The Influence of Stabilized Deconjugated Ursodeoxycholic Acid on Polymer-Hydrogel System of Transplantable NIT-1 Cells

Low-dose nano-gel incorporated with bile acids enhanced pharmacology of surgical implants

Aim: Major challenges to islet transplantation in Type 1 diabetes include host-inflammation, which results in failure to maintain survival and functions of transplanted islets. Therefore, this study investigated the applications of encapsulating the bile acid ursodeoxycholic acid (UDCA) with transplanted islets within improved nano-gel systems for Type 1 diabetes treatment. Materials & methods: Islets were harvested from healthy mice, encapsulated using UDCA-nano gel and transplanted into the diabetic mice, while the control group was transplanted encapsulated islets without UDCA. The two groups' survival plot, blood glucose, and inflammation and bile acid profiles were analyzed. Results & conclusion: UDCA-nano gel enhanced survival, glycemia and normalized bile acids' profile, which suggests improved islets functions and potential adjunct treatment for insulin therapy.

Novel hydrogel comprising non-ionic copolymer with various concentrations of pharmacologically active bile acids for cellular injectable gel

Deoxycholic acid (DCA) is a bile acid capable of forming micelles and modifying the properties of hydrogels. We incorporated DCA in sodium alginate (SA) and poloxamer 407 matrices creating novel DCA-copolymer hydrogel for therapeutic delivery. Hydrogels were assessed for common rheological properties. Biocompatibility and biological effect were examined on various cell lines. Cell viability was determent in normal and various hypoxic conditions, and full mitochondrial bioenergetic parameters were assessed in cell lines in order to illustrate hydrogel effects on survival, and cell metabolic profile within the hydrogels. Obtained data suggest that a low dose of DCA in permeable, biocompatible hydrogels can be beneficial for cells to combat hypoxic conditions.

Pharmacological Dose-Effect Profiles of Various Concentrations of Humanised Primary Bile Acid in Encapsulated Cells

Bile acids (BA)s are known surfactants and well-documented to play a major role in food digestion and absorption. Recently, potential endocrinological and formulation-stabilisation effects of BAs have been explored and their pharmacological effects on supporting cell survival and functions have gained wide interest. Hence, this study aimed to explore the hyper-glycaemic dependent dose-effect of the BA chenodeoxycholic acid (CDCA) when encapsulated with pancreatic β-cells, allowing assessment of CDCA's impacts when encapsulated. Four different concentrations of the BA were prepared, and viable cells were encapsulated and incubated for 2 days. Multiple analyses were carried out including confocal imaging, glucose-induced cellular mitochondrial viability indices, insulin production, inflammatory biomarker analyses and cellular bioenergetics measurements. There was a significant dose-effect with different concentrations of the BA, affecting cellular viability and antioxidant activities, cell functions and insulin release, inflammatory biomarkers, and cellular-bioenergetics at different oxidative stress levels. The results demonstrate that, when encapsulated, the BA CDCA exerts positive pharmacological effects at the cellular level, and such effects are concentration dependent.

Taurine Grafted Micro-Implants Improved Functions without Direct Dependency between Interleukin-6 and the Bile Acid Lithocholic Acid in Plasma

A recent study showed an association between diabetes development and the bile acid lithocholic acid (LCA), while another study demonstrated positive biological effects of the conjugated bile acid, taurocholic acid (TCA), on pancreatic cells. Thus, this study aimed to encapsulate TCA with primary islets (graft) and study the biological effects of the graft, post-transplantation, in diabetic mice, including effects on LCA concentrations. Sixteen mature adult mice were made diabetic and randomly divided into two equal groups, control and test (transplanted encapsulated islets without or with TCA). Graft pharmaceutical features pre-transplantation, and biological effects including on LCA concentrations post-transplantation, were measured. TCA-microcapsules had an oval shape and similar size compared with the control. The treatment group survived longer, showed improved glucose and interleukin-6 concentrations, and lower LCA concentrations in plasma, large intestine, faeces, liver and spleen, compared with control. Results suggest that TCA incorporation with islets encapsulated graft exerted beneficial effects, but there was no direct and significant dependency between concentrations of interleukin-6 and LCA.

