Microfluidic design for in-vitro liver zonation-a numerical analysis using COMSOL Multiphysics.

The liver is one of the most important organs, with a complex physiology. Current in-vitro approaches are not accurate for disease modeling and drug toxicity research. One of those features is liver zonation, where cells display different physiological states due to different levels of oxygen and nutrient supplements. Organ-on-a-chip technology employs microfluidic platforms that enable a controlled environment for in-vitro cell culture. In this study, we propose a microfluidic design embedding a gas channel (of ambient air), creating an oxygen gradient. We numerically simulate different flow rates and cell densities with the COMSOL Multiphysics package considering cell-specific consumption rates of oxygen and glucose. We establish the cell density and flow rate for optimum oxygen and glucose distribution in the cell culture chamber. Furthermore, we show that a physiologically relevant concentration of oxygen and glucose in the chip is reached after 24 h and 30 min, respectively. The proposed microfluidic design and optimal parameters we identify in this paper provide a tool for in-vitro liver zonation studies. However, the microfluidic design is not exclusively for liver cell experiments but is foreseen to be applicable in cell studies where different gas concentration gradients are critical, e.g., studying hypoxia or toxic gas impact.

Dual-crosslinked in-situ forming alginate/silk fibroin hydrogel with potential for bone tissue engineering.

This study aimed to improve the mechanical and biological properties of alginate-based hydrogels. For this purpose, in-situ forming hydrogels were prepared by dual crosslinking of Alginate (Alg)/Oxidized Alginate (OAlg)/Silk Fibroin (SF) through simultaneous ionic gelation using CaCO3-GDL and Schiff-base reaction. The resulting hydrogels were characterized by FTIR, SEM, compressive modulus, and rheological tests. Compared to the physically-crosslinked alginate hydrogel, the compressive modulus of dual-crosslinked Alg/OAlg/SF hydrogel increased from 28 to 67 kPa, due to the covalent imine bond formation. Then, MTT and DAPI staining assays were performed to demonstrate the biocompatibility of hydrogel. Furthermore, the differentiation potential of bone marrow mesenchymal stem cells encapsulated in hydrogel scaffolds to bone tissue was tested by ALP activity, Alizarin Red staining, and real-time PCR. The overall results showed the potential of Alginate/Oxidized Alginate/Silk Fibroin hydrogel scaffold for bone tissue engineering applications.

Investigation of osteogenesis and angiogenesis in perfusion bioreactors using improved multi-layer PCL-nHA-nZnO electrospun scaffolds.

PURPOSE: Bone tissue engineering aims to create a three-dimensional, matured, angiogenic scaffold with a suitable thickness that resembles a natural bone matrix. On the other hand, electrospun fibers, which researchers have considered due to their good biomimetic properties, are considered 2D structures. Due to the highly interwoven network and small pore size, achieving the desired thickness for bone lesions has always been challenging. In bone tissue engineering, bioreactors are crucial for achieving initial tissue maturity and introducing certain signals as flow parameters for differentiation. METHODS: In the present study, Human bone marrow mesenchymal stem cells (hBMSCs) and human umbilical vein endothelial cells (HUVECs) were co-cultured in a perfusion bioreactor on treated (improved pore size by gelatin sacrification and subsequent ultrasonication) 5-layer polycaprolactone-nano hydroxyapatite-nano zinc oxide (T-PHZ) scaffolds to investigate osteogenesis and angiogenesis simultaneously. The flow parameters and stresses on the cells were studied using two patterns of parallel and vertical scaffolds relative to the flow of the culture medium. In dynamic vertical flow (DVF), the culture medium flows perpendicular to the scaffolds, and in dynamic parallel flow (DPF), the culture medium flows parallel to the scaffolds. In all evaluations, static samples (S) served as the control group. RESULTS: Live/dead, and MTT assays demonstrated the biocompatibility of the 5-layer scaffolds and the suitability of the bioreactor's functional conditions. ALP activity, EDAX analysis, and calcium content measurements exhibited greater osteogenesis for T-PHZ scaffolds in DVF conditions. Calcium content increased by a factor of 2.2, 1.8, and 1.6 during days 7 to 14 of culture under DVF, DPF and S conditions, respectively. After 21 days of co-culturing, an immunohistochemistry (IHC) test was performed to investigate angiogenesis and osteogenesis. Five antibodies were investigated in DVF, CD31, VEGFA, and VEGFR2 for angiogenesis, osteocalcin, and RUNX2 for osteogenesis. Compressive stress applied in DVF mode has increased osteogenic activity compared to DPF. CONCLUSION: The results indicated the development of ideal systems for osteogenesis and angiogenesis on the treated multilayer electrospun scaffolds in the perfusion bioreactor.

