Polydimethylsiloxane Organic-Inorganic Composite Drug Reservoir with Gliclazide

A novel organic-inorganic gliclazide-loaded composite bead was developed by an ionic gelation process using acidified CaCl2, chitosan and tetraethylorthosilicate (TEOS) as a crosslinker. The beads were manufactured by crosslinking an inorganic silicone elastomer (-OH terminated polydimethylsiloxane, PDMS) with TEOS at different ratios before grafting onto an organic backbone (Na-alginate) using a 32 factorial experimental design. Gliclazide's encapsulation efficiency (EE%) and drug release over 8 h (% DR 8 h) were set as dependent responses for the optimisation of a pharmaceutical formula (herein referred to as 'G op') by response surface methodology. EE % and %DR 8 h of G op were 93.48% ± 0.19 and 70.29% ± 0.18, respectively. G op exhibited a controlled release of gliclazide that follows the Korsmeyer-Peppas kinetic model (R2 = 0.95) with super case II transport and pH-dependent swelling behaviour. In vitro testing of G op showed 92.17% ± 1.18 cell viability upon testing on C2C12 myoblasts, indicating the compatibility of this novel biomaterial platform with skeletal muscle drug delivery.

Biochemical changes to the inner ear contributing to diabetes-induced hearing loss: possible pharmacological targets for therapy

OBJECTIVES

Biochemical alterations due to diabetes development and progress are complex and diabetes-associated injury to various tissues has been well reported. Nevertheless, a close investigation of the literature demonstrates limited coverage regarding these biochemical and molecular alterations within the inner ear and their impact on the vestibulocochlear environment. A closer look at these may reveal pharmacological targets that could alleviate the severity of disease in patients.

KEY FINDINGS

Tight control of glucose levels within the highly metabolic inner ear structures is crucial for their physiology and function. Impaired glucose homeostasis is well known to occur in vestibulocochlear malfunctioning. Moreover, the involvement of insulin signalling, and glucose transporters were recently confirmed in vestibulocochlear structures and are believed to play a crucial role in auditory and vestibular functions.

CONCLUSION

Oxidative overload, glucolipotoxicity, perturbed blood rheology, endothelial dysfunction, compromised microvascular supply, and neurotoxicity are reported in many diabetic complications such as nephropathy, retinopathy, and diabetic neuropathy and are incriminated in the disruption of blood labyrinth barrier as well as vestibulocochlear neuritis. Dysfunctional insulin signalling was recently reported in the Organ of Corti. Insulin resistance in the inner ear niche warrants further studies to verify and uncover new pharmacological targets to manage this debilitating condition better.

Synergy between PEDF and Doxorubicin in Breast Cancer Cells: Effects on Metastatic and Metabolic Pathways

Pigment epithelium-derived factor (PEDF), a serine protease inhibitor (Serpin) family member, shows promise in inhibiting tumour growth. In our study, we explored the effects of PEDF on the efficacy of the frontline chemotherapy agent doxorubicin (Dox) in BC cells. We found that Dox+PEDF treatment significantly reduced glucose uptake in MDA-MB-231 cells compared to the control (p = 0.0005), PEDF (p = 0.0137), and Dox (p = 0.0171) alone but paradoxically increased it in MCF-7 cells. Our findings further revealed that PEDF, Dox, and Dox+PEDF substantially hindered tumour cell migration from tumour spheroids, with Dox+PEDF showing the most significant impact (p < 0.0001). We also observed notable decreases in the expression of metastatic markers (uPAR, uPA, CXCR4, MT1-MMP, TNF-α) across all treatment groups (p < 0.0001) in both cell lines. When it comes to metabolic pathways, PEDF increased phosphorylated IRS-1 (p-IRS1) levels in MDA-MB-231 and MCF-7 (p < 0.0001), while Dox decreased it, and the combination led to an increase. In MDA-MB-231 cells, treatment with PEDF, Dox, and the combination led to a notable decrease in both phosphorylated AKT (p-AKT) and total AKT levels. In MCF-7, while PEDF, Dox, and their combination led to a reduction in p-AKT, total levels of AKT increased in the presence of Dox and Dox+PEDF. Combining PEDF with Dox enhances the targeting of metastatic and metabolic pathways in breast cancer cell lines. This synergy, marked by PEDF's increasing roles in cancer control, may pave the way for more effective cancer treatments.

The Various Roles of PEDF in Cancer

Pigment epithelium-derived factor (PEDF) is a natural immunomodulator, anti-inflammatory, anti-angiogenic, anti-tumour growth and anti-metastasis factor, which can enhance tumour response to PEDF but can also conversely have pro-cancerous effects. Inflammation is a major cause of cancer, and it has been proven that PEDF has anti-inflammatory properties. PEDF's functional activity can be investigated through measuring metastatic and metabolic biomarkers that will be discussed in this review.

