The incorporation of water-soluble gel matrix into bile acid-based microcapsules for the delivery of viable β-cells of the pancreas, in diabetes treatment: biocompatibility and functionality studies

The effect of deoxycholic acid-based hydrogels on hepatic, muscle and pancreatic beta cells

Aim: The aim of this study is to test the biocompatibility of hydrogels with polysaccharides and bile acids on three murine cell lines. Materials & methods: Novel hydrogels containing poloxamer 407, polysaccharides (starch, pectin, acacia, carboxymethyl and methyl 2-hydroxyethyl cellulose) and deoxycholic acid were prepared using cold method, sterilized and used in biological assays to determine effects on hepatic, muscle, and pancreatic beta cells. Results and conclusion: Hydrogels with deoxycholic acid had tissue-depending effects on cellular survival and bioenergetics, resulting in the best cellular viability and bioenergetics within pancreatic beta cells. Further research is needed as proposed hydrogels may be beneficial for cell delivery systems of pancreatic beta 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.

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.

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.

Chenodeoxycholic Acid Pharmacology in Biotechnology and Transplantable Pharmaceutical Applications for Tissue Delivery: An Acute Preclinical Study

INTRODUCTION

Primary bile acids (PBAs) are produced and released into human gut as a result of cholesterol catabolism in the liver. A predominant PBA is chenodeoxycholic acid (CDCA), which in a recent study in our laboratory, showed significant excipient-stabilizing effects on microcapsules carrying insulinoma β-cells, in vitro, resulting in improved cell functions and insulin release, in the hyperglycemic state. Hence, this study aimed to investigate the applications of CDCA in bio-encapsulation and transplantation of primary healthy viable islets, preclinically, in type 1 diabetes.

METHODS

Healthy islets were harvested from balb/c mice, encapsulated in CDCA microcapsules, and transplanted into the epididymal tissues of 6 syngeneic diabetic mice, post diabetes confirmation. Pre-transplantation, the microcapsules' morphology, size, CDCA-deep layer distribution, and physical features such as swelling ratio and mechanical strength were analyzed. Post-transplantation, animals' weight, bile acids', and proinflammatory biomarkers' concentrations were analyzed. The control group was diabetic mice that were transplanted encapsulated islets (without PBA).

RESULTS AND CONCLUSION

Islet encapsulation by PBA microcapsules did not compromise the microcapsules' morphology or features. Furthermore, the PBA-graft performed better in terms of glycemic control and resulted in modulation of the bile acid profile in the brain. This is suggestive that the improved glycemic control was mediated via brain-related effects. However, the improvement in graft insulin delivery and glycemic control was short-term.

Probucol Pharmacological and Bio-Nanotechnological Effects on Surgically Transplanted Graft Due to Powerful Anti-Inflammatory, Anti-Fibrotic and Potential Bile Acid Modulatory Actions

INTRODUCTION

A major obstacle in islet transplantation and graft survival pre and post transplantation is islet apoptosis due to mainly inflammatory bio molecules released during islet harvesting and post graft transplantation and hence, subsequent graft fibrosis and failure. This study aimed to investigate if incorporation of the anti-inflammatory anti-hyperlipidaemic drug probucol (PB) would improve islet-graft survival and function, post transplantation in Type 1 diabetes (T1D).

METHODS

T1D was induced in mice, and biological profiles of the diabetic mice transplanted PB-microencapsulated islets harvested from healthy syngeneic mice were measured.

RESULTS AND CONCLUSION

Compared with sham (no PB), the treated group showed significant reduction in serum levels of interleukin-1β, interleukin-6, interleukin-12, interleukin-17, and tumour necrosis factor-α, accompanied by a 3-fold increase in survival duration, which suggests PB islet-protective effects, post transplantation.

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.

Physicochemical characterisation of kafirins extracted from sorghum grain and dried distillers grain with solubles related to their biomaterial functionality

