Chitosan microparticles encapsulating PEDF plasmid demonstrate efficacy in an orthotopic metastatic model of osteosarcoma

Multifunctional nanoparticles for the treatment and diagnosis of osteosarcoma

Osteosarcoma (OS) is a common primary malignant bone tumor in adolescents. Currently, the commonly used treatment strategies for OS include surgery, chemotherapy and radiotherapy. However, these methods have some problems that cannot be ignored, such as postoperative sequelae and severe side effects. Therefore, in recent years, researchers have been looking for other means to improve the treatment or diagnosis effect of OS and increase the overall survival rate of patients. With the development of nanotechnology, nanoparticles (NPs) have presented excellent properties in improving the therapeutic efficacy of drugs for OS. Nanotechnology makes it possible for NPs to combine various functional molecules and drugs to achieve multiple therapeutic effects. This review presents the important properties of multifunctional NPs for the treatment and diagnosis of OS and focuses on the research progress of common NPs applied for drug or gene delivery, phototherapy and diagnosis of OS, such as carbon-based quantum dots, metal, chitosan and liposome NPs. Finally, the promising prospects and challenges of developing multifunctional NPs with enhanced efficacy are discussed, which lays the foundation and direction for improving the future therapeutic and diagnostic methods of OS.

Applications of nanomaterials in endometriosis treatment

Endometriosis is a common disease of the reproductive system in women of childbearing age with an unclear pathogenesis. Endometriosis mainly manifests as dysmenorrhea, abdominal pain, and infertility. Currently, medical therapy and surgical treatment are usually used for endometriosis treatment. However, due to the high recurrence rate and many complications, it has greatly affected patients' quality of life. Nanotechnology is a new technology that mainly investigates the characteristics and applications of nanomaterials. To date, nanotechnology has received widespread attention in the field of biomedicine. Nanomaterials can not only be used as drugs to treat endometriosis directly, but also enhance the therapeutic effect of endometriosis by delivering drugs, siRNA, antibodies, vesicles, etc. This review comprehensively discusses nanomaterial-based therapies for endometriosis treatment, such as nanomaterial-based gene therapy, photothermal therapy, immunotherapy, and magnetic hyperthermia, which provides a theoretical reference for the clinical application of nanotechnology in the treatment of endometriosis.

Pigment epithelium-derived factor downregulation in oestrogen receptor positive breast cancer bone metastases is associated with menopause

Pigment epithelium-derived factor (PEDF) has a critical role in bone development and anti-tumour function in breast cancer (BC). As the expression and role of PEDF in BC bone metastases is unknown, we aimed to characterise PEDF in primary and metastatic BC. Subcellular PEDF localisation was semi-quantitatively analysed via immunohistochemistry in patient-matched, archived formalin-fixed paraffin-embedded primary BC and liver, lung, and decalcified bone metastases specimens. PEDF localisation was evaluated in 23 metastatic BC patients diagnosed with ER+, human epidermal growth factor receptor-2 (HER2) negative BC or TNBC. Cytoplasmic (p = 0.019) and membrane (p = 0.048) PEDF was lower in bone metastases compared to primary ER+/HER2- BC. In contrast, nuclear PEDF scores were higher in metastases compared to primary TNBC (p = 0.027), and increased membrane PEDF in metastatic tissue had improved disease-free interval (p = 0.016). Nuclear PEDF was decreased in bone metastases compared to primary ER+//HER2- BC in post-menopausal patients (p = 0.029). These novel findings indicate PEDF plays a role in clinical BC metastasis. Significantly lower PEDF levels in the post-menopausal compared to pre-menopausal setting suggests future PEDF research may have greater clinical importance in the post-menopausal ER+/HER2- BC population.

Chitosan Nanoparticles in Atherosclerosis-Development to Preclinical Testing

Chitosan is a natural biopolymer that is present in an abundant supply in sources such as crustacean shells, mushrooms, and insect exoskeletons. It can be used to make a variety of types of drug formulations and is generally safe to use in vivo; plus, it has inherent cholesterol-reducing properties. While an abundance of papers has tested this biopolymer in nanoparticles in cancer and diabetes research, there is a lag of usage, and hence the paucity of information, in the area of cardiovascular research, specifically in atherosclerosis, the topic of this review. This review highlights some of the deficiencies in this niche area of research, examines the range of chitosan nanoparticles that have been researched to date, and proposes several ways forward to advance this field. Nanoparticles used for both diagnostic and therapeutic purposes are reviewed, with a discussion on how these nanoparticles could be better researched in future and what lays ahead as the field potentially moves towards clinical trials in future.

The increasing role of pigment epithelium-derived factor in metastasis: from biological importance to a promising target

Pigment epithelium-derived factor (PEDF) is a non-inhibitory member of the serpin (serine protease inhibitor) family and is a well-known potent anti-tumor factor in a variety of cancers. It has been ascertained that PEDF regulates multiple metastatic processes through various plausible mechanisms, including inhibiting angiogenesis, inducing apoptosis, stimulating extracellular matrix (ECM) degradation, and suppressing the epithelial-to-mesenchymal transition (EMT) process. Although PEDF has been recognized as an anti-metastatic marker in most studies, its role remains controversial with conflicting reports of PEDF as a metastatic marker. The emerging insights into the mechanism(s) of PEDF in tumor progression and its therapeutic effects are discussed systematically in this review, aiming to improve our understanding in the context of metastasis and drug development.