The Impact of Pigment-Epithelium-Derived Factor on MCF-7 Cell Metabolism in the Context of Glycaemic Condition

Studies have demonstrated that pigment-epithelium-derived factor (PEDF) is a robust inhibitor of tumour growth and development, implying that this may serve as a promising target for therapeutic intervention. However, the precise impact of PEDF on cancerous cell metabolic pathways remains uncertain despite ongoing research. In this light, this study aimed to employ a metabolomics approach for understanding the metabolic reprogramming events in breast cancer across different glycaemic loads and their response to PEDF. Gas chromatography-quadrupole mass spectrometry (GC/Q-MS) analysis revealed metabolic alterations in ER+ human cell line MCF-7 cells treated with PEDF under varying glycaemic conditions. The identification of significantly altered metabolites was accomplished through MetaboAnalyst (v.5.0) and R packages, which enabled both multivariate and univariate analyses. Out of the 48 metabolites identified, 14 were chosen based on their significant alterations in MCF-7 cells under different glycaemic conditions and PEDF treatment (p < 0.05, VIP > 0.8). Dysregulation in pathways associated with amino acid metabolism, intermediates of the TCA cycle, nucleotide metabolism, and lipid metabolism were detected, and they exhibited different responses to PEDF. Our results suggest that PEDF has a diverse influence on the metabolism of MCF-7 cells in both normo- and hyperglycaemic environments, thereby warranting studies using patient samples to correlate our findings with clinical response in the future.

Pigment Epithelium-Derived Factor: Inhibition of Phosphorylation of Insulin Receptor (IR)/IR Substrate (IRS), Osteogeneration from Adipocytes, and Increased Levels Due to Doxorubicin Exposure

OBJECTIVES

Pigment epithelium-derived factor (PEDF) has been recently linked to insulin resistance and is capable of differentiating myocytes to bone. We examined in more detail the intricate signalling of the insulin pathway influenced by PEDF in skeletal myocytes. We tested whether this serpin is also capable of generating de novo bone from adipocytes in vitro and in vivo, and how the anticancer drug doxorubicin links with PEDF and cellular metabolism.

METHODS AND KEY FINDINGS

We demonstrate that PEDF can inhibit phosphorylation of insulin receptor (IR) and insulin receptor substrate (IRS) in skeletal myocytes. PEDF constitutively activates p42/44 MAPK/Erk, but paradoxically does not affect mitogenic signalling. PEDF did not perturb either mitochondrial activity or proliferation in cells representing mesenchymal stem cells, cardiomyocytes, and skeletal myocytes and adipocytes. PEDF induced transdifferentiation of adipocytes to osteoblasts, promoting bone formation in cultured adipocytes in vitro and gelfoam fatpad implants in vivo. Bone formation in white adipose tissue (WAT) was better than in brown adipose tissue (BAT). The frontline anticancer drug doxorubicin increased levels of PEDF in a human breast cancer cell line, mirroring the in vivo finding where cardiac muscle tissue was stained increasingly for PEDF as the dose of doxorubicin increased in mice. PEDF also increased levels of reactive oxygen species (ROS) and glutathione (GSH) in the breast cancer cell line.

CONCLUSIONS

PEDF may be used to regenerate bone from adipose tissue in cases of trauma such as fractures or bone cancers. The increased presence of PEDF in doxorubicin-treated tumour cells need further exploration, and could be useful therapeutically in future. The safety of PEDF administration in vivo was further demonstrated in this study.

Potential therapeutic role for pigment epithelium-derived factor in post-menopausal breast cancer bone metastasis

OBJECTIVES

This review discusses key oestrogens associated with the circulating pre- and post-menopausal milieu and how they may impact intratumoral oestrogen levels and breast cancer (BC) metastasis. It also identifies critical steps in BC metastasis to bone from the viewpoint of pigment epithelium-derived factor (PEDF) function, and discusses the role of several associated pro-metastatic biomarkers in BC bone metastasis.

KEY FINDINGS

PEDF is regulated by oestrogen in a number of oestrogen-sensitive tissues. Changes in circulating oestrogen levels associated with menopause may enhance the growth of BC bone metastases, leading to the establishment of a pre-metastatic niche. The establishment of such a pre-metastatic niche is driven by several key mediators, with pro-osteoclastic and pro-metastatic function which are upregulated by BC cells. These mediators appear to be regulated by oestrogen, as well as differentially affected by menopausal status. PEDF interacts with several pro-metastatic, pro-osteoclastic biomarkers, including C-X-C motif chemokine receptor 4 (CXCR4) and nuclear factor kappa B (NFκB) in BC bone metastasis.

CONCLUSION

Mediators such as CXCR4 and MT1-MMP underpin the ability of PEDF to function as an antimetastatic in other cancers such as osteosarcoma, highlighting the possibility that this serpin could be used as a therapeutic against BC metastasis in future.

Roles of pigment epithelium-derived factor in cardiomyocytes: implications for use as a cardioprotective therapeutic

OBJECTIVES

Cardiovascular diseases are the leading cause of death worldwide, with patients having limited options for treatment. Pigment epithelium-derived factor (PEDF) is an endogenous multifunctional protein with several mechanisms of action. Recently, PEDF has emerged as a potential cardioprotective agent in response to myocardial infarction. However, PEDF is also associated with pro-apoptotic effects, complicating its role in cardioprotection. This review summarises and compares knowledge of PEDF's activity in cardiomyocytes with other cell types and draws links between them. Following this, the review offers a novel perspective of PEDF's therapeutic potential and recommends future directions to understand the clinical potential of PEDF better.

