Nanoparticle-based drug delivery to the vagina: a review

Vaginal Administration of Contraceptives

While contraceptive drugs have enabled many people to decide when they want to have a baby, more than 100 million unintended pregnancies each year in the world may indicate the contraceptive requirement of many people has not been well addressed yet. The vagina is a well-established and practical route for the delivery of various pharmacological molecules, including contraceptives. This review aims to present an overview of different contraceptive methods focusing on the vaginal route of delivery for contraceptives, including current developments, discussing the potentials and limitations of the modern methods, designs, and how well each method performs for delivering the contraceptives and preventing pregnancy.

Engineering the drug carrier biointerface to overcome biological barriers to drug delivery

Micro and nanoscale drug carriers must navigate through a plethora of dynamic biological systems prior to reaching their tissue or disease targets. The biological obstacles to drug delivery come in many forms and include tissue barriers, mucus and bacterial biofilm hydrogels, the immune system, and cellular uptake and intracellular trafficking. The biointerface of drug carriers influences how these carriers navigate and overcome biological barriers for successful drug delivery. In this review, we examine how key material design parameters lead to dynamic biointerfaces and improved drug delivery across biological barriers. We provide a brief overview of approaches used to engineer key physicochemical properties of drug carriers, such as morphology, surface chemistry, and topography, as well as the development of dynamic responsive materials for barrier navigation. We then discuss essential biological barriers and how biointerface engineering can enable drug carriers to better navigate and overcome these barriers to drug delivery.

Lymph-directed immunotherapy - Harnessing endogenous lymphatic distribution pathways for enhanced therapeutic outcomes in cancer

The advent of immunotherapy has revolutionised the treatment of some cancers. Harnessing the immune system to improve tumour cell killing is now standard clinical practice and immunotherapy is the first line of defence for many cancers that historically, were difficult to treat. A unifying concept in cancer immunotherapy is the activation of the immune system to mount an attack on malignant cells, allowing the body to recognise, and in some cases, eliminate cancer. However, in spite of a significant proportion of patients that respond well to treatment, there remains a subset who are non-responders and a number of cancers that cannot be treated with these therapies. These limitations highlight the need for targeted delivery of immunomodulators to both tumours and the effector cells of the immune system, the latter being highly concentrated in the lymphatic system. In this context, macromolecular therapies may provide a significant advantage. Macromolecules are too large to easily access blood capillaries and instead typically exhibit preferential uptake via the lymphatic system. In contexts where immune cells are the therapeutic target, particularly in cancer therapy, this may be advantageous. In this review, we examine in brief the current immunotherapy approaches in cancer and how macromolecular and nanomedicine strategies may improve the therapeutic profiles of these drugs. We subsequently discuss how therapeutics directed either by parenteral or mucosal administration, can be taken up by the lymphatics thereby accessing a larger proportion of the body's immune cells. Finally, we detail drug delivery strategies that have been successfully employed to target the lymphatics.

Design of nanomaterials for applications in maternal/fetal medicine

Pregnancy complications are commonplace and the challenges of treatment during pregnancy with few options available pose a risk to the health of both the mother and baby. Patients suffering from conditions such as preeclampsia, placenta accreta, and intrauterine growth restriction have few treatment options apart from emergency caesarean section. Fortunately, researchers are beginning to develop nanomedicine-based therapies that could be utilized to treat conditions affecting the mother, placenta, or fetus to improve the prognosis for mothers and their unborn children. This review summarizes the field's current understanding of nanoparticle biodistribution and therapeutic effect following systemic or vaginal administration and overviews the design parameters researchers should consider when developing nanomedicines for maternal/fetal health. It also describes safety considerations for nanomedicines to limit undesirable maternal or fetal side effects and discusses future work that should be performed to advance nanomedicine for maternal/fetal health. With additional development and implementation, the application of nanomedicine to treat pregnancy complications may mitigate the need for emergency caesarean sections and allow pregnancies to extend to term.

Anti-α4β7 monoclonal antibody-conjugated nanoparticles block integrin α4β7 on intravaginal T cells in rhesus macaques

Intravenous administration of anti-α₄β₇ monoclonal antibody in macaques decreases simian immunodeficiency virus (SIV) vaginal infection and reduces gut SIV loads. Because of potential side effects of systemic administration, a prophylactic strategy based on mucosal administration of anti-α₄β₇ antibody may be safer and more effective. With this in mind, we developed a novel intravaginal formulation consisting of anti-α₄β₇ monoclonal antibody-conjugated nanoparticles (NPs) loaded in a 1% hydroxyethylcellulose (HEC) gel (NP-α₄β₇ gel). When intravaginally administered as a single dose in a rhesus macaque model, the formulation preferentially bound to CD4⁺ or CD3⁺ T cells expressing high levels of α₄β₇, and occupied ~40% of α₄β₇ expressed by these subsets and ~25% of all cells expressing α₄β₇ Blocking of the α₄β₇ was restricted to the vaginal tract without any changes detected systemically.

An effective vaginal gel to deliver CRISPR/Cas9 system encapsulated in poly (β-amino ester) nanoparticles for vaginal gene therapy

BACKGROUND

Gene therapy has held promises for treating specific genetic diseases. However, the key to clinical application depends on effective gene delivery.

METHODS

Using a large animal model, we developed two pharmaceutical formulations for gene delivery in the pigs' vagina, which were made up of poly (β-amino ester) (PBAE)-plasmid polyplex nanoparticles (NPs) based two gel materials, modified montmorillonite (mMMT) and hectorite (HTT).