Nanomedicines for Endometriosis: Lessons Learned from Cancer Research

Endometriosis is an incurable gynecological disease characterized by the abnormal growth of endometrium-like tissue, characteristic of the uterine lining, outside of the uterine cavity. Millions of people with endometriosis suffer from pelvic pain and infertility. This review aims to discuss whether nanomedicines that are promising therapeutic approaches for various diseases have the potential to create a paradigm shift in endometriosis management. For the first time, the available reports and achievements in the field of endometriosis nanomedicine are critically evaluated, and a summary of how nanoparticle-based systems can improve endometriosis treatment and diagnosis is provided. Parallels between cancer and endometriosis are also drawn to understand whether some fundamental principles of the well-established cancer nanomedicine field can be adopted for the development of novel nanoparticle-based strategies for endometriosis. This review provides the state of the art of endometriosis nanomedicine and perspective for researchers aiming to realize and exploit the full potential of nanoparticles for treatment and imaging of the disorder.

Chitosan applications in studying and managing osteosarcoma

Osteosarcoma has a high prevalence among children and adolescents. Common treatments of this disease are not promising enough. Molecular processes involved in the pathogenesis of osteosarcoma are not fully understood. Besides, the remnants of tumor cells after surgery can cause bone destruction and recurrence of the disease. Thus, there is a need to develop novel drugs or enhancing the currently-used drugs as well as identifying bone-repairing methods. Chitosan is a natural compound produced by the deacetylation of chitin. Research has shown that chitosan can be used in various fields due to its beneficial effects, such as biodegradability and biocompatibility. Regarding cancer, chitosan exerts several anti-tumor activities. Moreover, it can be used in diagnostic techniques, drug delivery systems, and cell culture methods. Herein, we aim to discuss the potential roles of chitosan in studying and treating osteosarcoma. We review the literature on chitosan's applications as a drug delivery system and how it can be combined with other substances to improve its ability of local drug delivery. We take a look into the studies concerning the possible benefits of chitosan in the field of bone tissue engineering and 3D culturing. Furthermore, anti-cancer activities of different compounds of chitosan are reviewed.

Therapeutic Potential of Pigment Epithelium-derived Factor in Cancer

Pigment epithelium-derived factor (PEDF) is one of the serine protease inhibitors with multifunctional properties, which is produced by various types of organs and tissues. There is an accumulating body of evidence that PEDF plays an important role in the maintenance of tissue homeostasis. Indeed, PEDF not only works as an endogenous inhibitor of angiogenesis, but also suppresses oxidative stress, inflammatory and thrombotic reactions in cell culture systems, animal models, and humans. Furthermore, we, along with others, have found that PEDF inhibits proliferation of, and induces apoptotic cell death in, numerous kinds of tumors. In addition, circulating as well as tumor expression levels of PEDF have been inversely associated with tumor growth and metastasis. These observations suggest that supplementation of PEDF proteins and/or enhancement of endogenous PEDF expression could be a novel therapeutic strategy for the treatment of cancer. Therefore, in this paper, we review the effects of PEDF on diverse types of cancer, and discuss its therapeutic perspectives.

Quantification of BSA-loaded chitosan/oligonucleotide nanoparticles using reverse-phase high-performance liquid chromatography

Therapeutic proteins are administered subcutaneously because of their instability in the gastrointestinal tract. Current research suggests that polymeric-based nanoparticles, microparticles and liposomes are ideal nanocarriers to encapsulate proteins for disease management. In order to develop a successful drug delivery system, it is crucial to determine drug release profile and stability. However, the non-active excipients in polymeric formulations can influence the quantification of proteins in analytical techniques. This study investigated the effect of nine common polymers on quantification of bovine serum albumin (BSA) using RP-HPLC method. The technique offers advantages such as short analytical time, high accuracy and selectivity. In the meantime, the technique can be employed to separate proteins including BSA, insulin and pigment epithelium-derived factor (PEDF). Furthermore, the RP-HPLC method was applied to quantify the drug release pattern of a novel BSA-loaded nanoparticulate formulation in simulated gastric and intestinal fluids. The nanoparticles were formulated by natural polymer (chitosan) and oligonucleotide (Dz13Scr) using complex coacervation. The prepared particles were found to have small size (337.87 nm), low polydispersity index (0.338) and be positively charged (10.23 mV). The in vitro drug release patterns were characterised using the validated RP-HPLC method over 12 h. Graphical abstract ᅟ.