KEY FINDINGS

PEDF's mechanisms as a pro-apoptotic and pro-survival protein are not well understood, despite PEDF's implication in several physiological and pathological activities. However, recent evidence suggests that PEDF may have significant cardioprotective properties mediated by key regulators dependent on cell type and context.

CONCLUSIONS

While PEDF's cardioprotective activity shares some key regulators with its apoptotic activity, cellular context and molecular features likely allow manipulation of PEDF's cellular activity, highlighting the importance of further investigation into its activities and its potential to be applied as a therapeutic to mitigate damage from a range of cardiac pathologies.

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.

Doxorubicin-induced cardiotoxicity: causative factors and possible interventions

OBJECTIVES

Doxorubicin (Dox) belongs to the anthracycline drug classification and is a widely administered chemotherapeutic. However, Dox use in therapy is limited by its cardiotoxicity, representing a significant drawback of Dox treatment applicability. A large amount of current research is on reducing Dox-induced cardiotoxicity by developing targeted delivery systems and investigating cardiotoxicity mechanisms. Recently, discrepancies have challenged the traditional understanding of Dox metabolism, mechanisms of action and cardiotoxicity drivers. This review summarises the current knowledge around Dox's metabolism, mechanisms of anticancer activity, and delivery systems and offers a unique perspective on the relationships between several proposed mechanisms of Dox-induced cardiotoxicity.

KEY FINDINGS

While there is a strong understanding of Dox's pharmacokinetic properties, it is unclear which enzymes contribute to Dox metabolism and how Dox induces its cytotoxic effect in neoplastic and non-neoplastic cells. Evidence suggests that there are several potentially synergistic mechanisms involved in Dox-induced cardiotoxicity.

SUMMARY

It has become clear that Dox operates in a multifactorial fashion dependent on cellular context. Accumulation of oxidative stress appears to be a common factor in cardiotoxicity mechanisms, highlighting the importance of novel delivery systems and antioxidant therapies.

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.

Update on Safety and Efficacy of HPV Vaccines: Focus on Gardasil

The human papillomavirus (HPV) is a highly contagious and prevalent virus that is primarily sexually transmitted. The Gardasil® quadrivalent vaccine, the Cevarix® bivalent vaccine and the Gardasil® 9 nonavalent vaccine were developed to prevent the spread of HPV as well as the incidence of its associated diseases. The aim of this mini-review is to critically analyze the safety and efficacy of both the Gardasil vaccines. A literature search was conducted on ProQuest, MedLine, Science Direct and Scopus databases. More than hundred articles were scanned, and from this, 38 most relevant papers involving human studies across several countries were closely reviewed. The literature deems the Gardasil® HPV vaccines to be safe and efficacious. Due to the novel nature of these vaccines, long-term efficacies, as well as their associated long-term adverse effects, are yet to be confirmed. Of some concern was the finding that a majority of these studies disclosed minor to major involvement with the vaccine manufacturers, and the inhibitory cost of use in developing nations. Gardasil is largely considered safe to use. However, considering that these vaccines are predominantly indicated for children, further comprehensive, impartial, and long-term studies are needed to critically assess safety and efficacy.

Impact of Drug Loading Method on Drug Release from 3D-Printed Tablets Made from Filaments Fabricated by Hot-Melt Extrusion and Impregnation Processes

The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.

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.

A glance at the actual role of glutamine metabolism in thyroid tumorigenesis

Thyroid cancers (TCs) are the most prevalent malignancy of the endocrine system and the seventh most common cancer in women. According to estimates from the Global Cancer Observatory (GCO) in 2020, the incidence of thyroid cancer globally was 586,000 cases. As thyroid cancer incidences have dramatically increased, identifying the most important metabolic pathways and biochemical markers involved in thyroid tumorigenesis can be critical strategies for controlling the prevalence and ultimately treatment of this disease. Cancer cells undergo cellular metabolism and energy alteration in order to promote cell proliferation and invasion. Glutamine is one of the most abundant free amino acids in the human body that contributes to cancer metabolic remodeling as a carbon and nitrogen source to sustain cell growth and proliferation. In the present review, glutamine metabolism and its regulation in cancer cells are highlighted. Thereafter, emphasis is given to the perturbation of glutamine metabolism in thyroid cancer, focusing on metabolomics studies.

Optimized Taste-Masked Microparticles for Orally Disintegrating Tablets as a Promising Dosage Form for Alzheimer's Disease Patients

The objective of this research was to optimize the tasted-masked microparticles for orally disintegrating tablets containing donepezil hydrochloride using quality risk assessment and design of experiment approaches. The double emulsion solvent evaporation technique using aminoalkyl methacrylate copolymer (AMC) was used to prepare taste-masked microparticles. Factors affecting the quality of the taste-masked microparticles were analyzed using an Ishikawa diagram. A risk-ranking approach was used to rank the formulation and process risks. Furthermore, the effect of AMC quantity, stirring time, and volume of outer water phase on various responses, such as particle size, the amount of drug dissolved at 5 min (Q5) in simulated saliva fluid, and mean dissolution time (MDT) in simulated gastric fluid, was investigated using the Box-Behnken design. The optimized microparticles were then used to prepare orally disintegrating tablets (ODTs) and evaluated by in vitro and in vivo testing. The results demonstrated that particle size was influenced by the AMC amount and stirring time. Q5 was significantly affected by the amount of AMC and the volume of the outer water phase. On the other hand, these two factors had a positive effect on MDT. The optimized microparticles had a particle size of 174.45 ± 18.19 µm, Q5 of 5.04%, and MDT of 5.97 min. The ODTs with taste-masked microparticles showed acceptable in vitro dissolution with an MDT of 5 min. According to the results of a panel of six human volunteers, they greatly improved palatability.

