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Abstract: Intrastromal cell therapy utilizing quiescent corneal stromal keratocytes (qCSKs) from human donor corneas emerges as a promising treatment for corneal opacities, aiming to overcome limitations of traditional surgeries by reducing procedural complexity and donor dependency. This investigation demonstrates the therapeutic efficacy of qCSKs in a male rat model of corneal stromal opacity, underscoring the significance of cell-delivery quality and keratocyte differentiation in mediating corneal opacity resolution and visual function recovery. Quiescent CSKs-treated rats display improvements in escape latency and efficiency compared to wounded, non-treated rats in a Morris water maze, demonstrating improved visual acuity, while stromal fibroblasts-treated rats do not. Advanced imaging, including multiphoton microscopy, small-angle X-ray scattering, and transmission electron microscopy, revealed that qCSK therapy replicates the native cornea’s collagen fibril morphometry, matrix order, and ultrastructural architecture. These findings, supported by the expression of keratan sulfate proteoglycans, validate qCSKs as a potential therapeutic solution for corneal opacities.

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Abstract: Recent studies apparently finding deleterious effects of radiation exposure on cataract formation in birds and voles living near Chernobyl represent a major challenge to current radiation protection regulations. This study conducted an integrated assessment of radiation exposure on cataractogenesis using the most advanced technologies available to assess the cataract status of lenses extracted from fish caught at both Chernobyl in Ukraine and Fukushima in Japan. It was hypothesised that these novel data would reveal positive correlations between radiation dose and early indicators of cataract formation. The structure, function and optical properties of lenses were analysed from atomic to millimetre length scales. We measured the short-range order of the lens crystallin proteins using Small Angle X-Ray Scattering (SAXS) at both the SPring-8 and DIAMOND synchrotrons, the profile of the graded refractive index generated by these proteins, the epithelial cell density and organisation and finally the focal length of each lens. The results showed no evidence of a difference between the focal length, the epithelial cell densities, the refractive indices, the interference functions and the short-range order of crystallin proteins (X-ray diffraction patterns) in lens from fish exposed to different radiation doses. It could be argued that animals in the natural environment which developed cataract would be more likely, for example, to suffer predation leading to survivor bias. But the cross-length scale study presented here, by evaluating small scale molecular and cellular changes in the lens (pre-cataract formation) significantly mitigates against this issue.

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Abstract: If you give a scientist a new piece of material and ask them to tell you about its properties, it won’t be long before they are pulling and stretching it. The technical term is “putting the material under strain” and doing this can reveal a lot about what’s inside. This conjures up images of springs, modern polymers and alloys being pulled apart by a metal vice, but you wouldn’t necessarily think about the human eye. You should.

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Abstract: The mechanical properties of connective tissues are tailored to their specific function, and changes can lead to dysfunction and pathology. In most mammalian tissues the mechanical environment is governed by the micro- and nano-scale structure of collagen and its interaction with other tissue components, however these hierarchical properties remain poorly understood. In this study we use the human cornea as a model system to characterise and quantify the dominant deformation mechanisms of connective tissue in response to cyclic loads of physiological magnitude. Synchronised biomechanical testing, x-ray scattering and 3D digital image correlation revealed the presence of two dominant mechanisms: collagen fibril elongation due to a largely elastic, spring-like straightening of tropocollagen supramolecular twist, and a more viscous straightening of fibril crimp that gradually increased over successive loading cycles. The distinct mechanical properties of the two mechanisms suggest they have separate roles in vivo. The elastic, spring-like mechanism is fast-acting and likely responds to stresses associated with the cardiac cycle, while the more viscous crimp mechanism will respond to slower processes, such as postural stresses. It is anticipated that these findings will have broad applicability to understanding the normal and pathological functioning of other connective tissues such as skin and blood vessels that exhibit both helical structures and crimp.

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Abstract: Purpose : The purpose of this study was to investigate the distribution of Ca, Fe and Zn using X-ray fluorescence in human RPE/Bruch’s membrane/choroid with and without early AMD. Methods : We used a set of unfixed frozen human retinal pigment epithelium (RPE)/choroid samples from young (n=1, female aged 34) and aged donors with (n=4, males, aged 73-78) and without (n=3, one female, aged 75-77) early AMD from Manchester Eye Tissue Repository. Using X-ray fluorescence microscopy (I18 Diamond light source, UK) with a 2 um beam, we obtained high-resolution Ca, Zn, Fe, sulphur, potassium, chloride and phosphorus maps covering areas up to 100 x 600 um2 of 30 um thick sections placed on quartz holders and scanned at room temperature Results : Calcification was observed in the 3 groups. In the 34-year old sample, sparse small Ca spherules (2x2 um2) at the RPE/Bruch’s membrane interface not colocalising with Zn or Fe. In aged samples, with and without AMD, calcified nodules within RPE cells, at RPE/Bruch’s membrane interface and within druse in AMD. Every calcified nodule colocalised with Zn. Quantification revealed two types (high Zn content, low Zn content). In aged donors without AMD, high-Zn calcified nodules with Ca concentration of 3083+1679 ppm (mean+SD) (maximum 12809+9311) and Zn 66+55 ppm (max 125+75). The average size was 27+15 um2. In aged samples with AMD, high-Zn calcified nodules with average Ca concentration of 4316+1723 ppm (max 13105+7563) and Zn 97+57 ppm (max 201+143). Size 26x10 um2. In the aged non-AMD group, the low zinc-calcification nodules contained an average Ca ppm of 915+259 (max 1475+380) and Zn 33+18 ppm (max 40+21). The average size 28x16 um2. In the AMD group, the low Zn calcified nodules average Ca ppm 1544+1450 (max 3526+5289) and average Zn ppm 47+23 (max 64+37). Average size 19x10 um2. Calcified plaques in Bruch’s membrane from aged donors with and without AMD. Some of these plaques colocalised with Zn and also Fe. Fe-loaded structures in the choriocapillaris underlying calcified nodules and plaques. Conclusions : Calcific nodules contain zinc in older eyes with and without AMD. Calcified nodules with lower amounts of Ca contained lower amounts of Zn, so the accumulation of Ca may occur in parallel to Zn. It is possible that iron-loaded structures in the choriocapillaris are macrophages.