Journal: Advanced Science
Article Title: Atrophic Skeletal Muscle‐Derived Extracellular Vesicles Transfer miR‐125a‐5p to Inhibit Bone Formation in Osteoporosis during Aging
doi: 10.1002/advs.202515362
Figure Lengend Snippet: Aged‐SKM‐EVs are increased and taken up by osteoblasts in bone during aging. (A) Representative Hematoxylin and Eosin (H&E) staining of cross‐sections from the mid‐belly of soleus (SOL) muscles and quantification of muscle fiber cross‐sectional area (CSA). n = 6 . Scale bar, 100 µm. (B) Representative tetanic force curve of SOL muscles from 6‐, 12‐, 18‐, and 24‐month‐old mice and quantification of maximal specific force during tetanic stimulation. n = 6 . (C) Representative micro‐CT reconstructed images and quantitative analysis of bone mineral density (BMD), bone volume/total volume (BV/TV), trabecular number (Tb.N), and trabecular separation (Tb.Sp) at the distal femoral metaphysis. Scale bar, 100 µm (upper panels) and 500 µm (lower panels). n = 6 . (D) Representative images of double fluorochrome labeling with calcein green and xylenol orange at the distal femoral metaphysis and quantitative bone histomorphometric analysis of mineral apposition rate (MAR). Scale bar, 25 µm. n = 6 . (E) Representative immunohistochemical staining of osteocalcin (OCN) in distal femoral sections and quantification of osteoblast surface per bone surface (Ob.S/BS). Scale bar, 50 µm. n = 6 . (F) Individual correlations between SOL muscle fiber CSA and BMD, and between CSA and Ob.S/BS. n = 24 . (G) Western blot analysis and quantification of protein expression of RAB27A expression in SOL muscles. n = 3 . (H) Representative immunohistochemical staining and quantification of RAB27A‐positive areas in SOL muscles. Scale bar, 100 µm. n = 6 . (I) Representative transmission electron microscopy (TEM) images of SKM‐EVs. Scale bar, 1 µm. (J) Nanoparticle tracking analysis (NTA) showing particle size distribution and concentration of SKM‐EVs. (K) Western blot analysis of canonical EV markers in SKM‐EVs. (L) Distribution and quantification of eGFP‐labeled EVs in skeletal muscle from HSA Cre ;Cd63 ( loxp − eGFP ) mice. Scale bar, 100 µm. n = 3 . (M) Representative fluorescence images showing circulating eGFP + PKH26 + EVs in plasma from HSA Cre ;Cd63 (loxp‐eGFP) mice, and quantification of the number density of eGFP + PKH26 + EVs (per µm 2 ). Scale bar, 100 nm. n = 6 . (N) Representative immunofluorescence staining of OCN in femoral sections (left), quantitative colocalization analysis (middle), and quantification of the percentage of CD63 GFP + OCN + cells among total OCN + cells (right). Nuclei were co‐stained with DAPI. Scale bar, 100 µm. n = 3 . All data are presented as mean ± SEM. P values were determined by one‐way analysis of variance (ANOVA) followed by Tukey's multiple comparisons test (A–E, G–H), or unpaired two‐tailed Student's t test (L–N). * P < 0.05, ** P < 0.01, *** P < 0.001.
Article Snippet: Cd63 (loxp‐eGFP) mice were obtained from Shanghai Model Organisms, and Dicer fl/fl mice were purchased from GemPharmatech.
Techniques: Staining, Muscles, Micro-CT, Labeling, Immunohistochemical staining, Western Blot, Expressing, Transmission Assay, Electron Microscopy, Concentration Assay, Fluorescence, Clinical Proteomics, Immunofluorescence, Two Tailed Test