Original articleAntiangiogenic activity of PLGA-Lupeol implants for potential intravitreal applications
Graphical abstract
Introduction
Angiogenesis is a natural process that occurs in the human body during fetal development or as a response to tissue damage, as part of wound healing process and renewing the blood flux in damage areas [1], [2]. When the human body loses its capacity to maintain adequately the equilibrium of angiogenic mediators, some diseases can develop, including arthritis, cancer, endometriosis, psoriasis, macular degeneration related to age and proliferative diabetic retinopathy [3], [4]. Macular degeneration related to age is the main cause of blindness in persons older than 60 years in industrialized countries [5]. The prevalence of blindness can vary between 10 and 15% among affected persons and estimates have shown a significantly rates increase until 2030 [6]. Currently, available treatments are limited to palliatives such as photodynamic therapy, intravitreal injections with corticoids, antiangiogenic compounds applied directly into eye and laser photocoagulation [7], [8], [9], [10]. The proliferative diabetic retinopathy is characterized by new important vascularization in retina, following to intravitreal interface, with possible loses of normal visual characteristics mainly due to traditional retinal detachment. In this sense, the inhibition of angiogenesis can be considered an important strategy to treat these intraocular diseases and have been explored in many published works [11], [12], [13], [14].
Lupeol is a natural pentaciclic triterpene with a lupane scaffold that can be found in diverse vegetables, including white cabbage, red pepper, cucumber, tomatoes, carrots, peas, and soy. Moreover, administration of lupeol does not result in systemic toxicity in animal models in doses ranging from 30 to 2000 mg kg−1 [15]. Triterpene can be isolated from medicinal plants, i.e. Celastraceae family plants, displaying clinically relevant biological properties related to inflammation, arthritis, cardiovascular disorders, cancer and wound healing processes [16], [17], [18]. You et al. [19] evaluated the antiangiogenic activity of lupeol on a tube-like formation assay using HUVEC cells (Human umbilical vein endothelial cells). The results revealed lupeol capacity to inhibit 80% of angiogenic processes at a non-toxic dose of 50 μg mL−1, whereas lower doses showed a significant reduction in antiangiogenic activity reaching only 40% of initial values. Other studies using an endothelial cell model have indicated that triterpenes can modulate growth factors such VEGF (Vascular endothelial growth factor) and are capable of inducing cellular differentiation, seeking to inhibit the vascular tissue growth, displaying an important antiangiogenic effect [20], [21], [22], [23].
Due to anatomical and physiologic characteristics of the eye, administration of ophthalmic medicines is difficult and many studies showed that only approximately 5% of the administrated dose are absorbed by intraocular tissues, making the treatment unfeasible for diseases located in posterior segment of the eye. Other available treatments require the use of high drug doses or are too invasive as intravitreal injections, exhibiting great risks and potentially serious side effects to the patient [24], [25], [26]. Seeking to overcome this negative scenario, research has been dedicated to developing new drug delivery systems, such as polymeric implants with the overall goal to be more selective and achieve favorable bioavailability profiles through sustained releasing of the therapeutic cargo [27], [28]. Such systems offer many advantages, including favorable patient compliance, biocompatibility, predictable biodegradation kinetic and mechanical resistance in various intravitreal applications [29], [30], [31]. In order to mitigate the cumulative risks associated with repeated intravitreal injections, some implantable polymeric systems have been approved by FDA and currently available, for example: Ozurdex® (Dexamethasone Intravitreal Implant); Iluvien® (Fluocinolone acetonide intravitreal implant) and Triesence® (Triamcinolone acetonide). In these systems, any cytotoxicity was observed as well as significant antiangiogenic activity were obtained, displaying the applicability of these systems in intravitreal applications. However, at present, no steroid has achieved US FDA approval for the treatment of pathologies associated to angiogenesis (except for ranibizumab, a monoclonal antibody).
In this work, we aimed to evaluate the anti-angiogenesis activity of PLGA ocular implants containing the lupeol, a non-steroid compound, in both in vitro and in vivo models.
Section snippets
Chemical and reagents
Poly (d,l-lactide-co-glycolide) in ratio of 75:25 [PLGA (75:25)] was purchased from Boehringer Ingelheim (Germany). All the solvents and reagents used in buffer solutions, in the preparation of the implants, and mobile phase were HPLC or analytical grade. Water was distilled, deionized and filtered through a 0.22 μm filter (Millipore, USA).