Single-Cellular Biological Effects of Cholesterol-Catabolic Bile Acid-Based Nano/Micro Capsules as Anti-Inflammatory Cell Protective Systems

Recent studies in our laboratories have shown promising effects of bile acids in ➀ drug encapsulation for oral targeted delivery (via capsule stabilization) particularly when encapsulated with Eudragit NM30D^® and ➁ viable-cell encapsulation and delivery (via supporting cell viability and biological activities, postencapsulation). Accordingly, this study aimed to investigate applications of bile acid-Eudragit NM30D^® capsules in viable-cell encapsulation ready for delivery. Mouse-cloned pancreatic β-cell line was cultured and cells encapsulated using bile acid-Eudragit NM30D^® capsules, and capsules' images, viability, inflammation, and bioenergetics of encapsulated cells assessed. The capsules' thermal and chemical stability assays were also assessed to ascertain an association between capsules' stability and cellular biological activities. Bile acid-Eudragit NM30D^® capsules showed improved cell viability (e.g., F1 < F2 & F8; p < 0.05), insulin, inflammatory profile, and bioenergetics as well as thermal and chemical stability, compared with control. These effects were formulation-dependent and suggest, overall, that changes in ratios of bile acids to Eudragit NM30D^® can change the microenvironment of the capsules and subsequent cellular biological activities.

'In vitro' assessments of microencapsulated viable cells as a result of primary bile acid-encapsulated formulation for inflammatory disorders

Background / Aim: Metformin is widely used in type 2 diabetes and exhibits many positive biological effects on pancreatic b-cells and muscle cells, such as supporting insulin release by b-cells and glucose uptake by muscle cells and reducing oxidative stress, particularly due to diabetes-associated hyperglycaemia. Interestingly, for type 1 diabetes, transplantation of healthy b-cells has been proposed as a novel way to replace insulin therapy. Recently, bile acid-formulations containing transplantable b-cells showed best stability. Hence, this study aimed to explore the effects of metformin-bile acid formulations in b-cell encapsulation and on the biological activities of b-cells and muscle-cells. Methods: Two sets of biological effects were examined, using metformin-bile acid formulations, on encapsulated b-cells and on muscle cells exposed to the formulations. Results: Various encapsulated b-cell formulations' cell viability, insulin levels, cellular oxidative stress, cellular inflammatory profile and bioenergetics at the normoand hyperglycaemic states showed differing results based upon the metformin concentration and the inclusion or absence of bile acid. Similar effects were observed with muscle cells. Low ratios of metformin and bile acids showed best biological effects, suggesting a formulation dependent result. The formulations' positive effects were more profound at the hyperglycaemic state suggesting efficient cell protective effects. Conclusion: Overall, metformin had positive impacts on the cells in a concentration-dependent manner, with the addition of chenodeoxycholic acid further improving results.

Pharmaceutical formulation and polymer chemistry for cell encapsulation applied to the creation of a lab-on-a-chip bio-microsystem

Microencapsulation of formulation designs further expands the field and offers the potential for use in developing bioartificial organs via cell encapsulation. Combining formulation design and encapsulation requires ideal excipients to be determined. In terms of cell encapsulation, an environment which allows growth and functionality is paramount to ensuring cell survival and incorporation into a bioartificial organ. Hence, excipients are examined for both individual properties and benefits, and compatibility with encapsulated active materials. Polymers are commonly used in microencapsulation, offering protection from the immune system. Bile acids are emerging as a tool to enhance delivery, both biologically and pharmaceutically. Therefore, this review will focus on bile acids and polymers in formulation design via microencapsulation, in the field of bioartificial organ development.

Pharmacological effects of novel microvesicles of basil, on blood glucose and the lipid profile: a preclinical study

Microencapsulation represents a process that can create targeted, controlled release kinetics of drugs, thus optimizing therapeutic efficacy. Our group has investigated the impact of this technology on Wistar rats to determine pharmacological efficacy of basil extracts. Animals were treated with water extract of Ocimum basilicum in microvesicles and with combination of basil extracts and 3α,7α-dihydroxy-12-keto-5-cholanate, also known as 12-monoketocholic acid (MKC) acid in microvesicles for 7 days. Alloxan was used to induce hyperglycemia. Pharmacological effects on glycemia were evaluated by measuring blood glucose levels in alloxan-induced diabetic rats. Microvesicles were prepared using the Büchi-based microencapsulating system developed in our lab. The dose of basil extract that was orally administered in rats was 200 mg/kg and the dose of MKC acid was 4 mg/kg as per established protocols. A seven-day treatment with basil aqueous extract, as well as a combination of basil and MKC acid extract in the pharmaceutical formulation, led to a statistically significant reduction in the blood glucose concentration of animals with alloxan-induced hyperglycemia compared to pre-treatment values (p < 0.05 and p < 0.01), which indicates that basil has hypoglycemic and antihyperglycemic effects. Microvesicles, as a pharmaceutical-technological formulation, substantially enhance the hypolipidemic action of basil extract with MKC acid.

The Effects of Primary Unconjugated Bile Acids on Nanoencapsulated Pharmaceutical Formulation of Hydrophilic Drugs: Pharmacological Implications

Introduction

In a recent study, in our laboratory, primary unconjugated bile acids, commonly found in humans, chenodeoxycholic acid (CDCA), have been shown to improve stability of nanoencapsulated lipophilic drugs and improve their release profile after oral administration likely via electrokinetic stabilisation. Hence, this study aimed to examine the effects of CDCA on exerting similar effects on hydrophilic drugs.

