Photokinetic Drug Delivery: Near infrared (NIR) Induced Permeation Enhancement of Bevacizumab, Ranibizumab and Aflibercept through Human Sclera

Light-responsive polymeric nanoparticles for retinal drug delivery: design cues, challenges and future perspectives

A multitude of sight-threatening retinal diseases, affecting hundreds of millions around the globe, lack effective pharmacological treatments due to ocular barriers and common drug delivery limitations. Polymeric nanoparticles (PNPs) are versatile drug carriers with sustained drug release profiles and tunable physicochemical properties which have been explored for ocular drug delivery to both anterior and posterior ocular tissues. PNPs can incorporate a wide range of drugs and overcome the challenges of conventional retinal drug delivery. Moreover, PNPs can be engineered to respond to specific stimuli such as ultraviolet, visible, or near-infrared light, and allow precise spatiotemporal control of the drug release, enabling tailored treatment regimens and reducing the number of required administrations. The objective of this study is to emphasize the therapeutic potential of light-triggered drug-loaded polymeric nanoparticles to treat retinal diseases through an exploration of ocular pathologies, challenges in drug delivery, current production methodologies and recent applications. Despite challenges, light-responsive PNPs hold the promise of substantially enhancing the treatment landscape for ocular diseases, aiming for an improved quality of life for patients.

Overview of Recent Advances in Nano-Based Ocular Drug Delivery

Ocular diseases profoundly impact patients' vision and overall quality of life globally. However, effective ocular drug delivery presents formidable challenges within clinical pharmacology and biomaterial science, primarily due to the intricate anatomical and physiological barriers unique to the eye. In this comprehensive review, we aim to shed light on the anatomical and physiological features of the eye, emphasizing the natural barriers it presents to drug administration. Our goal is to provide a thorough overview of various characteristics inherent to each nano-based drug delivery system. These encompass nanomicelles, nanoparticles, nanosuspensions, nanoemulsions, microemulsions, nanofibers, dendrimers, liposomes, niosomes, nanowafers, contact lenses, hydrogels, microneedles, and innovative gene therapy approaches employing nano-based ocular delivery techniques. We delve into the biology and methodology of these systems, introducing their clinical applications over the past decade. Furthermore, we discuss the advantages and challenges illuminated by recent studies. While nano-based drug delivery systems for ophthalmic formulations are gaining increasing attention, further research is imperative to address potential safety and toxicity concerns.

Pulsed Ultrasound-Mediated Enhancement on Transscleral and Transconjunctival Fluorescein Sodium Delivery to Rabbit Eye In Vivo

Purpose: To investigate the efficacy and safety of pulsed ultrasound (PUS) in enhancing fluorescein sodium (NaF) transport to the rabbit eye through the transscleral and transconjunctival routes in vivo. Methods: PUS and NaF were applied onto the supratemporal sclera/conjunctiva of healthy rabbit eyes. PUS (1 MHz, 2.37 W/cm2, 30% duty cycle, 5-min application time) was performed 3 times with a 5-min interval. In the same process, NaF was administered to the eye without PUS in the control. NaF concentrations in the vitreous and retina-choroid were determined by fluorescence measurement. The safety of PUS application was assessed based on temperature and intraocular pressure measurements, clinical observations, electroretinography, histology, and Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling assay. Results: In comparison to the control, higher NaF concentrations were found in the retina-choroid following transscleral (2.45-fold) and transconjunctival (2.97-fold) PUS applications (P < 0.05). NaF concentrations in the vitreous were 3.15 and 5.86 times greater in transscleral and transconjunctival PUS applications, respectively, compared with those obtained without PUS application (P < 0.05), and NaF level in the vitreous after transconjunctival PUS application was 2.61 times that of transscleral PUS application (P < 0.05). Ocular findings were transient and mild conjunctival injection, with no other structural and functional changes in PUS-treated eyes. Conclusions: PUS treatment can improve transscleral and transconjunctival delivery of NaF efficiently and safely. Transscleral and transconjunctival PUS applications offer potential clinical benefit in increasing drug penetration to the posterior segments of the eye for the noninvasive treatment of ocular diseases.

Management of toxic optic neuropathy via a combination of Wharton's jelly-derived mesenchymal stem cells with electromagnetic stimulation

PURPOSE

To investigate the effect of the combination of Wharton's jelly derived mesenchymal stem cells (WJ-MSC) and high frequency repetitive electromagnetic stimulation (rEMS) in the therapy of toxic optic neuropathies with severe symptoms after the available current therapy modalities which were unsucessful.