The biological relevance of pigment epithelium-derived factor on the path from aging to age-related disease

Pigment epithelium-derived factor (PEDF) is an endogenously produced protein that contributes to cell growth arrest, and reduced levels of PEDF are associated with the progression of cellular senescence and the aging process. However, the mechanisms underlying PEDF regulation of these events are not completely clear. Increased PEDF activity may induce anti-aging processes, suggesting the potential therapeutic value of PEDF as an anti-aging and age-related disease. In this review, we recapitulate the molecular and cellular mechanisms of aging following the characteristics and specific roles of the PEDF in cell cycle arrest and its relevance to cellular senescence and aging pathways. In this context, the discovery and fluctuations of PEDF in age-related diseases are summarised. In light of the importance of PEDF in cellular senescence and aging processes, better comprehension of the mechanism(s) of PEDF in the regulation of cell cycle and the aging process can conceivably facilitate the development of therapeutic strategies for diseases that occur with aging.

β-Cyclodextrin-containing chitosan-oligonucleotide nanoparticles improve insulin bioactivity, gut cellular permeation and glucose consumption

OBJECTIVES

The main objective of the present study was to develop a nanoparticulate drug delivery system that can protect insulin against harsh conditions in the gastrointestinal (GI) tract. The effects of the following employed techniques, including lyophilisation, cross-linking and nanoencapsulation, on the physicochemical properties of the formulation were investigated.

METHODS

We herein developed a nanocarrier via ionotropic gelation by using positively charged chitosan and negatively charged Dz13Scr. The lyophilised nanoparticles with optimal concentrations of tripolyphosphate (cross-linking agent) and β-cyclodextrin (stabilising agent) were characterised by using physical and cellular assays.

KEY FINDINGS

The addition of cryoprotectants (1% sucrose) in lyophilisation improved the stability of nanoparticles, enhanced the encapsulation efficiency, and ameliorated the pre-mature release of insulin at acidic pH. The developed lyophilised nanoparticles did not display any cytotoxic effects in C2C12 and HT-29 cells. Glucose consumption assays showed that the bioactivity of entrapped insulin was maintained post-incubation in the enzymatic medium.

CONCLUSIONS

Freeze-drying with appropriate cryoprotectant could conserve the physiochemical properties of the nanoparticles. The bioactivity of the entrapped insulin was maintained. The prepared nanoparticles could facilitate the permeation of insulin across the GI cell line.

Fabrication techniques for the preparation of orally administered insulin nanoparticles

The development of orally administered protein drugs is challenging due to their intrinsic unfavourable features, including large molecular size and poor chemical stability, both of which limit gastrointestinal (GI) absorption efficiency. Nanoparticles can overcome the GI barriers effectively and improve the oral bioavailability of proteins in the GI tract. They possess large surface area to volume ratio, and can facilitate the GI absorption of nanoparticles via the paracellular and transcellular routes. Nanoparticles can be prepared by various fabrication techniques that can encapsulate the fragile therapeutic proteins via hydrophobic bonding and electrostatic interaction. A desirable technique should involve minimal harsh conditions and encapsulate therapeutic proteins with preserved functionalities. The current review examines the characteristics of each preparation technique, and illustrates the examples of insulin-loaded nanoparticles that have been developed in each fabrication method. The following techniques, which include nanoprecipitation, hydrophobic conjugation, flash nanocomplexation, double emulsion, ionotropic gelation, and layer-by-layer adsorption, have been used to formulate ligand-modified nanoparticles for targeted delivery of insulin. Other techniques, including reduction, complex coacervation (polyelectrolyte complexation), hydrophobic ion pairing and emulsion solvent diffusion method, and sol-gel technology, were also discussed in the latter part of the review due to their extensive use in fabrication of insulin nanoparticles. This review also discusses the strategies that have been utilised during the formulation process to improve the stability and bioactivity of therapeutic proteins.

Pigment Epithelium-Derived Factor and Sex Hormone-Responsive Cancers

Oestrogens and androgens play important roles in normal and cancerous tissue and have been shown to negatively regulate pigment epithelium-derived factor (PEDF) expression in sex hormone-responsive tumours. PEDF suppresses tumour growth and its downregulation by oestrogen is implicated in tumorigenesis, metastasis, and progression. PEDF expression is reduced in cancerous tissue of the prostate, breast, ovary, and endometrium compared to their normal tissue counterparts, with a link between PEDF downregulation and sex hormone signalling observed in pre-clinical studies. PEDF reduces growth and metastasis of tumour cells by promoting apoptosis, inhibiting angiogenesis, increasing adhesion, and reducing migration. PEDF may also prevent treatment resistance in some cancers by downregulating oestrogen receptor signalling. By interacting with components of the tumour microenvironment, PEDF counteracts the proliferative and immunosuppressive effects of oestrogens, to ultimately reduce tumorigenesis and metastasis. In this review, we focus on sex hormone regulation of PEDF's anti-tumour action in sex hormone-responsive tumours.

