Silk Reservoirs for Local Delivery of Cisplatin for Neuroblastoma Treatment: In Vitro and In Vivo Evaluations

Implantation of In Situ Gelling Systems for the Delivery of Chemotherapeutic Agents

Implantation is a modern method of administering chemotherapeutic agents, with a highly targeted effect and better patient tolerance due to the low frequency of administration. Implants are capable of controlled release, which makes them a viable alternative to infusional chemotherapy, allowing patients to enjoy a better quality of life without the need for prolonged hospitalization. Compared to subcutaneous implantation, intratumoral implantation has a number of significant advantages in terms of targeting and side effects, but this area of chemotherapy is still poorly understood in terms of clinical trials. At the same time, there are more known developments of drugs in the form of implants and injections for intratumoral administration. The disadvantages of classical intratumoral implants are the need for surgical intervention to install the system and the increased risk of tumor rupture noted by some specialists. The new generation of implants are in situ implants-systems formed in the tumor due to a phase transition (sol-gel transition) under the influence of various stimuli. Among this systems some are highly selective for a certain type of malignant neoplasm. Such systems are injected and have all the advantages of intratumoral injections, but due to the phase transition occurring in situ, they form depot forms that allow the long-term release of chemotherapeutic agents.

Silk Fibroin as an Efficient Biomaterial for Drug Delivery, Gene Therapy, and Wound Healing

Silk fibroin (SF), an organic material obtained from the cocoons of a silkworm Bombyx mori, is used in several applications and has a proven track record in biomedicine owing to its superior compatibility with the human body, superb mechanical characteristics, and its controllable propensity to decay. Due to its robust biocompatibility, less immunogenic, non-toxic, non-carcinogenic, and biodegradable properties, it has been widely used in biological and biomedical fields, including wound healing. The key strategies for building diverse SF-based drug delivery systems are discussed in this review, as well as the most recent ways for developing functionalized SF for controlled or redirected medicines, gene therapy, and wound healing. Understanding the features of SF and the various ways to manipulate its physicochemical and mechanical properties enables the development of more effective drug delivery devices. Drugs are encapsulated in SF-based drug delivery systems to extend their shelf life and control their release, allowing them to travel further across the bloodstream and thus extend their range of operation. Furthermore, due to their tunable properties, SF-based drug delivery systems open up new possibilities for drug delivery, gene therapy, and wound healing.

Recombinant protein polymers as carriers of chemotherapeutic agents

Chemotherapy is the standard of care for the treatment of cancer and infectious diseases. However, its use is associated with severe toxicity and resistance arising mainly due to non-specificity, resulting in disease progression. The advancement in recombinant technology has led to the synthesis of genetically engineered protein polymers like Elastin-like polypeptide (ELP), Silk-like polypeptide (SLP), hybrid protein polymers with specific sequences to impart precisely controlled properties and to target proteins that have provided satisfactory preclinical outcomes. Such protein polymers have been exploited for the formulation and delivery of chemotherapeutics for biomedical applications. The use of such polymers has not only solved the limitation of conventional chemotherapy but has also improved the therapeutic index of typical drug delivery systems. This review, therefore, summarizes the development of such advanced recombinant protein polymers designed to deliver chemotherapeutics and also discusses the key challenges associated with their current usage and their application in the future.

Localized, on-demand, sustained drug delivery from biopolymer-based materials

INTRODUCTION

Local drug delivery facilitiates higher concentrations of drug molecules at or near the treatment site to enhance treatment efficiency and reduce drug toxicity and other systemic side effects. However, local drug delivery systems face challenges in terms of encapsulation, delivery, and controlled release of therapeutics.

AREAS COVERED

We provide an overview of naturally derived biopolymer-based drug delivery systems for localized, sustained, and on-demand treatment. We introduce the advantages and limitations of these systems for drug encapsulation, delivery, and local release, as well as recent applications.

EXPERT OPINION

Naturally derived biopolymers like cellulose, silk fibroin, chitosan, alginate, hyaluronic acid, and gelatin are good candidates for localized drug delivery because they are readily chemically modified, biocompatible, biodegradable (with the generation of metabolically compatible degradation products), and can be processed in aqueous and ambient environments to maintain the bioactivity of various therapeutics. The tradeoff between the effective treatment dosage and the response by local healthy tissue should be balanced during the design of these delivery systems. Future directions will be focused on strategies to design tunable and controlled biodegradation rates, as well as to explore commercial utility in substituting biopolymer-based systems for currently utilized synthetic polymers for implants for drug delivery.

