Affinity Proteomic Analysis of the Human Exosome and Its Cofactor Complexes

Mesenchymal Stem Cell-Derived Extracellular Vesicles Protect Rat Nucleus Pulposus Cells from Oxidative Stress

BACKGROUND

Oxidative stress (OS) is mainly associated with the pathogenesis of intervertebral disc (IVD) degeneration; it causes nucleus pulposus cells (NPCs) to undergo senescence and triggers autophagy and apoptosis. This study aims to evaluate the regeneration potential of extracellular vesicles (EVs) derived from human umbilical cord-mesenchymal stem cells (hUC-MSCs) in an in vitro rat NPC-induced OS model.

DESIGN

NPCs were isolated from rat coccygeal discs, propagated, and characterized. OS was induced by hydrogen peroxide (H₂O₂), which is confirmed by 2,7-dichlorofluorescein diacetate (H₂DCFDA) assay. EVs were isolated from hUC-MSCs and characterized by analyzing the vesicles using fluorescence microscope, scanning electron microscope (SEM), atomic force microscope (AFM), dynamic light scattering (DLS), and Western blot (WB). The in vitro effects of EVs on migration, uptake, and survival of NPCs were determined.

RESULTS

SEM and AFM topographic images revealed the size distribution of EVs. The phenotypes of isolated EVs showed that the size of EVs was 403.3 ± 85.94 nm, and the zeta potential was -0.270 ± 4.02 mV. Protein expression analysis showed that EVs were positive for CD81 and annexin V. Treatment of NPCs with EVs reduced H₂O₂-induced OS as evidenced by a decrease in reactive oxygen species (ROS) levels. Co-culture of NPCs with DiI-labeled EVs showed the cellular internalization of EVs. In the scratch assay, EVs significantly increased NPC proliferation and migration toward the scratched area. Quantitative polymerase chain reaction analysis showed that EVs significantly reduced the expression of OS genes.

CONCLUSION

EVs protected NPCs from H₂O₂-induced OS by reducing intracellular ROS generation and improved NPC proliferation and migration.

Affinity Isolation of Endogenous Saccharomyces Cerevisiae Nuclear Pore Complexes

Studying protein complexes in vitro requires the production of a relatively pure sample that maintains the full complement, native organization, and function of that complex. This can be particularly challenging to achieve for large, multi-component, membrane embedded complexes using the traditional recombinant expression and reconstitution methodologies. However, using affinity capture from native cells, suitable whole endogenous protein complexes can be isolated. Here we present a protocol for the affinity isolation of baker's yeast (S. cerevisiae) nuclear pore complexes, which are ~50 MDa assemblies made up of 552 distinct proteins and embedded in a double-membraned nuclear envelope. Producing this sample allowed us for the first time to perform analyses to characterize the mass, stoichiometry, morphology, and connectivity of this complex and to obtain its integrative structure with ~9 Å precision. We believe this methodology can be applied to other challenging protein complexes to produce similar results.

Exosomes derived from stem cells as an emerging therapeutic strategy for intervertebral disc degeneration

Intervertebral disc (IVD) degenerative diseases are a common problem in the world, and they cause substantial social and economic burdens for people. The current methods for treating IVD degenerative diseases mainly include surgery and conservative treatment, which cannot fundamentally restore the normal structure of the disc. With continuous research on the mechanism of degeneration and the development of regenerative medicine, rapid progress has been made in the field of regenerative medicine regarding the use of stem cell-derived exosomes, which are active biological substances used in intercellular communication, because they show a strong effect in promoting tissue regeneration. The study of exosomes in the field of IVD degeneration has just begun, and many surprising achievements have been made. This paper mainly reviews the biological characteristics of exosomes and highlights the current status of exosomes in the field of IVD degeneration, as well as future developments regarding exosomes.