Recent advances in intraocular and novel drug delivery systems for the treatment of diabetic retinopathy

Chitosan as a promising materials for the construction of nanocarriers for diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a condition that causes swelling of the blood vessels of the retina and leaks blood and fluids. It is the most severe form of diabetic eye disease. It causes vision loss in its advanced stage. Diabetic retinopathy is responsible for causing 26% of blindness. Very insufficient therapies are accessible for the treatment of DR. As compared to the conventional therapies, there should be enhanced research on the controlled release, shorter duration, and cost-effective therapy of diabetic retinopathy. The expansion of advanced nanocarriers-based drug delivery systems has been now employed to exploit as well as regulate the transport of many therapeutic agents to target sites via the increase in penetration or the extension of the duration of contact employing production by enclosing as well as distributing tiny molecules in nanostructured formulation. Various polymers have been utilized for the manufacturing of these nanostructured formulations. Chitosan possesses incredible biological and chemical properties, that have led to its extensive use in pharmaceutical and biomedical applications. Chitosan has been used in many studies because of its enhanced mucoadhesiveness and non-toxicity. Multiple studies have used chitosan as the best candidate for manufacturing nanocarriers and treating diabetic retinopathy. Numerous nanocarriers have been formulated by using chitosan such as nanostructured lipid carriers, solid lipid nanoparticles, liposomes, and dendrimers for treating diabetic retinopathy. This current review elaborates on the recent advancements of chitosan as a promising approach for the manufacturing of nanocarriers that can be used for treating diabetic retinopathy.

Enhancement efficiency delivery of antiviral Molnupiravir-drug via the loading with self-assembly nanoparticles of pycnogenol and cellulose which are decorated by zinc oxide nanoparticles for COVID-19 therapy

The target of the study is to modify the efficiency of Molnupiravir-drug (MOL) for COVID-19 therapy via the rearrangement of the building engineering of MOL-drug by loading it with self-assembly biomolecules nanoparticles (NPs) of pycnogenol (Pyc) and cellulose (CNC) which are decorated by zinc oxide nanoparticles. The synthesis and characterization of the modified drug are performing successfully, the loading and release process of the MOL drug on a nano surface is measured by UV-Vis spectroscopy under room temperature and different pH. The release efficiency of the MOL drug is calculated to be 65% (pH 6.8) and 69% (pH 7.4). The modified MOL drug displays 71% (pH 6.8) and 78% (pH 7.4) for CNC@Pyc.MOL nanocomposite, while CNC@Pyc.MOL.ZnO nanocomposite gave values at 76% (pH 6.8) and 78% (pH 7.4), the efficiency recorded after 19 h. The biological activity of the MOL-drug and modified MOL-drug is measured, and the cytotoxicity is performed by SRB technique, where the self-assembly (CNC@Pyc) appears to be a safe healthy, and high viability against the examined cell line. The antioxidant activity and anti-inflammatory are evaluated, where the nanocomposite that has ZnO NPs (CNC@Pyc.MOL.ZnO) gave high efficiency compared to the composite without ZnO NPs. The CPE-inhibition assay is used to identify potential antivirals against CVID-19 (229E virus), the viral inhibition (%) was reported at 37.6 % (for 800 µg/ml) and 18.02 % (for 400 µg/ml) of CNC@Pyc.MOL.ZnO. So, the modified MOL-drug was suggested as a replacement drug for the therapy of COVID-19 compared to MOL-drug, but the results need clinical trials.