Methods

Various CDCA-based formulations were produced for the orally administered hydrophilic drug, metformin. Analyses of these formulations included electrokinetic potentials, topography, drug and CDCA formulation contents, nano size distribution, heat-induced deformation and outer-core expansion indices, release profiles, shell-resistance ratio, and thermal and chemical indices. With the drug’s main target being pancreatic beta-cells, the formulations’ effects on cell viability, functions and inflammatory profiles were also investigated.

Results and Conclusions

CDCA-based metformin formulations exhibited improved stability and release profiles via thermal, chemical and electrokinetic effects, which were formulation-dependent suggesting potential applications of CDCA in the oral targeted delivery of hydrophilic drugs.

Polyelectrolytes Formulated with Primary Unconjugated Bile Acid Optimised Pharmacology of Bio-Engineered Implant

Introduction. Several studies have shown that different biomaterials and hydrogels comprising various bile acids such as chenodeoxycholic acid (CDCA), as well as excipients such as poly-(styrene)-sulphonate (PSS) and poly-(allyl)-amine (PAA), exhibited positive biological effects on encapsulated viable pancreatic β-cells. Hence, this study aimed to investigate whether incorporating CDCA with PSS and PAA will optimise the functions of encapsulated pancreatic islets post-transplantation in Type 1 diabetes (T1D). Methods. Mice were made T1D, divided into two equal groups, and transplanted with encapsulated islets in PSS-PAA (control) or with CDCA-PSS-PAA (treatment) microcapsules. The effects of transplanted microcapsules on blood glucose, inflammation and the bile acid profile were measured post-transplantation. Results and Conclusion. Compared with control, the treatment group showed better survival rate, improved glycaemic control, and lower inflammatory profile, illustrated by ↓ interleukin 1-β, interleukin-6, interleukin-12, and tumour-necrosis factor-α, and ↓ levels of the bile acid, as well as lithocholic acid in the plasma, liver, large intestine and faeces. The results suggest that CDCA incorporation with PSS-PAA microcapsules exerted beneficial effects on encapsulated islets and resulted in enhanced diabetes treatment, post-transplantation, at the local and systemic levels.

Pharmacological and Biological Study of Microencapsulated Probucol-Secondary Bile Acid in a Diseased Mouse Model

Probucol (PB) is a highly lipophilic drug with potential protective effects on pancreatic β-cells from inflammation and oxidation. PB has poor bioavailability and solubility, and despite many attempts, significant improvement in antidiabetic effects or absorption has yet to be discovered. Recently, the role of bile acids has been established in significant drug formulation stabilisation effects and as cell-penetrating agents. Promising results in pharmaceutical formulation studies on drug stability and release patterns when lithocholic acid (LCA) is conjugated with PB and sodium alginate (SA) have been demonstrated. Thus, this study aimed to develop and characterise PB microcapsules incorporating LCA and examine the biological effects of the microcapsules in vitro and in vivo. PB/LCA microcapsules were prepared using an encapsulation method, ionic gelation vibrational jet flow technology. LCA incorporation in PB microcapsules showed positive effects on β-cells with improved insulin release, antioxidant activity, and PB intracellular uptake. Diabetic mice gavaged LCA-PB microcapsules showed a significant reduction in diabetes signs and symptoms, better survival rate, reduced blood glucose levels, and pro-inflammatory cytokines, with an increase PB level in blood and tissues suggesting a potential therapy for treating diabetes mellitus.

Enhanced Bilosomal Properties Resulted in Optimum Pharmacological Effects by Increased Acidification Pathways

INTRODUCTION

Recent studies in our laboratory have shown that some bile acids, such as chenodeoxycholic acid (CDCA), can exert cellular protective effects when encapsulated with viable β-cells via anti-inflammatory and anti-oxidative stress mechanisms. However, to explore their full potential, formulating such bile acids (that are intrinsically lipophilic) can be challenging, particularly if larger doses are required for optimal pharmacological effects. One promising approach is the development of nano gels. Accordingly, this study aimed to examine biological effects of various concentrations of CDCA using various solubilising nano gel systems on encapsulated β-cells.

METHODS

Using our established cellular encapsulation system, the Ionic Gelation Vibrational Jet Flow technology, a wide range of CDCA β-cell capsules were produced and examined for morphological, biological, and inflammatory profiles.

RESULTS AND CONCLUSION

Capsules' morphology and topographic characteristics remained similar, regardless of CDCA or nano gel concentrations. The best pharmacological, anti-inflammatory, and cellular respiration, metabolism, and energy production effects were observed at high CDCA and nano gel concentrations, suggesting dose-dependent cellular protective and positive effects of CDCA when incorporated with high loading nano gel.

