Extracellular Vesicles Derived from Primary Adipose Stromal Cells Induce Elastin and Collagen Deposition by Smooth Muscle Cells within 3D Fibrin Gel Culture.

Eoghan M Cunnane,Katherine L Lorentz,Justin S Weinbaum,Aneesh K Ramaswamy,David A Vorp

doi:10.3390/bioengineering8050051

Abstract

Macromolecular components of the vascular extracellular matrix (ECM), particularly elastic fibers and collagen fibers, are critical for the proper physiological function of arteries. When the unique biomechanical combination of these fibers is disrupted, or in the ultimate extreme where fibers are completely lost, arterial disease can emerge. Bioengineers in the realms of vascular tissue engineering and regenerative medicine must therefore ideally consider how to create tissue engineered vascular grafts containing the right balance of these fibers and how to develop regenerative treatments for situations such as an aneurysm where fibers have been lost. Previous work has demonstrated that the primary cells responsible for vascular ECM production during development, arterial smooth muscle cells (SMCs), can be induced to make new elastic fibers when exposed to secreted factors from adipose-derived stromal cells. To further dissect how this signal is transmitted, in this study, the factors were partitioned into extracellular vesicle (EV)-rich and EV-depleted fractions as well as unseparated controls. EVs were validated using electron microscopy, dynamic light scattering, and protein quantification before testing for biological effects on SMCs. In 2D culture, EVs promoted SMC proliferation and migration. After 30 days of 3D fibrin construct culture, EVs promoted SMC transcription of the elastic microfibril gene FBN1 as well as SMC deposition of insoluble elastin and collagen. Uniaxial biomechanical properties of strand fibrin constructs were no different after 30 days of EV treatment versus controls. In summary, it is apparent that some of the positive effects of adipose-derived stromal cells on SMC elastogenesis are mediated by EVs, indicating a potential use for these EVs in a regenerative therapy to restore the biomechanical function of vascular ECM in arterial disease.

Highlights

Cardiovascular disease (CVD) is the primary cause of death globally, outside of the current COVID-19 pandemic, and encompasses disorders of the heart and blood vessels [1].Affected vessels can exhibit aneurysm or blockage and often require revascularization through minimally invasive endovascular repair or open bypass surgery [2,3]
We have previously demonstrated that delivering the secretome of adipose stromal cells (ASCs) to vascular smooth muscle cells (SMCs) in 3D gel culture increases the deposition of both elastin and collagen [15]
DLS analysis revealed the presence of two populations of particles within the extracellular vesicle (EV) isolate that exhibit different diameters (Figure 1C), with max peaks at 66 nm and 283 nm, which are indicative of exosomes and microvesicles, respectively [31]

Summary

Introduction

Cardiovascular disease (CVD) is the primary cause of death globally, outside of the current COVID-19 pandemic, and encompasses disorders of the heart and blood vessels [1].Affected vessels can exhibit aneurysm or blockage and often require revascularization through minimally invasive endovascular repair or open bypass surgery [2,3]. Non-surgical options for patients with small abdominal aortic aneurysm (AAA) Bioengineering 2021, 8, 51 below the “surgical” threshold) are limited to semi-annual surveillance, with current pharmacological agents proving ineffective and AAA rupture occurring in nearly a quarter of patients in this cohort [4,5,6]. Further reading on the development of tissue engineered/regenerative medicine solutions for these needs has been highlighted in reviews [11,12]. It is paramount to develop methods of inducing the synthesis of the key extracellular matrix (ECM) structural proteins, elastin and collagen, in target vascular cells and tissues

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