S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) Theses (Ph.D. / Sc.D._의학과)
Therapeutic Mechanisms of Human Adipose-Derived Mesenchymal Stem Cells in a Rat Tendon Injury Model
힘줄 손상 백서 모델에서의 인간 지방유래 중간엽 줄기세포의 치료 기전
- 의과대학 의학과
- Issue Date
- 서울대학교 대학원
- Mesenchymal stem cell transplantation; Heterologous transplantation; Tendon injuries; Achilles tendon; Collagen type I
- 학위논문 (박사)-- 서울대학교 대학원 : 의과대학 의학과 재활의학전공, 2016. 2. 정선근.
- Introduction: Mesenchymal stem cell (MSC) in treating tendon injury is well investigated by experimental animal models and several clinical trials have also reported safety and efficacy of the MSC therapy. However, therapeutic mechanisms of MSC for tendon injury have not fully understood and there is no in vivo study that MSCs can function as differentiated cells after transplantation. We aimed to investigate whether MSCs can differentiate into the tenogenic lineage and secrete their own proteins using a xenogeneic MSC transplantation model.
Methods: Bilateral Achilles tendons of 57 SD rats were given full-thickness rectangular injuries at the tendon insertion site to the midsubstance. They were randomly assigned to 3 groups after the modeling: 1) human adipose-derived mesenchymal stem cells (hASC) implantation with fibrin glue (106 cells in 60 μL) (Cell group), 2) fibrin glue injection with cell media by the same volume (Fibrin group), and 3) identical surgical procedure without any treatment (Sham group). After 2 and 4 weeks after modeling, all groups were evaluated by morphological, biomechanical, and histopathological (using modified Bonar score) analyses. Viability of tagged hASC was observed by immunofluorescence staining and protein expressions (collagen type I/III and tenascin-C) were evaluated by immunohistochemistry and Western blot analyses.
Results: Rupture rate of Cell group (11.1%) was lower than the rates of Sham (25.0%) and Fibrin (22.2%) groups. Cross sectional areas of tendons in Cell group were decreased (P = 0.008) while those in Sham group were increased (P = 0.005) from 2 to 4 weeks. At 2 weeks, ultimate tensile strength and stiffness of Cell group (49.4 ± 17.4 N and 10.1 ± 3.9 N/mm) were significantly higher than those of Sham group (31.2 ± 7.5 N, P = 0.037 and 4.7 ± 1.4 N/mm, P = 0.010, respectively). Stiffnesses of Cell group at 2 and 4 weeks were also significantly higher than those of Fibrin group (P = 0.037 in both). However, there were no significant differences of total modified Bonar score among three groups at both 2 and 4 weeks. From the immunofluorescent scanning at 1, 2, and 4 weeks after cell implantations, tagged hASCs were all observed. Cell group showed higher optical densities in immunohistochemistry than those of Sham and Fibrin groups in human-specific collagen type I at both 2 and 4 weeks and in human-specific tenascin-C at 2 weeks. Western blot analysis also revealed human-specific collagen type I expression was higher than that of Sham group.
Conclusions: Implanted hASCs to rat tendon injury model survived for 4 weeks and secreted human-specific collagen type I and tenascin-C. Human stem cells biomechanically enhanced rat tendon healing superior to sham and active control groups. To the best of the author's knowledge, this is the first in vivo report which proves the cell-originated protein synthesis by the implanted stem cells.