Insulin antagonises pigment epithelium-derived factor (PEDF)-induced modulation of lineage commitment of myocytes and heterotrophic ossification

Extensive bone defects arising as a result of trauma, infection and tumour resection and other bone pathologies necessitates the identification of effective strategies in the form of tissue engineering, gene therapy and osteoinductive agents to enhance the bone repair process. PEDF is a multifunctional glycoprotein which plays an important role in regulating osteoblastic differentiation and bone formation. PEDF treatment of mice and human skeletal myocytes at physiological concentration inhibited myogenic differentiation and activated Erk1/2 MAPK- dependent osteogenic transdifferentiation of myocytes. In mice, insulin, a promoter of bone regeneration, attenuated PEDF-induced expression of osteogenic markers such as osteocalcin, alkaline phosphatase and mineralisation for bone formation in the muscle and surrounding adipose tissue. These results provide new insights into the molecular aspects of the antagonising effect of insulin on PEDF-dependent modulation of the differentiation commitment of musculoskeletal environment into osteogenesis, and suggest that PEDF may be developed as an effective clinical therapy for bone regeneration as its heterotopic ossification can be controlled via co-administration of insulin.

Pigment epithelium-derived factor: a key mediator in bone homeostasis and potential for bone regenerative therapy

Objectives

Pigment epithelium-derived factor (PEDF), a multifunctional endogenous glycoprotein, has a very wide range of biological actions, notably in bone homeostasis. The question has been raised regarding the place of PEDF in the treatment of bone disorders and osteosarcoma, and its potential for tumour growth suppression.

Methods

The PubMed database was used to compile this review.

Key findings

Pigment epithelium-derived factor's actions in osteoid tissues include promoting mesenchymal stem cell commitment to osteoblasts, increasing matrix mineralisation, and promoting osteoblast proliferation. It shows potential to improve therapeutic outcomes in treatment of multiple cancer types and regrowth of bone after trauma or resection in animal studies. PEDF may possibly have a reduced adverse effect profile compared with current osteo-regenerative treatments; however, there is currently very limited evidence regarding the safety or efficacy in human models.

Summary

Pigment epithelium-derived factor is very active within the body, particularly in osseous tissue, and its physiological actions give it potential for treatment of both bone disorders and multiple tumour types. Further research is needed to ascertain the adverse effects and safety profile of PEDF as a therapeutic agent.

Biomaterials to suppress cancer stem cells and disrupt their tumoral niche

Lack of improvement in the treatment options of several types of cancer can largely be attributed to the presence of a subpopulation of cancer cells with stem cell signatures and to the tumoral niche that supports and protects these cells. This review analyses the main strategies that specifically modulate or suppress cancer stem cells (CSCs) and the tumoral niche (TN), focusing on the role of biomaterials (i.e. implants, nanomedicines, etc.) in these therapies. In the case of CSCs, we discuss differentiation therapies and the disruption of critical cellular signaling networks. For the TN, we analyze diverse strategies to modulate tumor hypervascularization and hypoxia, tumor extracellular matrix, and the inflammatory and tumor immunosuppressive environment. Due to their capacity to control drug disposition and integrate diverse functionalities, biomaterial-based therapies can provide important benefits in these strategies. We illustrate this by providing case studies where biomaterial-based therapies either show CSC suppression and TN disruption or improved delivery of major modulators of these features. Finally, we discuss the future of these technologies in the framework of these emerging therapeutic concepts.

Promising Nanocarriers for PEDF Gene Targeting Delivery to Cervical Cancer Cells Mediated by the Over-expressing FRα

Cervical cancer presents extremely low PEDF expression which is associated with tumor progression and poor prognosis. In this study, folate receptor α (FRα)-targeted nano-liposomes (FLP) were designed to enhance the anti-tumor effect by targeting delivery of exogenous PEDF gene to cervical cancer cells. The targeting molecule F-PEG-Chol was firstly synthesized by a novel simpler method. FLP encapsulating PEDF gene (FLP/PEDF) with a typical lipid-membrane structure were prepared by a film dispersion method. The transfection experiment found FLP could effectively transfect human cervical cancer cells (HeLa cells). FLP/PEDF significantly inhibited the growth of HeLa cells and human umbilical vein endothelial cells (HUVEC cells) and suppressed adhension, invasion and migration of HeLa cells in vitro. In the abdominal metastatic tumor model of cervical cancer, FLP/PEDF administered by intraperitoneal injection exhibited a superior anti-tumor effect probably due to the up-regulated PEDF. FLP/PEDF could not only sharply reduce the microvessel density but also dramatically inhibit proliferation and markedly induce apoptosis of tumor cells in vivo. Moreover, the preliminary safety investigation revealed that FLP/PEDF had no obvious toxicity. These results clearly showed that FLP were desired carriers for PEDF gene and FLP/PEDF might represent a potential novel strategy for gene therapy of cervical cancer.

Cell- and Gene- Based Therapeutics for Periodontal Regeneration

Periodontitis is a disease of the periodontium, characterized by loss of connective tissue attachment and supporting the alveolar bone. Therefore, to regenerate these lost tissues of the periodontium researchers have included a variety of surgical procedures including grafting materials growth factors and the use of barrier membranes, ultimately resulting into regeneration that is biologically possible but clinically unpredictable. Recently a newer approach of delivering DNA plasmids as therapeutic agents is gaining special attention and is called gene delivery method. Gene therapy being considered a novel approach have a potential to channel their signals in a very systematic and controlled manner thereby providing encoded proteins at all stages of tissue regeneration. The aim of this review was to enlighten a view on the application involving gene delivery and tissue engineering in periodontal regeneration.

