# Anti-Aging Effects of Nanovesicles Derived from Human Tonsil-Derived Mesenchymal Stem Cells
## 4 Discussion  
In this study, we explored the question of whether the nanovesicles derived from TMSCs can exert anti-aging properties. We isolated and confirmed characteristics of TMSCs and TMSC-NVs. TMSCs were highly proliferative MSC-like cells and TMSC-NVs possessed characteristics similar to those of exosomes. TMSC-NVs accelerated the proliferation and reduced senescence-associated \(\beta\)-galactosidase activities and vinculin expression in focal adhesion of both senescent HDFs. ECM production and the anti-oxidant gene involved in cellular senescence were upregulated in the senescent HDFs by treatment with TMSC-NVs. With these results, we suggest that TMSC-NVs can be utilized for skin rejuvenation and anti-aging purposes.  
In the past decade, the poor yield and inefficient separation procedure for exosome production have been challenged [19]. To overcome these issues, we sought to produce exosome-mimetic nanovesicles from human tonsil-derived mesenchymal stem cells using a relatively simple extrusion procedure [33]. In this study, even though the comparative data of characteristics with exosomes are not shown, TMSC-NVs express the exosome-specific markers (CD9 and CD63) and the size of TMSC-NVs is similar to that of exosomes, meaning that the characteristics of TMSC-NVs are similar to those of exosomes, and TMSC-NVs can be utilized as an alternative for exosome therapies.  
It has been reported that the mRNA and miRNA profiles of exosomes differ from their originated cells [13]. Here, numerous pieces of research have revealed the specific marker in exosomes to demonstrate the mechanism of tissue regeneration mediated by exosomes. For instance, [PERSON] et al. demonstrated that exosome-mediated delivery of miR-155 regulates insulin sensitivity and glucose homeostasis [34]. [PERSON] et al. reported that mesenchymal stem cell-derived exosomes are transferred to neurons and astrocytes and exosome-mediated miR-133 plays a key role in neurological recovery from stroke [35]. Even though the presented results show that the TMSC-NVs can be utilized as an alternative to exosomes for skin rejuvenation, the mechanism of regulation of cellular senescence via treatment with TMSC-NVs is unclear. Therefore, in further study, we plan to discover the key marker of TMSC-NVs in the regulation of cellular senescence.  
Cellular senescence is characterized as an irreversible arrest of cell growth, which occurs through alternation of the focal adhesive cytoskeleton [2; 3]. In the present study, cellular senescence was induced by both passage-associated senescent HDFs and UV-induced senescent HDFs, and TMSC-NVs decreased cellular senescence and increased cell proliferation, anti-oxidant gene expression and extracellular matrix production. However, the expression of _ELASTIN_ was increased in the passage-associated senescent HDFs but not in the UV-induced senescent HDFs. Our prediction is a difference in the senescence induction mechanism of both senescence models. It has been reported that senescence can be induced by various factors and the pathway of senescence induction can be different in each stimuli [36]. In particular, [PERSON] et al. reported different mRNA profiles among representative cellular senescence models, including a replicative senescence model, tert-butyl hydroperoxide-induced senescence model, and EtOH-induced senescence model [37]. Given these reports, we plan to explore the role of senescence in the regulation of extracellular matrix expression in each modeling procedure, which may provide further research for skin rejuvenation.  
The next frontier of exosome-mimetic nanovesicles for skin rejuvenation is demonstration of the regenerative potential from ex vivo to clinical trials. In this study, we determined the proangiogenic and anti-inflammatory effects of extracellular vesicles, which will be helpful in regenerative medicine.