2022, Vol. 26 ›› Issue (25): 3944-3950

Tail vein injection of bone marrow mesenchymal stem cells for repair of skull injury in aging mice

Zhang Jingying1, Li Ziyi1, Liu Xiaochuan1, Li Dan1, Wang Yang2, Wu zhuguo1   

Abstract: BACKGROUND: Local application of bone marrow mesenchymal stem cells has the ability to promote bone tissue regeneration and repair; however, whether it could play a significant role via vein injection and its ability of bone tissue regeneration and repair at different ages still need to be clarified.  
OBJECTIVE: To explore the effects of bone marrow mesenchymal stem cells on the repair ability of skull injury in young and aging mice via vein injection.
METHODS: Totally 40 1-month-old Kunming mice were obtained as young mice, and 40 12-month-old Kunming mice were obtained as aging mice. The mice were divided into young experimental group, young control group, aging experimental group, and aging control group. The bone defect was made in the cranium of the mice. At 1, 8, and 15 days after surgery, 0.2 mL bone marrow mesenchymal stem cell suspension (1×1010 L-1) was injected into the tail vein of mice in the experimental groups; meanwhile, an equal volume of saline was used in the control groups via tail vein. The mice were sacrificed at 1 and 3 weeks after surgery. The specimens were repaired for the following experiments: morphological, histopathological, optical, and immunohistochemical analyses.  
RESULTS AND CONCLUSION: (1) Micro-CT imaging: At 1 week after surgery, there was no significant difference in the size of bone defect area between the young and aging groups, and the size of the bone defect area was reduced significantly in the experimental groups at 3 weeks after surgery. (2) Hematoxylin-eosin staining and Masson staining: The collagen fibers appeared at 1 week after surgery; meanwhile, the bone matrix emerged at 3 weeks after surgery in the defect area. The collagen fibers and the bone matrix were significantly more in the experimental groups than those in the control groups. (3) Non-linear light microscopy: At 3 weeks after the operation, the comparison of collagen content in the defect area was as follows: young experimental group > young control group; aging experimental group > aging control group. (4) Immunohistochemical analysis: At 1 and 3 weeks after operation, Sirt1 protein expression was more in the young groups than that in the aging groups. At 1 week, the Sirt1 protein expression was more in the experimental groups than that in the control groups. At 3 weeks, the Sirt1 protein expression was less in the aging experimental group than that in the aging control group. (5) It is concluded that bone marrow mesenchymal stem cells promoted the repair of skull defects in the mice of different ages significantly via the tail vein injection, which mainly promotes bone regeneration by activating Sirt1 expression in mice.
Key words: stem cells, bone marrow mesenchymal stem cells, aging, skull injury, regenerative medicine, vein injection, Sirt1, tissue repair