Advancements in Assessments of Bio-Tissue Engineering and Viable Cell Delivery Matrices Using Bile Acid-Based Pharmacological Biotechnologies

The utilisation of bioartificial organs is of significant interest to many due to their versatility in treating a wide range of disorders. Microencapsulation has a potentially significant role in such organs. In order to utilise microcapsules, accurate characterisation and analysis is required to assess their properties and suitability. Bioartificial organs or transplantable microdevices must also account for immunogenic considerations, which will be discussed in detail. One of the most characterized cases is the investigation into a bioartificial pancreas, including using microencapsulation of islets or other cells, and will be the focus subject of this review. Overall, this review will discuss the traditional and modern technologies which are necessary for the characterisation of properties for transplantable microdevices or organs, summarizing analysis of the microcapsule itself, cells and finally a working organ. Furthermore, immunogenic considerations of such organs are another important aspect which is addressed within this review. The various techniques, methodologies, advantages, and disadvantages will all be discussed. Hence, the purpose of this review is providing an updated examination of all processes for the analysis of a working, biocompatible artificial organ.

A Review on Recent Advancement on Age-Related Hearing Loss: The Applications of Nanotechnology, Drug Pharmacology, and Biotechnology

Aging is considered a contributing factor to many diseases such as cardiovascular disease, Alzheimer’s disease, and hearing loss. Age-related hearing loss, also termed presbycusis, is one of the most common sensory impairments worldwide, affecting one in five people over 50 years of age, and this prevalence is growing annually. Associations have emerged between presbycusis and detrimental health outcomes, including social isolation and mental health. It remains largely untreatable apart from hearing aids, and with no globally established prevention strategies in the clinical setting. Hence, this review aims to explore the pathophysiology of presbycusis and potential therapies, based on a recent advancement in bile acid-based bio-nanotechnologies. A comprehensive online search was carried out using the following keywords: presbycusis, drugs, hearing loss, bile acids, nanotechnology, and more than 150 publications were considered directly relevant. Evidence of the multifaceted oxidative stress and chronic inflammation involvement in cellular damage and apoptosis that is associated with a loss of hair cells, damaged and inflamed stria vascularis, and neuronal signalling loss and apoptosis continues to emerge. New robust and effective therapies require drug delivery deeper into the various layers of the cochlea. Bile acid-based nanotechnology has gained wide interest in its permeation-enhancing ability and potential for numerous applications in treating presbycusis.

Pharmacological and Advanced Cell Respiration Effects, Enhanced by Toxic Human-Bile Nano-Pharmaceuticals of Probucol Cell-Targeting Formulations

Bile acids have recently been studied for potential applications as formulation excipients and enhancers for drug release; however, some bile acids are not suitable for this application. Unconjugated lithocholic acid (ULCA) has recently shown drug formulation-stabilizing and anti-inflammatory effects. Lipophilic drugs have poor gut absorption after an oral dose, which necessitates the administration of high doses and causes subsequent side effects. Probucol (PB) is a highly lipophilic drug with poor oral absorption that resulted in restrictions on its clinical prescribing. Hence, this study aimed to design new delivery systems for PB using ULCA-based matrices and to test drug formulation, release, temperature, and biological effects. ULCA-based matrices were formulated for PB oral delivery by applying the jet-flow microencapsulation technique using sodium alginate as a polymer. ULCA addition to new PB matrices improved the microcapsule’s stability, drug release in vitro (formulation study), and showed a promising effect in ex vivo study (p < 0.05), suggesting that ULCA can optimize the oral delivery of PB and support its potential application in diabetes treatment.

Micro-Nano formulation of bile-gut delivery: rheological, stability and cell survival, basal and maximum respiration studies

Probucol (PB) is a drug that exhibits significant hydrophobicity and substantial intra and inter individual variability in oral absorption, with a miniature bioavailability and complex three compartmental pharmacokinetic modelling due to its high lipid affinity, low stability and high octanol to water partition coefficient. Multiple attempts to formulate PB have not produced satisfactory stable matrices, drug-release profile or rheological flow properties for optimum manufacturing conditions, and with positive and none toxic biological effects. Lithocholic acid (LCA) has recently shown to optimise formulation and cell uptake of drugs. Hence, the aim of this study was to design new PB delivery system, using LCA, and examine its morphology, rheology, stability, and cellular effects. PB was formulated with LCA and sodium alginate (PB-LCA-SA) using various microencapsulation methodologies, and best formulation was investigated in vitro and ex vivo. Using our Ionic Gelation Vibrational Jet flow technology, PB-LCA-SA microcapsules showed good stability and significantly enhanced cell viability, cellular respiration, and reduced inflammation suggesting potential LCA applications in PB delivery and biological effects.

