Engineering a Human Pluripotent Stem Cell-Based in vitro Microphysiological System for Studying the Metformin Response in Aortic Smooth Muscle Cells

Mechanosignals in abdominal aortic aneurysms

Cumulative evidence has shown that mechanical and frictional forces exert distinct effects in the multi-cellular aortic layers and play a significant role in the development of abdominal aortic aneurysms (AAA). These mechanical cues collectively trigger signaling cascades relying on mechanosensory cellular hubs that regulate vascular remodeling programs leading to the exaggerated degradation of the extracellular matrix (ECM), culminating in lethal aortic rupture. In this review, we provide an update and summarize the current understanding of the mechanotransduction networks in different cell types during AAA development. We focus on different mechanosensors and stressors that accumulate in the AAA sac and the mechanotransduction cascades that contribute to inflammation, oxidative stress, remodeling, and ECM degradation. We provide perspectives on manipulating this mechano-machinery as a new direction for future research in AAA.

Bioengineering Systems for Modulating Notch Signaling in Cardiovascular Development, Disease, and Regeneration

The Notch intercellular signaling pathways play significant roles in cardiovascular development, disease, and regeneration through modulating cardiovascular cell specification, proliferation, differentiation, and morphogenesis. The dysregulation of Notch signaling leads to malfunction and maldevelopment of the cardiovascular system. Currently, most findings on Notch signaling rely on animal models and a few clinical studies, which significantly bottleneck the understanding of Notch signaling-associated human cardiovascular development and disease. Recent advances in the bioengineering systems and human pluripotent stem cell-derived cardiovascular cells pave the way to decipher the role of Notch signaling in cardiovascular-related cells (endothelial cells, cardiomyocytes, smooth muscle cells, fibroblasts, and immune cells), and intercellular crosstalk in the physiological, pathological, and regenerative context of the complex human cardiovascular system. In this review, we first summarize the significant roles of Notch signaling in individual cardiac cell types. We then cover the bioengineering systems of microfluidics, hydrogel, spheroid, and 3D bioprinting, which are currently being used for modeling and studying Notch signaling in the cardiovascular system. At last, we provide insights into ancillary supports of bioengineering systems, varied types of cardiovascular cells, and advanced characterization approaches in further refining Notch signaling in cardiovascular development, disease, and regeneration.

Risk reduction and pharmacological strategies to prevent progression of aortic aneurysms

INTRODUCTION

While size thresholds exist to determine when aortic aneurysms warrant surgical intervention, there is no consensus on how best to treat this disease before aneurysms reach the threshold for intervention. Since a landmark study in 1994 first suggested ß-blockers may be useful in preventing aortic aneurysm growth, there has been a surge in research investigating different pharmacologic therapies for aortic aneurysms - with very mixed results.

AREAS COVERED

We have reviewed the existing literature on medical therapies used for thoracic and abdominal aortic aneurysms in humans. These include ß-blockers, angiotensin II receptor blockers, and angiotensin-converting enzyme inhibitors as well as miscellaneous drugs such as tetracyclines, macrolides, statins, and anti-platelet medications.

EXPERT OPINION

While multiple classes of drugs have been explored for risk reduction in aneurysm disease, with few exceptions results have been disappointing with an abundance of contradictory findings. The vast majority of studies have been done in patients with abdominal aortic aneurysms or thoracic aortic aneurysm patients with Marfan Syndrome. There exists a striking gap in the literature when it comes to pharmacologic management of non-Marfan Syndrome patients with thoracic aortic aneurysms. Given the differences in pathogenesis, this is an important future direction for aortic aneurysm research.

Current pharmacological management of aortic aneurysm

ABSTRACT

Aortic aneurysm (AA) remains one of the primary causes of death worldwide. Of the major treatments, prophylactic operative repair is used for AA to avoid potential aortic dissection (AD) or rupture. To halt the development of AA and alleviate its progression into AD, pharmacological treatment has been investigated for years. Currently, β-adrenergic blocking agents, losartan, irbesartan, angiotensin-converting-enzyme inhibitors, statins, antiplatelet agents, doxycycline, and metformin have been investigated as potential candidates for preventing AA progression. However, the paradox between preclinical successes and clinical failures still exists, with no medical therapy currently available for ideally negating the disease progression. This review describes the current drugs used for pharmacological management of AA and their individual potential mechanisms. Preclinical models for drug screening and evaluation are also discussed to gain a better understanding of the underlying pathophysiology and ultimately find new therapeutic targets for AA.