FINDINGS

By conducting flow cytometry of the cervical cells, we found that PBAE-GFP-NPs-mMMT gel was more efficient than PBAE-GFP-NPs-HTT gel in delivering exogenous DNA intravaginally. Next, we designed specific CRISPR/SpCas9 sgRNAs targeting porcine endogenous retroviruses (PERVs) and evaluated the genome editing efficacy in vivo. We discovered that PERV copy number in vaginal epithelium could be significantly reduced by the local delivery of the PBAE-SpCas9/sgRNA NPs-mMMT gel. Comparable genome editing results were also obtained by high-fidelity version of SpCas9, SpCas9-HF1 and eSpCas9, in the mMMT gel. Further, we confirmed that the expression of topically delivered SpCas9 was limited to the vagina/cervix and did not diffuse to nearby organs, which was relatively safe with low toxicity.

INTERPRETATION

Our data suggested that the PBAE-NPs mMMT vaginal gel is an effective preparation for local gene therapy, yielding insights into novel therapeutic approaches to sexually transmitted disease in the genital tract.

FUNDING

This work was supported by the National Science and Technology Major Project of the Ministry of science and technology of China (No. 2018ZX10301402); the National Natural Science Foundation of China (81761148025, 81871473 and 81402158); Guangzhou Science and Technology Programme (No. 201704020093); National Ten Thousand Plan-Young Top Talents of China, Fundamental Research Funds for the Central Universities (17ykzd15 and 19ykyjs07); Three Big Constructions-Supercomputing Application Cultivation Projects sponsored by National Supercomputer Center In Guangzhou; the National Research FFoundation (NRF) South Africa under BRICS Multilateral Joint Call for Proposals; grant 17-54-80078 from the Russian Foundation for Basic Research.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Preparation and Characterization of Nanostructured Lipid Carriers for Improved Topical Drug Delivery: Evaluation in Cutaneous Leishmaniasis and Vaginal Candidiasis Animal Models

The present study aimed to develop, characterize and evaluate the amphotericin B-loaded nanostructured lipid carriers (AmB-NLCs) for topical treatment of cutaneous leishmaniasis (CL) and vulvovaginal candidiasis (VVC). AmB-NLCs were characterized for particle size, zeta potential, encapsulation efficiency and surface morphology. Prepared NLCs were also characterized for in vitro drug release, ex vivo skin permeation and deposition before evaluating their in vitro and in vivo efficacy. Cytotoxicity of NLCs was assessed on MRC-5 cells, whereas skin irritation potential was evaluated in vivo using rats. Significant accumulation of drug in to the skin supported the topical application potential of drug-loaded NLCs. Encapsulation of AmB in NLCs resulted in enhanced in vitro potency against promastigotes and intracellular amastigotes of L. major JISH 118 (IC50 ± SEM = 0.02 ± 0.1 μM for both) compared with free drug (IC50 ± SEM = 0.15 ± 0.2 & 0.14 ± 0.0, respectively). Similar improved potency of AmB-NLCs was also observed for other Leishmania and fungal strains compared with drug solution. Topical application of AmB-NLCs on L. major-infected BALB/c mice caused a significant reduction in parasite burden per mg of lesion (65 × 108 ± 13) compared with the control group (> 167.8 × 108 ± 11). Topical AmB-NLCs gel demonstrated superior efficacy in the vaginal C. albicans rat model for VVC as compared with plain AmB gel. Moreover, results of in vitro cytotoxicity assay and in vivo skin irritation test confirmed AmB-NLCs to be non-toxic and safe for topical use. In conclusion, NLCs may have promising potential as carrier for topical treatment of various conditions of skin and mucosa.

In vitro anti-inflammatory potential of phloretin microemulsion as a new formulation for prospective treatment of vaginitis

Phloretin is a promising polyphenolic compound known for its anti-inflammatory properties, but its poor solubility and low bioavailability hinder its clinical applicability. Till current date, its potential in the treatment of vaginitis has not been explored, and only very few papers reported its formulation as nanoparticles to overcome its pharmaceutical challenges. Therefore, in the current study, phloretin was formulated in microemulsion of 11 nm size, and its in vitro anti-inflammatory properties were explored using histamine and IL-6 release inhibition assays, protease inhibition assay, and membrane stabilization potential. The anti-inflammatory properties of phloretin microemulsion were compared to the drug phloretin, and the reference standard non-steroidal anti-inflammatory drugs (NSAIDs). Results proved that both phloretin and phloretin microemulsion significantly inhibited the release of the inflammatory mediators histamine and IL-6, inhibited protease action, and exhibited membrane stabilization potential. Phloretin microemulsion exhibited comparable anti-inflammatory properties to the NSAIDs diclofenac and indomethacin, and, hence, it can be delineated as a promising therapeutic tool in topical treatment of vaginal inflammation.

Engineered reproductive tissues

Engineered male and female biomimetic reproductive tissues are being developed as autonomous in vitro units or as integrated multi-organ in vitro systems to support germ cell and embryo function, and to display characteristic endocrine phenotypic patterns, such as the 28-day human ovulatory cycle. In this Review, we summarize how engineered reproductive tissues facilitate research in reproductive biology, and overview strategies for making engineered reproductive tissues that might eventually allow the restoration of reproductive capacity in patients.

Aerosol Delivery of Synthetic mRNA to Vaginal Mucosa Leads to Durable Expression of Broadly Neutralizing Antibodies against HIV

There is a clear need for low-cost, self-applied, long-lasting approaches to prevent human immunodeficiency virus (HIV) infection in both men and women, even with the advent of pre-exposure prophylaxis (PrEP). Broadly neutralizing antibodies represent an option to improve HIV prophylaxis, but intravenous delivery, cold-chain stability requirements, low cervicovaginal concentrations, and cost may preclude their use. Here, we present an approach to express the anti-GP120 broadly neutralizing antibody PGT121 in the primary site of inoculation, the female reproductive tract, using synthetic mRNA. Expression is achieved through aerosol delivery of unformulated mRNA in water. We demonstrated high levels of antibody expression for over 28 days with a single mRNA administration in the reproductive tract of sheep. In rhesus macaques, neutralizing antibody titers in secretions developed within 4 h and simian-HIV (SHIV) infection of ex vivo explants was prevented. Persistence of PGT121 in vaginal secretions and epithelium was achieved through the incorporation of a glycosylphosphatidylinositol (GPI) anchor into the heavy chain of the antibody. Overall, we present a new paradigm to deliver neutralizing antibodies to the female reproductive tract for the prevention of HIV infections.

