# Anti-Aging Effects of Nanovesicles Derived from Human Tonsil-Derived Mesenchymal Stem Cells
## 1 Introduction  
Aging is characterized by time-dependent loss of function and regenerative properties of organisms. Factors related to skin aging cause damage to cells, delaying skin regeneration and cell proliferation, known as cellular senescence. Cellular senescence is characterized by an irreversible arrest of the cell cycle [1] and alteration of the focal adhesive cytoskeleton [2, 3]. Cellular senescence in skin tissues is induced by various factors, such as oxidative stress [4, 5], mitochondrial dysfunction [6, 7], and ultraviolet irradiation [8, 9]. For the past several decades, many researchers have been conducting research to overcome cellular senescence for skin regeneration.  
Recently, to overcome cellular senescence, many studies have focused on the tissue regenerative potential of exosomes. Exosomes, which are known as nano-size biomimetic nanovesicles secreted across the plasma membrane from the originated cells by the endocytic pathway [10, 11], contain several components, including miRNA, mRNA, and proteins [12, 13, 14]. In addition, exosomes have been studied for skin rejuvenation and anti-aging approaches. For example, [PERSON] et al. demonstrated that exosomes derived fromadipose-derived mesenchymal stem cells promote the proliferation and migration of human dermal fibroblasts (HDFs) [15]. [PERSON] at el. demonstrated that the exosomes secreted from induced pluripotent stem cell-derived mesenchymal stem cells increase the proliferation of HDFs and HaCaT (immortalized human keratinocytes) [16]. Human umbilical cord blood stem cell-derived exosomes were studied for cutaneous wound healing via stimulation of the Wnt signaling pathway [17] and skin rejuvenation [18]. However, despite the potential of exosomes for therapeutic purposes, there are several hurdles, including low efficiency, long procedure time, and high technical expertise [19].  
To overcome those hurdles, many researchers have focused on the direct production of exosome-mimetic nanovesicles from somatic cells [20; 21; 22; 23]. These biomimetic nanovesicles can be directly isolated from the desired cells by sonication and/or extrusion and are reported to share similar characteristics with exosomes. Given the similar properties, cell-derived biomimetic nanovesicles could be utilized for drug delivery [24; 25], tissue regeneration [26; 27], and cancer targeting [28; 29]. In particular, it was reported that nanovesicles derived from human tonsil-derived mesenchymal stem cells attenuate liver fibrosis and inflammation [30; 31]. However, the anti-aging effects of nanovesicles derived from human tonsil-derived mesenchymal stem cells (TMSCs) have not yet been investigated.  
In this study, we examined the question of whether the nanovesicles derived from human tonsil-derived mesenchymal stem cells (TMSC-NVs) have a promising potential to decrease cellular senescence and increase cell proliferation. Both intrinsic replicative senescence and extrinsic ultraviolet B (UV)-irradiated senescence were employed in an in vitro model. TMSC-NVs were applied to these senescence models for assessment of their anti-aging effect.