Oral gavage of nano-encapsulated conjugated acrylic acid-bile acid formulation in type 1 diabetes altered pharmacological profile of bile acids, and improved glycaemia and suppressed inflammation

BACKGROUND

Ursodeoxycholic acid (UDCA) is a secondary hydrophilic bile acid, metabolised in the gut, by microbiota. UDCA is currently prescribed for primary biliary cirrhosis, and of recently has shown β-cell protective effects, which suggests potential antidiabetic effects. Thus, this study aimed to design targeted-delivery microcapsules for oral uptake of UDCA and test its effects in type 1 diabetes (T1D).

METHODS

UDCA microcapsules were produced using alginate-NM30 matrix. Three equal groups of mice (6-7 mice per group) were gavaged daily UDCA powder, empty microcapsules and UDCA microcapsules for 7 days, then T1D was induced by alloxan injection and treatments continued until mice had to be euthanised due to weight loss > 10% or severe symptoms develop. Plasma, tissues, and faeces were collected and analysed for bile acids' concentrations.

RESULTS

UDCA microcapsules brought about reduction in elevated blood glucose, reduced inflammation and altered concentrations of the primary bile acid chenodeoxycholic acid and the secondary bile acid lithocholic acid, without affecting survival rate of mice.

CONCLUSION

The findings suggest that UDCA exerted direct protective effects on pancreatic β-cells and this is likely to be associated with alterations of concentrations of primary and secondary bile acids in plasma and tissues. Three equal groups of mice were gavaged daily UDCA (ursodeoxycholic acid) powder, empty microcapsules and UDCA microcapsules for 7 days, then T1D was induced and treatments continued until mice had to be euthanised. UDCA microcapsules brought about reduction in elevated blood glucose, reduced inflammation and altered concentrations of the primary bile acid chenodeoxycholic acid and the secondary bile acid lithocholic acid, without affecting survival rate of mice. The findings suggest that UDCA exerted direct protective effects on pancreatic β-cells and this is likely to be associated with alterations of concentrations of primary and secondary bile acids in plasma and tissues.

Bile acid bio-nanoencapsulation improved drug targeted-delivery and pharmacological effects via cellular flux: 6-months diabetes preclinical study

The antilipidemic drug, probucol (PB), has demonstrated potential applications in Type 2 diabetes (T2D) through its protective effects on pancreatic β-cells. PB has poor solubility and bioavailability, and despite attempts to improve its oral delivery, none has shown dramatic improvements in absorption or antidiabetic effects. Preliminary data has shown potential benefits from bile acid co-encapsulation with PB. One bile acid has shown best potential improvement of PB oral delivery (ursodeoxycholic acid, UDCA). This study aimed to examine PB and UDCA microcapsules (with UDCA microcapsules serving as control) in terms of the microcapsules’ morphology, biological effects ex vivo, and their hypoglycemic and antilipidemic and anti-inflammatory effects in vivo. PBUDCA and UDCA microcapsules were examined in vitro (formulation studies), ex vivo and in vivo. PBUDCA microcapsules exerted positive effects on β-cells viability at hyperglycemic state, and brought about hypoglycemic and anti-inflammatory effects on the prediabetic mice. In conclusion, PBUDCA co-encapsulation have showed beneficial therapeutic impact of dual antioxidant-bile acid effects in diabetes treatment.

Modulatory Nano/Micro Effects of Diabetes Development on Pharmacology of Primary and Secondary Bile Acids Concentrations

BACKGROUND

Recent studies have suggested that hyperglycaemia influences the bile acid profile and concentrations of secondary bile acids in the gut.

INTRODUCTION

This study aimed to measure changes in the bile acid profile in the gut, tissues, and faeces in type 1 Diabetes (T1D) and Type 2 Diabetes (T2D).

METHODS

T1D and T2D were established in a mouse model. Twenty-one seven-weeks old balb/c mice were randomly divided into three equal groups, healthy, T1D and T2D. Blood, tissue, urine and faeces samples were collected for bile acid measurements.

RESULTS

Compared with healthy mice, T1D and T2D mice showed lower levels of the primary bile acid, chenodeoxycholic acid, in the plasma, intestine, and brain, and higher levels of the secondary bile acid, lithocholic acid, in the plasma and pancreas. Levels of the bile acid ursodeoxycholic acid were undetected in healthy mice but were found to be elevated in T1D and T2D mice.

CONCLUSION

Bile acid profiles in other organs were variably influenced by T1D and T2D development, which suggests similarity in effects of T1D and T2D on the bile acid profile, but these effects were not always consistent among all organs, possibly since feedback mechanisms controlling enterohepatic recirculation and bile acid profiles and biotransformation are different in T1D and T2D.