Nucleotropic doxorubicin nanoparticles decrease cancer cell viability, destroy mitochondria, induce autophagy and enhance tumour necrosis

Objective

Doxorubicin (Dox) is used clinically against various neoplasias, but suffers from serious side effects, and for the past three decades, this shortcoming has spurred research towards finding better drug delivery systems (DDSs) for this frontline drug.

Methods

A non-targeted nucleotropic Dox-loaded nanoparticle (DNP) DDS is described, which has a simple chemical design, is easy to formulate and administer, is inexpensive, non-biohazardous and may prove to be useful clinically.

Key findings

The DNP formulated via vortex-assisted complex coarcevation enhanced (300-fold) cell-inhibitory activity of the drug in a panel of human cancer cells (osteosarcoma, breast, prostate and colorectal cancer) and enhanced (10-fold) efficacy against osteosarcoma (OS) in vivo. The slow-release DNPs localised to the endoplasmic reticulum disrupted the mitochondria and entered the nucleus. Prominent cytosolic vacuolisation, budding off of portions of the cytoplasm, both suggestive of autophagy, were observed. Mice that were administered with DNPs intratumorally had the smallest tumours at the end of the study, with more necrotic hotspots.

Conclusion

This promising nucleotropic DDS enhances the cell delivery and activity of Dox against a variety of human cancer cell lines and in OS tumours in mice.

Mechanisms of PEDF-mediated protection against reactive oxygen species damage in diabetic retinopathy and neuropathy

Pigment epithelium-derived factor (PEDF) is a pluripotent glycoprotein belonging to the serpin family. PEDF can stimulate several physiological processes such as angiogenesis, cell proliferation, and survival. Oxidative stress plays an important role in the occurrence of diabetic retinopathy (DR), which is the major cause of blindness in young diabetic adults. PEDF plays a protective role in DR and there is accumulating evidence of the neuroprotective effect of PEDF. In this paper, we review the role of PEDF and the mechanisms involved in its antioxidative, anti-inflammatory, and neuroprotective properties.

The potential role of free chitosan in bone trauma and bone cancer management

Bone defects caused by fractures or cancer-mediated destruction are debilitating. Chitosan is commonly used in scaffold matrices for bone healing, but rarely as a free drug. We demonstrate that free chitosan promotes osteoblast proliferation and osteogenesis in mesenchymal stem cells, increases osteopontin and collagen I expression, and reduces osteoclastogenesis. Chitosan inhibits invasion of endothelial cells, downregulating uPA/R, MT1-MMP, cdc42 and Rac1. Better healing of bone fractures with greater trabecular bone formation was observed in mice treated with chitosan. Chitosan induces apoptosis in osteotropic prostate and breast cancer cells via caspase-2 and -3 activation, and reduces their establishment in bone. Chitosan is pro-apoptotic in osteosarcoma cells, but not their normal counterpart, osteoblasts, or chondrosarcoma cells. Systemic delivery of chitosan does not perturb angiogenesis, bone volume or instinctive behaviour in pregnant mice, but decreases foetal length and changes pancreatic secretory acini. With certain controls in place, chitosan could be useful for bone trauma management.

Nanomedicines in the future of pediatric therapy

Nanotechnology has become a key tool to overcome the main (bio)pharmaceutical drawbacks of drugs and to enable their passive or active targeting to specific cells and tissues. Pediatric therapies usually rely on the previous clinical experience in adults. However, there exists scientific evidence that drug pharmacokinetics and pharmacodynamics in children differ from those in adults. For example, the interaction of specific drugs with their target receptors undergoes changes over the maturation of the different organs and systems. A similar phenomenon is observed for toxicity and adverse effects. Thus, it is clear that the treatment of disease in children cannot be simplified to the direct adjustment of the dose to the body weight/surface. In this context, the implementation of innovative technologies (e.g., nanotechnology) in the pediatric population becomes extremely challenging. The present article overviews the different attempts to use nanotechnology to treat diseases in the pediatric population. Due to the relevance, though limited available literature on the matter, we initially describe from preliminary in vitro studies to preclinical and clinical trials aiming to treat pediatric infectious diseases and pediatric solid tumors by means of nanotechnology. Then, the perspectives of pediatric nanomedicine are discussed.

Pigment epithelium-derived factor as a natural matrix metalloproteinase inhibitor: a comparison with classical matrix metalloproteinase inhibitors used for cancer treatment

OBJECTIVES

In the 1990s, the discovery of the important role of matrix metalloproteinases (MMPs) in cancer angiogenesis, growth and metastasis galvanised research efforts to search for ways to inhibit these MMPs. To date, this has resulted in the investigation of approximately 50 MMPIs which have undergone various phases of clinical trials. However, despite a large body of research being devoted to discovery and development of MMPIs, results have largely not been supportive of this approach to anticancer treatment.

