Polyethylene Glycol Gel Research Articles

Optimizing a self-solidifying hydrogel as an endoscopically deliverable hydrogel coating system: a proof-of-concept study on porcine endoscopic submucosal dissection-induced ulcers

Endoscopic submucosal dissection (ESD) benefits patients in the early stages of cancer, but it poses various risks of complication. Strategies involving the application of clinically approved products to cover ulcers caused by ESD can reduce these complications, but the fixed nature of their properties limit the understanding of their effects on ulcer healing. This study was focused on Tetra–PEG gel, an innovative hydrogel with controllable physical properties made from a sulfhydryl–maleimide pair. The use of biocompatible polyethylene glycol (PEG) in Tetra–PEG gel may allow for its application as a biomaterial. The aims of our study were to identify the characteristics of a self-solidifying hydrogel for endoscopic application and to develop a new ulcer coating agent for post-ESD treatment. We developed a specialized double-lumen catheter and determined the optimal application conditions of the hydrogel. We examined the hydrodynamic properties of the gelling solutions and elucidated the pressure drop that occurred during device operation. Finally, by considering previous experimental results, we successfully applied the hydrogel to post-ESD ulcers in porcine stomachs. We believed that by further optimizing hydrogels with effectively controlled properties and by continuing to investigate them through animal experiments, we could expand our understanding of the relationships among material and ulcer healing properties and apply this knowledge to clinical applications.

Smart Hydrogel Reactor of Poly(N-isopropylacrylamide)/Polyethylene Glycol Interpenetrating Polymer Networks for Oxidative Coupling of 2-Naphthol

AbstractHydrogels with an interpenetrating polymer network (IPN) structure composed of poly(N-isopropylacrylamide) (poly-NIPAM) gel and a gel containing polyethylene glycol (PEG) chains were synthesized. They showed a typical temperature-responsive volume change in water owing to the constructed poly-NIPAM gel component. Oxidative coupling of 2-naphthol with IPN cryogels and a conventional catalyst, the CuCl2 complex of N,N,N′,N′-tetramethylenediamine, was conducted in water under an O2 atmosphere; the IPN gel prepared from PEG with a larger molecular weight of 11000 afforded a product with a good yield of 73% (91% conv.) during the reaction in basic media. The hydrogel effectively promoted the reaction but hardly produced any product without the catalyst, acting as a reactor vessel in the water. Owing to the low durability of the PEG gel component for hydrolysis, a limitation was also suggested during experiments on the recyclability of the hydrogel.

CCL21 and beta-cell antigen releasing hydrogels as tolerance-inducing therapy in Type I diabetes.

Type-I Diabetes (T1D) is caused by defective immunotolerance mechanisms enabling autoreactive T cells to escape regulation in lymphoid organs and destroy insulin-producing β-cells in the pancreas, leading to insulin dependence. Strategies to promote β-cell tolerance could arrest T1D. We previously showed that secretion of secondary lymphoid chemokine CCL21 by CCL21 transgenic β-cells induced tolerance and protected non-obese diabetic (NOD) mice from T1D. T1D protection was associated with formation of lymph node-like stromal networks containing tolerogenic fibroblastic reticular cells (FRCs). Here, we developed a polyethylene glycol (PEG) hydrogel platform with hydrolytically degradable PEG-diester dithiol crosslinkers to provide controlled and sustained delivery of CCL21 and β-cell antigens for at least 28days in vitro and recapitulate properties associated with the tolerogenic environment of CCL21 transgenic β-cells in our previous studies. CCL21 and MHC-II restricted antigens were tethered to gels via simple click-chemistry while MHC-I restricted antigens were loaded in PEG-based polymeric nanovesicles and incorporated in the gel networks. CCL21 and antigen release kinetics depended on the PEG gel tethering strategy and the linkers. Importantly, in vitro functionality, chemotaxis, and activation of antigen-specific T cells were preserved. Implantation of CCL21 and β-cell antigen gels under the kidney capsule of pre-diabetic NOD mice led to enrichment of adoptively transferred antigen-specific T cells, formation of gp38+FRC-like stromal cell networks, and increased regulation of specific T cells with reduced accumulation within pancreatic islets. Thus, our platform for sustained release of β-cell antigens and CCL21 immunomodulatory molecule could enable the development of antigen-specific tolerance therapies for T1D.