Microphysiological Constructs and Systems: Biofabrication Tactics, Biomimetic Evaluation Approaches, and Biomedical Applications

In recent decades, microphysiological constructs and systems (MPCs and MPSs) have undergone significant development, ranging from self-organized organoids to high-throughput organ-on-a-chip platforms. Advances in biomaterials, bioinks, 3D bioprinting, micro/nanofabrication, and sensor technologies have contributed to diverse and innovative biofabrication tactics. MPCs and MPSs, particularly tissue chips relevant to absorption, distribution, metabolism, excretion, and toxicity, have demonstrated potential as precise, efficient, and economical alternatives to animal models for drug discovery and personalized medicine. However, current approaches mainly focus on the in vitro recapitulation of the human anatomical structure and physiological-biochemical indices at a single or a few simple levels. This review highlights the recent remarkable progress in MPC and MPS models and their applications. The challenges that must be addressed to assess the reliability, quantify the techniques, and utilize the fidelity of the models are also discussed.

Spectroscopic study to verify the anti-hepatitis C virus (HCV) treatment through a delivery system of the sofosbuvir drug on chitosan and pycnogenol nanoparticles surface

The target of the current study is to create a novel hybrid nanocomposite (Cs@Pyc.SOF) by combining the anti-hepatitis C virus (HCV) drug sofosbuvir with the nano antioxidant pycnogenol (Pyc) and nano biomolecules like chitosan nanoparticles (Cs NPs). The characterization procedure works to verify the creation of nanocomposite (NCP) using several different techniques. UV-Vis spectroscopy is used to measure SOF loading efficiency. The various concentrations of the SOF drug were used to determine the binding constant rate Kb, which was found to be 7.35 ± 0.95 min-1 with an 83% loading efficiency. At pH 7.4, the release rate was 80.6% after two hours and 92% after 48 h, whereas at pH 6.8, it was 29% after two hours and 94% after 48 h. After 2 and 48 h, the release rate in water was 38% and 77%, respectively. . The SRB technique for fast screening is used for the cytotoxicity test, where the investigated composites show a safety status and high viability against the examined cell line. The cytotoxicity assay of the SOF hybrid materials has been identified with cell lines like mouse normal liver cells (BNL). So, Cs@Pyc.SOF was recommended as a substitute medication for the therapy of HCV, but the results need clinical studies.

Trends in Formulation Approaches for Sustained Drug Delivery to the Posterior Segment of the Eye

The eye, an intricate organ comprising physical and physiological barriers, poses a significant challenge for ophthalmic physicians seeking to treat serious ocular diseases affecting the posterior segment, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Despite extensive efforts, the delivery of therapeutic drugs to the rear part of the eye remains an unresolved issue. This comprehensive review delves into conventional and innovative formulation strategies for drug delivery to the posterior segment of the eye. By utilizing alternative nanoformulation approaches such as liposomes, nanoparticles, and microneedle patches, researchers and clinicians can overcome the limitations of conventional eye drops and achieve more effective drug delivery to the posterior segment of the eye. These innovative strategies offer improved drug penetration, prolonged residence time, and controlled release, enhancing therapeutic outcomes for ocular diseases. Moreover, this article explores recently approved delivery systems that leverage diverse polymer technologies, such as chitosan and hyaluronic acid, to regulate drug-controlled release over an extended period. By offering a comprehensive understanding of the available formulation strategies, this review aims to empower researchers and clinicians in their pursuit of developing highly effective treatments for posterior-segment ocular diseases.

Efficiency co-delivery of ellagic acid and oxygen by a non-invasive liposome for ameliorating diabetic retinopathy