KEY FINDINGS

The reasons for the general failure of these drugs in clinical trials include various unwanted side-effects, the use of healthy volunteers to provide drug dosages which did not correctly reflect dosages for cancer patients, and the exclusion of patients with early stage cancer in clinical trials despite MMPs being determined to be critical for the angiogenic switch, a process associated with early tumour growth. In contrast, a naturally-occurring endogenous protein and a non-functional serine protease inhibitor (serpin), pigment epithelium-derived factor (PEDF), has been proposed for cancer therapy partly due to its ability to regulate specific MMPs central to cancer progression.

SUMMARY

PEDF has been found to specifically downregulate membrane-type I matrix metalloproteinase (MT1-MMP) and furthermore, potentially matrix metalloproteinase-2 (MMP-2), two of the most commonly implicated MMPs in neoplasia.

Chitosans for delivery of nucleic acids

Alternatives to efficient viral vectors in gene therapy are desired because of their poor safety profiles. Chitosan is a promising non-viral nucleotide delivery vector because of its biocompatibility, biodegradability, low immunogenicity and ease of manufacturing. Since the transfection efficiency of chitosan polyplexes is relatively low compared to viral counterparts, there is an impetus to gain a better understanding of the structure-performance relationship. Recent progress in preparation and characterisation has enabled coupling analysis of chitosans structural parameters that has led to increased TE by tailoring of chitosan's structure. In this review, we summarize the recent advances that have lead to a more rational design of chitosan polyplexes. We present an integrated review of all major areas of chitosan-based transfection, including preparation, chitosan and polyplexes physicochemical characterisation, in vitro and in vivo assessment. In each, we present the obstacles to efficient transfection and the strategies adopted over time to surmount these impediments.

Finding chemo: the search for marine-based pharmaceutical drugs active against cancer

OBJECTIVES

Cancer affects the health of many people globally. The most common treatment that is used for cancer is chemotherapy, which has shown promising results but not without side effects. Some of these side effects jeopardise further treatment, and this eventually leads to advanced stages of malignancy and mortality. As a result, there is a need for better and safer anticancer compounds such as those found naturally. One of the most abundant natural environments to find such compounds is the sea, and this vast resource has been biomined since the 1950s.

KEY FINDINGS

There are currently three marine anticancer agents marketed (Yondelis, Cytosar-U and Halaven), with several others undergoing clinical trials. This review discusses marine-derived products in clinical use and in clinical trials, and discusses available literature on the growth suppression or pro-apoptotic properties of these compounds, and the molecular mechanisms underpinning these cell biological phenomena.

SUMMARY

The marine environment may hold promising anticancer compounds within its depths, warranting further research to be performed in this area, albeit with respect for the natural ecosystems that are being explored for drug discover and subsequently used for drug development.

Delivery of chemotherapeutic drugs in tumour cell-derived microparticles

Cellular microparticles are vesicular plasma membrane fragments with a diameter of 100-1,000 nanometres that are shed by cells in response to various physiological and artificial stimuli. Here we demonstrate that tumour cell-derived microparticles can be used as vectors to deliver chemotherapeutic drugs. We show that tumour cells incubated with chemotherapeutic drugs package these drugs into microparticles, which can be collected and used to effectively kill tumour cells in murine tumour models without typical side effects. We describe several mechanisms involved in this process, including uptake of drug-containing microparticles by tumour cells, synthesis of additional drug-packaging microparticles by these cells that contribute to the cytotoxic effect and the inhibition of drug efflux from tumour cells. This study highlights a novel drug delivery strategy with potential clinical application.

The effects of PEDF on cancer biology: mechanisms of action and therapeutic potential

The potent actions of pigment epithelium-derived factor (PEDF) on tumour-associated cells, and its extracellular localization and secretion, stimulated research on this multifunctional serpin. Such studies have identified several PEDF receptors and downstream signalling pathways. Known cellular PEDF responses have expanded from the initial discovery that PEDF induces retinoblastoma cell differentiation to its anti-angiogenic, antitumorigenic and antimetastatic properties. Although the diversity of PEDF activities seems to be complex, they are consistent with the varied mechanisms that regulate this multimodal factor. If PEDF is to be used for cancer management, a deeper appreciation of its many functions and mechanisms of action is needed.

Gadolinium-chitosan nanoparticles as a novel contrast agent for potential use in clinical bowel-targeted MRI: a feasibility study in healthy rats

BACKGROUND

MRI is of increasing importance in the diagnostic evaluation of gastrointestinal diseases, with depiction of mucosal enhancement obtained with conventional intravenous contrast. Routine clinical use of contrast agents has been carried out using intravenous injection for mucosal imaging. Contrast agents that specifically target the intestinal mucosa are therefore needed to improve clinical imaging of the mucosal surface.

PURPOSE

To synthesize a novel contrast agent for gadopentetic acid (Gd-DTPA)-loaded chitosan nanoparticles and observe the absorption of the nanoparticles in the colon wall of healthy rats by MR imaging in vivo.