Role of bioactive magnetic nanoparticles in the prevention of wound pathogenic biofilm formation using smart nanocomposites.

BACKGROUND: Biofilm formation and its resistance to various antibiotics is a serious health problem in the treatment of wound infections. An ideal wound dressing should have characteristics such as protection of wound from microbial infection, suitable porosity (to absorb wound exudates), proper permeability (to maintain wound moisture), nontoxicity, and biocompatibility. Although silver nanoparticles (AgNPs) have been investigated as antimicrobial agents, their limitations in penetrating into the biofilm, affecting their efficiency, have consistently been an area for further research. RESULTS: Consequently, in this study, the optimal amounts of natural and synthetic polymers combination, along with AgNPs, accompanied by iron oxide nanoparticles (IONPs), were utilized to fabricate a smart bionanocomposite that meets all the requirements of an ideal wound dressing. Superparamagnetic IONPs (with the average size of 11.8 nm) were synthesized through co-precipitation method using oleic acid to improve their stability. It was found that the addition of IONPs to bionanocomposites had a synergistic effect on their antibacterial and antibiofilm properties. Cytotoxicity assay results showed that nanoparticles does not considerably affect eukaryotic cells compared to prokaryotic cells. Based on the images obtained by confocal laser scanning microscopy (CLSM), significant AgNPs release was observed when an external magnetic field (EMF) was applied to the bionanocomposites loaded with IONPs, which increased the antibacterial activity and inhibited the formation of biofilm significantly. CONCLUSION: These finding indicated that the nanocomposite recommended can have an efficient properties for the management of wounds through prevention and treatment of antibiotic-resistant biofilm.

Rapid generation of homogenous tumor spheroid microtissues in a scaffold-free platform for high-throughput screening of a novel combination nanomedicine.

Combination nanomedicine is a potent strategy for cancer treatment. Exploiting different mechanisms of action, a novel triple drug delivery system of 5-fluorouracil, curcumin, and piperine co-loaded human serum albumin nanoparticles (5FU-CUR-PIP-HSA-NPs) was developed via the self-assembly method for suppressing breast tumor. Both hydrophobic and hydrophilic drugs were successfully encapsulated in the HSA NPs with a high drug loading efficiency (DLE) of 10%. Successful clinical translation of nanomedicines, however, is a challenging process requiring considerable preclinical in vitro and in vivo animal tests. The aim of this study was to develop a homemade preclinical 3D culture model in the standard 96-well plates in a cost and time-effective novel approach for the rapid generation of homogenous compact tumor spheroids for disease modeling, and anticancer therapeutic/nanomedicine screening. The knowledge of drug screening can be enhanced by employing such a model in a high-throughput manner. Accordingly, to validate the formulated drug delivery system and investigate the cellular uptake and cytotoxicity effect of the nanoformulation, 3D tumor spheroids were employed. The practicality of the nanomedicine system was substantiated in different tests. The in vitro uptake of the NPs into the tight 3D tumor spheroids was facilitated by the semi-spherical shape of the NPs with a proper size and surface charge. 5FU-CUR-PIP-HSA-NPs demonstrated high potency of migration inhibition as a part of successful anti-metastatic therapy as well. The remarkable differences in 2D and 3D cytotoxicities emphasize the importance of employing 3D tumor models as an intermediate step prior to in vivo animal experiments for drug/nanomedicine screening.

