Inhibition of autophagy alleviates the senescent state of rat mesenchymal stem cells during long-term culture

Abstract

Following a limited number of cell divisions, mesenchymal stem cells (MSCs) undergo senescence, and these senescent cells maintain metabolic modification and remain viable for long periods. Autophagy, an intracellular bulk degradation process, provides a survival effect for cells under stress. In this study, the effect of autophagy on senescent MSCs was analyzed. Following serial passaging, rat MSCs underwent replicative senescence, characterized by positive staining for senescence-associated β-galactosidase (SA-β-gal), and increased expression levels of p16 and p21. During MSC senescence, the levels of autophagic activity were increased, a greater number of autophagic vacuoles were observed in senescent MSCs by transmission electron microscopy, acridine orange staining was elevated and the expression levels of autophagy‑related proteins (microtubule‑associated protein 1A/1B‑light chain 3-II, Atg7 and Atg12) were increased. The role of autophagy in MSC senescence was further investigated through pharmacological inhibition of autophagy with bafilomycin A1 and 3-methyladenine. Inhibition of autophagy by pharmacological means reduced the rate of positive staining for SA-β-gal and the expression levels of senescence‑related proteins. In conclusion, these findings suggest that autophagy is activated during senescence and the autophagic activity may be a requirement for maintaining the senescent state of MSCs.

Autophagy inhibits the mesenchymal stem cell aging induced by D‐galactose through ROS/JNK/p38 signalling

“…This finding indicates that the senescence state of cells influences the regulatory effect of autophagy on cellular senescence . We found that previous studies observed that cellular senescence could be facilized by autophagy all in aged‐MSCs and the expression of senescence‐associated proteins was high in those MSCs. Whether the upregulated autophagy of normal MSCs can inhibit or delay MSC senescence is still unknown.…”

“…Nuclear lamina protein A upregulates autophagy level during the induction of MSC senescence . In replicative senescence MSCs, autophagy and ROS levels increase . In addition, the downregulation of autophagy can delay the senescence of MSCs .…”

Autophagy controls mesenchymal stem cell properties and senescence during bone aging

“…Numerous studies have indicated that with aging, autophagy decreases in different kinds of tissue such as kidney and brain (Kume et al., 2010; Lipinski et al., 2010). There are also studies revealing that autophagy is activated during aging in cells such as fibroblasts (Demirovic, Nizard, & Rattan, 2015) as in aged BMMSCs (Zheng et al., 2014). We demonstrated that autophagy is reduced in aged BMMSCs, which is consistent with the mainstream view.…”

“…Autophagy can protect BMMSCs from oxidative stress (Song, Song, & Tong, 2014), which indicates that autophagy plays a protective role in cell aging. Conversely, autophagy also has been proven to be a requirement for maintenance of replicative senescence of MSCs (Zheng et al., 2014). Therefore, whether and how autophagy regulates MSC aging remains unclear.…”

Molecular Mechanisms Contributing to Mesenchymal Stromal Cell Aging

“…Available data on the relationship between autophagy and senescence are partly contradictory: actually, autophagy may promote or counteract senescence depending on the cellular context and on the kind of stress [39]. Autophagy can protect BM-MSCs from oxidative stress [92] and, conversely, it has been proven to be a requirement for maintenance of replicative senescence of MSCs [93]. A possible interpretation of these contradictory results is that MSCs try to lead with stress by inducing autophagy to remove damaged components thus counteracting aging; however, in case of impaired autophagic flux and therefore of persistent cell damage, autophagy could worsen senescence.…”