Use of a nanoporous biodegradable miniature device to regulate cytokine release for cancer treatment

Modeling the diffusion-erosion crossover dynamics in drug release

A computational model is proposed to investigate drug delivery systems in which erosion and diffusion mechanisms are participating in the drug release process. Our approach allowed us to analytically estimate the crossover point between those mechanisms through the value of the parameter b (b_{c}=1) and the scaling behavior of parameter τ on the Weibull function, exp[-(t/τ)^{b}], used to adjust drug release data in pharmaceutical literature. Numerical investigations on the size dependence of the characteristic release time τ found it to satisfy either linear or quadratic scaling relations on either erosive or diffusive regimes. Along the crossover, the characteristic time scales with the average coefficient observed on the extreme regimes (i.e., τ∼L^{3/2}), and we show that this result can be derived analytically by assuming an Arrhenius relation for the diffusion coefficient inside the capsule. Based on these relations, a phenomenological expression for the characteristic release in terms of size L and erosion rate κ is proposed, which can be useful for predicting the crossover erosion rate κ_{c}. We applied this relation to the experimental literature data for the release of acetaminophen immersed in a wax matrix and found them to be consistent with our numerical results.

Antitumor Activity of Thermosensitive Hydrogels Packaging Gambogic Acid Nanoparticles and Tumor-Penetrating Peptide iRGD Against Gastric Cancer

Introduction

Gambogic acid (GA) is proved to have anti-tumor effects on gastric cancer. Due to poor solubility, non-specific biological distribution, toxicity to normal tissues and short half-life, it is hard to be applied into the clinic. To overcome these issues, we developed a thermosensitive and injectable hydrogel composed of hydroxypropyl cellulose, silk fibroin and glycerol, with short gelling time, good compatibility and sustained release, and demonstrated that the hydrogel packaged with gambogic acid nanoparticles (GA-NPs) and tumor-penetrating peptide iRGD could improve the anti-tumor activity.

Methods

The Gelling time and micropore size of the hydrogels were regulated through different concentrations of glycerol. Controlled release characteristics of the hydrogels were evaluated with a real-time near-infrared fluorescence imaging system. Location of nanoparticles from different carriers was traced by confocal laser scanning microscopy. The in vivo antitumor activity of the hydrogels packaging GA-NPs and iRGD was evaluated by investigating tumor volume and tumor size.

Results

The thermo-sensitive properties of hydrogels were characterized by 3-4 min, 37°C, when glycerol concentration was 20%. The hydrogels physically packaged with GA-NPs and iRGD showed higher fluorescence intensity than other groups. The in vivo study indicated that the co-administration of GA-NPs and iRGD by hydrogels had higher antitumor activity than the GA-loaded hydrogels and free GA combining with iRGD. Free GA group showed few antitumor effects. Compared with the control group, the body weight in other groups had no obvious change, and the count of leukocytes and hemoglobin was slightly decreased.

Discussion

The hydrogel constructed iRGD and GA-NPs exerted an effective anti-tumor effect possibly due to retention effect, local administration and continuous sustained release of iRGD promoting the penetration of nanoparticles into a deep part of tumors. The delivery system showed little systemic toxicity and would provide a promising strategy to improve anti-gastric cancer efficacy.

Chitosan/poly(γ-glutamic acid) nanoparticles incorporating IFN-γ for immune response modulation in the context of colorectal cancer

