Biology subjects

Feola, A. J.

Publications and source records attributed to Feola, A. J..

5 recordsLinked to original sources

bioRxiv2026

Microtubule stability modulates Schlemm's canal cell mechanobiology and outflow facility in glaucoma

PurposeThe inner wall of Schlemms canal (SC) is a mechanosensitive endothelial monolayer that provides resistance to conventional aqueous humor drainage, a process dependent on pore formation. This study examined how microtubule (MT) stability affects SC cell mechanobiology, transcellular pore formation, and aqueous humor outflow dynamics. MethodsMT stability in cultured SC cells from normal and glaucomatous human donors was manipulated pharmacologically. Changes in MT acetylation, phosphorylated myosin light chain, and F-actin were assessed by immunofluorescence and immunoblotting. GEF-H1 was knocked down using siRNA. Cellular stiffness was measured by atomic force microscopy. Transcellular pore formation was quantified using an established pore formation assay. Outflow facility was measured in enucleated mouse eyes using the iPerfusion system. ResultsMT stabilization in normal SC cells decreased actomyosin contractility and cellular stiffness, whereas MT destabilization increased contractility and stiffness; these effects involved the MT-associated Rho guanine nucleotide exchange factor GEF-H1. MT stability was also mechano-responsive to substrate stiffness. Furthermore, SC cells derived from glaucomatous donors exhibited reduced MT stability compared with normal SC cells. MT stabilization increased transcellular pore formation in both normal and glaucomatous SC cells. In ex vivo mouse eyes, paclitaxel perfusion to stabilize MTs significantly increased outflow facility relative to contralateral control eyes. ConclusionsOur data suggest that MT stability influences SC cell contractility, stiffness, and transcellular pore formation and can alter aqueous humor outflow facility. These findings identify MT-dependent cytoskeletal remodeling as an important contributor to the biomechanics of the conventional outflow pathway and suggest that MT-associated pathways may represent potential targets for improving outflow function in glaucoma.

cell biology↗

bioRxiv2026

Segmental outflow and trabecular meshwork stiffness in an ocular hypertensive mouse model

PurposeElevated intraocular pressure (IOP) due to increased outflow resistance through the trabecular meshwork (TM) is a major risk factor for primary open-angle glaucoma. Outflow through the TM is segmental, consisting of high flow (HF) and low flow (LF) regions. Here, we investigate how ocular hypertension impacts segmental outflow using a dexamethasone (DEX) mouse model and compare TM stiffness between HF and LF regions. MethodsNanoparticles containing DEX or vehicle were injected twice weekly in 2-4-month-old C57BL/6J mice (n=14), and IOP was measured weekly. At week 4, mouse eyes were perfused in vivo with fluorescent nanospheres to assess flow patterns and the circumferential percentage of high, intermediate, and low flow regions in each eye. Sagittal sections were collected from HF and LF regions, and atomic force microscopy (AFM) was used to measure tissue stiffness. Immunofluorescent labeling was used to compare fibronectin and -SMA protein levels. ResultsDEX treatment significantly elevated IOP by an average of 33.3% and altered tracer distribution but not the percentage of HF and LF regions around the circumference. No significant differences in TM stiffness were detected between DEX-treated and control mice, or between HF and LF regions. Increased fibronectin in LF regions of DEX-treated eyes suggested subtle TM structural changes that were not detected by AFM. ConclusionsDexamethasone alters segmental flow distribution and may impact cell contractility rather than ECM stiffness to cause IOP elevation in young mice. These findings better characterize the nature of segmental outflow and TM mechanics in this model of steroid-induced glaucoma.

bioengineering↗

bioRxiv2023

A Method for Analyzing AFM Force Mapping Data Obtained from Soft Tissue Cryosections

Atomic force microscopy (AFM) is a valuable tool for assessing mechanical properties of biological samples, but interpretations of measurements on whole tissues can be difficult due to the tissues highly heterogeneous nature. To overcome such difficulties and obtain more robust estimates of tissue mechanical properties, we describe an AFM force mapping and data analysis pipeline to characterize the mechanical properties of cryosectioned soft tissues. We assessed this approach on mouse optic nerve head and rat trabecular meshwork, cornea, and sclera. Our data show that the use of repeated measurements, outlier exclusion, and log-normal data transformation increases confidence in AFM mechanical measurements, and we propose that this methodology can be broadly applied to measuring soft tissue properties from cryosections.

bioengineering↗

bioRxiv2023

Aging and intraocular pressure homeostasis in mice

Age and elevated intraocular pressure (IOP) are the two primary risk factors for glaucoma, an optic neuropathy that is the leading cause of irreversible blindness. In most people, IOP is tightly regulated over a lifetime by the conventional outflow tissues. However, the mechanistic contributions of age to conventional outflow dysregulation, elevated IOP and glaucoma are unknown. To address this gap in knowledge, we studied how age affects the morphology, biomechanical properties and function of conventional outflow tissues in C57BL/6 mice, which have an outflow system similar to humans. As reported in humans, we observed that IOP in mice was maintained within a tight range over their lifespan. Remarkably, despite a constellation of age-related changes to the conventional outflow tissues that would be expected to hinder aqueous drainage and impair homeostatic function (decreased cellularity, increased pigment accumulation, increased cellular senescence and increased stiffness), outflow facility, a measure of conventional outflow tissue fluid conductivity, was stable with age. We conclude that the murine conventional outflow system has significant functional reserve in healthy eyes. However, these age-related changes, when combined with other underlying factors, such as genetic susceptibility, are expected to increase risk for ocular hypertension and glaucoma.

physiology↗

bioRxiv2023

A Histomorphometric and Computational Investigation of the Stabilizing Role of Pectinate Ligaments in the Aqueous Outflow Pathway

Murine models are commonly used to study glaucoma, the leading cause of irreversible blindness. Glaucoma is associated with elevated intraocular pressure (IOP), which is regulated by the tissues of the aqueous outflow pathway. In particular, pectinate ligaments (PLs) connect the iris and trabecular meshwork (TM) at the anterior chamber angle, with an unknown role in maintenance of the biomechanical stability of the aqueous outflow pathway, thus motivating this study. We conducted histomorphometric analysis and optical coherence tomography-based finite element (FE) modeling on three cohorts of C57BL/6 mice: young (2-6 months), middle-aged (11-16 months), and elderly (25-32 months). We evaluated the age-specific morphology of the outflow pathway tissues. Further, because of the known pressure-dependent Schlemms canal (SC) narrowing, we assessed the dependence of the SC lumen area to varying IOPs in age-specific FE models over a physiological range of TM/PL stiffness values. We found age-dependent changes in morphology of outflow tissues; notably, the PLs were more developed in older mice compared to younger ones. In addition, FE modeling demonstrated that murine SC patency is highly dependent on the presence of PLs, and that increased IOP caused SC collapse only with sufficiently low TM/PL stiffness values. Moreover, the elderly model showed more susceptibility to SC collapse compared to the younger models. In conclusion, our study elucidated the previously unexplored role of PLs in the aqueous outflow pathway, indicating their function in supporting TM and SC under elevated IOP.

bioengineering↗