Abstract
The network structure and biological components of natural extracellular matrix (ECM) are indispensable for promoting tissue regeneration. Electrospun nanofibrous scaffolds have been widely used in regenerative medicine to provide structural support for cell growth and tissue regeneration due to their natural ECM mimicking architecture, however, they lack biological functions. Extracellular vesicles (EVs) are potent vehicles of intercellular communication due to their ability to transfer RNAs, proteins, and lipids, thereby mediating significant biological functions in different biological systems. Matrix-bound nanovesicles (MBVs) are identified as an integral and functional component of ECM bioscaffolds mediating significant regenerative functions. Therefore, to engineer EVs modified electrospun scaffolds, mimicking the structure of the natural EV-ECM complex and the physiological interactions between the ECM and EVs, will be attractive and promising in tissue regeneration. Previously, using one-bead one-compound (OBOC) combinatorial technology, we identified LLP2A, an integrin α4β1 ligand, which had a strong binding to human placenta-derived mesenchymal stem cells (PMSCs). In this study, we isolated PMSCs derived EVs (PMSC-EVs) and demonstrated they expressed integrin α4β1 and could improve endothelial cell (EC) migration and vascular sprouting in an ex vivo rat aortic ring assay. LLP2A treated culture surface significantly improved PMSC-EV attachment, and the PMSC-EV treated culture surface significantly enhanced the expression of angiogenic genes and suppressed apoptotic activity. We then developed an approach to enable “Click chemistry” to immobilize LLP2A onto the surface of electrospun scaffolds as a linker to immobilize PMSC-EVs onto the scaffold. The PMSC-EV modified electrospun scaffolds significantly promoted EC survival and angiogenic gene expression, such as KDR and TIE2, and suppressed the expression of apoptotic markers, such as caspase 9 and caspase 3. Thus, PMSC-EVs hold promising potential to functionalize biomaterial constructs and improve the vascularization and regenerative potential. The EVs modified biomaterial scaffolds can be widely used for different tissue engineering applications.
Highlights
Natural extracellular space is a dynamic and responsive environment consisting of non-cellular components such as soluble factors, non-soluble extracellular matrix (ECM), and extracellular vesicles (EVs) (Mathivanan, 2017)
NTA showed that placental chorionic villus MSCs (PMSCs)-EVs have a size range of 137.4 ± 3.6 nm, which is within the expected size range of EVs (Figure 1C)
In addition to the characteristic EV markers, the Western blot results confirmed that PMSC-EVs expressed integrin α4 and integrin β1 that could be used as the junction to conjugate PMSC-EVs to biomaterial for simulating the natural ECM
Summary
Natural extracellular space is a dynamic and responsive environment consisting of non-cellular components such as soluble factors, non-soluble extracellular matrix (ECM), and extracellular vesicles (EVs) (Mathivanan, 2017). The ECM regulates many important processes including cellular proliferation, adhesion, migration, differentiation, tissue homeostasis and remodeling These functions do depend on ECM’s three-dimensional network, and on its biological components (Huleihel et al, 2016). We demonstrated that an integrin-based ligand modified electrospun scaffold improved EC functions in vitro and vascularization in vivo (Hao et al, 2017, 2020a) These approaches only improve the cell and tissue functions by promoting cell/tissue-biomaterial interaction, but do not promote the biological information and substance transfer simulating the dynamic native ECM (Teodori et al, 2014; Sood et al, 2019). To construct biofunctional scaffolds with biological information exchange and transmission will further promote the applications of biological materials in tissue regeneration
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