Cellular Genome-Scale Metabolic Modeling Identifies New Potential Drug Targets Against Hepatocellular Carcinoma.

Genome-scale metabolic modeling (GEM) is one of the key approaches to unpack cancer metabolism and for discovery of new drug targets. In this study, we report the Transcriptional Regulated Flux Balance Analysis-CORE (TRFBA-), an algorithm for GEM using key growth-correlated reactions using hepatocellular carcinoma (HCC), an important global health burden, as a case study. We generated a HepG2 cell-specific GEM by integrating this cell line transcriptomic data with a generic human metabolic model to forecast potential drug targets for HCC. A total of 108 essential genes for growth were predicted by the TRFBA-CORE. These genes were enriched for metabolic pathways involved in cholesterol, sterol, and steroid biosynthesis. Furthermore, we silenced a predicted essential gene, 11-beta dehydrogenase hydroxysteroid type 2 (HSD11B2), in HepG2 cells resulting in a reduction in cell viability. To further identify novel potential drug targets in HCC, we examined the effect of nine drugs targeting the essential genes, and observed that most drugs inhibited the growth of HepG2 cells. Some of these drugs in this model performed better than Sorafenib, the first-line therapeutic against HCC. A HepG2 cell-specific GEM highlights sterol metabolism to be essential for cell growth. HSD11B2 downregulation results in lower cell growth. Most of the compounds, selected by drug repurposing approach, show a significant inhibitory effect on cell growth in a wide range of concentrations. These findings offer new molecular leads for drug discovery for hepatic cancer while also illustrating the importance of GEM and drug repurposing in cancer therapeutics innovation.

Differentiation of the mesenchymal stem cells to pancreatic ß-like cells in alginate/trimethyl chitosan/alginate microcapsules.

Cell therapy is one of the proposed treatments for diabetes. Cell encapsulation and differentiation inside the biodegradable polymers overcome the limitations such as islet deficiency and the host immune responses. This study was set to encapsulate the mesenchymal stem cells (MSCs) and differentiate them into insulin-producing cells (IPCs). Human bone marrow-mesenchymal stem cells (hBM-MSCs) were encapsulated in alginate/trimethyl chitosan/alginate (Alg/TMC/Alg) coating. At first, morphology and swelling properties of the cell-free microcapsules were investigated. Next, a three-step protocol was used in the presence of exendin-4 and nicotinamide to differentiate hBM-MSCs into IPCs. Viability of the encapsulated cells was investigated using MTT assay. The differentiated cells were analyzed using a real-time RT-PCR to investigate Glut-2, Insulin, Pdx-1, Ngn-3, nestin, and Isl-1 gene expression. The results revealed that differentiation of the encapsulated cells was higher than non-encapsulated cells. Also, dithizone staining in  two-dimensional (2D) environment showed the differentiated cell clusters. In summary, here, hBM-MSCs after encapsulation in Alg/TMC/Alg microcapsules, as a new design, were differentiated properly in the presence of exendin-4 and nicotinamide as main inducers. A three-dimensional (3D) matrix is more similar to the native ECM in the body and prepares higher cell-cell contacts.

Use of Gelatin as a Sacrificial Agent in Combination with Ultrasonication to Improve Cell Infiltration and Osteogenesis of Nanofibrous PCL-nHA Scaffolds for Bone Tissue Engineering.

Objectives: In this study, gelatin was chosen as a novel sacrificial agent in co-electrospun with polycaprolacton-nanohydroxyapatite (PCL-nHA). Materials and Methods: After electrospinnig, gelatin was washed with water, and the prepared scaffold was ultrasonicated. Morphological and structural properties of the prepared scaffolds were studied by SEM. Fourier transform infrared (FTIR) spectroscopy and water contact angle analysis were used to evaluate the removal of gelatin. Results: According to the SEM results, the pore size of the modified scaffolds was increased 3-folds compared to the control sample. For PCL-nHA gelatin: (80:20) after the treatment, the average cell infiltration was 42.7 µm, while there was no infiltration for the control group. The modified electrospun scaffold significantly enhanced the osteogenic differentiation of hBMSCs as verified by increased ALP activity and upregulation of runt-related transcription factor 2 (RUNX2), collagen type 1 (COL1) and osteocalcin (OCN) genes. Conclusion: Co-electrospun PCL-nHA with gelatin as a sacrificial agent in combination with ultrasonication may be an effective, economic and controllable method to increase the pore size in electrospun scaffolds for bone tissue engineering applications.