Drug Delivery Systems for Diabetes Treatment

BACKGROUND

Insulin is essential for the treatment of Type 1 diabetes mellitus (T1DM) and is necessary in numerous cases of Type 2 diabetes mellitus (T2DM). Prolonged administration of anti-diabetic therapy is necessary for the maintenance of the normal glucose levels and thereby preventing vascular complications. A better understanding of the disease per se and the technological progress contribute to the development of new approaches with the aim to achieve better glycemic control.

OBJECTIVE

Current therapies for DM are faced with some challenges. The purpose of this review is to analyze in detail the current trends for insulin delivery systems for diabetes treatment.

RESULTS

Contemporary ways have been proposed for the management of both types of diabetes by adequate application of drug via subcutaneous, buccal, oral, ocular, nasal, rectal and pulmonary ways. Development of improved oral administration of insulin is beneficial regarding mimicking physiological pathway of insulin and minimizing the discomfort of the patient. Various nanoparticle carriers for oral and other ways of insulin delivery are currently being developed. Engineered specific properties of nanoparticles (NP): controlling toxicity of NP, stability and drug release, can allow delivery of higher concentration of the drug to the desired location.

CONCLUSIONS

The successful development of any drug delivery system relies on solving three important issues: toxicity of nanoparticles, stability of nanoparticles, and desired drug release rate at targeted sites. The main goals of future investigations are to improve the existing therapies by pharmacokinetic modifications, development of a fully automatized system to mimic insulin delivery by the pancreas and reduce invasiveness during admission.

Sustained-release Griffithsin nanoparticle-fiber composites against HIV-1 and HSV-2 infections

Human immunodeficiency virus (HIV-1) and herpes simplex virus 2 (HSV-2) affect hundreds of millions of people worldwide. The antiviral lectin, Griffithsin (GRFT), has been shown to be both safe and efficacious against HSV-2 and HIV-1 infections in vivo. The goal of this work was to develop a multilayered nanoparticle (NP)-electrospun fiber (EF) composite to provide sustained-release of GRFT, and to examine its safety and efficacy in a murine model of lethal HSV-2 infection. Composites were fabricated from polycaprolactone (PCL) fibers surrounding polyethylene oxide (PEO) fibers that incorporated methoxy poly(ethylene glycol)-b-poly(lactide-co-glycolide) (mPEG-PLGA) GRFT NPs. GRFT loading and release were determined via ELISA, showing that NP-EF composites achieved high GRFT loading, and provided sustained-release of GRFT for up to 90 d. The in vitro efficacy of GRFT NP-EFs was assessed using HIV-1 pseudovirus assays, demonstrating complete in vitro protection against HIV-1 infection. Additionally, sustained-release NP-EFs, administered 24 h prior to infection, prevented against a lethal dose of HSV-2 infection in a murine model. In parallel, histology and cytokine expression from murine reproductive tracts and vaginal lavages collected 24 and 72 h post-administration were similar to untreated mice, suggesting that NP-EF composites may be a promising and safe sustained-delivery platform to prevent HSV-2 infection. Future work will evaluate the ability to provide prolonged protection against multiple virus challenges, and different administration times with respect to infection.

Nanocarriers For Vaginal Drug Delivery

BACKGROUND

Vaginal drug delivery approach represents one of the imperative strategies for local and systemic delivery of drugs. The peculiar dense vascular networks, mucus permeability, and range of physiological characteristics of the vaginal cavity have been exploited for therapeutic benefit. Furthermore, the vaginal drug delivery has been curtailed due to the influence of different physiological factors like acidic pH, constant cervical secretion, microflora, cyclic changes during periods along with turnover of mucus of varying thickness.

OBJECTIVE

This review highlights advancement of nanomedicine and its prospective progress towards the clinic.

METHODS

Relevant literature reports and patents related to topics are retrieved and used.

RESULT

The extensive literature search and patent revealed that nanocarriers are efficacious over conventional treatment approaches.

CONCLUSION

Recently, nanotechnology based drug delivery approach has promised better therapeutic outcomes by providing enhanced permeation and sustained drug release activity. Different nanoplatforms based on drugs, peptides, proteins, antigens, hormones, nucleic material, and microbicides are gaining momentum for vaginal therapeutics.

Montmorillonite-based polyacrylamide hydrogel rings for controlled vaginal drug delivery

Vaginal drug delivery is regarded as a promising route against women-related health issues such as unwanted pregnancies and sexually transmitted infections. However, only a very few studies have been reported on the use of hydrogel rings with low cytotoxicity for vaginal drug delivery applications. Moreover, the effect of nanoparticles on hydrogel vaginal rings has not been clearly evaluated. To overcome these challenges, we hereby developed nanocomposite hydrogel rings based on polyacrylamide-sodium carboxymethyl cellulose-montmorillonite nanoparticles in the ring-shaped aluminum mold for controlled drug delivery. The hydrogel rings were synthesized by using N,N'-methylene bisacrylamide, N,N,N',N'-tetramethyl ethylene diamine, and ammonium persulfate, as a crosslinker, accelerator, and initiator, respectively. The obtained rings were 5.5 cm in diameters and 0.5 cm in rims. Chemical structures of the nanocomposite rings were confirmed by Fourier transform infrared, and Nuclear Magnetic Resonance spectroscopies. Additionally, the swelling ratio of hydrogels was appeared to be adjusted by the introduction of nanoparticles. In vitro release experiment of methylene blue, as a hydrophilic model drug, revealed that the nanocomposite rings could not only reduce burst effect (almost more than twice), but also achieve prolonged release for 15 days in the vaginal fluid simulant which mimic the vaginal conditions at pH of almost 4.2, and a temperature of 37 °C. Importantly, the resultant hydrogel rings with or without various concentrations of montmorillonite showed low cytotoxicity toward human skin fibroblasts. Furthermore, different antibacterial activities against Escherichia coli were observed for various concentrations of montmorillonite in hydrogels. These results suggest the great potential of montmorillonite-based hydrogel rings for vaginal drug delivery.