C2C12 cell model: its role in understanding of insulin resistance at the molecular level and pharmaceutical development at the preclinical stage

OBJECTIVES

The myoblast cell line, C2C12, has been utilised extensively in vitro as an examination model in understanding metabolic disease progression. Although it is indispensable in both preclinical and pharmaceutical research, a comprehensive review of its use in the investigation of insulin resistance progression and pharmaceutical development is not available.

KEY FINDINGS

C2C12 is a well-documented model, which can facilitate our understanding in glucose metabolism, insulin signalling mechanism, insulin resistance, oxidative stress, reactive oxygen species and glucose transporters at cellular and molecular levels. With the aid of the C2C12 model, recent studies revealed that insulin resistance has close relationship with various metabolic diseases in terms of disease progression, pathogenesis and therapeutic management. A holistic, safe and effective disease management is highly of interest. Therefore, significant efforts have been paid to explore novel drug compounds and natural herbs that can elicit therapeutic effects in the targeted sites at both cellular (e.g. mitochondria, glucose transporter) and molecular level (e.g. genes, signalling pathway).

SUMMARY

The use of C2C12 myoblast cell line is meaningful in pharmaceutical and biomedical research due to their expression of GLUT-4 and other features that are representative to human skeletal muscle cells. With the use of the C2C12 cell model, the impact of drug delivery systems (nanoparticles and quantum dots) on skeletal muscle, as well as the relationship between exercise, pancreatic β-cells and endothelial cells, was discovered.

Development of orally administered insulin-loaded polymeric-oligonucleotide nanoparticles: statistical optimization and physicochemical characterization

INTRODUCTION

Therapeutic peptides are administered via parenteral route due to poor absorption in the gastrointestinal (GI) tract, instability in gastric acid, and GI enzymes. Polymeric drug delivery systems have achieved significant interest in pharmaceutical research due to its feasibility in protecting proteins, tissue targeting, and controlled drug release pattern.

MATERIALS AND METHODS

In this study, the size, polydispersity index, and zeta potential of insulin-loaded nanoparticles were characterized by dynamic light scattering and laser Doppler micro-electrophoresis. The main and interaction effects of chitosan concentration and Dz13Scr concentration on the physicochemical properties of the prepared insulin-loaded nanoparticles (size, polydispersity index, and zeta potential) were evaluated statistically using analysis of variance. A robust procedure of reversed-phase high-performance liquid chromatography was developed to quantify insulin release in simulated GI buffer. Results and discussion: We reported on the effect of two independent parameters, including polymer concentration and oligonucleotide concentration, on the physical characteristics of particles. Chitosan concentration was significant in predicting the size of insulin-loaded CS-Dz13Scr particles. In terms of zeta potential, both chitosan concentration and squared term of chitosan were significant factors that affect the surface charge of particles, which was attributed to the availability of positively-charged amino groups during interaction with negatively-charged Dz13Scr. The excipients used in this study could fabricate nanoparticles with negligible toxicity in GI cells and skeletal muscle cells. The developed formulation could conserve the physicochemical properties after being stored for 1 month at 4 °C.

CONCLUSION

The obtained results revealed satisfactory results for insulin-loaded CS-Dz13Scr nanoparticles (159.3 nm, pdi 0.331, -1.08 mV). No such similar study has been reported to date to identify the main and interactive significance of the above parameters for the characterization of insulin-loaded polymeric-oligonucleotide nanoparticles. This research is of importance for the understanding and development of protein-loaded nanoparticles for oral delivery.

Lyophilisation Improves Bioactivity and Stability of Insulin-Loaded Polymeric-Oligonucleotide Nanoparticles for Diabetes Treatment

The oral bioavailability of therapeutic proteins is limited by the gastrointestinal barriers. Encapsulation of labile proteins into nanoparticles is a promising strategy. In order to improve the stability of nanoparticles, lyophilisation has been used to remove water molecules from the suspension. Although various cryoprotections were employed in the preparation of lyophilised nanoparticles, the selection of cryoprotectant type and concentration in majority of the developed formulation was not justified. In this study, nanoparticles were fabricated by cationic chitosan and anionic Dz13Scr using complex coacervation. The effect of cryoprotectant types (mannitol, sorbitol, sucrose and trehalose) and their concentrations (1, 3, 5, 7, 10% w/v) on physiochemical properties of nanoparticles were measured. Cellular assays were performed to investigate the impact of selected cryoprotectant on cytotoxicity, glucose consumption, oral absorption mechanism and gastrointestinal permeability. The obtained results revealed that mannitol (7% w/v) could produce nanoparticles with small size (313.2 nm), slight positive charge and uniform size distribution. The addition of cryoprotectant could preserve the bioactivity of entrapped insulin and improve the stability of nanoparticles against mechanical stress during lyophilisation. The gastrointestinal absorption of nanoparticles is associated with both endocytic and paracellular pathways. With the use of 7% mannitol, lyophilised nanoparticles induced a significant glucose uptake in C2C12 cells. This work illustrated the importance of appropriate cryoprotectant in conservation of particle physiochemical properties, structural integrity and bioactivity. An incompatible cryoprotectant and inappropriate concentration could lead to cake collapse and formation of heterogeneous particle size populations.