Lupeol extraction
Dried and pulverized stem of Maytenus salicifolia (2525.9 g) were subjected to exhaustive maceration in n-hexane at room temperature, yielding 14.7 g of hexane
Statistical analysis
The mean values and standard deviation were calculated. The statistical parameters were analyzed through ANOVA followed post-test of Tukey or Bonferroni where p ≤ 0.05 was considered as statistically significant. The Mann–Whitney non-parametric test was used to compare outcomes in both groups. The unpaired-test was used to compare outcomes of percent blood vessels in the CAM study. Values of p ≤ 0.05 were considered to be statistically significant. Interrelation between dark-adapted b-wave
Lupeol characterization
Lupeol was obtained as a white solid and its molecular structure are presented in Fig. 1. The IR spectrum of Lupeol presented absorption bands at 3313 cm−1 (OH), 1638 (CC) and 878 (CH). The 13C NMR spectral data were similar to the one related by Kundu [34].
Differential scanning calorimetry (DSC)
DSC curves for lupeol, blank PLGA 75:25 and lupeol-loaded PLGA ocular implants are presented in Fig. 2 (respectively A–C). Lupeol presented during the heating two important peaks that were correlated to phase transitions and melting point.
Conclusion
Polymeric implants constituted by PLGA polymer and lupeol at 30% (w/w) were prepared and physicochemical characterized, revealing existing only physical interactions among its contents. These findings demonstrate that lupeol molecular structure was maintained unaltered in polymeric matrix and through normal biodegradation can be released without modifications. Although lupeol presents antitumor and antiangiogenic effects in different models, it is clear these effects do not necessarily derive
Acknowlegdments
The authors would like to thank CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) and FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais) for their financial support.
References (51)
- et al.
Glypican-1 nanoliposomes for potentiating growth factor activity in therapeutic angiogenesis
Biomaterials
(2016) - et al.
Differential regulation of angiogenesis using degradable VEGF-binding microspheres
Biomaterials
(2016) - et al.
Diabetic retinopathy and transcriptional regulation of a small molecular weight G-Protein, Rac1
Exp. Eye Res.
(2016) - et al.
Anti-inflammatory role of sesamin in STZ induced mice model of diabetic retinopathy
J. Neuroimmunol.
(2016) - et al.
Long-term outcomes of treatment of neovascular age-related macular degeneration: data from an observational study
Ophthalmology
(2015) - et al.
Age-related macular degeneration and risk of total and cause-specific mortality over 15 years
Maturitas
(2016) - et al.
Photodynamic therapy in VEGF inhibition non-responders-Pharmacogenetic study in age-related macular degeneration assessed with swept-source optical coherence tomography
Photodiagn. Photodyn. Ther.
(2016) - et al.
Intravitreal bevacizumab in AMD complicated by submacular hemorrhage
J. Fr. D’ophtalmol.
(2016) - et al.
Observation on health quality of life before and after the injection of antiangiogenic drug in vitreous cavity to patients with wet age-related macular degeneration
Chin. Nurs. Res.
(2015) - et al.
Intravitreal bevacizumab for treatment of neovascular glaucoma. Report of 20 cases
J. Fr. Dèophtalmol.
(2009)
Impaired RBC deformability is associated with diabetic retinopathy in patients with type 2 diabetes
Diabetes Metab.
Multimodal characterization of proliferative diabetic retinopathy reveals alterations in outer retinal function and structure
Ophthalmology
Intravitreal bevacizumab increases intraocular interleukin-6 levels at 1 day after injection in patients with proliferative diabetic retinopathy
Cytokine
Beneficial health effects of lupeol triterpene: a review of preclinical studies
Life Sci.
Evaluation of the antiulcerogenic activity of Maytenus robusta (Celastraceae) in different experimental ulcer models
J. Ethnopharmacol.
Wound healing activity and docking of glycogen-synthase-kinase-3-beta-protein with isolated triterpenoid lupeol in rats
Phytomedicine
Anti-angiogenic activity of triterpene acids
Cancer Lett.
Modulation of angiogenic factors by ursolic acid
Biochem. Biophys. Res. Commun.
Effects of ursolic acid on different steps of the angiogenic process
Biochem. Biophys. Res. Commun.