A second-generation micro/nano capsules of an endogenous primary un-metabolised bile acid, stabilized by Eudragit-alginate complex with antioxidant compounds

Bile acids (BAs) are amphiphilic compounds and of recently have demonstrated wide range of formulation stabilizing effects. A recent study showed that primary un-metabolised bile acids (PUBAs) have β-cell protective effects, and synergistic antidiabetic effects when combined with antioxidant and anti-inflammatory drugs, such as probucol (PB). Thus, this study aimed to design and test microcapsules containing a PUBA incorporated with PB and an alginate-Eudragit matrix.

Six types of microcapsules were developed without (control) or with (test) PUBA, and tested for internal and external features and β-cell protective effects.

The incorporation of PB-alginate-Eudragit with PUBA produced stable microcapsules but did not exert consistent positive effects on cell viability in the hyperglycaemic state, which suggests that PUBA in alginate-Eudragit matrices did not exhibit synergistic effects with PB nor exerted antidiabetic effects.

Eudragit®-based microcapsules of probucol with a gut-bacterial processed secondary bile acid

AIM

Deoxycholic acid (DCA) has improved gliclazide oral absorption, while Eudragit^® (ED) polymers have improved formulation stability of antidiabetic drugs. The aim of the study is to test if DCA and ED encapsulation will optimize the release and stability of the potential antidiabetic drug probucol (PB).

MATERIALS & METHODS

The PB formulations were prepared using ED polymers and DCA, and formulations were analyzed for their rheological and biological properties.

RESULTS

Rheological properties and size distribution were similar among all groups. β-cell survival and biological activities were best with NM30D microcapsules. The inflammatory profile and oxidative stress effects of microcapsules remained similar among all groups.

CONCLUSION

ED NM30D and DCA incorporation can exert positive and stabilizing effects on PB oral microcapsules.

The biological effects of the hypolipidaemic drug probucol microcapsules fed daily for 4 weeks, to an insulin-resistant mouse model: potential hypoglycaemic and anti-inflammatory effects

Probucol (PB) is an hypolipidaemic drug with potential antidiabetic effects. We showed recently using in vitro studies that when PB was incorporated with stabilising lipophilic bile acids and microencapsulated using the polymer sodium alginate, the microcapsules showed good stability but poor and irregular PB release. This suggests that PB microcapsules may exhibit better release profile and hence better absorption, if more hydrophilic bile acids were used, such as ursodeoxycholic acid (UDCA). Accordingly, this study aimed to produce PB-UDCA microcapsules and examine PB absorption and antidiabetic effects in our mouse-model of insulin-resistance and diabetes (fed high-fat diet; HFD). The study also aimed to examine the effects of the microcapsules on the bile acid profile. Healthy mice (fed low-fat diet; LFD) were used as control. Seventy mice were randomly allocated into seven equal groups: LFD, HFD given empty microcapsules, HFD given metformin (M), HFD given standard-dose probucol (PB-SD), HFD given high-dose probucol (PB-H), HFD given UDCA microcapsules and HFD given PB-UDCA microcapsules. Blood glucose (BG), inflammatory biomarkers (TNF-α, IFN-γ, IL-1β, IL-6, IL-10, IL-12 and IL-17), plasma cholesterol, non-esterified fatty acids and triglycerides were analysed together with plasma bile acid and probucol concentrations. PB-UDCA microcapsules reduced BG in HFD mice, but did not reduce inflammation or improve lipid profile, compared with positive control (HFD) group. Although PB-UDCA microcapsules did not exert hypolipidaemic or antiinflammatory effects, they resulted in significant hypoglycaemic effects in a mouse model of insulin resistance, which suggests potential applications in insulin-resistance and glucose haemostasis.

Morphological, Stability, and Hypoglycemic Effects of New Gliclazide-Bile Acid Microcapsules for Type 1 Diabetes Treatment: the Microencapsulation of Anti-diabetics Using a Microcapsule-Stabilizing Bile Acid

When we administered orally a mixture of the anti-diabetic drug, gliclazide (G) and a primary bile acid, they exerted a hypoglycemic effect in a rat model of type 1 diabetes (T1D), but stability of mixture was limited. We aimed to develop and characterize microcapsules incorporating G with a microcapsule-stabilizing bile acid, ursodeoxycholic acid (UDCA). Sodium alginate (SA)-based microcapsules were prepared with either G or G with UDCA and analyzed in terms of morphological, physico-chemical, and electro-chemical characteristics at different pH and temperatures. The microcapsules' effects on viability on muscle cell line (C2C12) and on diabetic rats' blood glucose levels and inflammatory profiles were also examined. Bile acid-based microcapsules maintained their morphology, showed good stability, and compatibility profiles, and the incorporation of UDCA resulted in less G content per microcapsule (p < 0.01) and production of stronger microcapsules that were more resistant to mechanical pressure (p < 0.01). G-UDCA-SA microcapsules enhanced muscle cell viability at higher glucose concentrations compared with control (G-SA and UDCA-SA), and they had strong anti-inflammatory effects on diabetic rats. In addition, the incorporation of UDCA into G microcapsules enhanced the physical characteristics of the microcapsules and optimized G delivery after oral administration.