Analysis of the sustained release ability of bevacizumab-loaded tetra-PEG gel

Multiple intravitreal injections, which are painful and costly, are often required in the treatment of retinal disorders. Therefore, a novel drug delivery system using hydrogels is currently being evaluated as an alternative. This study aimed to evaluate the ability of tetra-armed polyethylene glycol (tetra-PEG) gel for sustained release in vitro. Bevacizumab-loaded tetra-PEG gel and 5-Carboxyfluorescein N-succinimidyl ester (FAM-NHS)-labeled IgG-loaded tetra-PEG gel were prepared by mixing tetra-PEG with thiol termini (tetra-PEG-SH) solution, maleimide termini (tetra-PEG-MA) solution, and bevacizumab or FAM-NHS labeled IgG. The gels were prepared with three different polymer concentrations of 1.5%, 5%, and 10%, then an in vitro release study performed to assess the sustained release ability of the drug-loaded tetra-PEG gels. High performance liquid chromatography (HPLC) was used to test the structural stability of the bevacizumab released from the tetra-PEG gel. The binding of bevacizumab to tetra-PEG-SH or MA was assessed using SDS-polyacrylamide gel electrophoresis (PAGE). The bioactivity of released bevacizumab was tested using KDR/NFAT-RE HEK293 cells. In addition, in vitro degradation and swelling studies were also performed. The in vitro release analysis showed that the release of bevacizumab was slower in the 5% and 10% tetra-PEG gels than that of 1.5% tetra-PEG gels. Similarly, the release of FAM-NHS-labeled IgG was slowest in the 1.5%, 5%, and 10% tetra-PEG gels, in that order. The 5% and 10% tetra-PEG gels released bevacizumab and FAM-NHS-labeled IgG over a period of 1–2 weeks. Both bevacizumab and FAM-NHS-labeled IgG were not fully released in 2 weeks. HPLC analysis showed that the retention time of the samples released from the bevacizumab-loaded tetra-PEG gel was similar to that of the bevacizumab standard. The SDS-PAGE analysis showed that bevacizumab binds to tetra-PEG-MA. The bioactivity assay test revealed no decrease in the bioactivity of the released bevacizumab. In vitro degradation and swelling studies revealed that 1.5%, 5%, and 10% tetra-PEG gels expanded by approximately 1.4-, 2-, and 3-fold, respectively. Based on the results of the release and swelling tests, 5% tetra-PEG gels are considered good candidates for controlled release systems for therapeutic antibodies such as bevacizumab. The binding of PEG to the therapeutic antibodies may reduce the availability of therapeutic antibodies that can be released.

In Vitro and Ectopic In Vivo Studies toward the Utilization of Rapidly Isolated Human Nasal Chondrocytes for Single-Stage Arthroscopic Cartilage Regeneration Therapy.

Nasal chondrocytes (NCs) have a higher and more reproducible chondrogenic capacity than articular chondrocytes, and the engineered cartilage tissue they generate in vitro has been demonstrated to be safe in clinical applications. Here, we aimed at determining the feasibility for a single-stage application of NCs for cartilage regeneration under minimally invasive settings. In particular, we assessed whether NCs isolated using a short collagenase digestion protocol retain their potential to proliferate and chondro-differentiate within an injectable, swiftly cross-linked and matrix-metalloproteinase (MMP)-degradable polyethylene glycol (PEG) gel enriched with human platelet lysate (hPL). NC-hPL-PEG gels were additionally tested for their capacity to generate cartilage tissue in vivo and to integrate into cartilage/bone compartments of human osteochondral plugs upon ectopic subcutaneous implantation into nude mice. NCs isolated with a rapid protocol and embedded in PEG gels with hPL at low cell density were capable of efficiently proliferating and of generating tissue rich in glycosaminoglycans and collagen II. NC-hPL-PEG gels developed into hyaline-like cartilage tissues upon ectopic in vivo implantation and integrated with surrounding native cartilage and bone tissues. The delivery of NCs in PEG gels containing hPL is a feasible strategy for cartilage repair and now requires further validation in orthotopic in vivo models.

