Penetrating-peptide-mediated non-invasive Axitinib delivery for anti-neovascularisation

Hydrophobic vehicles for hydrophilic drugs: Sustained intravitreal caffeine delivery with oleogels

Caffeine is the most widely consumed bioactive ingredient in the world, which has been found to show great therapeutic potential in several posterior eye diseases. While intravitreal injection represents the ideal administration route for these disorders, it remains challenging to achieve sustained release of caffeine in the vitreous. Herein, we address this issue by loading crystalline caffeine within oleogels (Ca@oleogels), oily delivery vehicles which provide a hydrophobic environment that is opposite to the hydrophilic nature of their cargos. Mathematical modeling of the in vitro release profiles indicated the diffusion process of the drug from Ca@oleogels was playing a dominating role in caffeine release. Furthermore, sustained intravitreal delivery was evidenced by higher drug levels from 12 h until the end of the pharmacokinetic study (240 h) and a 3.2-fold reduction in Cmax in Ca@oleogel dosed rabbits compared to their caffeine dosed counterparts. Superior therapeutic effects were obtained with Ca@oleogels in a laser-induced mouse choroidal neovascularization model. Advantages of Ca@oleogels as caffeine delivery vehicles included excellent biocompatibility, low cost and simplicity of manufacturing as well, which indicated they can be administrated safely and were readily amenable to scale-up production cost-effectively. Moreover, sustained release of another hydrophilic model drug (congo red) was also demonstrated with the same formulation design. Therefore, this strategy serves as a general solution to sustained intravitreal delivery of hydrophilic small molecule drugs.

Biphasic biomimetic scaffolds based on a regionally decalcified bone framework and pre-chondrogenic microspheres for osteochondral defect repair

Osteochondral defects are still facing a significant challenge in clinical surgery, making post-trauma repair difficult. Tissue engineering has provided a promising approach to solving these defects. However, existing scaffolds cannot replicate the complex biphasic cartilage-bone microenvironment with accuracy. We aimed to develop a biphasic biomimetic scaffold with regionally regulated vascularization that promoted chondrogenesis and osteogenesis through bidirectional regulation of endochondral ossification. This scaffold consisted of pre-chondrogenic microspheres (PCMs) and a decalcified bone frame prepared by decalcifying the cartilage layer and bone layer of the scaffold to varying degrees. Incorporation of PCMs into the cartilage layer created a microenvironment that promoted cartilage regeneration while axitinib was modified to inhibit vascularization and enhance cartilage regeneration. The bone layer provided a microenvironment that promoted endochondral ossification and facilitated bone repair. In vitro studies have shown that axitinib-modified cartilage layers significantly inhibit the VEGF expression of pre-chondrogenic cells, while decalcified bone powder from the bone layer significantly promotes the ossification of PCMs. In vivo experiments indicated that this decalcified bone frame controls the endochondral ossification of PCMs through regionalized angiogenesis, promoting the integrated regeneration and reconstruction of osteochondral defects in rabbit knee joints. These results suggest that our designed demineralized bone frame can precisely engineer the osteochondral regeneration microenvironment, providing theoretical guidance for the integrated regeneration and repair of anisotropic tissue injuries.

Frontier applications of retinal nanomedicine: progress, challenges and perspectives

The human retina is a fragile and sophisticated light-sensitive tissue in the central nervous system. Unhealthy retinas can cause irreversible visual deterioration and permanent vision loss. Effective therapeutic strategies are restricted to the treatment or reversal of these conditions. In recent years, nanoscience and nanotechnology have revolutionized targeted management of retinal diseases. Pharmaceuticals, theranostics, regenerative medicine, gene therapy, and retinal prostheses are indispensable for retinal interventions and have been significantly advanced by nanomedical innovations. Hence, this review presents novel insights into the use of versatile nanomaterial-based nanocomposites for frontier retinal applications, including non-invasive drug delivery, theranostic contrast agents, therapeutic nanoagents, gene therapy, stem cell-based therapy, retinal optogenetics and retinal prostheses, which have mainly been reported within the last 5 years. Furthermore, recent progress, potential challenges, and future perspectives in this field are highlighted and discussed in detail, which may shed light on future clinical translations and ultimately, benefit patients with retinal disorders.

Development of axitinib-loaded polymeric ocular implants for the treatment of posterior ocular diseases

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are the primary causes of vision impairment and blindness worldwide. The current treatment for these diseases is an intravitreal injection of anti-VEGF agents, which are costly and require frequent injections. Implants can be used to sustain the release of drugs and minimize side effects. Axitinib (AX) is a potent VEGF receptor inhibitor and a promising candidate for treating posterior ocular diseases, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). A sustained release of AX was successfully achieved from 3D-printed AX-loaded implants fabricated using the well-known 3D printing technique, semi-solid extrusion (SSE). AX at concentrations of 10% w/w and 20% w/w was incorporated within the polycaprolactone (PCL) and Precirol®-based matrix. The fabricated implants were characterized via FTIR spectroscopy, SEM imaging, and thermal analysis. The implants were also evaluated for their drug release and biocompatibility. The AX-loaded implants exhibited thermal stability, and no chemical interactions were found between AX and the matrix components. The release mechanism study of AX revealed that the concentration of drug loading influenced AX release from the implant, with a 10% w/w and 20 %w/w of AX showing first-order and Korsmeyer-Peppas mechanism, respectively. A biocompatibility study using ARPE-19 cells confirmed that AX-loaded implants are nontoxic and safe for ocular use.

FRET-based analysis on the fate of liposome and cyclodextrin@liposome nanocomposites from ocular surface to the posterior segment of the eye

Investigating the structural integrity of nanocarriers in vivo is vital for exploring the fate of nanocarriers from ocular surface to the posterior segment of the eye. Most of the published studies adopted the structural integrity ratio of nanocarriers to determine the fate of them, which lacked scientific support. In this study, two methods were used to explore the factors which affected the structural integrity of liposomes. A new method with the standard curve of FRET fluorescence intensity and carbocyanine 7 (Cy7) content was drawn for the first time. Secondly, we used the traditional method of drawing the standard curve of FRET fluorescence efficiency and structural integrity ratios. The results showed that liposomes with particle size about 120 nm, positively charged, polyethyleneglycol5000 (PEG5000) and glycine sarcosine (GS) modified had the highest Cy7 content in rabbit tissues. When the dosage of Cy7 was 25 μg, at 60 min, the content of Cy7 in intact liposomes and the structural integrity ratio of liposomes in sclera was 210.5 ± 14.9 ng and 19.8 ± 5.3 %, respectively. Compared with the structural integrity ratio, the Cy7 content in the intact carrier could better estimate the fate of nanocarriers in vivo scientifically. On this basis, the fate of dual-carrier nanocomposites and the inner cyclodextrin complexes in vivo was investigated. The intact cyclodextrin complexes could reach choroid-retina with the protection of outer liposomes. The structural integrity ratios of liposomes were also studied after crossing human conjunctival epithelial cells (HConEpiC) monolayer, but in vitro cellular experiments could not simulate the real situation in vivo. Finally, the tissue distribution of nanocomposites was studied in rabbit eyes. The concentration of dexamethasone (Dex) in choroid-retina was 158 ± 23 ng/g after 3 h, which exhibited better drug delivery ability compared with our previous study. Overall, the present study provides a new scientific method to estimate the structural integrity in vivo, which is beneficial for the rational design of drug delivery systems with more structural integrity in vivo and higher drug delivery efficiency.

A supramolecular hydrogel eye-drop alleviates inflammation via clathrin-mediated endocytosis

The modulation of inflammation is effective to treat many ocular surface diseases. Thus the low bioavailability of common anti-inflammatory eye-drops urges the development of ocular drug delivery systems to extend the ocular retention and enhance the cellular uptake for improving anti-inflammatory effect of eye-drops. Here we covalently conjugate two molecules of clinically anti-inflammatory drug (i.e., dexamethasone) with a small peptide (i.e., Tyr-Glu-Asn-Pro-Thr-Tyr) to generate an anti-inflammatory hydrogel eye-drop. With a self-assembled ability, the designed supramolecular hydrogel achieves gel-sol-gel transition by varying shearing forces which increases the pre-corneal retention of drug. The fluorescent imaging reveals the efficient cellular uptake of designed conjugate via clathrin-mediated endocytosis. A rodent model of endotoxin-induced uveitis verifies that the supramolecular hydrogel eye-drop suppresses inflammation responses without ocular irritation. As a rational approach to design anti-inflammatory drugs as eye-drops, this work overcomes the frequent instillation of clinical eye-drops and further improves the bioavailability of anti-inflammatory drugs, which may provide an effective and household way to fight ocular surface inflammation.