Advanced and multifaceted stability profiling of the first-line antidiabetic drugs metformin, gliclazide and glipizide under various controlled stress conditions

The antidiabetic drugs metformin, gliclazide and glipizide have been widely used and studied in terms of pharmacological and antidiabetic effects, and their individual stability has been studied in the literature. However, the drugs’ combined stability profiling remains poorly understood, and hence the aim of this study was to investigate the collective stability profiling of different combinations at various controlled conditions. Degradation assessments were carried out on metformin, glipizide and gliclazide by applying a stability-indicating HPLC method that was developed and validated in accordance with ICH guidelines. Glipizide, gliclazide, metformin and the binary mixtures (metformin/glipizide and metformin/gliclazide) were subjected to different forced degradation conditions and were detected at 227 nm by an isocratic separation on an Alltima CN column (250 mm × 4.6 mm × 5µ) utilizing a mobile phase that consists of 20 mM ammonium formate buffer (pH 3.5) and acetonitrile at a ratio of (45:55, v/v). The method is linear (R² = 0.9999) at the concentration range 2.5–150 µg/ml for metformin and 1.25–150 µg/ml for sulfonylureas respectively and offers a specific and sensitive tool for their determination in <10 min chromatographic run. All drug peaks were sharp and well separated. Stress degradation revealed that metformin has a remarkable sensitivity to alkaline stress, glipizide was more sensitive to thermal degradation while gliclazide exhibited almost full degradation in acidic, alkaline and oxidative stress conditions.

The role of pigment epithelium-derived factor in protecting against cellular stress

Since its discovery as a neurotrophic factor in retinal pigmented epithelium cells in the late 1980s, there has been an increase in understanding of the role that pigment epithelium-derived factor (PEDF) plays in cellular functions. PEDF plays an important role in mediating cellular protection during exposure to oxidative stress and inflammation by preventing stress-induced angiogenesis and apoptosis. PEDF acts to reduce oxidative stress by promoting mitochondrial stability and by regulating the expression of enzymes involved in ROS accumulation and clearance. PEDF protects against the negative effects of oxidative stress by regulating cell survival pathways and the expression of inflammatory and proangiogenic mediators. PEDF-mediated cellular protection may be of clinical importance in diseases characterised by oxidative stress, chronic inflammation and pathological neovascularization, indicating that targeting PEDF may be a potential focus for therapeutic interventions in chronic diseases. In this review, we provide a historical perspective on the discoveries of PEDF interactions and functions, and discuss recent in vitro, in vivo and clinical findings to provide a current summary of the important protective effects following cellular exposure to stress stimuli and future clinical potential of PEDF.

Bio-nanotechnological advancement of orally administered insulin nanoparticles: Comprehensive review of experimental design for physicochemical characterization

Therapeutic proteins are labile macromolecules that are prone to degradation during production, freeze-drying and storage. Recent studies showed that nanoparticles can enhance the stability and oral bioavailability of encapsulated proteins. Several conventional approaches (enzyme inhibitors, mucoadhesive polymers) and novel strategies (surface modification, ligand conjugation, flash nano-complexation, stimuli-responsive drug delivery systems) have been employed to improve the physiochemical properties of nanoparticles such as size, zeta potential, morphology, polydispersity index, drug release kinetics and cell-targeting capacity. However, clinical translation of protein-based nanoparticle is limited due to poor experimental design, protocol non-compliance and instrumentation set-up that do not reflect the physiological conditions, resulting in difficulties in mass production of nanoparticles and waste in research funding. In order to address the above concerns, we conducted a comprehensive review to examine the experimental designs and conditions for physical characterization of protein-based nanoparticles. Reliable and robust characterization is essential to verify the cellular interactions and therapeutic potential of protein-based nanoparticles. Importantly, there are a number of crucial factors, which include sample treatment, analytical method, dispersants, sampling grid, staining, quantification parameters, temperature, drug concentration and research materials, should be taken into careful consideration. Variations in research protocol and unreasonable conditions that are used in optimization of pharmaceutical formulations can have great impact in result interpretation. Last but not least, we reviewed all novel instrumentations and assays that are available to examine mucus diffusion capacity, stability and bioactivity of protein-based nanoparticles. These include circular dichroism, fourier transform infrared spectroscopy, X-ray diffractogram, UV spectroscopy, differential scanning calorimetry, fluorescence spectrum, Förster resonance energy transfer, NMR spectroscopy, Raman spectroscopy, cellular assays and animal models.

Doxorubicin Action on Mitochondria: Relevance to Osteosarcoma Therapy?

BACKGROUND

The mitochondria may very well determine the final commitment of the cell to death, particularly in times of energy stress. Cancer chemotherapeutics such as the anthracycline doxorubicin perturb mitochondrial structure and function in tumour cells, as evidenced in osteosarcoma, for which doxorubicin is used clinically as frontline therapy. This same mechanism of cell inhibition is also pertinent to doxorubicin's primary cause of side-effects, that to the cardiac tissue, culminating in such dire events as congestive heart failure. Reactive oxygen species are partly to blame for this effect on the mitochondria, which impact the electron transport chain.