Diabetic retinopathy (DR) is one of the serious complications of diabetes, which has become the fourth leading cause of vision loss worldwide. Current treatment of DR relies on intravitreal injections of antiangiogenic agents, which has made considerable achievements in reducing visual impairment. However, long-term invasive injections require advanced technology and can lead to poor patient compliance as well as the incidence of ocular complications including bleeding, endophthalmitis, retinal detachment and others. Hence, we developed non-invasive liposomes (EA-Hb/TAT&isoDGR-Lipo) for efficiency co-delivery of ellagic acid and oxygen, which can be administered intravenously or by eye drops. Among that, ellagic acid (EA), as an aldose reductase inhibitor, could remove excessive reactive oxygen species (ROS) induced by high glucose for preventing retinal cell apoptosis, as well as reduce retinal angiogenesis through the blockage of VEGFR2 signaling pathway; carried oxygen could ameliorate DR hypoxia, and further enhanced the anti-neovascularization efficacy. Our results showed that EA-Hb/TAT&isoDGR-Lipo not only effectively protected retinal cells from high glucose-induced damage, but also inhibited VEGF-induced vascular endothelial cells migration, invasion, and tube formation in vitro. In addition, in a hypoxic cell model, EA-Hb/TAT&isoDGR-Lipo could reverse retinal cell hypoxia, thereby reducing the expression of VEGF. Significantly, after being administered as an injection or eye drops, EA-Hb/TAT&isoDGR-Lipo obviously ameliorated the structure (central retinal thickness and retinal vascular network) of retina by eliminating ROS and down-regulating the expression of GFAP, HIF-1α, VEGF and p-VEGFR2 in a DR mouse model. In summary, EA-Hb/TAT&isoDGR-Lipo holds great potentials in improvement of DR, which provides a novel approach for the treatment of DR.

Emerging strategies of engineering retinal organoids and organoid-on-a-chip in modeling intraocular drug delivery: current progress and future perspectives

Retinal diseases are a rising concern as major causes of blindness in an aging society; therapeutic options are limited, and the precise pathogenesis of these diseases remains largely unknown. Intraocular drug delivery and nanomedicines offering targeted, sustained, and controllable delivery are the most challenging and popular topics in ocular drug development and toxicological evaluation. Retinal organoids (ROs) and organoid-on-a-chip (ROoC) are both emerging as promising in-vitro models to faithfully recapitulate human eyes for retinal research in the replacement of experimental animals and primary cells. In this study, we review the generation and application of ROs resembling the human retina in cell subtypes and laminated structures and introduce the emerging engineered ROoC as a technological opportunity to address critical issues. On-chip vascularization, perfusion, and close inter-tissue interactions recreate physiological environments in vitro, whilst integrating with biosensors facilitates real-time analysis and monitoring during organogenesis of the retina representing engineering efforts in ROoC models. We also emphasize that ROs and ROoCs hold the potential for applications in modeling intraocular drug delivery in vitro and developing next-generation retinal drug delivery strategies.

Exploring various novel diagnostic and therapeutic approaches in treating diabetic retinopathy

Diabetic retinopathy is regarded as a common manifestation of diabetes mellitus, being a prominent cause of visual impairment and blindness. This microvascular complication is marked by the appearance of microaneurysms, elevated vascular permeability, capillary blockage, and proliferation of neovasculature. The etiology behind retinopathy is ambiguous and the efficacy of current treatment strategies is minimal. Early diagnosis of this complication using a biomarker with high sensitivity and specificity is very essential for providing better therapeutic strategies. The current available therapeutic options are limited with various adverse effects. Laser treatment is not beneficial in all the situations, economic constraints being the major challenge. Surgical interventions are employed when pharmacotherapy and laser treatment fail. New pharmacological treatments are becoming a necessity for treating the condition. This review highlights the use of various diagnostic tools, emerging biomarkers for early detection of diabetic retinopathy, pathological mechanisms associated with the disease, current therapeutic approaches used and future strategies for more enhanced treatment options and more potent pharmacological actions.