Kafirin, the hydrophobic prolamin storage protein in sorghum grain is enriched when the grain is used for bioethanol production to give dried distillers grain with solubles (DGGS) as a by-product. There is great interest in DDGS kafirin as a new source for biomaterials. There is however a lack of fundamental understanding of how the physicochemical properties of DDGS kafirin having been exposed to the high temperature conditions during ethanol production, compare to kafirin made directly from the grain. An understanding of these properties is required to catalyse the utilisation of DDGS kafirin for biomaterial applications. The aim of this study was to extract kafirin directly from sorghum grain and from DDGS derived from the same grain and, then perform a comparative investigation of the physicochemical properties of these kafirins in terms of: polypeptide profile by sodium-dodecyl sulphate polyacrylamide gel electrophoresis; secondary structure by Fourier transform infra-red spectroscopy and x-ray diffraction, self-assembly behaviour by small-angle x-ray scattering, surface morphology by scanning electron microscopy and surface chemical properties by energy dispersive x-ray spectroscopy. DDGS kafirin was found to have very similar polypeptide profile as grain kafirin but contained altered secondary structure with increased levels of β-sheets. The structure morphology showed surface fractals and surface elemental composition suggesting enhanced reactivity with possibility to endow interfacial wettability. These properties of DDGS kafirin may provide it with unique functionality and thus open up opportunities for it to be used as a novel food grade biomaterial.

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.

In vitro platform establishes antigen-specific CD8+ T cell cytotoxicity to encapsulated cells via indirect antigen recognition

The curative potential of non-autologous cellular therapy is hindered by the requirement of anti-rejection therapy. Cellular encapsulation within nondegradable biomaterials has the potential to inhibit immune rejection, but the efficacy of this approach in robust preclinical and clinical models remains poor. While the responses of innate immune cells to the encapsulating material have been characterized, little attention has been paid to the contributions of adaptive immunity in encapsulated graft destabilization. Avoiding the limitations of animal models, we established an efficient, antigen-specific in vitro platform capable of delineating direct and indirect host T cell recognition to microencapsulated cellular grafts and evaluated their consequential impacts. Using ovalbumin (OVA) as a model antigen, we determined that alginate microencapsulation abrogates direct CD8⁺ T cell activation by interrupting donor-host interaction; however, indirect T cell activation, mediated by host antigen presenting cells (APCs) primed with shed donor antigens, still occurs. These activated T cells imparted cytotoxicity on the encapsulated cells, likely via diffusion of cytotoxic solutes. Overall, this platform delivers unique mechanistic insight into the impacts of hydrogel encapsulation on host adaptive immune responses, comprehensively addressing a long-standing hypothesis of the field. Furthermore, it provides an efficient benchtop screening tool for the investigation of new encapsulation methods and/or synergistic immunomodulatory agents.

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.

Histological effects of pharmacologically active human bile acid nano/micro-particles in Type-1 diabetes

Aim: Gliclazide (G) is a drug prescribed for Type 2 diabetics, although recent studies suggest it has desirable effects in both types of diabetes, Type 1 diabetes and Type 2 diabetes. G has an inconsistent absorption due to poor formulation and bile acids (BAs) have shown significant promise in drug formulation optimization. Hence, the study aimed to examine G effects on histopathological, anti-inflammatory and antidiabetic effects when encapsulated with BAs. Materials & methods: Rats were randomized into eight groups, of which seven were made Type 1 diabetes and treated with various BA-based treatments. Tissue histopathology, inflammation and the bile acid profile were analyzed. Results & conclusion: G capsules showed no histological but the most anti-inflammatory effects, which suggest significant beneficial effects in diabetes treatment.

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.

Bio Micro-Nano Technologies of Antioxidants Optimised Their Pharmacological and Cellular Effects, ex vivo, in Pancreatic β-Cells

Introduction

Recent formulation and microencapsulation studies of probucol (PB) using the polymer sodium alginate (SA) and bile acids have shown promising results but PB stability, and pharmacology profiles remain suboptimal. This study aimed to investigate novel polymers for the nano and micro encapsulation of PB, with the anti-inflammatory bile acid ursodeoxycholic acid (UDCA).

Material and methods

Six formulations using three types of polymers were investigated with and without UDCA. The polymers were NM30D, RL30D, and RS30D and they were mixed with SA and PB at set ratios and microencapsulated using oscillating-voltage-mediated nozzle technology coupled with ionic gelation. The microcapsules were examined for physical and biological effects using pancreatic β-cells.

Results and discussion

UDCA addition did not adversely affect the morphology and physical features of the microcapsules. Despite thermal stability remaining unchanged, bile acid incorporation did enhance the electrokinetic stability of the formulation system for NM30D and RL30D polymers. Mechanical stability remained similar in all groups. Enhanced uptake of PB from the microcapsule by pancreatic β-cells was only seen with NM30D-UDCA-intercalated microcapsules and this effect was sustained at both glucose levels of 5.5 and 35.5 mM.