Prostate Cancer Treatment with Pencil Beam Proton Therapy Using Rectal Spacers sans Endorectal Balloons.

PurposeProton beam radiotherapy (PBT) has been used for the definitive treatment of localized prostate cancer with low rates of high-grade toxicity and excellent patient-reported quality-of-life metrics. Technological advances such as pencil beam scanning (PBS), Monte Carlo dose calculations, and polyethylene glycol gel rectal spacers have optimized prostate proton therapy. Here, we report the early clinical outcomes of patients treated for localized prostate cancer using modern PBS–PBT with hydrogel rectal spacing and fiducial tracking without the use of endorectal balloons.Materials and MethodsThis is a single institutional review of consecutive patients treated with histologically confirmed localized prostate cancer. Prior to treatment, all patients underwent placement of fiducials into the prostate and insertion of a hydrogel rectal spacer. Patients were typically given a prescription dose of 7920 cGy at 180 cGy per fraction using a Monte Carlo dose calculation algorithm. Acute and late toxicity were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE), version 5. Biochemical failure was defined using the Phoenix definition.ResultsFrom July 2018 to April 2020, 33 patients were treated (median age, 75 years). No severe acute toxicities were observed. The most common acute toxicity was urinary frequency. With a median follow-up of 18 months, there were no high-grade genitourinary late toxicities; however, one grade 3 gastrointestinal toxicity was observed. Late erectile dysfunction was common. One treatment failure was observed at 21 months in a patient treated for high-risk prostate cancer.ConclusionEarly clinical outcomes of patients treated with PBS–PBT using Monte Carlo–based planning, fiducial placement, and rectal spacers sans endorectal balloons demonstrate minimal treatment-related toxicity with good oncologic outcomes. Rectal spacer stabilization without the use of endorectal balloons is feasible for the use of PBS–PBT.

Novel micropatterning technique reveals dependence of cell-substrate adhesion and migration of social amoebas on parental strain, development, and fluorescent markers.

Cell-substrate adhesion of the social amoeba Dictyostelium discoideum, a model organism often used for the study of chemotaxis, is non-specific and does not involve focal adhesion complexes. Therefore, micropatterned substrates where adherent Dictyostelium cells are constrained to designated microscopic regions are difficult to make. Here we present a micropatterning technique for Dictyostelium cells that relies on coating the substrate with an ∼1μm thick layer of polyethylene glycol (PEG) gel. We show that, when plated on a substrate with narrow parallel stripes of PEG-gel and glass, Dictyostelium cells nearly exclusive adhere to and migrate along the glass stripes, thus providing a model system to study one-dimensional migration of amoeboid cells. Surprisingly, we find substantial differences in the adhesion to PEG-gel and glass stripes between vegetative and developed cells and between two different axenic laboratory strains of Dictyostelium, AX2 and AX4. Even more surprisingly, we find that the distribution of Dictyostelium cells between PEG-gel and glass stripes is significantly affected by the expression of several fluorescent protein markers of the cytoskeleton. We carry out atomic force microscopy based single cell force spectroscopy measurements that confirm that the force of adhesion to PEG-gel substrate can be significantly different between vegetative and developed cells, AX2 and AX4 cells, and cells with and without fluorescent markers. Thus, the choice of parental background, the degree of development, and the expression of fluorescent protein markers can all have a profound effect on cell-substrate adhesion and should be considered when comparing migration of cells and when designing micropatterned substrates.