A Nanogel Formulation of Anti-VEGF Peptide for Ocular Neovascularization Treatment

Age-related macular degeneration (AMD) is an eye disorder that can lead to visual impairment in elder patients, and current treatments include repeated injections of monoclonal antibody-based antivascular endothelial growth factor (anti-VEGF) agents. This study investigates the potential of a nanoformulation of a peptide anti-VEGF molecule for neovascular AMD. Anti-VEGF peptide HRHTKQRHTALH (HRH), which has high affinity to VEGF-Fc receptor, was used as the bioactive agent to control neovascularization of the retina. The nanoformulation consisting of hyaluronic acid nanogel was generated by incorporating divinyl sulfone and cholesterol to increase the stability and control the size of the nanodrug. The encapsulation efficacy of nanogel was 65%, and drug release was 34.72% at the end of 192 h. Obtained nanogels were efficiently internalized in 15 min by human umbilical vascular endothelial cells (HUVECs) and ARPE-19 cells, and results indicate that nanoformulation is not toxic to ARPE-19 cells, whereas it inhibits HUVEC proliferation owing to anti-VEGF peptide in the nanogel structure. In the coculture experiment in which retinal penetration was modeled, it was observed that the nanogel reached HUVECs and negatively affected their proliferation without disturbing the monolayer of ARPE-19 cells. In vivo experiments with chick chorioallantoic membrane revealed that nanogel formulation has higher antiangiogenesis activity compared to free HRH. Additionally, in an oxygen-induced retinopathy model, the excessive growth of blood vessels was notably suppressed in mice treated with HRH-loaded nanogel. This research indicates that nanogels formulated in this study are promising candidates as a topical treatment for AMD.

Liposome‐Based Permeable Eyedrops for Effective Posterior Segment Drug Delivery

Topical eyedrop administration is identified as an ideal non‐invasive strategy for ocular drug delivery. However, multiple complex ocular barriers greatly restrict their effectiveness in the treatment of posterior ocular disease. Herein, a liposome‐based permeable eyedrops (pDrops) capable of overcoming multiple ocular barriers and achieving efficient posterior drug delivery is presented. pDrops have a core‐shell structure in which drugs are encapsulated inside the liposome core with a chitosan shell. This chitosan coating significantly enhances the pDrops’ binding to mucin in tears and facilitates the temporary opening of tight junctions in cornea/conjunctive epithelial cells, thereby achieving prolonged preocular retention and enhanced posterior segment drug delivery. In this study, hydrophilic ganciclovir (GCV) and hydrophobic curcumin (CUR) are employed as model drugs. Upon topical instillation, pDrops effectively overcome ocular barriers and delivered GCV to the posterior segment in both rat and rabbit eyes. Notably, CUR delivery by pDrops demonstrates significantly enhanced therapeutic efficacy in light‐damaged retina of mice. Considering that pDrops can deliver both hydrophobic and hydrophilic drugs to the posterior segment of the eye, it can potentially become a feasible platform for the non‐invasive delivery of various drug molecules and improve the treatment efficiency of posterior ocular diseases.

Multifunctional Nanotherapeutics with Long-Acting Release against Macular Degeneration by Minimally Invasive Administration