Conclusion

UDCA addition enhanced PB delivery and biological effects in a formulation-dependent manner.

Bile acid-polymer-probucol microparticles: protective effect on pancreatic β-cells and decrease in type 1 diabetes development in a murine model

Studies in our laboratory have shown potential applications of the anti-atherosclerotic drug probucol (PB) in diabetes due to anti-inflammatory and β-cell protective effects. The anti-inflammatory effects were optimized by incorporation of the anti-inflammatory bile acid, ursodeoxycholic acid (UDCA). This study aimed to test PB absorption, tissue accumulation profiles, effects on inflammation and type 1 diabetes prevention when combined with UDCA. Balb/c mice were divided into three equal groups and gavaged daily PB powder, PB microcapsules or PB-UDCA microcapsules for one week, at a constant dose. Mice were injected with a single dose of intraperitoneal/subcutaneous alloxan to induce type-1 diabetes and once diabetes was confirmed, treatments were continued for 3 days. Mice were euthanized and blood and tissues collected for analysis of PB and cytokine levels. The PB-UDCA group showed the highest PB concentrations in blood, gut, liver, spleen, brain, and white adipose tissues, with no significant increase in pancreas, heart, skeletal muscles, kidneys, urine or feces. Interferon gamma in plasma was significantly reduced by PB-UDCA suggesting potent anti-inflammatory effects. Blood glucose levels remained similar after treatments, while survival was highest among the PB-UDCA group. Our findings suggest that PB-UDCA resulted in best PB blood and tissue absorption and reduced inflammation.

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.

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.

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.

Flow vibration-doubled concentric system coupled with low ratio amine to produce bile acid-macrocapsules of β-cells

BACKGROUND

Pancreatic β-cell microencapsulation using sodium alginate (SA), polylornithine (PLO) copolymers, and ultrasoluble hydrogels, polystyrenes and polyallamines (PAA), has been heavily studied. However, long-term success remains limited due to poor macrocapsules' physical properties and cell functions. Our study aimed to incorporate percentages of PAA and ursodeoxycholic acid, into SA and PLO dispersion mixture and examine best microencapsulating methods and best macrocapsules containing β-cells.

METHODS/RESULTS

Microencapsulating parameters were examined and the Flow-Vibrational Nozzle built-in system was screened and found to be most efficient at high frequency (1900 Hz). Macrocapsules were produced with or without ursodeoxycholic acid in percentages: 0.018SA:0.01PLO:0.005PAA:0.04ursodeoxycholic acid (up to 100% H2O). Using the refined microencapsulation method with vibrational frequency of 1900 Hz, macrocapsules with ursodeoxycholic acid had optimized cell viability and biological functions and ameliorated inflammatory biomarkers.

CONCLUSION

High frequency and air-pressure with Flow-Vibrational encapsulation using the mixture: 0.018SA:0.01PLO:0.005PAA:0.04ursodeoxycholic acid resulted in better cell biology suggesting potentials in β-cell transplantation.

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.

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

PURPOSE

The encapsulation of pancreatic β-cells in biocompatible matrix has generated great interest in diabetes treatment. Our work has shown improved microcapsules when incorporating the bile acid ursodeoxycholic acid (UDCA), in terms of morphology and cell viability although cell survival remained low. Thus, the study aimed at incorporating the polyelectrolytes polyallylamine (PAA) and poly-l-ornithine (PLO), with the polymer sodium alginate (SA) and the hydrogel ultrasonic gel (USG) with UDCA and examined cell viability and functionality post microencapsulation.

METHODS

Microcapsules without (control) and with UDCA (test) were produced using 1% PLO, 2.5% PAA, 1.8% SA and 4.5% USG. Pancreatic β-cells were microencapsulated and the microcapsules' morphology, surface components, cellular and bile acid distribution, osmotic and mechanical stability as well as biocompatibilities, insulin production, bioenergetics and the inflammatory response were tested.

RESULTS

Incorporation of UDCA at 4% into a PLO-PAA-SA formulation system increased cell survival (p < 0.01), insulin production (p < 0.01), reduced the inflammatory profile (TNF-α, IFN-ϒ, IL-6 and IL-1β; p < 0.01) and improved the microcapsule physical and mechanical strength (p < 0.01).

CONCLUSIONS

β-cell microencapsulation using 1% PLO, 2.5% PAA, 1.8% SA, 4.5% USG and the bile acid UDCA (4%) has good potential in cell transplantation and diabetes treatment.