ABSTRACT
BackgroundIt has been proved that,after being forced,the biological soft tissue has stable biomechanical characteristics.However,there is rare study on corneal biomechanics.Rabbit is a main animal for experimental study in ophthalmology.But the biomechanical study of cornea in normal rabbit has not been reported.ObjectiveThis study was to investigate the biomechanical properties of normal rabbit central cornea and acquire the parameter. Methods Ten rabbits were sacrificed and the whole corneas were obtained and 20 central cornea specimens with 7 mm×5 mm of rabbit were prepared and tested on BOSE electroforce 3220-AT biomechanics machine under the room temperature and suitable humidity environment.Uniaxial tension,stress between strain,relaxation and creep were performed and the curves were drawn.The data was collected by wintest system to evaluate the biomechanical parameters of rabbit corneal tissue. ResultsThe maximum distortion intension of rabbit cornea was (7.7432±0.6099)MPa.After three cyclic loading,the stress gradually attenuated and the stress and strain flattened as the time change with the relaxation rate 30.33％.The deformation of the specimens enhanced with time decrease with the creep rate 24.33％. ConclusionsThe biomechanical characteristics of normal rabbit cornea are revealed in this study,which offer the basis for the experimental research of rabbit model aimed at corneal disease.
ABSTRACT
Background Researches demonstrated that dendritic cells(DCs) are uniformly immature in the central cornea but mature in the peripheral region of cornea.So an important question is which factor impact the maturation of DCs,especially in terms of corneal transplant rejection and the known roles of DCs in the development and persistence of some corneal diseases.Objective This study aimed to examine whether corneal stroma cells (CSCs) inhibit DCs maturation through secreting transforming growth factor beta 2 (TGF-β2) and prostaglandin E2 (PGE2).Methods DCs,T cells and CSCs were isolated and cultured from clean BALB/c and C57BL/6 mice.The level of PGE2 and TGF-β2in CSCs culture supernatant and the fresh RPMI 1640 medium were then analyzed by enzyme linked immunosorbent assay (ELISA).During the DCs maturation stage,the neutralizing TGF-β2 antibody and the EP2 receptor antagonist AH6809 were added in the CSCs culture supernatant respectively.According to the different treatment,cultured cells were assigned to different groups as follows:control group,CSCs culture supernatant group,AH6809 group,TGF-β2 antibody group,AH6809 +TGF-β2 antibody group.Subsequently,the cellular surface markers for DCs,including CD11c,CD80,CD86,and MHC- Ⅱ,were analyzed by flow cytometry.The capability of stimulating the proliferation of T lymphocytes was evaluated by allogeneic mixed lymphocyte reactions,and the function of endocytosis was assessed by fluorescein isothiocyanate-dextran(FITC) uptake.Results The data of ELISA showed a higher concentration of TGF-β2 and PGE2 in murine CSCs culture supernatant than in the fresh RPMI 1640 medium.Compared with the CSCs culture supernatant group,the expression of CD80,CD86,and MHC- Ⅱ was up-regulated ( P ＜ 0.05 ),the expression of dextran was down-regulated ( P ＜ 0.05 ),and the stimulate index was increased( P＜ 0.05 ) in the TGF-β2 antibody group; the expression of CD86,and MHC-Ⅱ was up-regulated (P＜0.05),the expression of dextran was down-regulated ( F =13.740,P =0.006 ),and the stimulate index was increased(P＜0.05) in the AH6809 group;the expression of MHC-Ⅱ was up-regulated and the stimulate index was increased with statistical difference in interaction(P＜0.05 ) in the AH6809+TGF-β2 antibody group.Compared with the control group,the expression of CD80 and CD86,and the stimulate index was still lower(P＜0.05 ).Conclusions TGF-β2 and PGE2 contribute to the inhibitory effects on DCs maturation mediated by murine CSCs in vitro and further have additive effect on the immunosuppression of DCs.