Background: Idiopathic pulmonary fibrosis (IPF) is an age-related disease with no cure. Mesenchymal stem cell (MSC)-based therapy has emerged as a novel strategy for IPF treatment. Nevertheless, MSCs derived from patients with IPF (IPF-MSCs) become senescent, thereby reducing their beneficial effects in IPF. MicroRNAs (miRNAs) mediate the senescence of MSCs, but the underlying mechanisms are not fully understood. We investigated the mechanisms by which miR-199a-5p regulates IPF-MSC senescence and whether its inhibition could rejuvenate IPF-MSCs and enhance their therapeutic efficacy.
Methods: Control-MSCs and IPF-MSCs were isolated from the adipose tissue of age-matched healthy and IPF donors, respectively. Cell senescence was examined by senescence-associated β-galactosidase (SA-β-gal) staining. The level of miR-199a-5p was measured by RT-PCR. Autophagy was determined using a transmission electron microscope (TEM). The therapeutic efficacy of anti-miR-199a-5p-IPF-MSCs was assessed using a mouse model of bleomycin-induced lung fibrosis.
Results: Despite similar surface makers, IPF-MSCs exhibited increased cellular senescence and decreased proliferative capacity compared with control-MSCs. The expression of miR-199a-5p was significantly enhanced in the serum of IPF patients and IPF-MSCs compared with that of healthy donors and control-MSCs. The upregulation of miR-199a-5p induced senescence of control-MSCs, whereas the downregulation rescued IPF-MSC senescence. Mechanistically, miR-155-5p suppressed autophagy of MSCs via the AMPK signaling pathway by downregulating the expression of Sirtuin 1(Sirt1), resulting in cellular senescence. Accordingly, miR-155-5p inhibition promoted autophagy and ameliorated IPF-MSC senescence by activating the Sirt1/AMPK signaling pathway. Compared with IPF-MSCs, the transplantation of anti-miR-199a-5p-IPF-MSCs increased the ability to prevent progression of pulmonary fibrosis in bleomycin-treated mice.
Conclusions: Our study shows that miR-199a-5p regulates MSC senescence in patients with IPF by regulating the Sirt1/AMPK signaling pathway and miR-199a-5p is a novel target to rejuvenate IPF-MSCs and enhance their beneficial effects.
Keywords: Idiopathic pulmonary fibrosis; Mesenchymal stem cells; Rejuvenation; Senescence; miR-199a-5p.