Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA.
Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA.
Exp Eye Res. 2024 Sep;246:109992. doi: 10.1016/j.exer.2024.109992. Epub 2024 Jul 6.
Previous studies have shown that pharmaceutical agents such as lipoic acid have the ability to soften the lens, presenting a promising avenue for treating presbyopia. One obstacle encountered in the preclinical stage of such agents is the need for precise measurements of lens elasticity in experimental models. This study aimed to evaluate the effects of 25-hydroxycholesterol, lipoic acid, and obeticholic acid on the viscoelastic properties of mouse lenses using a custom-built elastometer system. Data were acquired on lenses from C57BL/6J female mice from two age groups: young (age: 8-10 weeks) and old (age: 32-43 weeks). OD lenses were used as the control and OS lenses were treated. Control lenses were immersed in Dulbecco's Modified Eagle Medium (DMEM) and treatment lenses were immersed in a compound solution containing 25-hydroxycholesterol (5 young and 5 old), lipoic acid at 2.35 mM (5 young and 5 old), lipoic acid at 0.66 mM (5 old), or obeticholic acid (5 old) at 37 °C for 18 h. After treatment, the mouse lenses were placed in a DMEM-filled chamber within a custom-built elastometer system that recorded the load and lens shape as the lens was compressed by 600 μm at a speed of 50 μm/s. The load was continuously recorded during compression and during stress-relaxation. The compression phase was fit with a linear function to quantify lens stiffness. The stress-relaxation phase was fit with a 3-term exponential relaxation model providing relaxation time constants (t, t, t), and equilibrium load. The lens stiffness, time constants and equilibrium load were compared for the control and treated groups. Results revealed an increase in stiffness with age for the control group (young: 1.16 ± 0.11 g/mm, old: 1.29 ± 0.14 g/mm) and relaxation time constants decreased with age (young: t = 221.9 ± 29.0 s, t = 24.7 ± 3.8 s, t = 3.12 ± 0.87 s, old: t = 183.0 ± 22.0 s, t = 20.6 ± 2.6 s and t = 2.24 ± 0.43 s). Among the compounds tested, only 25-hydroxycholesterol produced statistically significant changes in the lens stiffness, relaxation time constants, and equilibrium load. In conclusion, older mouse lenses are stiffer and less viscous than young mouse lenses. Notably, no significant change in lens stiffness was observed following treatment with lipoic acid, contrary to previous findings.
先前的研究表明，药物制剂如硫辛酸具有软化晶状体的能力，为治疗远视提供了有前途的途径。在这些制剂的临床前阶段遇到的一个障碍是需要在实验模型中对晶状体弹性进行精确测量。本研究旨在使用定制的弹性计系统评估 25-羟胆固醇、硫辛酸和奥贝胆酸对小鼠晶状体粘弹性的影响。数据采集于来自两个年龄组的 C57BL/6J 雌性小鼠的晶状体：年轻（年龄：8-10 周）和老年（年龄：32-43 周）。OD 晶状体用作对照，OS 晶状体进行处理。对照晶状体浸泡在 Dulbecco 的改良 Eagle 培养基（DMEM）中，处理晶状体浸泡在含有 25-羟胆固醇（5 个年轻和 5 个老年）、2.35mM 硫辛酸（5 个年轻和 5 个老年）、0.66mM 硫辛酸（5 个老年）或奥贝胆酸（5 个老年）的化合物溶液中在 37°C 下孵育 18 小时。处理后，将小鼠晶状体置于定制弹性计系统内充满 DMEM 的腔室内，该系统记录了当晶状体以 50μm/s 的速度被压缩 600μm 时的负载和晶状体形状。在压缩和应力松弛过程中连续记录负载。将压缩阶段拟合为线性函数，以量化晶状体的刚度。将松弛阶段拟合为具有 3 个项的指数松弛模型，提供松弛时间常数（t、t 和 t）和平衡负载。比较了对照组和处理组的晶状体刚度、时间常数和平衡负载。结果表明，对照组晶状体的刚度随年龄增长而增加（年轻组：1.16±0.11g/mm，老年组：1.29±0.14g/mm），松弛时间常数随年龄减小（年轻组：t=221.9±29.0s，t=24.7±3.8s，t=3.12±0.87s，老年组：t=183.0±22.0s，t=20.6±2.6s 和 t=2.24±0.43s）。在所测试的化合物中，只有 25-羟胆固醇使晶状体的刚度、松弛时间常数和平衡负载发生了统计学上的显著变化。总之，与年轻的小鼠晶状体相比，年龄较大的小鼠晶状体更硬且粘性更小。值得注意的是，与之前的研究结果相反，用硫辛酸处理后，晶状体的刚度没有明显变化。