The effect of carrier addition on Anammox start-up and microbial community: a review

The Anaerobic Ammonia Oxidation (Anammox) wastewater treatment process has attracted significant attention ever since its discovery in the Netherlands in the 1990′s. This has mostly been due to the potential cost-effectiveness associated with the process in large scale application. However, the application of the Anammox process on an industrial-scale has been curtailed mainly due to the long start-up time of the Anammox bacteria. In order to ensure the feasibility of industrial-scale Anammox application, researchers have employed various means; experimenting with different reactor types, membrane types, as well as the usage of chemicals such as hydrazine, acyl-homoserinelactones (AHL), etc. Most recently however, more attention has been directed towards the addition of biomass carriers such as biochar, zeolites, sponges, non-woven membrane etc. for the optimization of the Anammox process. This article provides an up-to-date overview of the various carriers (Non-woven fabric, Biochar, Down-flow hanging sponge, Zeolite, Zero-violent iron, Polyethylene glycol gel, Activated-carbon, Polyethylene sponge, etc.) that have so far been used to better the performance of the Anammox process. It also focuses on the effect of these biomass carrier additions on the microbial growth and community structure. Understanding the metabolomics of microorganisms in carrier-amended media promises to enhance our knowledge of carriers’ influence on the microbial community structure. Generally, the metabolic effects of carrier-amendment on microbial growth and community are largely uninvestigated. Future researches focusing on this area could tremendously improve our comprehension of the inner-workings of the carrier amended Anammox set-up.

Synergistic effect of PEG and hydrosol treatments of solution on preparing Al2O3 coating by cathode plasma electrolytic deposition

Al2O3 coatings were prepared by cathode plasma electrolytic deposition (CPED) in the solutions containing Al(NO3)3 · 9H2O, polyethylene glycol (PEG) and hydrosol treated at different conditions. It was found that the deposition efficiency of Al2O3 coatings could be improved by adding PEG in Al(NO3)3 solution and hydrosol treatment of the Al(NO3)3 solution respectively, while the deposition efficiency was synergistically enhanced by both together. It was proved that Al2O3 gel was formed in the solution after hydrosol treatment. Therefore, there is a synergistic effect of PEG and Al2O3 gel on preparing Al2O3 coating by CPED. Such synergistic effect can be mainly attributed to the formation of thin gas sheath on the cathode surface under the action of PEG and Al2O3 gel together. Consequently, at 120 V, the over-potential in the gas sheath is decreased, while the over-potential in Al2O3 coating is increased. At the same time, the current density of the cathode is decreased, so a thick Al2O3 coating can be prepared by CPED in an effective way.

Preparation and characterization of polyethylene glycol (PEG) hydrogel as shape-stabilized phase change material

A kind of PEG8000 hydrogels as shape-stabilized phase change materials (SSPCMs) were prepared by using a simple sol-gel technique. Their thermal characteristics were studied under the modified mass ratio of PEG and water. The optimized PEG hydrogel (PEGH) was placed at high temperature of 70°C to remove excess liquid water. This temperature was less than the apparent melting temperature (74±1°C) but over its phase transition temperature of about 9°C. Obtained PEG gel displayed an excellent thermal energy density of 154.2J/g, and the value was twice that of reported form-stable composite PCM in literature. Therefore, it can be remarkably noted that the PEG hydrogel provides a new way for the preparation of SSPCMs, and has an important potential for heating/cooling applications in buildings.

Injectable Polyethylene Glycol Gel as Dermal Filler: 01 Year Clinical and Ultrasound Follow-Up