Influence of Biotechnological Processes, Speed of Formulation Flow and Cellular Concurrent Stream-Integration on Insulin Production from β-cells as a Result of Co-Encapsulation with a Highly Lipophilic Bile Acid

Introduction

We have shown that incorporation of the hydrophilic bile acid, ursodeoxycholic acid, into β-cell microcapsules exerted positive effects on microcapsules' morphology and size, but these effects were excipient and method dependent. Cell viability remained low which suggests low octane-water solubility and formation of highly hydrophilic dispersion, which resulted in low lipophilicity dispersion and compromised cellular permeation of the incorporated bile acid. Thus, this study aimed at investigating various microencapsulating methodologies using highly lipophilic bile acid (LPBA), in order to optimise viability and functions of microencapsulated β-cells.

Methods

Four different types of microcapsules were produced with (test) and without (control) LPBA, totalling eight different microcapsules. Microencapsulating methodologies were screened for best microcapsule-cell functions and microencapsulating processes were examined in terms of frequency, formulation flow, total bath-gelation time and cellular concurrent stream-integration rate, cell-viability, insulin production and inflammatory profile.

Results

Optimum biotechnological processes include formation frequency (Hz) of 2350, formulation flow (ml/min) of 1.2, total gelation time (min) of 18 and cellular concurrent stream-integration rate (ml/min) of 0.7. In all formulations, LPBA consistently improved cell viability, insulin production, mitochondrial activities and ameliorated inflammation.

Conclusion

The deployed biotechnological processes and LPBA optimised formation and functions of β-cell microcapsules, which suggests potential applications in diabetes mellitus via the creation of more stable β-cell microcapsules capable of delivering adequate levels of insulin to control glycaemia and potentially curing diabetes.

Electrokinetic potential-stabilization by bile acid-microencapsulating formulation of pancreatic β-cells cultured in high ratio poly-L-ornithine-gel hydrogel colloidal dispersion: applications in cell-biomaterials, tissue engineering and biotechnological applications

INTRODUCTION

Current trials for β-cell transplantation have been hindered by poor cell viability and function post-transplantation. Recently, electric charges of the microencapsulating formulation carrying β-cells have shown significant effects on cell survival and function. Thus, this study aimed at investigating the effects of electric charge, of novel colloidal formulation containing β-cells, on cell viability, biological activity and insulin release.

METHODS

A new formulation, containing high ratios of poly-L-ornithine, suspending electrical-stimulation hydrogel and polystyrene sulphone (1:1:0.1 ratio), was used to form microcapsules utilizing 800 V and 2000 Hz encapsulating conditions. The bile acid, ursodeoxycholic acid, was added into the microcapsules to measure its effects on electric charges.

RESULTS

The electric charge of the microencapsulating formulation was enhanced by bile acid addition, and resulted in better cell viability and function.

CONCLUSION

Ursodeoxycholic acid microencapsulated with poly-L-ornithine, suspending electrical-stimulation hydrogel and polystyrene sulphone at 1:1:0.1 ratio, using 800 V and 2000 Hz microencapsulating conditions, produced enhanced electrokinetic parameters of microcapsules with optimized cell functions. This suggests that electric charge of formulations containing pancreatic β-cell may have significant effects on cell mass and functions, post-transplantation.

Encapsulated Islet Transplantation: Where Do We Stand?

Transplantation of pancreatic islets encapsulated within immuno-protective microcapsules is a strategy that has the potential to overcome graft rejection without the need for toxic immunosuppressive medication. However, despite promising preclinical studies, clinical trials using encapsulated islets have lacked long-term efficacy, and although generally considered clinically safe, have not been encouraging overall. One of the major factors limiting the long-term function of encapsulated islets is the host's immunological reaction to the transplanted graft which is often manifested as pericapsular fibrotic overgrowth (PFO). PFO forms a barrier on the capsule surface that prevents the ingress of oxygen and nutrients leading to islet cell starvation, hypoxia and death. The mechanism of PFO formation is still not elucidated fully and studies using a pig model have tried to understand the host immune response to empty alginate microcapsules. In this review, the varied strategies to overcome or reduce PFO are discussed, including alginate purification, altering microcapsule geometry, modifying alginate chemical composition, co-encapsulation with immunomodulatory cells, administration of pharmacological agents, and alternative transplantation sites. Nanoencapsulation technologies, such as conformal and layer-by-layer coating technologies, as well as nanofiber, thin-film nanoporous devices, and silicone based NanoGland devices are also addressed. Finally, this review outlines recent progress in imaging technologies to track encapsulated cells, as well as promising perspectives concerning the production of insulin-producing cells from stem cells for encapsulation.