IFN-γ therapy has been approved by the Food and Drug Administration (FDA) for the treatment of chronic granulomatous disease and severe malignant osteopetrosis. Despite the promising IFN-γ-based therapeutic applications, its limited success in clinical trials is related with limitations inherent to its molecular properties and with the difficulties to deliver it locally or with adequate periodicity to achieve a therapeutic effect. We have previously shown that chitosan (Ch)/poly(γ-glutamic acid) (γ-PGA) nanoparticles (NPs) are immunostimulatory, impairing colorectal cancer cell invasion. Ch is a biocompatible cationic polysaccharide extensively studied and already approved for biomedical applications while γ-PGA is a poly(amino acid), biodegradable and negatively charged. Here, we evaluated the potential of Ch/γ-PGA NPs as vehicles for IFN-γ and their ability to modulate immune cells' phenotype. In this study, Ch/IFN-γ/γ-PGA nanoparticles (IFN-γ-NPs) prepared by a co-acervation method, presenting a size of approximately 180 nm and a low polydispersity index, were tested for their immunomodulatory activity. These IFN-γ-NPs induced an immunostimulatory profile on dendritic cells (DCs) with increased cell surface costimulatory molecules and secretion of pro-inflammatory cytokines, including IL-6, IL-12p40 and TNF-α. IFN-γ-NPs also modulated the IL-10-stimulated macrophage profile, increasing their ability to secrete the pro-inflammatory cytokines IL-6, IL-12p40 and TNF-α. Concomitantly, these phenotypic alterations enhanced T cell proliferation. In addition, the ability of DCs and macrophages to induce colorectal cancer cell invasion was hampered in the presence of IFN-γ-NPs. Although the major observations were mediated by Ch/γ-PGA NPs, the incorporation of IFN-γ into NPs potentiated the expression of CD40 and CD86, and the impairment of colorectal cancer cell invasion. This work bridges the previously reported immunostimulatory capacity of Ch/γ-PGA NPs with their potential as carriers for immunomodulatory molecules, like IFN-γ, opening new avenues for their use in clinical settings.

How does the pathophysiological context influence delivery of bone growth factors?

"Orthobiologics" represents an important category of therapeutics for the regeneration of bone defects caused by injuries or diseases, and bone growth factors are a particularly rapidly growing sub-category. Clinical application of bone growth factors has accelerated in the last two decades with the introduction of BMPs into clinical bone repair. Optimal use of growth factor-mediated treatments heavily relies on controlled delivery, which can substantially influence the local growth factor dose, release kinetics, and biological activity. The characteristics of the surrounding environment, or "context", during delivery can dictate growth factor loading efficiency, release and biological activity. This review discusses the influence of the surrounding environment on therapeutic delivery of bone growth factors. We specifically focus on pathophysiological components, including soluble components and cells, and how they can actively influence the therapeutic delivery and perhaps efficacy of bone growth factors.

Nanomaterials, inflammation, and tissue engineering

Nanomaterials exhibit unique properties that are absent in the bulk material because decreasing material size leads to an exponential increase in surface area, surface area to volume ratio, and effective stiffness, resulting in altered physiochemical properties. Diverse categories of nanomaterials such as nanoparticles, nanoporous scaffolds, nanopatterned surfaces, nanofibers, and carbon nanotubes can be generated using advanced fabrication and processing techniques. These materials are being increasingly incorporated in tissue engineering scaffolds to facilitate the development of biomimetic substitutes to replace damaged tissues and organs. Long-term success of nanomaterials in tissue engineering is contingent upon the inflammatory responses they elicit in vivo. This review seeks to summarize the recent developments in our understanding of biochemical and biophysical attributes of nanomaterials and the inflammatory responses they elicit, with a focus on strategies for nanomaterial design in tissue engineering applications.

Drug delivery nanoparticles in skin cancers

Nanotechnology involves the engineering of functional systems at nanoscale, thus being attractive for disciplines ranging from materials science to biomedicine. One of the most active research areas of the nanotechnology is nanomedicine, which applies nanotechnology to highly specific medical interventions for prevention, diagnosis, and treatment of diseases, including cancer disease. Over the past two decades, the rapid developments in nanotechnology have allowed the incorporation of multiple therapeutic, sensing, and targeting agents into nanoparticles, for detection, prevention, and treatment of cancer diseases. Nanoparticles offer many advantages as drug carrier systems since they can improve the solubility of poorly water-soluble drugs, modify pharmacokinetics, increase drug half-life by reducing immunogenicity, improve bioavailability, and diminish drug metabolism. They can also enable a tunable release of therapeutic compounds and the simultaneous delivery of two or more drugs for combination therapy. In this review, we discuss the recent advances in the use of different types of nanoparticles for systemic and topical drug delivery in the treatment of skin cancer. In particular, the progress in the treatment with nanocarriers of basal cell carcinoma, squamous cell carcinoma, and melanoma has been reported.