Living Lactobacillus-ZnO nanoparticles hybrids as antimicrobial and antibiofilm coatings for wound dressing application.

Probiotic bacteria are able to produce antimicrobial substances as well as to synthesize green metal nanoparticles (NPs). New antimicrobial and antibiofilm coatings (LAB-ZnO NPs), composed of Lactobacillus strains and green ZnO NPs, were employed for the modification of gum Arabic-polyvinyl alcohol-polycaprolactone nanofibers matrix (GA-PVA-PCL) against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The physicochemical properties of ZnO NPs biologically synthesized by L. plantarum and L. acidophilus, LAB-ZnO NPs hybrids and LAB-ZnO NPs@GA-PVA-PCL were studied using FE-SEM, EDX, EM, FTIR, XRD and ICP-OES. The morphology of LAB-ZnO NPs hybrids was spherical in range of 4.56-91.61 nm with an average diameter about 34 nm. The electrospun GA-PVA-PCL had regular, continuous and without beads morphology in the scale of nanometer and micrometer with an average diameter of 565 nm. Interestingly, the LAB not only acted as a biosynthesizer in the green synthesis of ZnO NPs but also synergistically enhanced the antimicrobial and antibiofilm efficacy of LAB-ZnO NPs@GA-PVA-PCL. Moreover, the low cytotoxicity of ZnO NPs and ZnO NPs@GA-PVA-PCL on the mouse embryonic fibroblasts cell line led to make them biocompatible. These results suggest that LAB-ZnO NPs@GA-PVA-PCL has potential as a safe promising antimicrobial and antibiofilm dressing in wound healing against pathogens.

High cell density culture of recombinant E. coli in the miniaturized bubble columns.

Miniaturized bubble columns (MBCs) can provide mass transfer characteristics similar to stirred tank bioreactors. In this study, a new application was developed for MBCs to investigate the effect of feeding strategy and medium type on the fed-batch culture of recombinant E. coli. The results showed that the exponential feeding strategy and defined M9 medium were more suitable to achieve the high cell density culture (HCDC). The maximum obtained cell concentration in exponential feeding strategy in the defined medium without induction, was at OD600 of 169, while glucose concentration was maintained under 2 g/L. To the best of our knowledge, this cell concentration cannot be achieved in lab or pilot scale bubble columns. At the end of the process, adverse effect of the metabolic burden due to induction and mass transfer limitations decreased the obtained final cell concentration to OD600 of 116. Finally, a comparison of the results for fed-batch culture in the stirred tank bioreactor with those of the MBCs showed that their lower cell concentrations were due to the hydrodynamics limitations of MBCs. Yet, it was found that the MBCs are efficient tools in development of feeding strategies and evaluation of medium components for HCDC of recombinant E. coli.

Synthesis and characterization of antimicrobial wound dressing material based on silver nanoparticles loaded gum Arabic nanofibers.

Gum Arabic (GA) is a biocompatible polymer with the necessary requirements for a wound dressing. However, electrospinning of GA is a bottleneck due to its physico-chemical properties. The aim of this study was to fabricate an antimicrobial nanofibers mat from GA with suitable porosity, water absorption, water vapor permeability and mechanical strength. For this purpose, the composition of polycaprolacton (PCL)-coated GA-polyvinyl alcohol (PVA) nanofibers mat was optimized based on the possible highest porosity, water absorption and water vapor permeability, and then silver nanoparticles (AgNPs) loaded nanofibers mat was prepared based on this composition. The synthesis of AgNPs was supported by UV-vis and ICP analyses. The structure of mat and its constituents were characterized by FE-SEM, XRD and FTIR. The results showed that the average diameter of nanofibers was in the range of 150 to 250 nm with the porosity, water absorption and water vapor permeability of 37.34%, 547.30% and 2235.50 g/m2.day, respectively. The antimicrobial activity of mat against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans was proved. Moreover, the cytotoxicity of mat showed the good biocompatibility for the mouse embryonic fibroblast cells. This study introduced PCL-coated GA-PVA-AgNPs as an effective antimicrobial mat alternative for commercial wound dressing.

