Novel treatment strategy of targeting epigenetic dysregulation in pancreatic neuroendocrine tumors.

BACKGROUND: Epigenetic dysregulation is an integral step in the progression of pancreatic neuroendocrine tumors. We hypothesized that tumor suppressor repression by DNA methyltransferase 1 in pancreatic neuroendocrine tumors could be targeted with epigenetic treatment. METHODS: Resected pancreatic neuroendocrine tumors from 32 patients were stained for DNA methyltransferase 1 and scored. Human (BON1) and murine (STC) pancreatic neuroendocrine tumor cells were treated with DNA methyltransferase 1 inhibitor 5-azacytidine and chemotherapeutic agents 5-fluorouracil and temozolomide. Cell proliferation assay and tumor suppressor gene analysis were performed with qRT-PCR and Clarion S microarray. Tumor measurements were compared in a murine treatment model. RESULTS: High DNA methyltransferase scores were associated with high Ki-67 (6.7% vs 70.6% P < .01), mitotic rate (0.0% vs 31.3%), and grade (20.0% vs 80.4%, P < .01). Treatment with 5-azacytidine and chemotherapy resulted in a reduction of cell proliferation compared to chemotherapy alone in BON1 (77.3% vs 53.1%, P < .001) and STC (73.4% vs 34.2%, P < .001). Treatment with 5-azacytidine and chemotherapy resulted in upregulation of tumor suppressors CDKN1A (7.6 rel. fold, P < .001), BRCA2 (4.3 rel. fold, P < .001), and CDH1 (6.0 rel. fold, P = .026) in BON1 and CDKN1a (14.5 rel. fold, P < .001) and CDH (17.5 rel. fold, P < .001) in STC. In microarray, 5-azacytidine drove global genetic changes in combination treatment. In vivo tumors treated with chemotherapy measured 88.6 ± 19.54 mm3 vs 52.89 ± 10.51 mm3 in those treated with combination therapy (P = .009). CONCLUSION: Epigenetic dysregulation with DNA methyltransferase 1 is associated with pancreatic neuroendocrine tumors and is a potential targetable strategy. 5-azacytidine and chemotherapy in combination can reduce cell proliferation, upregulate silenced tumor suppressor genes, and decrease in vivo tumors in pancreatic neuroendocrine tumors.

Utilization Large Animal Research as an Adjunct for Surgical Education Increases Perceived Resident Confidence.

Surgical education has evolved over time to incorporate supplemental modalities of training beyond the operating room. Even with the utility of simulation software and didactic education, there is still a need to provide surgical residents with experience in live tissue dissection and tissue handling while maintaining patient safety. In our program, after two clinical years, residents participate in a year of translational research which uses porcine models for complex open abdominal procedures. During the porcine surgeries, our residents are guided by the supervising attending to perform key portions of the procedure typically reserved for those more senior trainees. We found in a survey that research residents after two clinical years found this experience with large animal surgeries helped them better navigate anatomic structures and would recommend this to future trainees. We believe this dual-purpose research-training model provides a valuable resource that can be adapted to other programs.

Impact of adipose-derived stem cells on aortic tensile strength in a model of abdominal aortic aneurysm.

Introduction: Abdominal Aortic Aneurysm (AAA) is a highly morbid condition and is the 11th leading cause of death in the United States. Treatment options are limited to operative interventions, with minimal non-operative options. Prior literature has demonstrated a benefit to the use of mesenchymal stem cells (MSCs) in attenuating AAA formation. We demonstrate the utility of MSCs in treating AAA in swine, focusing on the mechanical and structural characteristics of aortic tissue after treatment. Methods: 16 Yorkshire pigs underwent retroperitoneal exposure of the infrarenal aorta, with subsequent induction of AAA with peri-adventitial elastase and collagenase. A 1 × 4 cm piece of Gelfoam, an absorbable gelatin-based hemostatic agent, was soaked in media or human MSCs and placed directly on the vessel for control and experimental animals. At postoperative day 21, animals were sacrificed and the infrarenal aorta at this location was harvested for analysis. Tensile strength was measured using a tensiometer, from which Young's modulus and maximum strain were calculated. Results: All animals survived the surgery and post-operative course. Young's elastic modulus for the aneurysm control group was 15.83 ± 1.61 compared to 22.13 ± 2.34 for the stem cell treated segment, p = 0.0316. There was no significant difference in the peak stress between groups. Conclusions: This is the first study to demonstrate the mechanical effects of stem cell therapy on a model of AAA in swine. Young's modulus, which characterizes the intrinsic capacity of a tissue to withstand stress, was greater in the animals treated with MSCs compared to control animals with aneurysms. This methodology can be utilized in future large animal models to develop cell and drug-based therapies for AAA.