OBJECTIVE

As this review highlights that, there is much more to be learnt about the mitochondria and how it is affected by such effective but toxic drugs as doxorubicin.

CONCLUSION

Such information will aid researchers who search for cancer treatment able to preserve mitochondrial number and function in normal cells.

Zoledronic Acid: Pleiotropic Anti-Tumor Mechanism and Therapeutic Outlook for Osteosarcoma

BACKGROUND

Osteosarcoma is considered the most frequent primary bone malignancy. Lung metastasis is the leading cause of death and the most consistent factor for predicting negative patient outcome in osteosarcoma. Third-generation nitrogen-containing bisphosphonates, such as zoledronic acid, have been shown to reduce osteolysis induced by bone metastasis and exhibit highly selective localization and retention in bone, thus making them attractive agents in the treatment of bone metastasis. Studies have shown that zoledronic acid exerts pleiotropic anti-tumor effects against osteosarcoma cells in vitro, including anti-proliferative, anti-angiogenic, and immunomodulatory effects. However, the efficacy of zoledronic acid against primary tumor growth and pulmonary metastasis of osteosarcoma is controversial, which has limited its clinical application.

OBJECTIVE

The present review summarizes the controversial effects of zoledronic acid on primary tumor burden and pulmonary metastases in osteosarcoma. We also analyze the clinical effectiveness of zoledronic acid alone and in combination with chemotherapeutic drugs for the treatment of osteosarcoma.

CONCLUSION

Zoledronic acid exhibits diverse anti-tumor effects in osteosarcoma in vitro, however, the in vivo effect is still controversial. Further preclinical and clinical studies are needed to clarify the effects of zoledronic acid in osteosarcoma.

The Effect of Krill Oil and n-3 Polyunsaturated Fatty Acids on Human Osteosarcoma Cell Proliferation and Migration

BACKGROUND

Osteosarcoma (OS) is a neoplastic condition afflicting mostly the young, as the lesion usually occurs in areas of bone growth with tumour cells metastasising to the lungs in advanced disease. There is no real cure for the disease, with conventional drugs causing side-effects that decrease the quality of life of sufferers. Newer and safer drugs are needed, and one avenue is to use natural compounds that can stunt the growth of the tumour.

OBJECTIVE

In this study, two such biological entities were evaluated: krill oil and fish oil. Human OS cells were exposed to krill oil, fish oil, EPA and DHA in time-course assays lasting up to 72h.

RESULTS

Krill oil inhibited 23, 50 and 64% of cell proliferation at 24, 48 and 72h respectively, while fish oil resulted in no significant changes although an increase was observed at 24h. Interestingly EPA and DHA promoted OS cell proliferation and migration in this neoplasia. The inhibitory effect of krill oil was comparable to 0.5 and 1µM doxorubicin, a commonly used clinical drug for OS treatment.

CONCLUSION

These results indicate that krill oil may be used in combination with standard clinical practices to control primary tumour growth, and more importantly, metastasis.

Triple-threat activity of PEDF in bone tumors: Tumor inhibition, tissue preservation and cardioprotection against doxorubicin

Pigment epithelium-derived factor (PEDF) is known for its osteogenic properties, but its effects against primary and secondary bone tumors have not comprehensively been demonstrated. We show the ubiquitous expression of PEDF in murine embryonic tissue. Continuous administration of PEDF in pregnant mice for five days did not adversely affect foetal health, despite PEDF's known potent antiangiogenic properties. In the case of the devastating childhood bone cancer osteosarcoma, PEDF has direct anticancer activity per se, and protects against the toxicity of doxorubicin in the heart, small intestine and testes. PEDF demonstrated anti-proliferative and pro-apoptotic effects against human prostate and breast cancer cells, tumors which are known to metastasize to bone as the preferred secondary site. Caspase-2 was activated in both tumor cell types by PEDF. In models of prostate and breast cancer in bone, PEDF significantly reduced tumor volumes. When combined with zoledronic acid, continuously-administered PEDF significantly reduced breast tumor volume at the bone, and was able to preserve the quality of bone better than the combination therapy. These multiple positive findings make PEDF an ideal endogenous and safe biological for possible future clinical testing.

Circulating Tumour Cells (CTC), Head and Neck Cancer and Radiotherapy; Future Perspectives

Head and neck cancer is the seventh most common cancer in Australia and globally. Despite the current improved treatment modalities, there is still up to 50⁻60% local regional recurrence and or distant metastasis. High-resolution medical imaging technologies such as PET/CT and MRI do not currently detect the early spread of tumour cells, thus limiting the potential for effective minimal residual detection and early diagnosis. Circulating tumour cells (CTCs) are a rare subset of cells that escape from the primary tumour and enter into the bloodstream to form metastatic deposits or even re-establish themselves in the primary site of the cancer. These cells are more aggressive and accumulate gene alterations by somatic mutations that are the same or even greater than the primary tumour because of additional features acquired in the circulation. The potential application of CTC in clinical use is to acquire a liquid biopsy, by taking a reliable minimally invasive venous blood sample, for cell genotyping during radiotherapy treatment to monitor the decline in CTC detectability, and mutational changes in response to radiation resistance and radiation sensitivity. Currently, very little has been published on radiation therapy, CTC, and circulating cancer stem cells (CCSCs). The prognostic value of CTC in cancer management and personalised medicine for head and neck cancer radiotherapy patients requires a deeper understanding at the cellular level, along with other advanced technologies. With this goal, this review summarises the current research of head and neck cancer CTC, CCSC and the molecular targets for personalised radiotherapy response.