Preparation and Characterization of Nanocomposite Scaffolds (Collagen/ß-TCP/SrO) for Bone Tissue Engineering.

Background: Nowadays, production of nanocomposite scaffolds based on natural biopolymer, bioceramic, and metal ions is a growing field of research due to the potential for bone tissue engineering applications. Methods: In this study, a nanocomposite scaffold for bone tissue engineering was successfully prepared using collagen (COL), beta-tricalcium phosphate (ß-TCP) and strontium oxide (SrO). A composition of ß-TCP (4.9 g) was prepared by doping with SrO (0.05 g). Biocompatible porous nanocomposite scaffolds were prepared by freeze-drying in different formulations [COL, COL/ß-TCP (1:2 w/w), and COL/ß-TCP-Sr (1:2 w/w)] to be used as a provisional matrix or scaffold for bone tissue engineering. The nanoparticles were characterized by X-ray diffraction, Fourier transforms infrared spectroscopy and energy dispersive spectroscopy. Moreover, the prepared scaffolds were characterized by physicochemical properties, such as porosity, swelling ratio, biodegradation, mechanical properties, and biomineralization. Results: All the scaffolds had a microporous structure with high porosity (~ 95-99%) and appropriate pore size (100-200 µm). COL/ß-TCP-Sr scaffolds had the compressive modulus (213.44 ± 0.47 kPa) higher than that of COL/ß-TCP (33.14 ± 1.77 kPa). In vitro cytocompatibility, cell attachment and alkaline phosphatase (ALP) activity studies performed using rat bone marrow mesenchymal stem cells. Addition of ß-TCP-Sr to collagen scaffolds increased ALP activity by 1.33-1.79 and 2.92-4.57 folds after 7 and 14 days of culture, respectively. Conclusion: In summary, it was found that the incorporation of Sr into the collagen-ß-TCP scaffolds has a great potential for bone tissue engineering applications.

Osteogenic induction of human mesenchymal stem cells in multilayered electrospun scaffolds at different flow rates and configurations in a perfusion bioreactor.

Electrospun scaffolds are potentially interesting in bone tissue engineering due to a strong structural similarity to the natural bone matrix. To investigate the osteogenic behavior of cells on the scaffolds, dynamic culture of cells is essential to simulate the biological environment. In the present study, human mesenchymal stem cells (hMSCs) were cultured on multilayer nanohydroxyapatite-polycaprolactone electrospun scaffolds at different configurations (horizontal with or without pressure and parallel with the medium flow) and flow rates in a perfusion bioreactor. Alkaline phosphatase (ALP) activity, cell viability, Ca deposition and RUNX2 expression were determined in three different dynamic states, and compared with static culture after 1, 3, 7, and 14 days. Among dynamic groups, RUNX2 gene expression upregulated more in a horizontal state at a low flow rate without mechanical pressure (LF) and parallel flow (PF), than static group on day 7. At a high flow rate with mechanical pressure, Ca deposition and ALP activity increased 2.34 and 1.7 folds more than in static culture over 7 days, respectively. Furthermore, ALP activity, Ca deposition and RUNX2 gene expression increased in PF samples. PF provided longer culture time with higher cell differentiation. Therefore, high flow rate with mechanical pressure and PF are suggested for producing differentiated cell structure for bone tissue engineering.

The effect of modified electrospun PCL-nHA-nZnO scaffolds on osteogenesis and angiogenesis.