The effect of molecular weights of microencapsulating polymers on viability of mouse-cloned pancreatic β-cells: biomaterials, osmotic forces and potential applications in diabetes treatment

INTRODUCTION

Ideal cell-containing microcapsules should be capable of maintaining cell viability and exhibit significant structural stability to support cellular functionality. To date, such microcapsules remain unavailable; thus, this study used our well-established microencapsulating methods to examine a total of 32 different microencapsulating formulations and correlate polymers' molecular weights (M_wt) and UDCA addition, with cell viability and microcapsules' stability, postmicroencapsulation.

METHODS

MIN6 mouse-cloned pancreatic β-cells were microencapsulated using control (n = 16; without UDCA) and test (n = 16; with UDCA) different polymers. Confocal microscopic imaging, cell viability, and microcapsules' stability were assessed.

RESULTS

Best cell viability (>50%) was obtained at average M_wt of 50,000 g/mol (poly-l-ornithine), followed by 110,000 g/mol (poly-l-lysine). There was no linear correlation between M_wt and viability. Confocal imagining showed similar microcapsules' shape and cell distribution among all different polymers' molecular weights, which suggests that the microencapsulating method was efficient and maintained microcapsules' uniformity. UDCA addition resulted in enhanced osmotic stability of the microcapsules and improved cell viability, when the formulation contained 1% polylornithine, 1% polyethylene glycol, 20% Eudragit^® NM30D, 1% polytetrafluoroethylene, or 5% pentamethylcyclopentasiloxane.

CONCLUSIONS

UDCA addition improved microenvironmental conditions within the microcapsules but this effect was largely dependent on the polymer systems used.

Innovative Microcapsules for Pancreatic β-Cells Harvested from Mature Double-Transgenic Mice: Cell Imaging, Viability, Induced Glucose-Stimulated Insulin Measurements and Proinflammatory Cytokines Analysis

PURPOSE

Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an alginate-ursodeoxycholic acid (UDCA) matrix produced microcapsules with good stability and cell viability. In this study, we investigated if translation of this formulation to microencapsulation of primary β-cells harvested from mature double-transgenic healthy mice would also generate stable microcapsules with good cell viability.

METHODS

Islets of Langerhans were isolated from Ngn3-GFP/RIP-DsRED mice by intraductal collagenase P digestion and density gradient centrifugation, dissociated into single cells and the β-cell population purified by Fluorescence Activated Cell Sorting. β-cells were microencapsulated using either alginate-poly-l-ornithine (F1; control) or alginate-poly-l-ornithine-UDCA (F2; test) formulations. Microcapsules were microscopically examined and microencapsulated cells were analyzed for viability, insulin and cytokine release, 2 days post-microencapsulation.

RESULTS

Microcapsules showed good uniformity and morphological characteristics and even cell distribution within microcapsules with or without UDCA. Two days post microencapsulation cell viability, mitochondrial ATP and insulin production were shown to be optimized in the presence of UDCA whilst production of the proinflammatory cytokine IL-1β was reduced. Contradictory to our previous studies, UDCA did not reduce production of any other pro-inflammatory biomarkers.

CONCLUSIONS

These results suggest that UDCA incorporation improves microcapsules' physical and morphological characteristics and improves the viability and function of encapsulated mature primary pancreatic β-cells.

The impact of allylamine-bile acid combinations on cell delivery microcapsules in diabetes

OBJECTIVE

In a recent study, we developed a new microencapsulating method for β-cell microencapsulation, but cell viability declined rapidly, post microencapsulation, due to potential polymer-polyelectrolyte chelation and non-porous microcapsules' membranes resulting in cell apoptosis. Thus, this study tested the effects of incorporating cationic polyamine at 1% w/v, on microcapsule strength and cell viability, in the absence or presence of an anionic tertiary bile acid (ATBA) with potential cell-protective effects.

METHODS

1% w/v polyamine was used without or with ATBA, to form β-cell microcapsules and physical and biological analyses was carried out 50 h post microencapsulation.

RESULTS

Microcapsules containing 1% w/v polyamine showed weak physical properties and low cell viability and ATBA incorporation resulted in >30% reduction in cell viability and increased levels of pro-inflammatory cytokines.

CONCLUSION

Neither 1% w/v polyamine nor the presence of ATBA resulted in optimised cell viability, but rather reduced cell viability, enhanced inflammation and lowered insulin secretion.