Complications of intravitreal steroid injections
Optometry
Intravitreal tissue plasminogen activator, ranibizumab, and gas injection for submacular hemorrhage in polypoidal choroidal vasculopathy
Ophthalmology
Dexamethasone-loaded poly(epsilon-caprolactone) intravitreal implants: a pilot study
Eur. J. Pharm. Biopharm.
Intraocular pressure monitoring post intravitreal steroids: a systematic review
Surv. Ophthalmol.
A review of implantable intravitreal drug delivery technologies for the treatment of posterior segment eye diseases
J. Pharm. Sci.
Implants for drug delivery to the posterior segment of the eye: a focus on stimuli-responsive and tunable release systems
J. Control. Release
Cited by (17)
Molecular pharmacology and therapeutic advances of the pentacyclic triterpene lupeol
2022, PhytomedicineCitation Excerpt :The therapeutic application of lupeol is limited by its poor solubility, bioavailability, and drug delivery (Zhang et al., 2019b). Though poor drug delivery along with poor bioavailability and distribution, anticancer activity was reported as the major limitation of lupeol development at the pharmaceutical level, numerous novel approaches of targeted drug delivery and innovative methods are developed, including lupeol entrapped chitosan-gelatin hydrogel films (Patel et al., 2018), PGLA-lupeol implants (Soares et al., 2017), lupeol-loaded PEGylated liposomes (Zhang et al., 2019b), NF-κB-PLGA nanoparticles loaded with lupeol (Cháirez-Ramírez et al., 2015), solid lipid nanoparticles (SLN) (Priyanka et al., 2017), nanoemulsion preconcentrate (NPs) (Jyotshna et al., 2020), gold nanoparticles (Bociort et al., 2020) along with various lupeol derivatives (Table 13). The various challenges concerning pharmacokinetics parameters along with new strategies are presented in Table 13.
Wearable and implantable devices for drug delivery: Applications and challenges
2022, BiomaterialsCitation Excerpt :This ocular implant showed evident inhibition in the proliferation and migration of in vitro human umbilical vein endothelial cells (HUVECs) and significantly reduced the formation of new vesicles without impacting cellular viability. Further, when tested on the chorioallantoic membrane model, the developed implant significantly reduced (more than 30% in comparison to untreated control) angiogenetic activity similar to that of bevacizumab (a clinically approved anti-VEGF monoclonal antibody) [198]. Another group demonstrated the potential of 3D printed alginate and PCL-based core-shell rod-like implants to facilitate localized co-delivery of dexamethasone and bevacizumab, encapsulated in alginate core and PCL shell, respectively.
Intravitreal lupeol: A new potential therapeutic strategy for noninfectious uveitis
2021, Biomedicine and PharmacotherapyCitation Excerpt :Lupeol is reported to present an extensive range of pharmacological properties, including anti-inflammatory, antimicrobial, anti-angiogenic, antidiabetic, antioxidant, antineoplastic. In addition, it has potential to attenuate neuroinflammation and neurodegeneration and to protect heart, liver, and skin [8–10]. It is also able to attenuate development of cataract in rats [11].
Novel hybrid lipid nanocapsules loaded with a therapeutic monoclonal antibody – Bevacizumab – and Triamcinolone acetonide for combined therapy in neovascular ocular pathologies
2021, Materials Science and Engineering CCitation Excerpt :Angiogenesis is a complex process that involves degradation of the basement membrane, proliferation and migration of endothelial cells to the intracellular matrix; followed by alignment and rearrangement of endothelial cells in a tubular structure and formation of a new basement membrane. Considering that proliferation and cellular migration are basic endothelial cell activities which greatly influence vessel formation [37], assays of cellular migration and tube formation were performed to evaluate in vitro antiangiogenic properties of BVZ-TA-LNC. The main purpose was to determine whether BVZ still had bioactivity after being attached to the LNC surface.
Recent advances in intraocular sustained-release drug delivery devices
2019, Drug Discovery TodayCitation Excerpt :The most widely used in both literature and commercially is PLGA. It can be engineered to achieve sustained release for several small molecules [15–17]. Commercially, PLGA is co-extruded with dexamethasone in Ozurdex® (Allergan) to achieve 6 months of drug delivery.
In Situ Formation of Injectable Gelatin Methacryloyl (GelMA) Hydrogels for Effective Intraocular Delivery of Triamcinolone Acetonide
2023, International Journal of Molecular Sciences