Large bone defects treatment is one of the challenges in current bone tissue engineering approaches. Various strategies have been proposed to address this issue, among which, prevascularization by coculturing of angiogenic and osteogenic cells on the scaffolds can alleviate this problem. In the present study, modified fibrous scaffolds were prepared by electrospinning and subsequent ultrasonication of polycaprolactone (PCL) containing nano-hydroxyapatite (n-HA), with/without nano-zinc oxide (n-ZnO), and polyethylene oxide [PEO] as a sacrificial agent. The physical, mechanical, and chemical characteristics of the scaffolds were evaluated. The results showed the presence of n-ZnO, which in turn increased Young's module of the scaffolds from 5.5 ± 0.67 to 6.7 ± 1.77 MPa. Moreover, MTT, SEM, alkaline phosphatase (ALP) activity, chicken embryo chorioallantoic membrane (CAM) assay, and real-time RT-PCR were utilized to investigate the biocompatibility, cell adhesion and infiltration, osteoconductivity, angiogenic properties, and expression of osteogenic and angiogenic related genes. ALP assay showed that the highest enzyme activity was noted when the modified scaffolds containing n-ZnO were seeded with HUVEC:hBMSC at the cell ratio of 1:5. CAM assay showed induction of angiogenesis for the scaffolds containing n-ZnO. Real-time RT-PCR results showed significant upregulation of angiogenic related genes. Thus, the scaffolds containing n-ZnO may have great potential for osteogenesis and angiogenesis in tissue engineering applications.

A benchmark-driven approach to reconstruct metabolic networks for studying cancer metabolism.

Genome-scale metabolic modeling has emerged as a promising way to study the metabolic alterations underlying cancer by identifying novel drug targets and biomarkers. To date, several computational methods have been developed to integrate high-throughput data with existing human metabolic reconstructions to generate context-specific cancer metabolic models. Despite a number of studies focusing on benchmarking the context-specific algorithms, no quantitative assessment has been made to compare the predictive performance of these methods. Here, we integrated various and different datasets used in previous works to design a quantitative platform to examine functional and consistency performance of several existing genome-scale cancer modeling approaches. Next, we used the results obtained here to develop a method for the reconstruction of context-specific metabolic models. We then compared the predictive power and consistency of networks generated by our method to other computational approaches investigated here. Our results showed a satisfactory performance of the developed method in most of the benchmarks. This benchmarking platform is of particular use in algorithm selection and assessing the performance of newly developed algorithms. More importantly, it can serve as guidelines for designing and developing new methods focusing on weaknesses and strengths of existing algorithms.

Hydrodynamics and mass transfer in miniaturized bubble column bioreactors.

Miniaturized bubble columns (MBCs) have different hydrodynamics in comparison with the larger ones, but there is a lack of scientific data on MBCs. Hence, in this study, the effect of gas hold-up, flow regimes, bubble size distribution on volumetric oxygen mass transfer coefficient at different pore size spargers and gas flow rates in MBCs in the presence and absence of microorganisms were investigated. It was found that flow regime transition occurred around low gas flow rates of 1.18 and 0.85 cm/s for small (16-40 µm) and large (40-100 µm) pore size spargers, respectively. Gas hold-up and KLa in MBC with small size sparger were higher than those with larger one, with an increasing effect in the presence of microorganisms. A comparison revealed that the wall effect on the flow regime and gas hold-up in MBCs was greater than bench-scale bubble columns. The KLa values significantly increased up to tenfold using small pore size sparger. In the MBC and stirred tank bioreactors, the maximum obtained cell concentrations were OD600 of 41.5 and 43.0, respectively. Furthermore, it was shown that in MBCs, higher KLa and lower turbulency could be achieved at the end of bubbly flow regime.

Determination of Biological Activity of Recombinant Reteplase Using Clot Lysis Time and Activated Partial Thromboplastin Time (APTT) Lysis Methods: A Comparative Study.