Ocular Delivery of Therapeutic Proteins: A Review

Therapeutic proteins, including monoclonal antibodies, single chain variable fragment (ScFv), crystallizable fragment (Fc), and fragment antigen binding (Fab), have accounted for one-third of all drugs on the world market. In particular, these medicines have been widely used in ocular therapies in the treatment of various diseases, such as age-related macular degeneration, corneal neovascularization, diabetic retinopathy, and retinal vein occlusion. However, the formulation of these biomacromolecules is challenging due to their high molecular weight, complex structure, instability, short half-life, enzymatic degradation, and immunogenicity, which leads to the failure of therapies. Various efforts have been made to overcome the ocular barriers, providing effective delivery of therapeutic proteins, such as altering the protein structure or including it in new delivery systems. These strategies are not only cost-effective and beneficial to patients but have also been shown to allow for fewer drug side effects. In this review, we discuss several factors that affect the design of formulations and the delivery of therapeutic proteins to ocular tissues, such as the use of injectable micro/nanocarriers, hydrogels, implants, iontophoresis, cell-based therapy, and combination techniques. In addition, other approaches are briefly discussed, related to the structural modification of these proteins, improving their bioavailability in the posterior segments of the eye without affecting their stability. Future research should be conducted toward the development of more effective, stable, noninvasive, and cost-effective formulations for the ocular delivery of therapeutic proteins. In addition, more insights into preclinical to clinical translation are needed.

Chitosan modified 5-fluorouracil nanostructured lipid carriers for treatment of diabetic retinopathy in rats: A new dimension to an anticancer drug

Diabetic retinopathy (DR) is one of the chronic complications of diabetes. It includes retinal blood vessels' damage. If untreated, it leads to loss of vision. The existing treatment strategies for DR are expensive, invasive, and need expertise during administration. Hence, there is a need to develop a non-invasive topical formulation that can penetrate deep to the posterior segment of retina and treat the damaged retinal vessels. In addition, it should also provide sustained release. In recent years, novel drug delivery systems (NDDS) have been explored for treating DR and found successful. In this study, chitosan (CS) modified 5-Fluorouracil Nanostructured Lipid Carriers (CS-5-FU-NLCs) were prepared by modified melt emulsification-ultrasonication method and optimized by Box-Behnken Design. The size, polydispersity index, zeta potential and entrapment efficiency of CS-5-FU-NLCs were 163.2 ± 2.3 nm, 0.28 ± 1.52, 21.4 ± 0.5 mV and 85.0 ± 0.2 %, respectively. The in vitro drug release and ex vivo permeation study confirmed higher and sustained drug release in CS-5-FU-NLCs as compared to 5-FU solution. HET-CAM Model ensured the non-irritant nature of CS-5-FU-NLCs. In vivo ocular studies of CS-5-FU-NLCs confirmed antiangiogenic effect of 5-FU by CAM model and diabetic retinopathy induced rat model, indicating successful delivery of 5-FU to the retina.

Current Treatments and Innovations in Diabetic Retinopathy and Diabetic Macular Edema

Diabetic retinopathy (DR) is one of the leading causes of blindness worldwide. Multiple treatment options have been used over time to attempt to modify the natural progression of the disease in both proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME). These two retinal complications are the result of microvascular occlusions and vascular hyperpermeability and are considered one of the leading causes of irreversible blindness in patients of working age. It is now well demonstrated that PDR and DME are associated with increased levels of inflammatory and pro-angiogenic factors in the ocular compartment. To date, laser photocoagulation, vascular endothelial growth factor (VEGF) inhibitors, and corticosteroids have demonstrated efficacy in their treatment in large randomized controlled trials and in real-life observational studies. This manuscript aims to provide a comprehensive review of current treatments, including the main drugs used in diabetic pathologic manifestations, as well as new therapeutic alternatives, such as extended-release intraocular devices.