Applications of nanotechnology for melanoma treatment, diagnosis, and theranostics

Melanoma is the most aggressive type of skin cancer and has very high rates of mortality. An early stage melanoma can be surgically removed, with a survival rate of 99%. However, metastasized melanoma is difficult to cure. The 5-year survival rates for patients with metastasized melanoma are still below 20%. Metastasized melanoma is currently treated by chemotherapy, targeted therapy, immunotherapy and radiotherapy. The outcome of most of the current therapies is far from optimistic. Although melanoma patients with a mutation in the oncogene v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) have an initially higher positive response rate to targeted therapy, the majority develop acquired drug resistance after 6 months of the therapy. To increase treatment efficacy, early diagnosis, more potent pharmacological agents, and more effective delivery systems are urgently needed. Nanotechnology has been extensively studied for melanoma treatment and diagnosis, to decrease drug resistance, increase therapeutic efficacy, and reduce side effects. In this review, we summarize the recent progress on the development of various nanoparticles for melanoma treatment and diagnosis. Several common nanoparticles, including liposome, polymersomes, dendrimers, carbon-based nanoparticles, and human albumin, have been used to deliver chemotherapeutic agents, and small interfering ribonucleic acids (siRNAs) against signaling molecules have also been tested for the treatment of melanoma. Indeed, several nanoparticle-delivered drugs have been approved by the US Food and Drug Administration and are currently in clinical trials. The application of nanoparticles could produce side effects, which will need to be reduced so that nanoparticle-delivered drugs can be safely applied in the clinical setting.

Nano- and microfabrication for overcoming drug delivery challenges

This highlight article describes current nano- and microfabrication techniques for creating drug delivery devices. We first review the main physiological barriers to delivering therapeutic agents. Then, we describe how novel fabrication methods can be utilized to combine many features into a single physiologically relevant device to overcome drug delivery challenges.

A naonoporous cell-therapy device with controllable biodegradation for long-term drug release

Herein we describe the development and implementation of a nanoporous cell-therapy device with controllable biodegradation. Dopamine-secreting PC12 cells were housed within newly formulated alginate-glutamine degradable polylysine (A-GD-PLL) microcapsules. The A-GD-PLL microcapsules provided a 3-D microenvironment for good spatial cell growth, viability and proliferation. The microcapsules were subsequently placed within a poly(ethylene glycol) (PEG)-coated poly(ε-caprolactone) (PCL) chamber covered with a PEG-grafted PCL nanoporous membrane formed by phase inversion. To enhance PC12 cell growth and to assist in controlled degradation of both the PC12 cells and the device construct, small PCL capsules containing neural growth factor (PCL-NGF) and a poly(lactic-co-glycolic acid) pellet containing glutamine (PLGA-GLN) were also placed within the PCL chamber. Release of NGF from the PCL-NGF capsules facilitated cell proliferation and viability, while the controlled release of GLN from the PLGA-GLN pellet resulted in A-GD-PLL microcapsule degradation and eventual PC12 cell death following a pre-specified period of time (4 weeks in this study). In vivo, our device was found to be well tolerated and we successfully demonstrated the controlled release of dopamine over a period of four weeks. This integrated biodegradable device holds great promise for the future treatment of a variety of diseases.

Nanostructured thin film polymer devices for constant-rate protein delivery

Herein long-term delivery of proteins from biodegradable thin film devices is demonstrated, where a nanostructured polymer membrane controls release. Protein was sealed between two poly(caprolactone) films, which generated the thin film devices. Protein release for 210 days was shown in vitro, and stable activity was established through 70 days with a model protein. These thin film devices present a promising delivery platform for biologic therapeutics, particularly for application in constrained spaces.

Electrochemically controlled drug-mimicking protein release from iron-alginate thin-films associated with an electrode

Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe(2+) ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe(3+) ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe(2+) cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential.