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

Mesenchymal Stem Cell-Conditioned Media-Loaded Microparticles Enhance Acute Patency in Silk-Based Vascular Grafts

Coronary artery disease leads to over 360,000 deaths annually in the United States, and off-the-shelf bypass graft options are currently limited and/or have high failure rates. Tissue-engineered vascular grafts (TEVGs) present an attractive option, though the promising mesenchymal stem cell (MSC)-based implants face uncertain regulatory pathways. In this study, "artificial MSCs" (ArtMSCs) were fabricated by encapsulating MSC-conditioned media (CM) in poly(lactic-co-glycolic acid) microparticles. ArtMSCs and control microparticles (Blank-MPs) were incubated over 7 days to assess the release of total protein and the vascular endothelial growth factor (VEGF-A); releasates were also assessed for cytotoxicity and promotion of smooth muscle cell (SMC) proliferation. Each MP type was loaded in previously published "lyogel" silk scaffolds and implanted as interposition grafts in Lewis rats for 1 or 8 weeks. Explanted grafts were assessed for patency and cell content. ArtMSCs had a burst release of protein and VEGF-A. CM increased proliferation in SMCs, but not after encapsulation. TEVG explants after 1 week had significantly higher patency rates with ArtMSCs compared to Blank-MPs, but similar to unseeded lyogel grafts. ArtMSC explants had lower numbers of infiltrating macrophages compared to Blank-MP explants, suggesting a modulation of inflammatory response by the ArtMSCs. TEVG explants after 8 weeks showed no significant difference in patency among the three groups. The ArtMSC explants showed higher numbers of SMCs and endothelial cells within the neotissue layer of the graft compared to Blank-MP explants. In sum, while the ArtMSCs had positive effects acutely, efficacy was lost in the longer term; therefore, further optimization is needed.

Biomedical Applications of Collagen

Extracellular matrix proteins (ECMs) provide structural support and dynamic signaling cues that regulate cell behavior and tissue morphogenesis [...].

Muscle and Adipose Tissue Communicate with Extracellular Vesicles

In numerous body locations, muscle and adipose tissue are in close contact. Both tissues are endocrine organs that release cytokines, playing a crutial role in the control of tissue homeostasis in health and diseases. Within this context, the identification of the signals involved in muscle–fat crosstalk has been a hot topic over the last 15 years. Recently, it has been discovered that adipose tissue and muscles can release information embedded in lipid-derived nanovesicles called ‘extracellular vesicles’ (EVs), which can modulate the phenotype and the homeostasis of neighboring recipient cells. This article reviews knowledge on EVs and their involvement in the communication between adipose tissue and muscle in several body locations. Even if the works are scarce, they have revolutionized our vision in the field of metabolic and cardiovascular diseases.

Extracellular Vesicles: Interplay with the Extracellular Matrix and Modulated Cell Responses

The discovery that cells secrete extracellular vesicles (EVs), which carry a variety of regulatory proteins, nucleic acids, and lipids, has shed light on the sophisticated manner by which cells can communicate and accordingly function. The bioactivity of EVs is not only defined by their internal content, but also through their surface associated molecules, and the linked downstream signaling effects they elicit in target cells. The extracellular matrix (ECM) contains signaling and structural molecules that are central to tissue maintenance and repair. Recently, a subset of EVs residing within the extracellular matrix has been identified. Although some roles have been proposed for matrix-bound vesicles, their role as signaling molecules within the ECM is yet to be explored. Given the close association of EVs and the ECM, it is not surprising that EVs partly mediate repair and regeneration by modulating matrix deposition and degradation through their cellular targets. This review addresses unique EV features that allow them to interact with and navigate through the ECM, describes how their release and content is influenced by the ECM, and emphasizes the emerging role of stem-cell derived EVs in tissue repair and regeneration through their matrix-modulating properties.

Different levels of EGF, VEGF, IL-6, MCP-1, MCP-3, IP-10, Eotaxin and MIP-1α in the adipose-derived stem cell secretome in androgenetic alopecia

Hair folliculogenesis and hair growth mediated by the secretory properties of white adipocytes may pave the way for the adipose-derived (AD) regenerative therapy for androgenetic alopecia (AGA). Quantitative and qualitative secretome profiling of AD stem cells (ADSCs) from different zones of hair growth in patients with AGA were analysed. 1mm punch samples of adipose tissue associated with hair follicles, of three scalp areas (balding, non-balding and transition zone) and one periumbilical sample, were used for ADCS isolation. The ADCS secretome was analysed in conditioned media using a 41plex assay. Among the thirty-five signalling proteins analysed, the levels of VEGF, EGF, IL-6, Eotaxin, MCP-3, IFNγ-inducible Protein-10 and MIP-1α were higher in the balding zone compared with the non-balding and periumbilical zones. In contrast, MCP-1 was lowest in the balding zone in comparison to the other zones. The observed differences in the secretome suggest crosstalk between angiogenic and inflammatory processes underlying AGA etiology and may prove relevant in both the diagnosis of AGA and the application of ADSC secretome for AGA treatment.

Functionalized Silk Vascular Grafts with Decellularized Human Wharton's Jelly Improves Remodeling via Immunomodulation in Rabbit Jugular Vein

Cell-free polymeric tissue-engineered vascular grafts (TEVGs) have shown great promise towards clinical translation; however, their limited bioactivity and remodeling ability challenge this cause. Here, a novel cell-free bioresorbable small diameter silk TEVG system functionalized with decellularized human Wharton's jelly (dWJ) matrix is developed and successfully implanted as interposition grafts into rabbit jugular vein. Implanted TEVGs remain patent for two months and integrate with host tissue, demonstrating neo-tissue formation and constructive remodeling. Mechanistic analysis reveals that dWJ matrix is a reservoir of various immunomodulatory cytokines (Interleukin-8, 6, 10, 4 and tumor necrosis factor alpha (TNF-α)), which aids in upregulating M2 macrophage-associated genes facilitating pro-remodeling behavior. Besides, dWJ treatment to human endothelial cells upregulates the expression of functional genes (cluster of differentiation 31 (CD31), endothelial nitric oxide synthase (eNOS), and vascular endothelial (VE)-cadherin), enables faster cell migration, and elevates nitric oxide (NO) production leading to the in situ development of endothelium. The dWJ functionalized silk TEVGs support increased host cell recruitment than control, including macrophages and vascular cells. It endows superior graft remodeling in terms of a dense medial layer comprising smooth muscle cells and elevates the production of extracellular matrix proteins (collagen and elastin). Altogether, these findings suggest that dWJ functionalization imitates the usefulness of cell seeding and enables graft remodeling.