Association of VEGF Gene Polymorphism (rs699947) with Glaucoma and In-Silico Study of Antiglaucoma Bioactive Compounds

Vascular endothelial growth factor (VEGF) is a useful expert in various maturation and other problems such as glaucoma. VEGF gene is located on the short arm of chromosome 6. It has 8 exons and 6 introns. This investigation was planned to check out the relationship of VEGF polymorphism with glaucoma patients and to cause in silico limitation of carbonic anhydrase to diminish the intraocular strain of watery humor to fix glaucoma. In this examination, a large portion of the glaucoma patients (n = 70) were males (66%) when contrasted with females (34%) as the p-value was 0.025 which showed critical outcomes and subsequently demonstrated that the sickness was more predominant in males. Glaucoma for the most part influences people between the ages of 50-60 years followed by the age bunch between 30 and 40 years. Around 36 (51.4%) were experiencing watering in the eyes, 28 (40%) had photophobia, 9 (12.8%) had a hazy cornea, 6 (8.6%) had expanded eye globe, and 15 patients (21.3%) had rosy eyes. Factual tests showed that VEGF quality SNP rs699947 had no huge relationship with glaucoma (POAG). In this study, various carbonic anhydrase inhibitor phytochemicals and synthetic chemicals were screened in silico which may be used as antiglaucoma drugs.

Single subcutaneous injection of the minocycline nanocomposite-loaded thermosensitive hydrogel for the effective attenuation of experimental autoimmune uveitis

Autoimmune uveitis induces a serious pathological and inflammatory response in the retina/choroid and results in vision impairment and blindness. Here, we report a minocycline (Mino) nanocomposite-loaded hydrogel offering a high drug payload and sustained drug release for the effective control of ocular inflammation via a single subcutaneous injection. In the presence of divalent cations (i.e., Ca²⁺), Mino was found to co-assemble with a phosphorylated peptide (i.e., NapGFFpY) via electrostatic interaction and consequently generating Mino nanocomposite. The drug entrapment efficiency (EE) of the Mino nanocomposite varied from 29.93±0.76% to 67.90±6.57%, depending on different component concentrations. After incorporation into 30 wt% poly (D,L-lactide)-b-poly (ethylene glycol)-b-poly (D,L-lactide) (PDLLA-PEG-PDLLA) thermosensitive hydrogel, the resulting Mino nanocomposite-loaded hydrogel provided a sustained drug release over 21 days. In the experimental autoimmune uveitis (EAU) rat model, a single subcutaneous injection of the Mino nanocomposite-loaded hydrogel effectively alleviated ocular inflammation in a dose-dependent manner. As indicated by optical coherence tomography (OCT) and electroretinogram (ERG) measurements, the Mino nanocomposite-loaded hydrogel treatment not only remarkably reduced destruction of the retina by EAU, but also greatly rescued retinal functions. Moreover, the proposed Mino nanocomposite-loaded hydrogel exerted its therapeutic effect on EAU primarily through a significant reduction of the influx of leukocytes and Th17 cells as well as suppression of microglia activation and apoptosis in the retina. Overall, the proposed Mino nanocomposite-loaded hydrogel might be a promising strategy for the clinical management of EAU.

Nanocarriers, Progenitor Cells, Combinational Approaches, and New Insights on the Retinal Therapy

Progenitor cells derived from the retinal pigment epithelium (RPECs) have shown promise as therapeutic approaches to degenerative retinal disorders including diabetic retinopathy, age-related macular degeneration and Stargardt disease. However, the degeneration of Bruch's membrane (BM), the natural substrate for the RPE, has been identified as one of the major limitations for utilizing RPECs. This degeneration leads to decreased support, survival and integration of the transplanted RPECs. It has been proposed that the generation of organized structures of nanofibers, in an attempt to mimic the natural retinal extracellular matrix (ECM) and its unique characteristics, could be utilized to overcome these limitations. Furthermore, nanoparticles could be incorporated to provide a platform for improved drug delivery and sustained release of molecules over several months to years. In addition, the incorporation of tissue-specific genes and stem cells into the nanostructures increased the stability and enhanced transfection efficiency of gene/drug to the posterior segment of the eye. This review discusses available drug delivery systems and combination therapies together with challenges associated with each approach. As the last step, we discuss the application of nanofibrous scaffolds for the implantation of RPE progenitor cells with the aim to enhance cell adhesion and support a functionally polarized RPE monolayer.