Magnetic Iron Oxide Nanoparticle Labeling of Photoreceptor Precursors for Magnetic Resonance Imaging

Intravitreal therapeutic nanoparticles for age-related macular degeneration: Design principles, progress and opportunities

Age-related macular degeneration (AMD) is a leading cause of vision loss in the elderly. The current standard treatment for AMD involves frequent intravitreal administrations of therapeutic agents. While effective, this approach presents challenges, including patient discomfort, inconvenience, and the risk of adverse complications. Nanoparticle-based intravitreal drug delivery platforms offer a promising solution to overcome these limitations. These platforms are engineered to target the retina specifically and control drug release, which enhances drug retention, improves drug concentration and bioavailability at the retinal site, and reduces the frequency of injections. This review aims to uncover the design principles guiding the development of highly effective nanoparticle-based intravitreal drug delivery platforms for AMD treatment. By gaining a deeper understanding of the physiology of ocular barriers and the physicochemical properties of nanoparticles, we establish a basis for designing intravitreal nanoparticles to optimize drug delivery and drug retention in the retina. Furthermore, we review recent nanoparticle-based intravitreal therapeutic strategies to highlight their potential in improving AMD treatment efficiency. Lastly, we address the challenges and opportunities in this field, providing insights into the future of nanoparticle-based drug delivery to improve therapeutic outcomes for AMD patients.

Nanoparticles in ocular applications and their potential toxicity

Nanotechnology has been developed rapidly in recent decades and widely applied in ocular disease therapy. Nano-drug delivery systems overcome the bottlenecks of current ophthalmic drug delivery and are characterized with strong biocompatibility, stability, efficiency, sustainability, controllability, and few side effects. Nanoparticles have been identified as a promising and generally safe ophthalmic drug-delivery system based on the toxicity assessment in animals. Previous studies have found that common nanoparticles can be toxic to the cornea, conjunctiva, and retina under certain conditions. Because of the species differences between humans and animals, advanced in vitro cell culture techniques, such as human organoids, can mimic the human organism to a certain extent, bringing nanoparticle toxicity assessment to a new stage. This review summarizes the advanced application of nanoparticles in ocular drug delivery and the potential toxicity, as well as some of the current challenges and future opportunities in nanotoxicological evaluation.

Advances of functional nanomaterials for magnetic resonance imaging and biomedical engineering applications

Functional nanomaterials have been widely used in biomedical fields due to their good biocompatibility, excellent physicochemical properties, easy surface modification, and easy regulation of size and morphology. Functional nanomaterials for magnetic resonance imaging (MRI) can target specific sites in vivo and more easily detect disease-related specific biomarkers at the molecular and cellular levels than traditional contrast agents, achieving a broad application prospect in MRI. This review focuses on the basic principles of MRI, the classification, synthesis and surface modification methods of contrast agents, and their clinical applications to provide guidance for designing novel contrast agents and optimizing the contrast effect. Furthermore, the latest biomedical advances of functional nanomaterials in medical diagnosis and disease detection, disease treatment, the combination of diagnosis and treatment (theranostics), multi-model imaging and nanozyme are also summarized and discussed. Finally, the bright application prospects of functional nanomaterials in biomedicine are emphasized and the urgent need to achieve significant breakthroughs in the industrial transformation and the clinical translation is proposed. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Subretinal versus intravitreal administration of human CD34+ bone marrow-derived stem cells in a rat model of inherited retinal degeneration

Background

To evaluate whether subretinal or intravitreal injection of human CD34+ bone marrow-derived stem cells (BMSC) can have protective effects on retinal degeneration that may be enhanced by coadministration of exosomes harvested from human bone marrow mesenchymal stem cells (MSCs).

Methods

Human CD34+ cells were harvested from the mononuclear cell fraction of bone marrow using magnetic beads and labeled with EGFP. Exosomes were harvested from cultured human MSCs under hypoxic conditions. Royal College of Surgeons (RCS) 3-weeks-old rats, immunosuppressed with cyclosporine A, received subretinal or intravitreal injection of CD34+ cells (50,000 cells), CD34+ cells with exosomes (50,000 cells+10 µg), exosomes alone (10 µg), or PBS. Retinal function was examined using electroretinography (ERG), and the eyes were harvested for histologic and immunohistochemical analysis.

Results

The b-wave amplitude of ERG at 2 weeks after injection was significantly higher in eyes with subretinal or intravitreal CD34+ BMSC alone or in combination with exosomes when compared to PBS injected eyes or untreated contralateral eyes. At 4 weeks after injection, the ERG signal decreased in all groups but eyes with subretinal CD34+ BMSCs alone or combined with exosomes showed partially preserved ERG signal and preservation of the outer nuclear layer of the retina near the injection site on histology when compared to eyes with PBS injection. Immunohistochemical analysis identified the human cells in the outer retina. Subretinal or intravitreal exosome injection had no effect on retinal degeneration when administered alone or in combination with CD34+ cells.

Conclusions

Both subretinal and intravitreal injection of human CD34+ BMSCs can provide functional rescue of degenerating retina, although the effects were attenuated over time in this rat model. Regional preservation of the outer retina can occur near the subretinal injection site of CD34+ cells. These results suggest that CD34+ cells may have therapeutic potential in retinal degeneration.