Facial alterations that occur with aging are result of combined effects of soft tissue atrophy with loss of facial volume, gravitational factor and decrease of elastic tissue. In order to minimize these alterations, minimally invasive procedures such as cutaneous filling have been gaining space in clinical practice. In 2008, Scientech Corporation - Italia introduced hydrogel of polyethylene glycol (PEG) REMAKE® as cutaneous filler. This prospective study was developed to prove the effectiveness, safety and durability over the 12 months after the application of PEG hydrogel, commercialized under the name of REMAKE®. 40 female volunteers were included, between 30 and 60 years, with signs of malar region volume loss between 2 and 3 (Raspaldo's classification) and Nasogenian furrow accentuation, with score between 2 and 3 (Day and collaborators' classification). No patient had carried out procedures of temporary filling for 1 year or permanent filling at any time. Objective parameters always show the scale of the improvement and an evaluation was selected through ultrasound exams and surface scan for evaluation of size and depth of wrinkles improvement. Evaluations by the US were carried out for 30, 120 and 360 days of product use, in a pilot group of 18 patients randomly selected to measure the product in the application plan and numerically assess alterations of volume (absorption/migration). Its durability of up to 01 year after application is proved when no significant reduction.

Comparison of two different rectal spacers in prostate cancer external beam radiotherapy in terms of rectal sparing and volume consistency

Background and purposeIn external beam radiation (EBRT) of the prostate, the rectum is the dose-limiting organ at risk, and sparing of the anterior rectal wall is a prerequisite for safe delivery of doses beyond 70Gy. Spatial sparing of the rectum can be achieved by introducing a spacer material into the retroprostatic space, thus separating the anterior rectal wall from the PTV. Materials and methodsTwo spacer technologies, Spacer OAR, a polyethylene glycol gel and ProSpace, a saline inflated balloon, were compared in terms of spacer volume, stability, and dose reduction to the anterior rectum wall in 78 patients. ResultsBoth spacer systems significantly reduced the rectum surface encompassed by the 95% isodose (gel: −35%, p<0.01; balloon −63.4%, p<0.001) compared to a control group. The balloon spacer was superior in reducing rectum dose (−27.7%, p=0.034), but exhibited an average volume loss of >50% during the full course of treatment of 37–40 fractions, while the volume of gel spacers remained fairly constant. ConclusionsIn choosing between the two spacer technologies, the advantageous dose reduction of the balloon needs to be weighed up against the better volume consistency of the gel spacer with respect to the duration of hypofractionated vs normofractionated regimens.

Biological wastewater treatment of 1,4-dioxane using polyethylene glycol gel carriers entrapping Afipia sp. D1

A biological treatment system for 1,4-dioxane-containing wastewater was developed using the bacterium Afipia sp. D1, which can utilize 1,4-dioxane as the sole carbon source. Strain D1 was entrapped in a polyethylene glycol gel carrier to stably maintain it in a bioreactor, and continuous feeding tests were performed to treat model industrial wastewater containing 1,4-dioxane. 1,4-Dioxane removal activity rapidly increased soon after the start of feeding of influent with 400mg/L 1,4-dioxane, and the volumetric removal rate reached 0.67kg dioxane/m(3)/d on day 36 by a stepwise increase in loading. The start-up period of the 1,4-dioxane treatment reactor was approximately 1 month, and stable removal performance was subsequently achieved for more than 1 month. The average 1,4-dioxane effluent concentration and 1,4-dioxane removal efficiency were 3.6mg/L and 99%, respectively, during stable operation. Further 1,4-dioxane degradation activity of the of the gel carrier was characterized in batch experiments with respect to temperature. The optimum temperature for 1,4-dioxane treatment was 31.7°C, and significant removal was observed at a temperature as low as 6.9°C. The apparent activation energy for 1,4-dioxane degradation was estimated to be 47.3kJ/mol. This is the first report of the development of a 1,4-dioxane biological treatment system using gel entrapment technology.

Automation Highlights from the Literature

Automation Highlights from the Literature

Gel pad array chip for high throughput and multi-analyte microbead-based immunoassays

We present here a gel pad array chip for high-throughput and multi-analyte microbead-based immunoassays. The chip is fabricated by photo-patterning of two polymeric gels, polyacrylamide gel and polyethylene glycol (PEG) gel, on a glass slide. The resulting chip consists of 40 polyacrylamide gel pad array units for the immobilization of microbeads and each gel pad array is surrounded with a PEG micropillar ring to confine the samples within the microarray. As a proof of concept, this chip was tested for quantitative immunoassays for two model cancer markers, human chorionic gonadotropin (hCG) and prostate specific antigen (PSA), in serum samples. Detection limits below the physiological threshold level for cancer diagnosis were achieved with good inter- and intra-chip reproducibility. Moreover, by using spatial encoded microbeads, simultaneous detection of both hCG and PSA on each gel pad array is achieved with single filter fluorescence imaging. This gel pad array chip is easy to use, easy to fabricate with low cost materials and minimal equipment and reusable. It could be a useful tool for common biolabs to customize their own microbead array for multi-analyte immunoassays.