MATERIAL AND METHODS

This prospective, open-label clinical phase-3 study was conducted at Ankara University Faculty of Medicine, Department of Ophthalmology between April 2019 and April 2021. Thirty-six eyes of 18 patients with toxic optic neuropathy (TON) were included in the study. Within 1-3 months after the emergency interventions, patients with various degrees of sequela visual disturbances were studied in this clinical trial. The cases were divided into three groups according to similar demographic characteristics. Group 1: Consists of 12 eyes of 12 patients treated with the WJ-MSC and rEMS combination in one eye. Group 2: Consists of 12 eyes of 12 patients treated with only rEMS in one eye. Group 3: Consists of 12 eyes of six patients treated with only WJ-MSC in both eyes. The course was evaluated by comparing the quantitive functional and structural assessment parameters measured before and at the fourth month of applications in each group.

RESULTS

The mean best corrected visual acuity (BCVA) delta change percentages of the groups can be ranked as: Group 1 (47%) > Group 3 (32%) > Group 2 (21%). The mean fundus perimetry deviation index (FPDI) delta change percentages of the groups can be ranked as: Group 1 (95%) > Group 2 (33%) > Group 3 (27%). The mean ganglion cell complex (GCC) thickness delta change (decrease in thickness) percentages can be ranked as: Group 1 (- 21%) > Group 3 (- 15%) > Group 2 (- 13%). The visual evoked potential (VEP) P100 latency delta change percentages of the groups can be ranked as: Group 1 (- 18%) > Group 3 (- 10%) > Group 2 (- 8%). The P100 amplitude delta change percentages of the groups can be ranked as: Group 1 (105%) > Group 3 (83%) > Group 2 (24%).

CONCLUSION

Toxic optic neuropathies are emergent pathologies that can result in acute and permanent blindness. After poisoning with toxic substances, progressive apoptosis continues in optic nerve axons and ganglion cells. After the proper first systemic intervention in intensive care clinic, the WJ-MSC and rEMS combination seems very effective in the short-term period in cases with TON. To prevent permanent blindness, a combination of WJ-MSC and rEMS application as soon as possible may increase the chance of success in currently untreatable cases. Trial Registration ClinicalTrials.gov ID: NCT04877067.

Novel Drug Delivery Systems Fighting Glaucoma: Formulation Obstacles and Solutions

Glaucoma is considered to be one of the biggest health problems in the world. It is the main cause of preventable blindness due to its asymptomatic nature in the early stages on the one hand and patients' non-adherence on the other. There are several approaches in glaucoma treatment, whereby this has to be individually designed for each patient. The first-line treatment is medication therapy. However, taking into account numerous disadvantages of conventional ophthalmic dosage forms, intensive work has been carried out on the development of novel drug delivery systems for glaucoma. This review aims to provide an overview of formulation solutions and strategies in the development of in situ gel systems, nanosystems, ocular inserts, contact lenses, collagen corneal shields, ocular implants, microneedles, and iontophoretic devices. The results of studies confirming the effectiveness of the aforementioned drug delivery systems were also briefly presented.

Management of retinitis pigmentosa by Wharton's jelly derived mesenchymal stem cells: preliminary clinical results

PURPOSE

The aim of this study is to determine if umbilical cord Wharton's jelly derived mesenchymal stem cells implanted in sub-tenon space have beneficial effects on visual functions in retinitis pigmentosa patients by reactivating the degenerated photoreceptors in dormant phase.

MATERIAL AND METHODS

This prospective, open-label, phase-3 clinical trial was conducted between April of 2019 and October of 2019 at Ankara University Faculty of Medicine, Department of Ophthalmology. 32 RP patients (34 eyes) were included in the study. The patients were followed for 6 months after the Wharton's jelly derived mesenchymal stem cell administration, and evaluated with consecutive examinations. All patients underwent a complete routine ophthalmic examination, and best corrected visual acuity, optical coherens tomography angiography, visual field, multifocal and full-field electroretinography were performed. The quantitative results were obtained from a comparison of the pre-injection and final examination (6th month) values.