MATERIAL AND METHODS

A contrast agent was successfully synthesized by a modified emulsion coalescence method, and the resulting agents were characterized in detail by dynamic light-scattering spectroscopy and inductively coupled plasma emission spectroscopy. The cytotoxicity of Gd-chitosan nanoparticles was evaluated by an MTT assay. Gadolinium-chitosan (Gd@chitosan) nanoparticles were administered to the colon mucosa of healthy rats by rectal administration, and MRI scans in vivo were carried out with a 3.0 T imaging scanner at various time points.

RESULTS

The prepared Gd@chitosan nanoparticles were ~420 nm in diameter with a 74.4% Gd-DTPA content. The MTT assay indicated little cytotoxicity. MRI results showed that nanoparticles can be retained in both the stratum submucosum and epithelial cells of the colon for almost 80 min. Transmission electron microscopy images further revealed that Gd@chitosan nanoparticles were localized inside the mucosal cells or intercellular space, while tissue from Gd-DTPA aqueous solution administration showed nothing. Due to the infusion of Gd@chitosan nanoparticles, the MR signal intensity of colon mucosa increased from about 6% to 35%, and the contrast enhancement was highest at 20 min after administration.

CONCLUSION

Gd@chitosan nanoparticles with high Gd-DTPA content were successfully prepared for use as a novel MRI contrast agent. All results indicated that rectally administered Gd@chitosan nanoparticles have the potential for MRI diagnosis of colon mucosal disease.

Effective antitumor gene therapy delivered by polyethylenimine-conjugated stearic acid-g-chitosan oligosaccharide micelles

Non-viral vesicle composing of low-molecular weight polyethylenimine-conjugated stearic acid-g-chitosan oligosaccharide (CSOSA-g-PEI) was synthesized for gene delivery and therapy. The synthesized CSOSA-g-PEI had good ion-buffer capabilities and DNA-binding capacity, which could form positively charged nano-sized particles (100-150 nm) with plasmid DNA; in vitro gene transfection tests demonstrated that CSOSA-g-PEI presented much lower cytotoxicity and corresponding transfection efficiency in comparison with Lipofectamine 2000 in both human cancer cells (Hela and MCF-7). The gene transfection of CSOSA-g-PEI/pDNA could be further enhanced in the presence of serum or by adding arginine during incubation of CSOSA-g-PEI micelles with plasmid DNA. The biodistribution experiments demonstrated CSOSA-g-PEI conjugate highly localized in the tumor tissue and indicated a persistently increased accumulation. In vivo antitumor activity results showed that CSOSA-g-PEI/plasmid pigment epithelium-derived factor formulation could effectively suppress the tumor growth (above 60% tumor inhibition) without systematic toxicity against animal body after intravenous injection.

Recent advances in polymeric microspheres for parenteral drug delivery--part 2

INTRODUCTION

Currently marketed microsphere products are manufactured with the use of organic solvents which have a negative impact on the environment and stability of biological molecules. With recent advances in fabrication technologies, solvent free methods have demonstrated potential for the preparation of microspheres.

AREAS COVERED

New technical advances recently achieved in solvent based microsphere manufacturing processes have allowed for major improvement in product quality and properties. Novel solvent free fabrication methods combined with newly functionalized biodegradable polymers have been explored for their application in the preparation of microspheres containing biological molecules.

EXPERT OPINION

Novel fabrication methods for microspheres have been recently reported but technical challenges and development risks remain high for scale up from bench to industrial commercialization. While the applications of microspheres for delivery of proteins, genes and vaccines have shown promise for clinical use, the approval of newly functionalized polymers as carriers may still face scrutiny on safety and biocompatibility, which can be key factors in securing the regulatory approval of the product.

Co-nanoencapsulated doxorubicin and Dz13 control osteosarcoma progression in a murine model

Objectives

Chitosan is a green (natural, abundant, biodegradable, biocompatible) biopolymer that can be formulated to encapsulate a variety of therapeutic compounds. This study aimed to investigate chitosan nanoparticles (NPs) as a means of improving delivery of the clinically used anti-cancer agent doxorubicin (Dox) and the preclinical lead compound Dz13 oligonucleotide together.

Methods

A novel chitosan NP system encapsulating Dox and Dz13 was designed, biophysically characterised and tested in a clinically relevant model of the metastasising bone tumour, osteosarcoma (OS).

Key findings

By careful alteration of the concentration of the individual components, a final formulation of Dz13-Dox NPs (DDNPs) was achieved, with high (>91%) loading of both compounds, which consisted of individual 50-nm particles forming aggregates as large as 500 nm, with a large positive ζ-potential. The DDNPs could be stored at various temperatures for a week without loss in activity but were prone to degradation in serum. DDNPs successfully inhibited OS tumour growth more effectively than treatment with NPs of Dz13 and Dox-chitosan, as well as Dox administered intraperitoneally. Apart from inhibiting tumour growth, DDNPs protected the affected bone from substantial destruction by aggressive tumour growth and reduced the incidence of metastasis to the lungs without causing adverse effects in mice.