Treatment of Abdominal Aortic Aneurysm Utilizing Adipose-Derived Mesenchymal Stem Cells in a Porcine Model.

INTRODUCTION: The current treatment paradigm of abdominal aortic aneurysms (AAA) focuses on observing patients until their disease reaches certain thresholds for intervention, with no preceding treatment available. There is an opportunity to develop novel therapies to prevent further aneurysmal growth and decrease the risk of a highly morbid rupture. We used a porcine model of aortic dilation to assess the ability of human adipose-derived mesenchymal stem cells (MSCs) to attenuate aortic dilation. MATERIALS AND METHODS: Twelve Yorkshire pigs received periadventitial injections (collagenase and elastase) into a 4-cm segment of infrarenal aorta. Animals were treated with either 1 × 106 MSCs placed onto Gelfoam or treated with media as a control. Aortic diameters were measured at the time of surgery and monitored at postoperative day (POD) 7 and 14 with ultrasound. Animals were sacrificed on POD 21. Aortic tissue was harvested for histopathological analyses and immunohistochemistry. Groups were compared with paired t-tests or Mann-Whitney U-tests. RESULTS: All animals survived until POD 21. The mean aortic diameter was reduced in the aortic dilation + MSC treatment group compared to aortic dilation control animals (1.10 ± 0.126 versus 1.48 cm ± 0.151, P < 0.001). Aortic media thickness was reduced in the aortic dilation group compared to the aortic dilation + MSC group (609.14 IQR 445.21-692.93 µm versus 643.55 IQR 560.91-733.88 µm, P = 0.0048). There was a significant decrease in the content of collagen and alpha-smooth muscle actin and elastin perturbation in the aortic dilation group as compared to the aortic dilation + MSC group. Immunohistochemistry demonstrated an increased level of vascular endothelial growth factor, tissue inhibitor of matrix metalloproteinase 1, and tissue inhibitor of matrix metalloproteinase 3 expression in the aorta of aortic dilation + MSC animals. CONCLUSIONS: Stem cell therapy suppressed the aortic dilation in a porcine model. Animals from the aortic dilation group showed more diseased gross features, histologic changes, and biochemical properties of the aorta compared to that of the aortic dilation + MSC treated animals. This novel finding should prompt further investigation into translatable drug and cell therapies for aneurysmal disease.

The State of Racial and Gender Diversity in Cardiothoracic Surgery Training.

BACKGROUND: The field of cardiothoracic surgery has been striving to increase its gender and racial diversity. We sought to examine changes in gender and racial diversity in cardiothoracic fellowships and integrated residencies in the past decade. METHODS: Accreditation Council for Graduate Medical Education data were obtained from 2011 to 2019. Linear trends were assessed for year-by-year data. Average percentages of women and underrepresented minorities were then calculated in 3-year intervals. Intervals were compared with Student's t test and χ2 tests. RESULTS: There was no statistically significant increase in percent female trainees in cardiothoracic fellowships (18.5% to 22.1%, P = .10) or integrated residencies (22.8% to 27.8%, P = .17), despite a significant increase in percent female applicants to fellowship (18.2% to 35.3%, P < .01) and integrated residency (8.9% to 33.0%, P < .01). Cardiothoracic fellowships had no increase in underrepresented minority trainees (8.3% to 9.4%, P = .48). Underrepresented minority trainees in integrated residencies increased from 2.7% to 6.9% (P = .03). Although there was no significant increase in underrepresented minority applicants to fellowships (10.2% to 11.3%, P = .66), the percent of underrepresented minority applicants to integrated residencies increased from 13.1% to 19.3% (P < .01). CONCLUSIONS: Cardiothoracic surgery training programs are attracting more female applicants, but that has not yet resulted in a higher percentage of female trainees. Although percentages of underrepresented minorities increased among integrated residency applicants and trainees, they remain low compared with other specialties. These data reflect positive changes but also highlight that much remains to be done to increase diversity in cardiothoracic surgery training.