RESULTS

The mean best corrected visual acuity was 70.5 letters prior to Wharton's jelly derived mesenchymal stem cell application and 80.6 letters at the 6th month (p = 0.01). The mean visual field median deviation value was 27.3 dB before the treatment and 24.7 dB at the 6th month (p = 0.01). The mean outer retinal thickness was 100.3 μm before the treatment and 119.1 μm at 6th month (p = 0.01). In the multifocal electroretinography results, P1 amplitudes improved in ring1 from 24.8 to 39.8 nv/deg2 (p = 0.01), in ring2 from 6.8 to 13.6 nv/deg2 (p = 0.01), and in ring3 from 3.1 to 5.7 nv/deg2 (p = 0.02). P1 implicit times improved in ring1 from 44.2 to 32.4 ms (p = 0.01), in ring2 from 45.2 to 33.2 ms (p = 0.02), and in ring3 from 41.9 to 32.4 ms (p = 0.01). The mean amplitude improved in 16 Tds from 2.4 to 5.0 nv/deg2 (p = 0.01) and in 32 Tds from 2.4 to 4.8 nv/deg2 (p = 0.01) in the full-field flicker electroretinography results. Full field flicker electroretinography mean implicit time also improved in 16 Tds from 43.3 to 37.9 ms (p = 0.01). No ocular or systemic adverse events related to the two types of surgical methods and/or Wharton's jelly derived mesenchymal stem cells itself were observed during the follow-up period.

CONCLUSION

RP is a genetic disorder that can result in blindness with outer retinal degeneration. Regardless of the type of genetic mutation, sub-tenon Wharton's jelly derived mesenchymal stem cell administration appears to be an effective and safe option. There are no serious adverse events or ophthalmic / systemic side effects for 6 months follow-up. Although the long-term adverse effects are still unknown, as an extraocular approach, subtenon implantation of the stem cells seems to be a reasonable way to avoid the devastating side effects of intravitreal/submacular injection. Further studies that include long-term follow-up are needed to determine the duration of efficacy and the frequency of application.

TRIAL REGISTRATION

SHGM56733164. Redistered 28 January 2019 https://shgm.saglik.gov.tr/organ-ve-doku-nakli-koordinatorlugu/56733164/203 E.507.

Management of Deep Retinal Capillary Ischemia by Electromagnetic Stimulation and Platelet-Rich Plasma: Preliminary Clinical Results

INTRODUCTION

To investigate the efficacy of retinal electromagnetic stimulation and sub-tenon autologous platelet-rich plasma in the treatment of deep retinal capillary ischemia.

METHODS

The study included 28 eyes of 17 patients aged 15-76 years (mean 37.9 years) who had deep retinal capillary ischemia. Patients who had acute-onset paracentral scotoma in the last 1 month were included in the study between January 2018 and January 2019. The diagnosis of deep retinal capillary ischemia was based on clinical history and typical findings of optical coherence tomography angiography. The eyes were divided into three groups: group 1 (n = 7 eyes) received electromagnetic stimulation alone; group 2 (n = 7 eyes) received electromagnetic stimulation and sub-tenon autologous platelet-rich plasma injection; group 3 had no intervention and served as a control group (n = 14 eyes). The patients underwent ten sessions of electromagnetic stimulation in groups 1 and 2. Sub-tenon autologous platelet-rich plasma injection was performed immediately after the first, fifth, and tenth sessions of electromagnetic stimulation in group 2. The deep retinal capillary density and best corrected visual acuity changes were investigated before and after treatment at the first month.

RESULTS

The mean deep retinal capillary density was 52.0% before electromagnetic stimulation and 56.1% after ten sessions of application in group 1; this improvement was statistically significant (p = 0.01). In the combined treatment group (group 2), the mean deep retinal capillary density was 46.9% before the treatment and 56.5% after the treatment; this increase was also statistically significant (p = 0.01). Statistically significant best corrected visual acuity improvement (p = 0.01) could be achieved only in group 2. The combined treatment was significantly superior (p < 0.01) to treatment with only electromagnetic stimulation regarding best corrected visual acuity and deep retinal capillary density. In the control group (group 3), there was no statistically significant change (p = 0.09) in the mean deep retinal capillary density and best corrected visual acuity.

CONCLUSION

Treatment of the underlying cause is a priority in the treatment of deep retinal capillary ischemia. However, in the acute period, local ischemia treatment is necessary to prevent permanent retinal damage and scotomas. In mild cases, only electromagnetic stimulation, which is non-invasive and easy to use, might have a beneficial effect on deep retinal capillary density. In more severe cases, sub-tenon fresh autologous platelet-rich plasma injection together with electromagnetic stimulation may be more effective in the treatment of local ischemia of the retina in order to augment the response.

FUNDING

The Rapid Service Fees were funded by the Ankara University Tecnopolis Institute.

CLINICAL TRIAL REGISTRATION

titck.gov.tr identifier, 2018-136.