surgical-perfusion-isolation-porcine-pancreas-for-islet

Surgical Perfusion and Isolation of the Porcine Pancreas for Islet Isolation

Pancreatic islet transplantation is an emerging treatment for type I diabetes; however, it is limited by donor matching and availability. Porcine islet ...

Washington University School of Medicine

The development of abdominal aortic aneurysms (AAA) is presumed to result from multiple genetic and environmental factors, with exposure to tobacco smoke the single largest known factor predisposing to aneurysm growth. We have attempted to adapt the elastase-perfused animal model to determine whether tobacco exposure can lower the threshold of aortic injury necessary for AAA development.

Cigarette smoking increases aortic dilatation without affecting matrix metalloproteinase-9 and -12 expression in a modified mouse model of aneurysm formation.

Ligamentous attachments maintain the normal anatomic position of the gastroesophageal (GE) junction. Failure of these elastic ligaments through an alteration in collagen synthesis, deposition, and metabolism may be a primary etiology of hiatal hernia formation. Differential expression of zinc-dependent matrix metalloproteinases (MMPs) is largely responsible for collagen remodeling. The purpose of this study was to survey baseline levels of MMPs in supporting ligaments of the GE junction from patients without hiatal hernia.

Differential regulation of MMP-2 in the gastrohepatic ligament of the gastroesophageal junction.

Inhibiting the growth of small abdominal aortic aneurysms (AAAs) is a clinically valuable goal and fills an important therapeutic void. Based on studies in animals and humans, inhibition of the activity of elastolytic matrix metalloproteinases (MMPs) has the potential to slow AAA expansion and limit morbidity and the need for surgery. Previous attempts to make use of the synthetic MMP inhibitors in the treatment of chronic conditions have been limited by intolerable side effects. The limited-spectrum synthetic MMP inhibitor, XL784, was well tolerated and devoid of side-effects associated with other nonspecific MMP inhibitors in phase I studies. We hypothesized that clinically relevant doses of XL784 would be effective at inhibiting aneurysm development in a mouse model.

Effect of novel limited-spectrum MMP inhibitor XL784 in abdominal aortic aneurysms.

The purpose of this study was to evaluate potential mechanisms promoting abdominal aortic aneurysm development with tobacco smoke (TS) exposure.

Novel mechanism of aortic aneurysm development in mice associated with smoking and leukocytes.

The purpose of this study was to further elucidate the role of the vascular smooth muscle cells (SMCs) in abdominal aortic aneurysm (AAA) disease. We hypothesized that that AAA SMCs are unique and actively participate in the process of degrading the aortic matrix.

Smooth muscle cells from abdominal aortic aneurysms are unique and can independently and synergistically degrade insoluble elastin.

Demonstrate that periadventitial delivery of adipose-derived mesenchymal stem cells (ADMSCs) slows aneurysm progression in an established murine elastase-perfusion model of abdominal aortic aneurysm (AAA).

Periadventitial adipose-derived stem cell treatment halts elastase-induced abdominal aortic aneurysm progression.

Autophagy is a catabolic cellular mechanism that degrades dysfunctional proteins and organelles. Atherosclerotic plaque formation is enhanced in mice with macrophages deficient for the critical autophagy protein ATG5. We showed that exposure of macrophages to lipids that promote atherosclerosis increased the abundance of the autophagy chaperone p62 and that p62 colocalized with polyubiquitinated proteins in cytoplasmic inclusions, which are characterized by insoluble protein aggregates. ATG5-null macrophages developed further p62 accumulation at the sites of large cytoplasmic ubiquitin-positive inclusion bodies. Aortas from atherosclerotic mice and plaques from human endarterectomy samples showed increased abundance of p62 and polyubiquitinated proteins that colocalized with plaque macrophages, suggesting that p62-enriched protein aggregates were characteristic of atherosclerosis. The formation of the cytoplasmic inclusions depended on p62 because lipid-loaded p62-null macrophages accumulated polyubiquitinated proteins in a diffuse cytoplasmic pattern. Lipid-loaded p62-null macrophages also exhibited increased secretion of interleukin-1β (IL-1β) and had an increased tendency to undergo apoptosis, which depended on the p62 ubiquitin-binding domain and at least partly involved p62-mediated clearance of NLRP3 inflammasomes. Consistent with our in vitro observations, p62-deficient mice formed greater numbers of more complex atherosclerotic plaques, and p62 deficiency further increased atherosclerotic plaque burden in mice with a macrophage-specific ablation of ATG5. Together, these data suggested that sequestration of cytotoxic ubiquitinated proteins by p62 protects against atherogenesis, a condition in which the clearance of protein aggregates is disrupted.

