Expression Of CTGF And Biomechanical Properties Study Of Fibroblasts Of Rabbit Experimental Myopia After Posterior Scleral Reinforcement

Objective: To evaluate the expression of CTGF and biomechanical properties of fiboblasts of rabbit experimental myopia after Posterior Scleral Reinforcement (PSR).And then to discuss the mechanism of Posterior Scleral Reinforcement in the treatment of myopia in view of Cytology-Histology- Biomechanics.Methods: 45 three-week-old rabitts were monocularly treated by eyelid suturation randomly to prepare experimental myopia eye, another eye in each animal was untreated as self-control(SC). Before and after the experiment, diopter was measured using retinoscopy and the ocular axial was determined by A-scan ultrasonography.After 60 days, the experimental myopia eyes were divided into two groups randomly. Group A was treated by Posterior Scleral Reinforcement. Group B was treated by similar operation, but not to place reinforce strap. After three months and six month, the scleral fibroblasts of each group were cultured and passaged 2 generations in vitro respectively. The cultured cells was determined to be fibroblasts using immunocytolchemistory methods. The fibroblasts of Group A was devided into posterior sclerotic zone (3 months after operation), transition zone (3 months after operation), posterior sclerotic zone (6 months after operation), and transition zone (6 months after operation) four groups. The fibroblasts of Group B was devided into posterior sclerotic zone (3 months after operation) and posterior sclerotic zone (6 months after operation) groups. Immunocytolchemistry was used to detect the expression of CTGF in the fibroblasts of each group. And utilized the micropipette aspiration technique coupled with a viscoelastic solid model to investigate the viscoelastic properties of fibroblasts from each group. All datas were statistically analyzed by SPSS 13.0 system. Results:1 The experimental myopia of rabbit induced results: Diopter had no significant difference in binocular before induced. Eye became myopic on average of (1.80±1.37)D, eye elongated on average of (0.45±0.29)mm after suturation for 60 days. There was obviously difference between them (Student's t test, P <0.05).2 The curative effect of Posterior Scleral Reinforcement: Diopter had no significant difference between Group A and Group B three months after operation (P >0.05).The eyes in Group B elongated on average of (0.59±0.35)mm six months after operation compared with Group B.There was obvious difference between them (Student's t test, P <0.05).3 The results of cells cultured and determinedCultured cells began to grow out of the sclera after 4-6 days, and the culture in transition zone after 3-5 days, and grew to confluent after 2-3 weeks. The cultured cells was determined to be fibroblasts using immunocytolchemistory methods.4 Histopathological changes were observedObserved with light microscope, collagen fibers in posterior sclera of experimental eye arranged disorderly, the diameter arranged irregularly, fibers gap changed larger, the fibers had different directions, the lamellar structure was not clear, collagen fibers were dissolved partly or completely, some even had fractured phenomenon. While the normal eye had no such changes as mentioned above.5 Expression of CTGF in posterior scleral in different periodsThe expression of CTGF was located in nucleolus and cytoplasm, The expression of CTGF was located in cytoplasm, in the normal eye it was seldom or even nothing. and it was higher in Group A than in Group B, either three or six months after operation. There was significant difference between them (P<0.05).6 Expression of CTGF in different tissues The expression of CTGF was located in nucleolus and cytoplasm. Three months after operation, it was higher in Group A1 than in Group B1 and in Group A2 than in Group A1.There was significant difference between them (P<0.05). Six months after operation, it was higher in Group A3 than in Group B3 and in Group A4 than in Group A3.There was significant difference between them (P<0.05). There was no obvious difference between Group A1 and Group A3, Group A2 and Group A4 (P>0.05).7 Biomechanical research for scleral fibroblasts7.1 Biomechanical research for scleral fibroblasts of Group A and Group BThree months after operation, experimental studies have shown that the viscoelastic properties of the scleral fibroblasts in Group A and Group B exhibited no obvious difference(P>0.05). The Young's modulus and apparent viscosity of the scleral fibroblasts in Group A (E∝=0.3521±0.0853kPa,μ=2.8733±0.6154kPa·s) were compared with that in Group B (E∝=0.3418±0.0911kPa,μ=2.8183±0.590kPa·s).Six months after operation, experimental studies have shown that the viscoelastic properties of the scleral fibroblasts in Group A and Group B also exhibited no obvious difference(P>0.05). The Young's modulus and apparent viscosity of the scleral fibroblasts in Group A (E∝=0.3612±0.12 11kPa,μ=2.9282±0.6694kPa·s) were compared with that in Group B(E∝=0.3476±0.0821kPa,μ=2.8206±0.5935 kPa·s).7.2 Neither in Group A nor Group B, the Young's modulus and apparent viscosity of the scleral fibroblasts in different periods after operation have no significant difference(P>0.05).7.3 The Young's modulus and apparent viscosity of the fibroblasts in transition zone tissues in different periods after operation have no significant difference(P>0.05).Conclusions:1 Eyelid suturation can induce axial growth and lead to myopia in young rabbit.2 The expression of CTGF in experimental eye treated by Posterior Scleral Reinforcement was higher than control eye. It demonstrated that surgery and implants itself are stimulating the formation of the transitional zone.3 The expression of CTGF in transition zone tissues was higher than posterior sclerotic zone tissues. It demonstrated that CTGF has been involved in the surgery itself and the reinforcement strip caused by the formation of the transitional zone.4 The biomechanical characteristics (Young's modulus and apparent viscosity) of the scleral fibroblasts have no significant difference in different periods after operation. It demonstrated that the enhancement of Posterior Scleral Reinforcement was caused by transition zone tissues.5 The biomechanical characteristics (Young's modulus and apparent viscosity ) of fibroblasts in transition zone tissues have no significant difference in different periods after operation. It demonstrated that the joint between cells and strengthening the overall effect of the mechanical role of the strip to prevent worsening of myopia and its complications from occurring, rather than through the mechanical changes in a single cell work.