Neovascular age-related macular degeneration (AMD), a leading cause of blindness, requires frequent intravitreal injection of antivascular endothelial growth factor (anti-VEGF), which could generate a succession of complications with poor patient compliance. The current VEGF-targeting therapies often fail in half of patients due to the complex pathologic microenvironment of excessive reactive oxygen species (ROS) production, and increased levels of inflammation are accompanied by choroidal neovascularization (CNV). We herein reported multifunctional nanotherapeutics featuring superior antioxidant and anti-inflammation properties that aim to reverse the pathological condition, alongside its strong targeted antiangiogenesis to CNV and its ability to provide long-term sustained bioactive delivery via the minimally invasive subconjunctival injection, so as to achieve satisfactory wet AMD treatment effects. Concretely, the nanomedicine was designed by coencapsulation of astaxanthin (AST), a red pigmented carotenoid known for its antioxidative, anti-inflammatory and antiapoptotic properties, and axitinib (AXI), a small molecule tyrosine kinase inhibitor that selectively targets the vascular epidermal growth factor receptor for antiangiogenesis, into the Food and Drug Administration (FDA) approved poly(lactic-co-glycolic acid) (PLGA), which forms the nanodrug of PLGA@AST/AXI. Our results demonstrated that a single-dose subconjunctival administration of PLGA@AST/AXI showed a rational synergistic effect by targeting various prevailing risk factors associated with wet AMD, ensuring persistent drug release profiles, maintaining good ocular biocompatibility, and causing no obvious mechanical damage. Such attributes are vital and hold significant potential in treating ocular posterior segment diseases. Moreover, this nanotherapeutic strategy represents a versatile and broad-spectrum nanoplatform, offering a promising alternative for the complex pathological progression of other neovascular diseases.

Gemfibrozil-Platinum(IV) Precursors for New Enhanced-Starvation and Chemotherapy In Vitro and In Vivo

A brand-new enhanced starvation is put forward to trigger sensitized chemotherapy: blocking tumor-relation blood vessel formation and accelerating nutrient degradation and efflux. Following this concept, two cisplatin-like gemfibrozil-derived Pt(IV) prodrugs, GP and GPG, are synthesized. GP and GPG had nanomolar IC50 against A2780 cells and higher selectivity against normal cells than cisplatin. Bioactivity results confirmed that GP and GPG highly accumulated in cells and induced DNA damage, G2-phase arrest, and p53 expression. Besides, they could increase ROS and MDA levels and reduce mitochondrial membrane potential and Bcl-2 expression to promote cell apoptosis. In vivo, GP showed superior antitumor activity in A2780 tumor-bearing mice with no observable tissue damage. Mechanistic studies suggested that highly selective chemotherapy could be due to the new enhanced starvation effect: blocking vasculature formation via inhibiting the CYP2C8/EETs pathway and VEGFR2, NF-κB, and COX-2 expression and cholesterol efflux and degradation acceleration via increasing ABCA1 and PPARα.

Recent advances in nanocrystal-based technologies applied for ocular drug delivery

INTRODUCTION

The intricate physiological barriers of the eye and the limited volume of eye drops impede efficient delivery of poorly water-soluble drugs. In the last decade, nanocrystals have emerged as versatile drug delivery systems in various administration routes from bench to bedside. The unique superiorities of nanocrystals, mainly embodied in high drug-loading capacity, good mucosal adhesion and penetration, and greatly improved drug solubility, reveal a promising prospect for ocular delivery of poorly water-soluble drugs.

AREAS COVERED

This article focuses on the ophthalmic nanocrystal technologies and products that are in the literature, clinical trials, and even on the market. The recent research progress in the preparation, ocular application, and absorption of nanocrystals are highlighted, and the pros and cons of nanocrystals in overcoming the physiological barriers of the eye are also summarized.

EXPERT OPINION

Nanocrystals have demonstrated success as glucocorticoid eye drops in the treatment of anterior segment diseases. However, the thermodynamic stability of nanocrystals remains the major challenge in product development. New technologies for efficiently optimizing stabilizers and sterilization processes are still expected. Strategies to confer more diverse functions via surface modification are also worth exploration to improve the potential of nanocrystals in delivering poorly water-soluble drugs to posterior segment of the eye.

Challenges and strategies for ocular posterior diseases therapy via non-invasive advanced drug delivery