Systemic leptin administration alters callus VEGF levels and enhances bone fracture healing in wildtype and ob/ob mice

INTRODUCTION

Leptin's role in bone formation has been reported, however, its mechanism of affecting bone metabolism is remaining unclear. In this study, we aimed to test whether leptin has a positive effect on fracture healing through the possible mechanism of increasing vascular endothelial growth factor (VEGF) expression in callus tissue.

METHODS

Standardized femur fractures were created in leptin-deficient ob/ob and wildtype C57BL/6J mice, and recombinant mouse leptin or its vehicle (physiological saline) was administered intraperitoneally during the study. Body weight, radiological, histologic and immunoblotting analyses were performed at different stages of fracture healing.

KEY FINDINGS

The results showed that leptin treatment led to lower rate of body weight change in both mice genotypes. Radiological and histological analyses showed that the experimental groups had better fracture healing at 14, 21 and 28 days compared to the control groups. Leptin-treated groups had significantly higher VEGF expression in callus compared with the control groups at 2 and 3 weeks post-fracture except normal mice at 2 weeks, and leptin-deficient mice had higher VEGF levels in calluses than normal mice at the same timepoint.

CONCLUSION

Low-dose systemically-administered leptin has a positive effect on promoting fracture healing during the latter stages in a clinically-relevant mouse bone fracture model, and increase callus VEGF levels.

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.

Delivery of therapeutics for deep-seated ocular conditions - status quo

OBJECTIVES

There is a need for research into designing effective pharmaceutical systems for delivering therapeutic drugs to the posterior of the eye for glaucoma-related pathology, macular degeneration, diabetic retinopathy, macular oedema, retinitis and choroiditis. Conventionally, eye drops have been extensively utilised for topical drug delivery to the anterior segment of the eye, but are less effective for delivery of therapeutics to the back of the eye due to significant barriers hampering drug penetration into the target intraocular tissue. This review explores some of the current and novel delivery systems employed to deliver therapeutics to the back of the eye such as those using liposomes, ocular implants, in situ gels, and nanoparticles, and how they can overcome some of these limitations.

KEY FINDINGS

Issues such as blinking, precorneal fluid drainage, tear dilution and turnover, conjunctiva and nasal drug absorption, the corneal epithelium, vitreous drug clearance, and the blood-ocular barriers are reviewed and discussed.

SUMMARY

Further studies are needed to address their shortcomings such as drug compatibility and stability, economic viability and patient compliance.

Treatment of bone disorders with parathyroid hormone: success and pitfalls

Bone diseases such as osteoporosis, osteoarthritis, bone tumours and bone fractures are rather common and not just in the elderly. Parathyroid hormone (PTH) is responsible for maintaining calcium homeostasis, increasing bone mineral density (BMD), increasing cortical and trabecular bone thickness and thus increasing bone strength. Teriparatide (PTH 1-34) has the same effects as endogenous PTH and is pharmacologically used to treat bone diseases such as osteoporosis, osteoarthritis, bone fractures and bone tumours. This review discusses how PTH 1-34 plays a role in managing bone diseases. Clinical studies have shown that short or intermittent dosing of PTH 1-34 has minimal adverse effects, while long-term dosing (over two years) has been linked to de novo osteoarthritis and bone deformation. Currently PTH therapy is only approved in the treatment of post-menopausal osteoporosis, however it is also proven to have effects in treating osteoarthritis, bone tumours and bone fractures. If the patient undergoing therapy is closely monitored, the major pitfalls are very unlikely to take place, thus it is highly recommended that patients be closely monitored by a medical practitioner.

Transdifferentiation of adipocytes to osteoblasts: potential for orthopaedic treatment

OBJECTIVES

As both adipocytes and osteoblasts originate from the same pool of mesenchymal stem cells, increasing clinical evidence has emerged of the plasticity between the two lineages. For instance, the downregulation of osteoblast differentiation and upregulation of adipogenesis are common features of conditions such as multiple myeloma, obesity and drug-induced bone loss in diabetes mellitus. However, despite in-vitro and in-vivo observations of adipocyte transdifferentiation into osteoblasts, little is known of the underlying mechanisms.

KEY FINDINGS

This review summarises the current knowledge of this particular transdifferentiation process whereby the Wnt/β-catenin signalling pathway and Runx2 overexpression have been postulated to play a critical role.

SUMMARY

Furthermore, due to the possibility of a novel therapy in the treatment of bone conditions, a number of agents with the potential to induce adipo-to-osteoblast transdifferentiation have been investigated such as all-trans retinoic acid, bone morphogenetic protein-9 and vascular endothelial growth factor.