Age-associated callus senescent cells produce TGF-β1 that inhibits fracture healing in aged mice
Jiatong Liu, … , Hengwei Zhang, Lianping Xing
Jiatong Liu, … , Hengwei Zhang, Lianping Xing
Published April 15, 2022
Citation Information: J Clin Invest. 2022;132(8):e148073. https://doi.org/10.1172/JCI148073.
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Research Article Aging Bone biology Article has an altmetric score of 8

Age-associated callus senescent cells produce TGF-β1 that inhibits fracture healing in aged mice

Abstract

Cellular senescence plays an important role in human diseases, including osteoporosis and osteoarthritis. Senescent cells (SCs) produce the senescence-associated secretory phenotype to affect the function of neighboring cells and SCs themselves. Delayed fracture healing is common in the elderly and is accompanied by reduced mesenchymal progenitor cells (MPCs). However, the contribution of cellular senescence to fracture healing in the aged has not to our knowledge been studied. Here, we used C57BL/6J 4-month-old young and 20-month-old aged mice and demonstrated a rapid increase in SCs in the fracture callus of aged mice. The senolytic drugs dasatinib plus quercetin enhanced fracture healing in aged mice. Aged callus SCs inhibited the growth and proliferation of callus-derived MPCs (CaMPCs) and expressed high levels of TGF-β1. TGF-β–neutralizing Ab prevented the inhibitory effects of aged callus SCs on CaMPCs and promoted fracture healing in aged mice, which was associated with increased CaMPCs and proliferating cells. Thus, fracture triggered a significant cellular senescence in the callus cells of aged mice, which inhibited MPCs by expressing TGF-β1. Short-term administration of dasatinib plus quercetin depleted callus SCs and accelerated fracture healing in aged mice. Senolytic drugs represent a promising therapy, while TGF-β1 signaling is a molecular mechanism for fractures in the elderly via SCs.

Authors

Jiatong Liu, Jun Zhang, Xi Lin, Brendan F. Boyce, Hengwei Zhang, Lianping Xing

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Figure 6

CM from aged callus inhibits the growth of MPCs, which is prevented by senolytic drugs.

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CM from aged callus inhibits the growth of MPCs, which is prevented by s...
Young and aged mice were sacrificed on 10 dpf. (A) Callus pieces were cultured for 2 days to generate CM. CaMPCs were treated with 30% of CM for 2 days and subjected to growth, proliferation, apoptosis, and senescence analyses. (B) Cell growth, as in Figure 5E. n = 4 wells. The experiment was repeated twice. (C) Cell proliferation was assessed according to the percentage of cells incorporating BrdU. BrdU+ cells are indicated by white arrowheads. Scale bars: 100 mm. Original magnification, ×4 (enlarged insets). n = 4 wells. The experiment was repeated once. (D) Cell apoptosis was measured by flow cytometry as the percentage of annexin V+ cells. The experiment was repeated once. (E) Cellular was senescence assessed according to the percentage of SA–β-gal+ cells. n = 4 wells. The experiment was repeated once. (F) The expression of senescence markers was determined by qPCR. n = 3 wells. Relative mRNA expression is the fold change versus young cells as 1. The experiment was repeated once. *P < 0.05, by unpaired, 2-tailed Student’s t test (B, C, E, and F). (G) CaMPCs were treated with CM with or without 200 nM dasatinib plus 20 μM quercetin. n = 4 wells. The experiment was repeated once. *P < 0.05, for vehicle versus D+Q, by 2-way ANOVA followed by Tukey’s post hoc test. Only comparisons between vehicle versus D+Q treatment in young or aged mice are shown. ctl, control.