Improved magnetic delivery of cells to the trabecular meshwork in mice

MAGNETICALLY STEERED CELL THERAPY FOR REDUCTION OF INTRAOCULAR PRESSURE AS A TREATMENT STRATEGY FOR OPEN-ANGLE GLAUCOMA

Trabecular meshwork (TM) cell therapy has been proposed as a next-generation treatment for elevated intraocular pressure (IOP) in glaucoma, the most common cause of irreversible blindness. Using a magnetic cell steering technique with excellent efficiency and tissue-specific targeting, we delivered two types of cells into a mouse model of glaucoma: either human adipose-derived mesenchymal stem cells (hAMSCs) or induced pluripotent cell derivatives (iPSC-TM cells). We observed a 4.5 [3.1, 6.0] mmHg or 27% reduction in intraocular pressure (IOP) for nine months after a single dose of only 1500 magnetically-steered hAMSCs, explained by increased outflow through the conventional pathway and associated with an higher TM cellularity. iPSC-TM cells were also effective, but less so, showing only a 1.9 [0.4, 3.3] mmHg or 13% IOP reduction and increased risk of tumorigenicity. In both cases, injected cells remained detectable in the iridocorneal angle three weeks post-transplantation. Based on the locations of the delivered cells, the mechanism of IOP lowering is most likely paracrine signaling. We conclude that magnetically-steered hAMSC cell therapy has potential for long-term treatment of ocular hypertension in glaucoma.

One Sentence Summary

A novel magnetic cell therapy provided effective intraocular pressure reduction in a mouse model, motivating future translational studies.

Intracameral Puncture Lowers Intraocular Pressure and Triggers an Immune Response in the Conventional Outflow Tract

Purpose

Intracameral injection is an effective delivery method for biomedical agents and therapeutics to conventional outflow tract tissues. However, the effect of intracameral injections on intraocular pressure and aqueous dynamics has not been well characterized, warranting further investigation.

Methods

Wild type 3-5-month-old C57BL/6 mice were subjected to intracameral puncture (ICP, without injection of any material). Following ICP, intraocular pressure (IOP), outflow facility, aqueous production, episcleral vessel diameter, and macrophage densities were measured.

Results

On day 1, IOP was significantly reduced by 30% ( p < 0.0001; n=25) while outflow facility ( p = 0.306; n=15) and aqueous production ( p = 0.163; n=9) were unchanged. As well, Schlemm's canal filtration area was unchanged, however distal vessels were dilated ( p < 0.001) at day 1 post ICP. Correspondingly, macrophage density was significantly increased around episcleral vessels ( p < 0.0005) at day 1. Macrophage densities in Schlemm's canal and trabecular meshwork, while unchanged at day 1, were significantly increased by day 3 ( p < 0.0001).

Conclusions

Coincident with significantly reduced IOP one day after ICP, there was an influx of macrophages into the distal portion of the conventional outflow tissues and a dilation of episcleral vessels, likely reducing distal outflow resistance. Our study demonstrates the importance of considering the drug delivery method to the eye due to its effects on the immune response and conventional outflow homeostasis.

Advancements and Prospects in Nanorobotic Applications for Ophthalmic Therapy

This study provides a bibliometric and bibliographic review of emerging applications of micro- and nanotechnology in treating ocular diseases, with a primary focus on glaucoma. We aim to identify key research trends and analyze advancements in devices and drug delivery systems for ocular treatments. The methodology involved analyzing 385 documents indexed on the Web of Science using tools such as VOSviewer and Bibliometrix. The results show a marked increase in scientific output, highlighting prominent authors and institutions, with England leading in the field. Key findings suggest that nanotechnology holds the potential to address the limitations of conventional treatments, including low ocular bioavailability and adverse side effects. Nanoparticles, nanovesicles, and polymer-based systems appear promising for prolonged and controlled drug release, potentially offering enhanced therapeutic efficacy. In conclusion, micro- and nanotechnology could transform ocular disease treatment, although challenges remain concerning the biocompatibility and scalability of these devices. Further clinical studies are necessary to establish these innovations within the therapeutic context of ophthalmology.

Modeling complex age-related eye disease

Modeling complex eye diseases like age-related macular degeneration (AMD) and glaucoma poses significant challenges, since these conditions depend highly on age-related changes that occur over several decades, with many contributing factors remaining unknown. Although both diseases exhibit a relatively high heritability of >50%, a large proportion of individuals carrying AMD- or glaucoma-associated genetic risk variants will never develop these diseases. Furthermore, several environmental and lifestyle factors contribute to and modulate the pathogenesis and progression of AMD and glaucoma. Several strategies replicate the impact of genetic risk variants, pathobiological pathways and environmental and lifestyle factors in AMD and glaucoma in mice and other species. In this review we will primarily discuss the most commonly available mouse models, which have and will likely continue to improve our understanding of the pathobiology of age-related eye diseases. Uncertainties persist whether small animal models can truly recapitulate disease progression and vision loss in patients, raising doubts regarding their usefulness when testing novel gene or drug therapies. We will elaborate on concerns that relate to shorter lifespan, body size and allometries, lack of macula and a true lamina cribrosa, as well as absence and sequence disparities of certain genes and differences in their chromosomal location in mice. Since biological, rather than chronological, age likely predisposes an organism for both glaucoma and AMD, more rapidly aging organisms like small rodents may open up possibilities that will make research of these diseases more timely and financially feasible. On the other hand, due to the above-mentioned anatomical and physiological features, as well as pharmacokinetic and -dynamic differences small animal models are not ideal to study the natural progression of vision loss or the efficacy and safety of novel therapies. In this context, we will also discuss the advantages and pitfalls of alternative models that include larger species, such as non-human primates and rabbits, patient-derived retinal organoids, and human organ donor eyes.