Posterior segment diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vital factor that seriously threatens human vision health and quality of life, the treatment of which poses a great challenge to ophthalmologists and ophthalmic scientists. In particular, ocular posterior drug delivery in a non-invasive manner is highly desired but still faces many difficulties such as rapid drug clearance, limited permeability and low drug accumulation at the target site. At present, many novel non-invasive topical ocular drug delivery systems are under development aiming to improve drug delivery efficiency and biocompatibility for better therapy of posterior segment oculopathy. The purpose of this review is to present the challenges in the noninvasive treatment of posterior segment diseases, and to propose strategies to tackle these bottlenecks. First of all, barriers to ocular administration were introduced based on ocular physiological structure and behavior, including analysis and discussion on the influence of ocular structures on noninvasive posterior segment delivery. Thereafter, various routes of posterior drug delivery, both invasive and noninvasive, were illustrated, along with the respective anatomical obstacles that need to be overcome. The widespread and risky application of invasive drug delivery, and the need to develop non-invasive local drug delivery with alternative to injectable therapy were described. Absorption routes through topical administration and strategies to enhance ocular posterior drug delivery were then discussed. As a follow-up, an up-to-date research advances in non-invasive delivery systems for the therapy of ocular fundus lesions were presented, including different nanocarriers, contact lenses, and several other carriers. In conclusion, it seems feasible and promising to treat posterior oculopathy via non-invasive local preparations or in combination with appropriate devices.

Next-Generation Nanomedicine Approaches for the Management of Retinal Diseases

Retinal diseases are one of the leading causes of blindness globally. The mainstay treatments for these blinding diseases are laser photocoagulation, vitrectomy, and repeated intravitreal injections of anti-vascular endothelial growth factor (VEGF) or steroids. Unfortunately, these therapies are associated with ocular complications like inflammation, elevated intraocular pressure, retinal detachment, endophthalmitis, and vitreous hemorrhage. Recent advances in nanomedicine seek to curtail these limitations, overcoming ocular barriers by developing non-invasive or minimally invasive delivery modalities. These modalities include delivering therapeutics to specific cellular targets in the retina, providing sustained delivery of drugs to avoid repeated intravitreal injections, and acting as a scaffold for neural tissue regeneration. These next-generation nanomedicine approaches could potentially revolutionize the treatment landscape of retinal diseases. This review describes the availability and limitations of current treatment strategies and highlights insights into the advancement of future approaches using next-generation nanomedicines to manage retinal diseases.

Polymer- and lipid-based nanocarriers for ocular drug delivery: Current status and future perspectives

Ocular diseases seriously affect patients' vision and life quality, with a global morbidity of over 43 million blindness. However, efficient drug delivery to treat ocular diseases, particularly intraocular disorders, remains a huge challenge due to multiple ocular barriers that significantly affect the ultimate therapeutic efficacy of drugs. Recent advances in nanocarrier technology offer a promising opportunity to overcome these barriers by providing enhanced penetration, increased retention, improved solubility, reduced toxicity, prolonged release, and targeted delivery of the loaded drug to the eyes. This review primarily provides an overview of the progress and contemporary applications of nanocarriers, mainly polymer- and lipid-based nanocarriers, in treating various eye diseases, highlighting their value in achieving efficient ocular drug delivery. Additionally, the review covers the ocular barriers and administration routes, as well as the prospective future developments and challenges in the field of nanocarriers for treating ocular diseases.

Nano-based eye drop: Topical and noninvasive therapy for ocular diseases

Eye drops are the most accessible therapy for ocular diseases, while inevitably suffering from their lower bioavailability which highly restricts the treatment efficacy. The introduction of nanotechnology has attracted considerable interest as it has advantages over conventional ones such as prolonged ocular surface retention time and enhanced ocular barrier penetrating properties, and achieving higher bioavailability and improved treatment efficacy. This review describes various ocular diseases treated with eye drops as well as the physiological and anatomical ocular barriers faced with through drug administration. It also summarizes the recent advances regarding the utilization of nanotechnology in developing eye drops, and how to optimize the nanocarrier-based ocular drug delivery systems. The prospective future research directions for nano-based eye drops are also discussed here.

HIF in Gastric Cancer: Regulation and Therapeutic Target

HIF means hypoxia-inducible factor gene family, and it could regulate various biological processes, including tumor development. In 2021, the FDA approved the new drug Welireg for targeting HIF-2a, and it is mainly used to treat von Hippel-Lindau syndrome, which demonstrated its good prospects in tumor therapy. As the fourth deadliest cancer worldwide, gastric cancer endangers the health of people all across the world. Currently, there are various treatment methods for patients with gastric cancer, but the five-year survival rate of patients with advanced gastric cancer is still not high. Therefore, here we reviewed the regulatory role and target role of HIF in gastric cancer, and provided some references for the treatment of gastric cancer.