Recombinant plasminogen activator (reteplase) is a third generation thrombolytic agent which has been used on coronary artery thrombosis and acute myocardial infarction. Clot lysis assay is usually considered as a unique method to evaluate biological activity of reteplase. In this study biological activity of reteplase was determined by APTT (activated partial thromboplastin time) lysis method. Validity of this method was evaluated in comparison with reference method, clot lysis time assay. Results of APTT lysis test showed good reproducibility (relative standard deviation (RSD) 3-5% for within day analysis and 4-7% for between day analysis), and accuracy (101.3-102.7%). APTT lysis responses were linear in range of 0.001-0.1 mg/mL reteplase. Therefore, APTT lysis method is applicable for biological activity determination of reteplase. Although more comprehensive studies are required to approve this test as a reference method, APTT lysis method seems to be valuable to receive more attention due to advantages of technical simplicity, sensitivity, applicability, and cost efficiency.

Self-assembled and pH-sensitive mixed micelles as an intracellular doxorubicin delivery system.

Nanocarrier-based drug delivery systems have been explored extensively in cancer therapy. Among the vast number of different nanocarrier systems applied to deliver chemotherapeutics to cancer tumor, intelligent systems which deliver drug to various sites in the body have attracted considerable attentions. Finding a specific stimulant that triggers the carrier to release its payload in the target tissue is a key parameter for efficacy of delivery systems. Acidic pH of cancer tumor helps a pH-sensitive carrier to release drug at the tumor site. In this study, a pH-sensitive mixed micellar system was developed using Dextran-Stearic Acid (Dex-SA) and Dextran-Histidine (Dex-His) conjugated polymers to deliver doxorubicin (DOX) to cancer cells. Drug release from this micellar system showed higher release rate at acidic pH than that of in neutral environment, where the release was 56 and 76% at pH 7.4 and acidic pH, respectively. Finally, the in vitro cytotoxicity and cell uptake of DOX-loaded micelles and free DOX on U87 MG cell line showed that micellar systems had more anti-proliferation effect and uptake compared to free drug.

Immunoisolation of stem cells by simultaneous encapsulation and PEGylation.

Today, cell therapy is known as an important tool in the treatment of chronic diseases where cells lose their normal function. Immunoisolation systems using microencapsulation or PEGylation have been developed to evade the problem of rejection by the immune system. The aim of the present study was to investigate a combination of microencapsulation and PEGylation methods in coating mouse embryonic stem cells (mESCs) to determine its effect in reducing the host's immune response. Therefore, methoxy polyethylene glycol (mPEG) binding on alginate-trimethyl chitosan (TMC) microcapsules was investigated using FTIR. Furthermore, survival of the microencapsulated mESCs was confirmed using AO/PI staining and MTT assays. In addition, the effect of mESCs co-cultured with foreign lymphocytes was evaluated. Overall, interleukin-2 (IL-2) secretions as a response of the immune system revealed that mESCs microencapsulation in alginate-TMC-PEG, reduced the immune system response. The results suggested that IL-2 secretion was reduced to 62% at seventh day.

Normal Insulin Secretion from Immune-Protected Islets of Langerhans by PEGylation and Encapsulation in the Alginate-Chitosan-PEG.

BACKGROUND: Pancreatic islet transplantation is one of the most promising strategies for treating patients with type I diabetes mellitus. OBJECTIVE: We aimed to assess the immunoisolation properties of the multilayer encapsulated islets using alginate-chitosan-PEG for immunoprotection and insulin secretion from the encapsulated islets induced under different glucose concentrations in vitro. MATERIALS AND METHODS: In this study, the islets were isolated from Wistar rats. The biological function (insulin secretion) of the immunoisolated islets following to PEGylation and encapsulation in the alginate-chitosan-PEG, separately, in addition to their immuno-protection in a co-culturing with the lymphocytes isolated from the male C57BL/6 mice were investigated, respectively. RESULTS: Alginate-chitosan-PEG decreased IL-2 secretion from the lymphocytes co-cultured with islets. Also, insulin secretion from the encapsulated and PEGylated groups was stimulated by glucose (i.e., 5.6 and 16.7 mM of glucose, respectively); showed insulin secretion similar to the naked islets, without coating, after 30 and 60 min of incubation. CONCLUSION: In conclusion, encapsulation and PEGylation have no negative effect on the insulin secretion and glucose sensitivity of the islets for all of the groups. Also, encapsulation decreased IL-2 secretion from the lymphocytes.