Conclusion

This NP is a promising formulation that could be useful for clinical management of OS.

Systemically administered PEDF against primary and secondary tumours in a clinically relevant osteosarcoma model

Background:

Pigment epithelium-derived factor (PEDF) is an endogenous glycoprotein with a potential role as a therapeutic for osteosarcoma. Animal studies have demonstrated the biological effects of PEDF on osteosarcoma; however, these results are difficult to extrapolate for human use due to the chosen study design and drug delivery methods.

Methods:

In this study we have attempted to replicate the human presentation and treatment of osteosarcoma using a murine orthotopic model of osteosarcoma. The effects of PEDF on osteosarcoma cell lines were evaluated in vitro prior to animal experimentation. Orthotopic tumours were induced by intra-tibial injection of SaOS-2 osteosarcoma cells. Treatment with PEDF was delayed until after the macroscopic appearance of primary tumours. Pigment epithelium-derived factor was administered systemically via an implanted intraperitoneal micro-osmotic pump.

Results:

In vitro, PEDF inhibited proliferation, induced apoptosis and inhibited cell cycling of osteosarcoma cells. Pigment epithelium-derived factor promoted adhesion to Collagen I and inhibited invasion through Collagen I. In vivo, treatment with PEDF caused a reduction in both primary tumour volume and burden of pulmonary metastases. Systemic administration of PEDF did not cause toxic effects on normal tissues.

Conclusion:

Systemically delivered PEDF is effective in suppressing the size of primary and secondary tumours in an orthotopic murine model of osteosarcoma.

Animal models of osteosarcoma

Appendicular osteosarcoma (OS) is a primary mesenchymal tumor arising from malignantly transformed osteoblasts. In people, OS is the most common nonhematopoietic, primary skeletal neoplasm diagnosed in adolescents and is the second leading cause of cancer-related fatalities within this age group. Despite aggressive therapeutic management, including limb-sparing surgeries and dose-intense systemic chemotherapies, 30-40% of patients will experience progressive metastatic disease within 5 years of diagnosis. In order to reduce the fatality rate associated with recurrent or metastatic OS, a more thorough understanding of OS pathogenesis and biology is required. Towards this pursuit, comparative animal models of OS have been developed and are actively being studied to expand our fundamental understanding of OS. It is anticipated that specific animal models of OS, which most accurately recapitulate the natural disease process in people, will be most useful for advancing our understanding of OS biology, and will facilitate the discovery of disease pathogenesis and the identification of novel therapeutic strategies for managing this lethal metastatic bone sarcoma.

Pigment epithelium-derived factor as an anticancer drug and new treatment methods following the discovery of its receptors: a patent perspective

Traditional forms of cancer therapy, which include chemotherapy, have largely been overhauled due to the significant degree of toxicity they pose to normal, otherwise healthy tissue. It is hoped that the use of biological agents, most of which are endogenously present in the body, will lead to safer treatment outcomes, without sacrificing efficacy. The finding that pigment epithelium-derived factor (PEDF), a naturally-occurring protein, is a potent angiogenesis inhibitor has become the basis for studying the role of PEDF in tumours that are highly resistant to chemotherapy. The determination of the direct role of PEDF against cancer paves the way for understanding and developing PEDF as a novel drug. This review focuses on the patent applications behind testing the anticancer therapeutic effect of PEDF via its receptors as an antiangiogenic agent and as a direct anticancer agent. The majority of the PEDF patents describe the antiangiogenic ability and usage of recombinant vectors as the mode of treatment delivery. PEDF's therapeutic potential against different diseases and the discovery of its receptors open possibilities for improving PEDF-based peptide design and drug delivery modes.

Pigment epithelium-derived factor as an impending therapeutic agent against vascular epithelial growth factor-driven tumor-angiogenesis

In spite of the recent epidemiological study indicating a positive decrease in cancer trends, cancer remains to be one of the major causes of deaths and there is an anticipated increase in the number of new cancer cases to be recorded in the following years to come. It is important for researchers to improve the current therapeutic agents involved against cancer, particularly targeting to inhibit tumor cell growth, survival, and metastasis. Many researchers investigate the crucial role of a proangiogenic factor, vascular endothelial growth factor (VEGF) in the process of tumor angiogenesis, where the formation of new blood vessels carrying essential nutrients to the tumor cell becomes a critical factor for tumor growth. Since the establishment of VEGF's integral role in mediating tumor angiogenesis and tumor cell survival, current efforts are dedicated to developing therapeutic agents against VEGF and one of the emerging candidate under this category is pigment epithelium-derived factor (PEDF).

In vitro and in vivo biological activity of PEDF against a range of tumors

BACKGROUND

Pigment epithelium-derived factor (PEDF) is an emerging anti-cancer agent that targets both tumor tissue and its supporting vasculature. These direct and indirect effects of PEDF have been examined in vitro and in vivo for a range of malignancies.

OBJECTIVE

This review seeks to present PEDF as a potential anti-cancer agent with applications across multiple malignancies. We refer closely to experimental methodology whilst still highlighting the clinical significance of PEDF in cancer, drawing on biological findings in vitro and in vivo.