Utilizing Liposomal Quercetin and Gallic Acid in Localized Treatment of Vaginal Candida Infections

Vulvovaginal candidiasis (VVC) is a widely spread fungal infection that causes itching, pain and inflammation at the vaginal site. Although common, currently available treatment suffers from limited efficacy and high recurrence. In addition, the growing problem of resistance to azole drugs used in current treatments emphasizes the need for superior treatment options. Antimicrobial polyphenols are an attractive approach offering multitargeting therapy. We aimed to develop novel liposomes for simultaneous delivery of two polyphenols (quercetin, Q, and gallic acid, GA) that, when released within the vaginal cavity, act in synergy to eradicate infection while alleviating the symptoms of VVC. Q was selected for its anti-itching and anti-inflammatory properties, while GA for its reported activity against Candida. Novel liposomes containing only Q (LP-Q), only GA (LP-GA) or both polyphenols (LP-Q+GA) were in the size range around 200 nm. Q was efficiently entrapped in both LP-Q and in LP-Q+GA (85%) while the entrapment of GA was higher in LP-Q+GA (30%) than in LP-GA (25%). Liposomes, especially LP-Q+GA, promoted sustained release of both polyphenols. Q and GA acted in synergy, increasing the antioxidant activities of a single polyphenol. Polyphenol-liposomes were not cytotoxic and displayed stronger anti-inflammatory effects than free polyphenols. Finally, LP-GA and LP-Q+GA considerably reduced C. albicans growth.

A vaginal nanoformulation of a SphK inhibitor attenuates lipopolysaccharide-induced preterm birth in mice

Aim: Previously, we have shown that inhibition of SphK by the SphK inhibitor-II (SKI II) prevents lipopolysaccharide-induced preterm birth in mice. The aim of this study was to develop a vaginal self-nanoemulsifying drug-delivery system (SNEDDS) for SKI II. Materials & methods: A SKI II-loaded SNEDDS was characterized and tested in a murine preterm birth model. Results: The SNEDDS immediately formed a gel and then slowly emulsified to nanoglobules with over 500-fold enhancement of SKI II solubility at vaginal pH. Intravaginal administration of the SKI II SNEDDS significantly decreased lipopolysaccharide-induced preterm birth in mice. Conclusion: A vaginal nanoformulation of SKI II represents a novel, noninvasive approach to prevent preterm birth.

Current Advances in Chitosan Nanoparticles Based Drug Delivery and Targeting

Nanoparticles (NPs) have been found to be potential targeted and controlled release drug delivery systems. Various drugs can be loaded in the NPs to achieve targeted delivery. Chitosan NPs being biodegradable, biocompatible, less toxic and easy to prepare, are an effective and potential tool for drug delivery. Chitosan is natural biopolymer which can be easily functionalized to obtain the desired targeted results and is also approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration [US FDA]). Various methods for preparation of chitosan NPs include, ionic cross-linking, covalent cross-linking, reverse micellar method, precipitation and emulsion-droplet coalescence method. Chitosan NPs are found to have plethora of applications in drug delivery diagnosis and other biological applications. The key applications include ocular drug delivery, per-oral delivery, pulmonary drug delivery, nasal drug delivery, mucosal drug delivery, gene delivery, buccal drug delivery, vaccine delivery, vaginal drug delivery and cancer therapy. The present review describes the formation of chitosan, synthesis of chitosan NPs and their various applications in drug delivery.

Injectable Vaginal Hydrogels as a Multi-Drug Carrier for Contraception

Injectable intravaginal hydrogels could deliver drugs systemically without hepatic first pass effect. This paper focuses on the contraceptive function of an injectable temperature-sensitive four-arm star-shaped poly(D,L-lactic-co-glycolic acid)-b-methoxy poly(ethylene glycol) (4sPLGA-mPEG) block copolymer hydrogels as a carrier of three drugs. In vitro controlled release profiles were investigated via HPLC, and it showed that the cumulative release amounts of indomethacin (IMC), gestodene (GSD), and ethinyl estradiol (EE) from copolymer hydrogels could be regulated by adjusting the lactide/glycolide (LA/GA) mol ratio. In addition, in vitro release profiles of IMC, GSD, and EE well corresponded to Higuchi model. The acute toxicity of copolymer hydrogels loaded with different dosage contents multi-drug was evaluated in vivo. As to the high dosage group, the uterus was hydropic at day 1 and ulcerated at day 5, followed with intestinal adhesion. Regarding the middle dosage group, no festering of tissues was observed and, blood coagulum existed in the uterus at different days. For low dosage group, no significant tissue necrosis was found. Finally, the antifertility experiments confirmed that hydrogels loaded with the multi-drug had an excellent contraceptive effect. The above results indicated that injectable copolymer hydrogel as a multi-drug carrier was promising as a novel contraception method.

Relating Advanced Electrospun Fiber Architectures to the Temporal Release of Active Agents to Meet the Needs of Next-Generation Intravaginal Delivery Applications

Electrospun fibers have emerged as a relatively new delivery platform to improve active agent retention and delivery for intravaginal applications. While uniaxial fibers have been explored in a variety of applications including intravaginal delivery, the consideration of more advanced fiber architectures may offer new options to improve delivery to the female reproductive tract. In this review, we summarize the advancements of electrospun coaxial, multilayered, and nanoparticle-fiber architectures utilized in other applications and discuss how different material combinations within these architectures provide varied durations of release, here categorized as either transient (within 24 h), short-term (24 h to one week), or sustained (beyond one week). We seek to systematically relate material type and fiber architecture to active agent release kinetics. Last, we explore how lessons derived from these architectures may be applied to address the needs of future intravaginal delivery platforms for a given prophylactic or therapeutic application. The overall goal of this review is to provide a summary of different fiber architectures that have been useful for active agent delivery and to provide guidelines for the development of new formulations that exhibit release kinetics relevant to the time frames and the diversity of active agents needed in next-generation multipurpose applications.

Antiretroviral Hydrophobic Core Graft-Copolymer Nanoparticles: The Effectiveness against Mutant HIV-1 Strains and in Vivo Distribution after Topical Application

PURPOSE

Developing and testing of microbicides for pre-exposure prophylaxis and post-exposure protection from HIV are on the list of major HIV/AIDS research priorities. To improve solubility and bioavailability of highly potent anti-retroviral drugs, we explored the use of a nanoparticle (NP) for formulating a combination of two water-insoluble HIV inhibitors.

METHODS

The combination of a non-nucleoside HIV reverse transcriptase inhibitor (NNRTI), Efavirenz (EFV), and an inhibitor of HIV integrase, Elvitegravir (ELV) was stabilized with a graft copolymer of methoxypolyethylene glycol-polylysine with a hydrophobic core (HC) composed of fatty acids (HC-PGC). Formulations were tested in TZM-bl cells infected either with wild-type HIV-1_IIIB, or drug-resistant HIV-1 strains. In vivo testing of double-labeled NP formulations was performed in female rats after a topical intravaginal administration using SPECT/CT imaging and fluorescence microscopy.

RESULTS

We observed a formation of stable 23-30 nm NP with very low cytotoxicity when EFV and ELV were combined with HC-PGC at a 1:10 weight ratio. For NP containing ELV and EFV (at 1:1 by weight) we observed a remarkable improvement of EC50 of EFV by 20 times in the case of A17 strain. In vivo imaging and biodistribution showed in vivo presence of NP components at 24 and 48 h after administration, respectively.

CONCLUSIONS

insoluble orthogonal inhibitors of HIV-1 life cycle may be formulated into the non-aggregating ultrasmall NP which are highly efficient against NNRTI-resistant HIV-1 variant.

Vaginal delivery of mucus-penetrating organic nanoparticles for photothermal therapy against cervical intraepithelial neoplasia in mice

Photosensitizer-based photothermal therapy (PTT) may be a good choice for the treatment of severe cervical intraepithelial neoplasia (CIN) compared with conventional thermal ablation.

Mucosal Vaccine Approaches for Prevention of HIV and SIV Transmission

Optimal protective immunity to HIV will likely require that plasma cells, memory B cells and memory T cells be stationed in mucosal tissues at portals of viral entry. Mucosal vaccine administration is more effective than parenteral vaccine delivery for this purpose. The challenge has been to achieve efficient vaccine uptake at mucosal surfaces, and to identify safe and effective adjuvants, especially for mucosally administered HIV envelope protein immunogens. Here, we discuss strategies used to deliver potential HIV vaccine candidates in the intestine, respiratory tract, and male and female genital tract of humans and nonhuman primates. We also review mucosal adjuvants, including Toll-like receptor agonists, which may adjuvant both mucosal humoral and cellular immune responses to HIV protein immunogens.

[Acute and chronic toxicity of 0.5% podophyllotoxin-loaded nanostructured lipid carriers to vaginal mucosa in rabbits and rats]

OBJECTIVE

To test the acute and chronic toxicity of topical application of 0.5% podophyllotoxin-loaded nanostructured lipid carriers (POD-NLC) to the vaginal mucosa.

METHODS

Twelve New Zealand rabbits were randomized into 3 groups and subjected to daily topical applications of normal saline (control group), 0.5% podophyllotoxin tincture (POD-T) or 0.5% POD-NLC on the vaginal mucosa for 10 consecutive days, and the pathological changes in the mucosa were graded using the Eckstein scoring system.The acute toxicity of POD-NLC was tested in 20 SD female rats, which received intravaginal administration of POD-NLC or vehicle for 3 times within 24 h; After 14 days of continuous observation, the rats were dissected for calculating the viscera coefficient.For testing the chronic toxicity of POD-NLC, 80 SD female rats were randomized into 4 groups and subjected to daily intravaginal administration of the vehicle or POD-NLC at low, moderate or high doses for 13 consecutive weeks.The rats were weighed once a week and at the end of the experiment, 2/3 of the rats from each group were sacrificed to collect blood samples, calculate the viscera coefficient, and examine the pathological changes in the liver.The remaining 1/3 rats were observed for another 2 weeks without further drug treatment and the same examinations were performed.

RESULTS

In the rabbits, 0.5% POD-NLC elicited only mild irritation while POD-T caused moderate irritation of the vaginal mucosa.In the acute toxicity test, the organ coefficients were comparable between the rats treated with the vehicle and POD-NLC (P>0.05).Long-term intravaginal administration of POD-NLC did not produce significant changes in the behavior, activity, body weight, blood biochemical profiles or organ coefficient as compared with the vehicle control group (P>0.05).

CONCLUSIONS

Intravaginal administration of 0.5% POD-NLC causes very mild irritation without obvious acute or chronic toxicity to the vaginal mucosa in rabbits and rats.

Design, Characterization, and Biopharmaceutical Behavior of Nanoparticles Loaded with an HIV-1 Fusion Inhibitor Peptide

New therapeutic alternatives to fight against the spread of HIV-1 are based on peptides designed to inhibit the early steps of HIV-1 fusion in target cells. However, drawbacks, such as bioavailability, short half-life, rapid clearance, and poor ability to cross the physiological barriers, make such peptides unattractive for the pharmaceutical industry. Here we developed, optimized, and characterized polymeric nanoparticles (NPs) coated with glycol chitosan to incorporate and release an HIV-1 fusion inhibitor peptide (E1) inside the vaginal mucosa. The NPs were prepared by a modified double emulsion method, and optimization was carried out by a factorial design. In vitro, ex vivo, and in vivo studies were carried out to evaluate the optimized formulation. The results indicate that the physicochemical features of these NPs enable them to incorporate and release HIV fusion inhibitor peptides to the vaginal mucosa before the fusion step takes place.

Pharmaceutical Approaches to HIV Treatment and Prevention

Human immunodeficiency virus (HIV) infection continues to pose a major infectious disease threat worldwide. It is characterized by the depletion of CD4+ T cells, persistent immune activation, and increased susceptibility to secondary infections. Advances in the development of antiretroviral drugs and combination antiretroviral therapy have resulted in a remarkable reduction in HIV-associated morbidity and mortality. Antiretroviral therapy (ART) leads to effective suppression of HIV replication with partial recovery of host immune system and has successfully transformed HIV infection from a fatal disease to a chronic condition. Additionally, antiretroviral drugs have shown promise for prevention in HIV pre-exposure prophylaxis and treatment as prevention. However, ART is unable to cure HIV. Other limitations include drug-drug interactions, drug resistance, cytotoxic side effects, cost, and adherence. Alternative treatment options are being investigated to overcome these challenges including discovery of new molecules with increased anti-viral activity and development of easily administrable drug formulations. In light of the difficulties associated with current HIV treatment measures, and in the continuing absence of a cure, the prevention of new infections has also arisen as a prominent goal among efforts to curtail the worldwide HIV pandemic. In this review, the authors summarize currently available anti-HIV drugs and their combinations for treatment, new molecules under clinical development and prevention methods, and discuss drug delivery formats as well as associated challenges and alternative approaches for the future.

Modeling of nanoparticle transport through the female reproductive tract for the treatment of infectious diseases

The secreted mucus layer in the vaginal epithelium presents a formidable barrier to the transport of active agents for the prevention and treatment of female reproductive tract (FRT) infections. Nanoparticle-mediated drug delivery has been proposed to help facilitate the transport and release of active agents through the cervicovaginal mucus (CVM) and underlying mucosa. However, both nanoparticles (NPs) and free active agents face a variety of challenges, often requiring the administration of high localized doses to circumvent leakage and poor penetration to targeted intravaginal tissue compartments. To address these challenges, "stealth" NP modifications have been investigated, due to their favorable mucus-penetrating properties, resulting in improved intravaginal active agent retention and transport. A number of other NP characteristics including size, surface modification type, ligand density, and co-modification, as well as the complexity of the FRT tissue are involved in obtaining adequate tissue penetration and, if needed, cell internalization. Studies that systematically investigate variations of these characteristics have yet to be conducted, with the goal to obtain a better understanding of what properties most impact prophylactic and therapeutic benefit. To complement the progress made with experimental evaluation of active agent transport in in vitro and in vivo, mathematical modeling has recently been applied to analyze the transport performance of agents and delivery vehicles in the FRT. Here, we build upon this work to simulate NP transport through mucus gel, epithelial, and stromal compartments, with the goal to provide a platform that can systematically evaluate transport based on NP and tissue characteristics. Model parameters such as PEG density and NP release (decay) rate from mucus gel into the epithelium, are set from previous in vitro and in vivo experimental work that assessed the transport of poly(lactic-co-glycolic acid (PLGA) NPs. The modeling results show that while unmodified and 2% PEG-modified NPs were retained in mucus for ∼1-4 h, dependent upon decay constant values, and traverse to the epithelium, no NP penetration was observed in the stroma. In contrast, NPs modified with 3% PEG, exhibited prolonged retention in each compartment, remaining for ∼4-6 h. Moreover, a significant concentration of NPs is observed in the stroma, indicating a transition in transport behavior. For NPs modified with 5, 8, or 25% PEG, steady retention profiles were noted, which gradually decline over 24 h. To supplement this modeling study and to develop a more representative experimental system that may be useful in future work, we report on the feasibility of constructing single and multicellular layered (MCL) culture systems to represent the epithelial and stromal tissue of the FRT. We anticipate that a combined mathematical/experimental approach may longer term enable prediction and customization of patient tissue-specific approaches to attain effective NP-mediated drug delivery and release for the treatment of infectious disease.

Vaginal drug delivery for the localised treatment of cervical cancer

Cervical cancer is usually treated by surgery, with the more advanced cancers requiring adjuvant chemotherapy or radiotherapy. The location of the cervix makes it easily accessible through the vagina for the localised delivery of chemotherapeutic drugs. Localised delivery has the advantage of direct delivery to the site of action resulting in a lower dose having to be required and a reduction in systemic side effects. This approach would be advantageous for fertility sparing surgery, whereby localised delivery could be used to reduce tumour size allowing for a much smaller tumour to be removed, reducing the risk of preterm birth. Furthermore, localised delivery could be used after surgery to reduce the risk of recurrence, which is significantly higher in fertility sparing surgery compared to standard surgery. In this paper, we discuss the number of vaginal dosage forms that have investigated for this purpose, including tablets, rings, bioadhesive and cervical caps. APIs under investigation have ranged from well-established chemotherapeutic drugs to more experimental compounds.

Approaches in Polymeric Nanoparticles for Vaginal Drug Delivery: A Review of the State of the Art

The vagina is a region of administration with a high contact surface to obtain local or systemic effects. This anatomical area represents special interest for government health systems for different sexually transmitted infections. However, the chemical changes of the vagina, as well as its abundant mucus in continuous exchange, act as a barrier and a challenge for the development of new drugs. For these purposes, the development of new pharmaceutical forms based on nanoparticles has been shown to offer various advantages, such as bioadhesion, easy penetration of the mucosa, and controlled release, in addition to decreasing the adverse effects of conventional pharmaceutical forms. In order to obtain nanoparticles for vaginal administration, the use of polymers of natural and synthetic origin including biodegradable and non-biodegradable systems have gained great interest both in nanospheres and in nanocapsules. The main aim of this review is to provide an overview of the development of nanotechnology for vaginal drug release, analyzing the different compositions of polymeric nanoparticles, and emphasizing new trends in each of the sections presented. At the end of this review, a section analyzes the properties of the vehicles employed for the administration of nanoparticles and discusses how to take advantage of the properties that they offer. This review aims to be a reference guide for new formulators interested in the vaginal route.

Nanoparticle-mediated drug delivery to treat infections in the female reproductive tract: evaluation of experimental systems and the potential for mathematical modeling

A variety of drug-delivery platforms have been employed to deliver therapeutic agents across cervicovaginal mucus (CVM) and the vaginal mucosa, offering the capability to increase the longevity and retention of active agents to treat infections of the female reproductive tract (FRT). Nanoparticles (NPs) have been shown to improve retention, diffusion, and cell-specific targeting via specific surface modifications, relative to other delivery platforms. In particular, polymeric NPs represent a promising option that has shown improved distribution through the CVM. These NPs are typically fabricated from nontoxic, non-inflammatory, US Food and Drug Administration-approved polymers that improve biocompatibility. This review summarizes recent experimental studies that have evaluated NP transport in the FRT, and highlights research areas that more thoroughly and efficiently inform polymeric NP design, including mathematical modeling. An overview of the in vitro, ex vivo, and in vivo NP studies conducted to date – whereby transport parameters are determined, extrapolated, and validated – is presented first. The impact of different NP design features on transport through the FRT is summarized, and gaps that exist due to the limitations of iterative experimentation alone are identified. The potential of mathematical modeling to complement the characterization and evaluation of diffusion and transport of delivery vehicles and active agents through the CVM and mucosa is discussed. Lastly, potential advancements combining experimental and mathematical knowledge are suggested to inform next-generation NP designs, such that infections in the FRT may be more effectively treated.

pH-responsive delivery of Griffithsin from electrospun fibers

Human immunodeficiency virus (HIV-1) affects over 36 million people globally. Current prevention strategies utilize antiretrovirals that have demonstrated protection, but result in antiviral resistance, adverse toxicity, and require frequent administration. A novel biologic, griffithsin (GRFT), has demonstrated outstanding safety and efficacy against laboratory and primary HIV isolates and against intravaginal murine herpes simplex virus 2 (HSV-2) challenge, making it a promising microbicide candidate. However, transient activity and instability remain concerns surrounding biologic delivery, particularly in the harsh environment of the female reproductive tract (FRT). Recently, electrospun fibers (EFs) have demonstrated promise for intravaginal delivery, with the potential to conserve active agent until release is needed. The goal of this study was to fabricate and characterize pH-responsive fibers comprised of poly(lactic-co-glycolic acid) (PLGA) or methoxypolyethylene glycol-b-PLGA (mPEG-PLGA) with varying ratios of poly(n-butyl acrylate-co-acrylic acid) (PBA-co-PAA), to selectively release GRFT under pH-conditions that mimic semen introduction. Fibers comprised of mPEG-PLGA:PBA-co-PAA (90:10 w/w) demonstrated high GRFT loading that was maintained within simulated vaginal fluid (SVF), and pH-dependent release upon exposure to buffered and SVF:simulated semen solutions. Moreover, GRFT fibers demonstrated potent in vitro efficacy against HIV-1 and safety in vaginal epithelial cells, suggesting their future potential for efficacious biologic delivery to the FRT.

Nanolipid Gel of an Antimycotic Drug for Treating Vulvovaginal Candidiasis-Development and Evaluation

This paper focuses on the development and evaluation of mucoadhesive vaginal gel of fluconazole using nanolipid carriers to enhance tissue deposition in treating vulvovaginal candidiasis. Treatment of vulvovaginal candidiasis includes antimycotic agents prescribed for 1 to 7 days or longer, in relapse either orally or topically. The delivery of fluconazole as nanolipid carriers in vaginal gel can be proposed as suitable alternative to the existing conventional formulations to improve the patient acceptability, compliance and localized drug action. The nanolipid carriers of fluconazole were prepared by phase inversion temperature technique and incorporated into Carbopol 974P as gelling polymer. GRAS excipients selected and optimized were Precirol ATO 5, oleic acid and Kolliphor RH 40 to produce nanolipid dispersions. Stable nanolipid dispersions were developed using sodium dodecyl sulfate as the charge inducer. The optimized nanolipid dispersion of fluconazole had particle size, polydispersity index and zeta potential value of 158.33 ± 2.55 nm, 0.278 ± 0.003 and - 27.33 ± 0.40 mV, respectively and the average entrapment of fluconazole in the lipid carriers was found to be 67.24 ± 0.87%. The optimized vaginal gel had satisfactory mucoadhesive strength and rheological properties to facilitate vaginal application. The fluconazole release from the gel was sustained showing 30.69 ± 1.02% drug deposition in the porcine vaginal mucosa at the end of 8 h with improved antifungal activity against Candida albicans during well diffusion studies. The optimized gel was non-irritant to the vaginal mucosa of female Wistar rats with no signs of erythema or edema.

Starch-Chitosan Polyplexes: A Versatile Carrier System for Anti-Infectives and Gene Delivery

Despite the enormous potential of nanomedicine, the search for materials from renewable resources that balance bio-medical requirements and engineering aspects is still challenging. This study proposes an easy method to make nanoparticles composed of oxidized starch and chitosan, both isolated from natural biopolymers. The careful adjustment of C/N ratio, polymer concentration and molecular weight allowed for tuning of particle characteristics. The system's carrier capability was assessed both for anti-infectives and for nucleic acid. Higher starch content polyplexes were found to be suitable for high encapsulation efficiency of cationic anti-infectives and preserving their bactericidal function. A cationic carrier was obtained by coating the anionic polyplex with chitosan. Coating allowed for a minimal amount of cationic polymer to be employed and facilitated plasmid DNA loading both within the particle core and on the surface. Transfection studies showed encouraging result, approximately 5% of A549 cells with reporter gene expression. In summary, starch-chitosan complexes are suitable carriers with promising perspectives for pharmaceutical use.

Chitosan Loaded into a Hydrogel Delivery System as a Strategy to Treat Vaginal Co-Infection

Polymeric hydrogels are common dosage forms designed for the topical administration of antimicrobial drugs to treat vaginal infections. One of the major advantages of using chitosan in these formulations is related to the intrinsic and broad antimicrobial activity exerted on bacteria and fungi by this natural polymer. Most vaginal yeast infections are caused by the pathogenic fungus Candida albicans. However, despite the anti-Candida activity towards and strains susceptibility to low molecular weight chitosan being documented, no information is available regarding the antimicrobial efficacy of mixed hydrogels in which chitosan is dispersed in a polymeric matrix. Therefore, the aim of the study is to evaluate the anti-Candida activity against eight different albicans and non-albicans strains of a mixed hydroxypropyl methylcellulose (HPMC)/chitosan hydrogel. Importantly, chitosan was dispersed in HPMC matrix either assembled in nanoparticles or in a monomolecular state to eventually correlate any variation in terms of rheological and mucoadhesive properties, as well as anti-Candida activity, with the chitosan form. Hydrogels containing 1% w/w chitosan, either as free polymer chain or assembled in nanoparticles, showed an improved mucoadhesiveness and an anti-Candida effect against all tested albicans and non-albicans strains. Overall, the results demonstrate the feasibility of preparing HPMC/CS mixed hydrogels intended for the prevention and treatment of Candida infections after vaginal administration.

Efficacy and safety concerns over the use of mucus modulating agents for drug delivery using nanoscale systems

Drug delivery to the mucus covered mucosae is fraught with difficulties and many different approaches have been developed to permeate the mucus barrier. Generally by modifying the delivery system to avoid interaction with the mucus. These modifications are reviewed here in terms of efficacy and safety. These are particular problems for oral delivery the pharmaceutical industry's favoured route for drug administration. For effective delivery through the gastrointestinal tract a drug must pass through three barriers in sufficient amounts to yield a biological effect. These barriers are the digestive barrier in the lumen, the mucus barrier, and the epithelial barrier. Other approaches involve mucolytic agents added with or prior to the delivery system or agents regulating mucus production and are reviewed here. In terms of safety, a key property of a mucus modulating delivery system is that it must not damage the protective function of the mucus layer.

The role of mucus in cell-based models used to screen mucosal drug delivery

The increasing interest in developing tools to predict drug absorption through mucosal surfaces is fostering the establishment of epithelial cell-based models. Cell-based in vitro techniques for drug permeability assessment are less laborious, cheaper and address the concerns of using laboratory animals. Simultaneously, in vitro barrier models that thoroughly simulate human epithelia or mucosae may provide useful data to speed up the entrance of new drugs and new drug products into the clinics. Nevertheless, standard cell-based in vitro models that intend to reproduce epithelial surfaces often discard the role of mucus in influencing drug permeation/absorption. Biomimetic models of mucosae in which mucus production has been considered may not be able to fully reproduce the amount and architecture of mucus, resulting in biased characterization of permeability/absorption. In these cases, artificial mucus may be used to supplement cell-based models but still proper identification and quantification are required. In this review, considerations regarding the relevance of mucus in the development of cell-based epithelial and mucosal models mimicking the gastro-intestinal tract, the cervico-vaginal tract and the respiratory tract, and the impact of mucus on the permeability mechanisms are addressed. From simple epithelial monolayers to more complex 3D structures, the impact of the presence of mucus for the extrapolation to the in vivo scenario is critically analyzed. Finally, an overview is provided on several techniques and methods to characterize the mucus layer over cell-based barriers, in order to intimately reproduce human mucosal layer and thereby, improve in vitro/in vivo correlation.

The role of mucus on drug transport and its potential to affect therapeutic outcomes

A layer of mucus covers the surface of all wet epithelia throughout the human body. Mucus is a hydrogel mainly composed of water, mucins (glycoproteins), DNA, proteins, lipids, and cell debris. This complex composition yields a tenacious viscoelastic hydrogel that lubricates and protects the exposed epithelia from external threats and enzymatic degradation. The natural protective role of mucus is nowadays acknowledged as a major barrier to be overcome in non-invasive drug delivery. The heterogeneity of mucus components offers a wide range of potential chemical interaction sites for macromolecules, while the mesh-like architecture given to mucus by the intermolecular cross-linking of mucin molecules results in a dense network that physically, and in a size-dependent manner, hinders the diffusion of nanoparticles through mucus. Consequently, drug diffusion, epithelial absorption, drug bioavailability, and ultimately therapeutic outcomes of mucosal drug delivery can be attenuated.