COVID-19's impact on lung tissue: A case report.

INTRODUCTION: The novel coronavirus has spread globally, however, there continues to be little information regarding management, treatment, and complications encountered by infected patients. Prior to COVID-19, guidelines had been well established for managing empyema, however, evidence is lacking for such patients possessing a COVID-19 infection. In the spirit of collaborative knowledge, we endeavor to present a COVID-19 case from our tertiary care institution. CASE PRESENTATION: A 59-year-old Caucasian male with a past medical history of chronic obstructive pulmonary disease and hypertension was transferred to our hospital for escalation of care of COVID pneumonia. Pharmaceutical treatment included an IL-6 inhibitor (tocilizumab). The patient's hospital course was complicated by superimposed bacterial pneumonia with development of a loculated pleural empyema. On day 57, a left anterolateral muscle-sparing thoracotomy and complete pulmonary decortication was performed. The patient made a successful recovery. CLINICAL DISCUSSION: This patient's vascular dysfunction associated with shunting secondary to pulmonary microthrombi, provides rationale for the liberal use of therapeutic anticoagulation in COVID patients. The superimposed bacterial pneumonia raises concerns over the use of tocilizumab in COVID-19 patients. It is necessary to understand whether current guidelines will need to be amended for the treatment of coagulopathies to avoid pulmonary vascular dysfunction. CONCLUSION: Thoracic surgery can be carried out safely, both for patients and practitioners, during the pandemic. Microvascular occlusions within the pulmonary vasculature contribute to the severe hypoxia and need for anticoagulation in severe COVID-19 cases. Clinical pathways for common clinical presentations, such as empyema, may need to be re-evaluated during this global crisis.

Multicenter validation of the American Association for the Surgery of Trauma grading scale for acute cholecystitis.

BACKGROUND: The American Association for the Surgery of Trauma (AAST) patient assessment committee has created grading systems for emergency general surgery diseases to assist with clinical decision making and risk adjustment during research. Single-institution studies have validated the cholecystitis grading system as associated with patient outcomes. Our aim was to validate the grading system in a multi-institutional fashion and compare it with the Parkland grade and Tokyo Guidelines for acute cholecystitis. METHODS: Patients presenting with acute cholecystitis to 1 of 8 institutions were enrolled. Discrete data to assign the AAST grade were collected. The Parkland grade was collected prospectively from the operative surgeon from four institutions. Parkland grade, Tokyo Guidelines, AAST grade, and the AAST preoperative grade (clinical and imaging subscales) were compared using linear and logistic regression to the need for surgical "bailout" (subtotal or fenestrated cholecystectomy, or cholecystostomy), conversion to open, surgical complications (bile leak, surgical site infection, bile duct injury), all complications, and operative time. RESULTS: Of 861 patients, 781 underwent cholecystectomy. Mean (SD) age was 51.1 (18.6), and 62.7% were female. There were six deaths. Median AAST grade was 2 (interquartile range [IQR], 1-2), and median Parkland grade was 3 (interquartile range [IQR], 2-4). Median AAST clinical and imaging grades were 2 (IQR, 2-2) and 1 (IQR, 0-1), respectively. Higher grades were associated with longer operative times, and worse outcomes although few were significant. The Parkland grade outperformed the AAST grade based on area under the receiver operating characteristic curve. CONCLUSION: The AAST cholecystitis grading schema has modest discriminatory power similar to the Tokyo Guidelines, but generally lower than the Parkland grade, and should be modified before widespread use. LEVEL OF EVIDENCE: Diagnostic study, level IV.