METHODS

A Pubmed database search was performed limiting the scope of this discussion paper mainly to PEDF's biological role in cancer, specifically lung, breast, prostatic, ovarian and pancreatic carcinomas, melanoma, glioma and osteosarcoma.

CONCLUSIONS

The biological roles of PEDF are diverse and multidimensional. As an anti-cancer agent, PEDF has great potential as a focused anti-neoplastic therapy against a variety of tumor types.

Cancer, chitosan nanoparticles and catalytic nucleic acids

Objectives

The aim of this review was to examine gene therapy involving DNAzyme and siRNA encapsulation into chitosan nanoparticles, discussing the current and future status of this drug delivery system in enhancing drug delivery and cancer therapy.

Key findings

Cancer is a disease state in which the cells in our body undergo mutations at the genetic level and are transformed, acquiring the ability to replicate limitlessly. Conventional cancer treatment involves the use of surgery and cytotoxic chemotherapy and/or radiotherapy, which have the potential of harming normal, otherwise healthy, non-neoplastic cells. Newer forms of therapy such as immunotherapy and gene therapy have shown initial promise, but still require better ways to limit exposure to cancerous lesions in the body. As a result drug delivery systems have been developed in attempts to deliver therapeutics specifically to the target lesion site. One recent drug delivery system has revolved around the use of chitosan nanoparticle technology, where therapeutics are encapsulated into nanoparticles and targeted to tumours.

Summary

Though few, attempts at encapsulating therapeutics such as deoxyribozymes and small or short interfering RNA have been optimistic and encouraging.

Review: doxorubicin delivery systems based on chitosan for cancer therapy

Objectives

This review sheds insight into an increasingly popular polymer that has been widely explored as a potential drug delivery system. The abundant, biodegradable and biocompatible polysaccharide chitosan, with many other favourable properties, has been favoured as a drug delivery system for the purposes of encapsulating and delivery of doxorubicin with reduced side-effects.

Key findings

Doxorubicin is frequently used as a frontline chemotherapeutic agent against a variety of cancers. It has largely been able to demonstrate anti-tumour effects, though there are major shortfalls of doxorubicin, which include serious side-effects such as cardiomyopathy and myelosuppression, and also an ever-present danger of extravasation during drug administration. In view of this, drug delivery systems are currently being explored as alternative methods of drug delivery in a bid to more effectively direct doxorubicin to the specific lesion site and reduce its systemic side-effects. Liposomes and dendrimers have been tested as potential carriers for doxorubicin; however they are not the focus of this review.

Summary

Recent advancements in doxorubicin and chitosan technology have shown some preliminary though promising results for cancer therapy.

Delivery strategies of melanoma vaccines: an overview

For many years, various cancer vaccines have been widely evaluated, however clinical responses remain rare. In this review, we attempt to address the question of which delivery strategies and platforms are feasible to produce clinical response and define the characteristics of the strategy that will induce long-lasting antitumor response. We limit our analysis and discussion to microparticles/nanoparticles, liposomes, heat-shock proteins, viral vectors and different types of adjuvants. This review aims to provide an overview of the specific characteristics, strengths and limitations of these delivery systems, focusing on their impacts on the development of melanoma vaccine. To date, only adoptive T-cell transfer has shown promising clinical outcomes compared to other treatments.

Preparation of preformed porous PLGA microparticles and antisense oligonucleotides loading

The objective of this study was to load preformed highly porous microparticles with drug. The microparticles were prepared by a modified multiple emulsion (w/o/w) solvent evaporation method with the addition of pore formers (NaCl into the internal aqueous phase or of glycerol monooleate to the poly(lactide-co-glycolide) (PLGA) polymer phase). The drug-free solidified microparticles were then washed with either water (for NaCl) or hexane (for glycerol monooleate) to extract the pore formers. The drug was then loaded into the preformed porous microparticles by incubation in aqueous drug solutions followed by air- or freeze-drying. The drug was strongly bound to the polymeric surface with air-dried microparticles. A biphasic drug release with an initial rapid release phase (burst effect) was followed by a slower release up to several weeks. The initial burst was dependent on the drug loading and could be significantly reduced by wet (non-aqueous) temperature curing.

The use of chitosan formulations in cancer therapy

With the advent of the theranostics era in biomedical research, gene therapy is poised to offer more, provided that more efficient delivery vehicles are discovered and developed. Chitosan is a biomatrix that is abundant, biocompatible, biodegradable, versatile, inexpensive and safe. These features have paved the way for its use in gene therapy, mainly for delivery of therapeutic plasmids and more recently for siRNA. Recent studies show that chitosan per se exhibits anticancer properties both in vitro and in animal models, most probably through the p21/Cip and p27/Kip pathways. This review looks at the in vivo studies using chitosan technology towards cancer gene therapy, drawing some support from non-cancer studies. The future of this promising technology lies in the evolution of new ideas for enhanced nucleic acid drug pharmacokinetics and, consequently, pharmacodynamics for cancer patients.