Pharmacological Effects of Cisplatin Combination with Natural Products in Cancer Chemotherapy

Cisplatin and other platinum-based drugs, such as carboplatin, ormaplatin, and oxaliplatin, have been widely used to treat a multitude of human cancers. However, a considerable proportion of patients often relapse due to drug resistance and/or toxicity to multiple organs including the liver, kidneys, gastrointestinal tract, and the cardiovascular, hematologic, and nervous systems. In this study, we sought to provide a comprehensive review of the current state of the science highlighting the use of cisplatin in cancer therapy, with a special emphasis on its molecular mechanisms of action, and treatment modalities including the combination therapy with natural products. Hence, we searched the literature using various scientific databases., such as MEDLINE, PubMed, Google Scholar, and relevant sources, to collect and review relevant publications on cisplatin, natural products, combination therapy, uses in cancer treatment, modes of action, and therapeutic strategies. Our search results revealed that new strategic approaches for cancer treatment, including the combination therapy of cisplatin and natural products, have been evaluated with some degree of success. Scientific evidence from both in vitro and in vivo studies demonstrates that many medicinal plants contain bioactive compounds that are promising candidates for the treatment of human diseases, and therefore represent an excellent source for drug discovery. In preclinical studies, it has been demonstrated that natural products not only enhance the therapeutic activity of cisplatin but also attenuate its chemotherapy-induced toxicity. Many experimental studies have also reported that natural products exert their therapeutic action by triggering apoptosis through modulation of mitogen-activated protein kinase (MAPK) and p53 signal transduction pathways and enhancement of cisplatin chemosensitivity. Furthermore, natural products protect against cisplatin-induced organ toxicity by modulating several gene transcription factors and inducing cell death through apoptosis and/or necrosis. In addition, formulations of cisplatin with polymeric, lipid, inorganic, and carbon-based nano-drug delivery systems have been found to delay drug release, prolong half-life, and reduce systemic toxicity while other formulations, such as nanocapsules, nanogels, and hydrogels, have been reported to enhance cell penetration, target cancer cells, and inhibit tumor progression.

Targeting Oncogenic Transcriptional Networks in Neuroblastoma: From N-Myc to Epigenetic Drugs

Neuroblastoma (NB) is one of the most frequently occurring neurogenic extracranial solid cancers in childhood and infancy. Over the years, many pieces of evidence suggested that NB development is controlled by gene expression dysregulation. These unleashed programs that outline NB cancer cells make them highly dependent on specific tuning of gene expression, which can act co-operatively to define the differentiation state, cell identity, and specialized functions. The peculiar regulation is mainly caused by genetic and epigenetic alterations, resulting in the dependency on a small set of key master transcriptional regulators as the convergence point of multiple signalling pathways. In this review, we provide a comprehensive blueprint of transcriptional regulation bearing NB initiation and progression, unveiling the complexity of novel oncogenic and tumour suppressive regulatory networks of this pathology. Furthermore, we underline the significance of multi-target therapies against these hallmarks, showing how novel approaches, together with chemotherapy, surgery, or radiotherapy, can have substantial antineoplastic effects, disrupting a wide variety of tumorigenic pathways through combinations of different treatments.

Systemic and Local Silk-Based Drug Delivery Systems for Cancer Therapy

For years, surgery, radiotherapy, and chemotherapy have been the gold standards to treat cancer, although continuing research has sought a more effective approach. While advances can be seen in the development of anticancer drugs, the tools that can improve their delivery remain a challenge. As anticancer drugs can affect the entire body, the control of their distribution is desirable to prevent systemic toxicity. The application of a suitable drug delivery platform may resolve this problem. Among other materials, silks offer many advantageous properties, including biodegradability, biocompatibility, and the possibility of obtaining a variety of morphological structures. These characteristics allow the exploration of silk for biomedical applications and as a platform for drug delivery. We have reviewed silk structures that can be used for local and systemic drug delivery for use in cancer therapy. After a short description of the most studied silks, we discuss the advantages of using silk for drug delivery. The tables summarize the descriptions of silk structures for the local and systemic transport of anticancer drugs. The most popular techniques for silk particle preparation are presented. Further prospects for using silk as a drug carrier are considered. The application of various silk biomaterials can improve cancer treatment by the controllable delivery of chemotherapeutics, immunotherapeutics, photosensitizers, hormones, nucleotherapeutics, targeted therapeutics (e.g., kinase inhibitors), and inorganic nanoparticles, among others.

Silk Fibroin Microneedle Patches for the Sustained Release of Levonorgestrel

The sustained release of levonorgestrel, a contraceptive, from silk-based microneedle patches was demonstrated for transdermal delivery. Modifications in the formulation of the silk protein and drug loading enabled the tuning of drug loading and release rates from the microneedle patches over time. Sustained drug release reached up to 100 days when the drug was loaded directly inside the microneedles, while release continued for more than a year when the drug was loaded inside microparticles prior to casting inside the microneedle patches. When coupled with the shelf-stable, refrigeration-less features of the silk protein matrix utilized in the microneedle fabrication, these findings suggest that long-acting contraception patches are feasible. This advance could provide practical options for women to have access to new options for protection against unwanted pregnancy.

Enhancing sustained-release local therapy: Single versus dual chemotherapy for the treatment of neuroblastoma

BACKGROUND

Neuroblastoma is the most common pediatric extracranial solid malignancy with limited effective treatment. We have shown that sustained-release, single drugs delivered locally through a silk-based biomaterial are effective in decreasing orthotopic neuroblastoma xenograft growth. We further optimized this approach and hypothesized that increasing doses of local chemotherapy or delivering 2 chemotherapeutic agents simultaneously inhibit additional tumor growth.

METHODS

MYCN-amplified and non-MYCN-amplified neuroblastoma cells were treated with combinations of cisplatin, vincristine, doxorubicin, and etoposide to determine cytotoxicity and synergy. Drug-loaded silk material was created, and the amounts of drug released from the material over time were recorded. Murine orthotopic neuroblastoma xenografts were generated; tumors were implanted with single- or dual-agent chemotherapy-loaded silk. Ultrasound was used to monitor tumor growth, and tumor histology was evaluated.

RESULTS

In vitro, vincristine/cisplatin combination was synergistic and significantly decreased cell viability relative to other combinations. Both drugs loaded into silk could be released effectively for over 2 weeks. Locally implanted vincristine/cisplatin silk induced increased tumor growth suppression compared with either agent alone in MYCN-amplified tumors (P < .05). The dose-dependent effect seen in MYCN-amplified tumors treated with combination therapy diminished at higher doses in non-MYCN-amplified tumors, with little benefit with doses >50 μg to 500 μg for vincristine-cisplatin, respectively. Tumor histology demonstrated tumor cell necrosis adjacent to drug-loaded silk material and presence of large cell neuroblastoma.

CONCLUSION

Local delivery of sustained release chemotherapy can suppress tumor growth especially at high doses or with 2 synergistic drugs. Locally delivered dual therapy is a promising approach for future clinical testing.

Extended release formulations using silk proteins for controlled delivery of therapeutics

INTRODUCTION

Silk is a promising biomaterial for controlled delivery of therapeutics and has a unique protein chemistry that can be tuned to form different carrier formats. The protein has been studied for sustained release depot systems for the targeted or localized delivery of drugs.

AREAS COVERED

An overview of natural silk proteins for controlled delivery of therapeutics is provided, with a focus on the features of silk proteins that allow them to be useful tools for controlled delivery. Recent applications of natural silk proteins as controlled delivery systems are also summarized.

EXPERT OPINION

The versatility of silk proteins makes them desirable biomaterials for a broad range of applications for controlled delivery of both small and large molecules. Further, the degradation profile leading to peptides and amino acids provides compatibility with pH-sensitive therapeutics. While silk sericin and spider silks are under study, silk fibroin extracted from silkworms (e.g. Bombyx mori) dominates pharmaceutical studies with silk. Silk fibroin can be formed into drug delivery tools for systemic or local injections, topical and transdermal applications, and implantation; depending on the target disease and therapeutic molecule. In vitro to in vivo correlations and scale-up needs are the next steps towards clinical applications.