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Fig. 4 | Stem Cell Research & Therapy

Fig. 4

From: Bone morphogenetic protein 4 rescues the bone regenerative potential of old muscle-derived stem cells via regulation of cell cycle inhibitors

Fig. 4

The bone regenerative capacity of old MDSCs is inferior to young MDSCs despite expressing similar levels of BMP4. A Micro-CT 3D images at different time points after cell transplantation. B Quantification of new bone volume in the skull defect at different time points showed significantly less new bone formed by old MDSCs/BMP4/GFP compared to young MDSCs/BMP4/GFP in the skull defect area when both young and old MDSCs/ BMP4/GFP have BMP4 secretion level of around 30 ng/million cells/24 h. *P < 0.05, **P < 0.01. C H&E staining for the new bone on the skull defect. The new bone is mainly trabecular bone (TB) constituted of new bone matrix and bone marrow including myeloid cells (green arrows, red blood cells (black arrows) and megakaryocytes (Blue arrows). No significant differences between young and old MDSCs/BMP4/GFP groups were found. Scale bars = 200 µm. D–E Herovici’s staining for the new bone on the skull defect and quantification. COL1 stained red/pink color. COL3 3 stained blue color. The newly formed bone tissues showed cancellous bone structure in both groups. Quantification of COL1 area percentage showed no significant difference between young and old MDSCs/BMP4/GFP groups. Scale bars = 200 µm. F–G Immunohistochemistry of GFP to trace donor cells for the new bone on the skull defect with associated quantification. The new bone area showed that most of the osteoblasts and osteocytes are GFP positive in both groups. Quantification for GFP positive area of the new bone on the skull defect showed lower GFP+ area percentage in the newly regenerated bone in old MDSCs/BMP4/GFP group compared to young MDSCs/BMP4/GFP group. P = 0.0009. Scale bars = 100 µm

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