in orthotopic murine head and neck squamous cell carcinoma.

Immunotherapy clinical trials targeting the programmed-death ligand axis (PD-1/PD-L1) show that most head and neck squamous cell carcinoma (HNSCC) patients are resistant to PD-1/PD-L1 inhibition. We investigated whether local radiation to the tumor can transform the immune landscape and render poorly immunogenic HNSCC tumors sensitive to PD-L1 inhibition. We used the first novel orthotopic model of HNSCC with genetically distinct murine cell lines. Tumors were resistant to PD-L1 checkpoint blockade, harbored minimal PD-L1 expression and tumor infiltrating lymphocytes at baseline, and were resistant to radiotherapy. The combination of radiation and PD-L1 inhibition significantly enhanced tumor control and improved survival. This was mediated in part through upregulation of PD-L1 on tumor cells and increased T-cell infiltration after RT, resulting in a highly inflamed tumor. Depletion of both CD4 and CD8 T-cells completely abrogated the effect of anti PD-L1 with radiation on tumor growth. Our findings provide evidence that radiation to the tumor can induce sensitivity to PD-L1 checkpoint blockade in orthotopic models of HNSCC. These findings have direct relevance to high risk HNSCC patients with poorly immunogenic tumors and who may benefit from combined radiation and checkpoint blockade.