Inclusion bodies enriched for p62 and polyubiquitinated proteins in macrophages protect against atherosclerosis.

The receptor tyrosine kinase AXL promotes migration, invasion, and metastasis. Here, we evaluated the role of AXL in endometrial cancer. High immunohistochemical expression of AXL was found in 76% (63/83) of advanced-stage, and 77% (82/107) of high-grade specimens and correlated with worse survival in uterine serous cancer patients. In vitro, genetic silencing of AXL inhibited migration and invasion but had no effect on proliferation of ARK1 endometrial cancer cells. AXL-deficient cells showed significantly decreased expression of phospho-AKT as well as uPA, MMP-1, MMP-2, MMP-3, and MMP-9. In a xenograft model of human uterine serous carcinoma with AXL-deficient ARK1 cells, there was significantly less tumor burden than xenografts with control ARK1 cells. Together, these findings underscore the therapeutic potentials of AXL as a candidate target for treatment of metastatic endometrial cancer.

AXL modulates extracellular matrix protein expression and is essential for invasion and metastasis in endometrial cancer.

The monocyte chemoattractant protein-1/CCR2 (chemokine receptor 2) axis plays an important role in abdominal aortic aneurysm (AAA) pathogenesis, with effects on disease progression and anatomic stability. We assessed the expression of CCR2 in a rodent model and human tissues, using a targeted positron emission tomography radiotracer (Cu-DOTA-ECL1i).

CCR2 Positron Emission Tomography for the Assessment of Abdominal Aortic Aneurysm Inflammation and Rupture Prediction.

Abdominal aortic aneurysms (AAAs) are prevelant with aging, and AAA rupture is associated with high mortality. There is currently no effective medical therapy for AAA rupture. Previous work demonstrated that the monocyte chemoattractant protein (MCP-1) / C-C chemokine receptor type 2 (CCR2) axis critically regulates AAA inflammation, matrix-metalloproteinase (MMP) production, and extracellular matrix (ECM) stability. Here we similarly observed that  mice have significantly reduced AAA expansion and rupture. We therefore hypothesized that a dietary modulation of the CCR2 axis may therapeutically impact AAA risk of rupture. Since ketone bodies (KBs) can trigger repair mechanisms in response to inflammation, we specifically evaluated whether systemic ketosis  can reduce CCR2 and AAA progression. Male Sprague-Dawley rats underwent surgical AAA formation using porcine pancreatic elastase (PPE), and received daily β-aminopropionitrile (BAPN) to promote AAA rupture. Animals with AAAs received either a standard diet (SD), ketogenic diet (KD), or exogenous KBs (EKB). Animals recieving KD and EKB reached a state of ketosis, and had significant reduction in AAA expansion and incidence of rupture. Ketosis also led to significantly reduced aortic CCR2 content, improved MMP balance, and reduced ECM degradation. In summary, this study demonstrates that ketosis plays a crucial role in AAA pathobiology, and provides the impetus for future clinical studies investigating the potential benefit of ketosis for prevention of AAA expansion and rupture.

Ketosis Prevents Abdominal Aortic Aneurysm Rupture Through C-C Chemokine Receptor Type 2 Downregulation and Enhanced MMP Balance.

Abdominal aortic aneurysms (AAAs) are prevalent with aging, and AAA rupture is associated with increased mortality. There is currently no effective medical therapy to prevent AAA rupture. The monocyte chemoattractant protein (MCP-1)/C-C chemokine receptor type 2 (CCR2) axis critically regulates AAA inflammation, matrix-metalloproteinase (MMP) production, and extracellular matrix (ECM) stability. We therefore hypothesized that a diet intervention that can modulate CCR2 axis may therapeutically impact AAA risk of rupture. Since ketone bodies (KBs) can trigger repair mechanisms in response to inflammation, we evaluated whether systemic ketosis in vivo could reduce CCR2 and AAA progression. Male Sprague-Dawley rats underwent surgical AAA formation using porcine pancreatic elastase and received daily β-aminopropionitrile to promote AAA rupture. Rats with AAAs received either a standard diet, ketogenic diet (KD), or exogenous KBs (EKB). Rats receiving KD and EKB reached a state of ketosis and had significant reduction in AAA expansion and incidence of rupture. Ketosis also led to significantly reduced aortic CCR2 content, improved MMP balance, and reduced ECM degradation. Consistent with these findings, we also observed that Ccr2-/- mice have significantly reduced AAA expansion and rupture. In summary, this study demonstrates that CCR2 is essential for AAA expansion, and that its modulation with ketosis can reduce AAA pathology. This provides an impetus for future clinical studies that will evaluate the impact of ketosis on human AAA disease.

Ketosis prevents abdominal aortic aneurysm rupture through C-C chemokine receptor type 2 downregulation and enhanced extracellular matrix balance.

A vascular anastomosis is a critical surgical skill that involves connecting blood vessels. Traditional handsewn techniques can be challenging and resource intensive. To address these issues, we have developed a unique sutureless anastomotic device called Vaso-Lock. This intraluminal device connects free vascular ends using anchors to maintain traction and enable a rapid anastomosis. We tested the anastomotic capability of Vaso-Locks in a pig common carotid-internal jugular arteriovenous model. The use of Vaso-Lock allowed us to accomplish this procedure in less than 10 min, in contrast to the approximately 40 min required for a handsewn anastomosis. The Vaso-Lock effectively maintained patency for at least 6 weeks without causing significant tissue damage. Histological analysis revealed that the device was successfully incorporated into the arterial wall, promoting a natural healing process. Additionally, organ evaluations indicated no adverse effects from using the Vaso-Lock. Our findings support the safety and effectiveness of the Vaso-Lock for arteriovenous anastomosis in pigs, with potential applicability for translation to humans. Our novel sutureless device has the potential to advance surgical practice and improve patient outcomes.

Article	Year
Cigarette smoking increases aortic dilatation without affecting matrix metalloproteinase-9 and -12 expression in a modified mouse model of aneurysm formation. Journal of vascular surgery\| PubMed ID: 17398058	2007
Differential regulation of MMP-2 in the gastrohepatic ligament of the gastroesophageal junction. Surgical endoscopy\| PubMed ID: 20054578	2010
Effect of novel limited-spectrum MMP inhibitor XL784 in abdominal aortic aneurysms. Journal of cardiovascular pharmacology and therapeutics\| PubMed ID: 22894883	2012
Novel mechanism of aortic aneurysm development in mice associated with smoking and leukocytes. Arteriosclerosis, thrombosis, and vascular biology\| PubMed ID: 23042818	2012
Smooth muscle cells from abdominal aortic aneurysms are unique and can independently and synergistically degrade insoluble elastin. Journal of vascular surgery\| PubMed ID: 24080131	2014
Periadventitial adipose-derived stem cell treatment halts elastase-induced abdominal aortic aneurysm progression. Regenerative medicine\| PubMed ID: 25431910	2014
Inclusion bodies enriched for p62 and polyubiquitinated proteins in macrophages protect against atherosclerosis. Science signaling\| PubMed ID: 26732762	2016
AXL modulates extracellular matrix protein expression and is essential for invasion and metastasis in endometrial cancer. Oncotarget\| PubMed ID: 27764792	2016
CCR2 Positron Emission Tomography for the Assessment of Abdominal Aortic Aneurysm Inflammation and Rupture Prediction. Circulation. Cardiovascular imaging\| PubMed ID: 32164451	2020
Ketosis Prevents Abdominal Aortic Aneurysm Rupture Through C-C Chemokine Receptor Type 2 Downregulation and Enhanced MMP Balance. Research square\| PubMed ID: 37461581	2023
Ketosis prevents abdominal aortic aneurysm rupture through C-C chemokine receptor type 2 downregulation and enhanced extracellular matrix balance. Scientific reports\| PubMed ID: 38228786	2024
Vaso-Lock for sutureless anastomosis in a pig arteriovenous loop model. Biomaterials\| PubMed ID: 38574456	2024

Batool Arif

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