DuraSeal® as a spacer to reduce rectal doses in low-dose rate brachytherapy for prostate cancer

The purpose of this study was to evaluate the utility of off-label use of DuraSeal® polyethylene glycol (PEG) gel in low-dose rate (LDR) prostate brachytherapy seed implantation to reduce rectal doses. Diluted DuraSeal® was easy to use and, in spite of a clearance effect, useful in decreasing D2cc rectal doses.

Enhancement of hydrogen production from palm oil mill effluent via cell immobilisation technique

Clostridium sp. LS2 was immobilised by entrapment in polyethylene glycol (PEG) gel beads to improve the biohydrogen production rate from palm oil mill effluent (POME). We sought to explore and optimise the hydrogen production capability of the immobilised cells by studying the conditions for cell immobilisation, including PEG concentration, cell loading and curing times, as well as the effects of temperature and K2HPO4 (500–2000 mg/L), NiCl2 (0.1–5.0 mg/L), FeCl2 (100–400 mg/L) MgSO4 (50–200 mg/L) concentrations on hydrogen production rate. The results showed that by optimising the PEG concentration (10% w/v), initial biomass (2.2 g dry weight), curing time (80 min) and temperature (37 °C), as well as the concentrations of K2HPO4 (2000 mg/L), NiCl2 (1 mg/L), FeCl2 (300 mg/L) and MgSO4 (100 mg/L), a maximum hydrogen production rate of 7.3 L/L-POME/day and a yield of 0.31 L H2/g chemical oxygen demand were obtained during continuous operation. We believe that this process may be potentially expanded for sustained and large-scale hydrogen production. Copyright © 2014 John Wiley & Sons, Ltd.

BMP4 inhibits the proliferation of breast cancer cells and induces an MMP-dependent migratory phenotype in MDA-MB-231 cells in 3D environment

BackgroundBone morphogenetic protein 4 (BMP4) belongs to the transforming growth factor β (TGF-β) family of proteins. BMPs regulate cell proliferation, differentiation and motility, and have also been reported to be involved in cancer pathogenesis. We have previously shown that BMP4 reduces breast cancer cell proliferation through G1 cell cycle arrest and simultaneously induces migration in a subset of these cell lines. Here we examined the effects of BMP4 in a more physiological environment, in a 3D culture system.MethodsWe used two different 3D culture systems; Matrigel, a basement membrane extract from mouse sarcoma cells, and a synthetic polyethylene glycol (PEG) gel. AlamarBlue reagent was used for cell proliferation measurements and immunofluorescence was used to determine cell polarity. Expression of cell cycle regulators was examined by Western blot and matrix metalloproteinase (MMP) expression by qRT-PCR.ResultsThe MCF-10A normal breast epithelial cells formed round acini with correct apicobasal localization of α6 integrin in Matrigel whereas irregular structures were seen in PEG gel. The two 3D matrices also supported dissimilar morphology for the breast cancer cells. In PEG gel, BMP4 inhibited the growth of MCF-10A and the three breast cancer cell lines examined, thus closely resembling the 2D culture conditions, but in Matrigel, no growth inhibition was observed in MDA-MB-231 and MDA-MB-361 cells. Furthermore, BMP4 induced the expression of the cell cycle inhibitor p21 both in 2D and 3D culture, thereby partly explaining the growth arrest. Interestingly, MDA-MB-231 cells formed large branching, stellate structures in response to BMP4 treatment in Matrigel, suggestive of increased cell migration or invasion. This effect was reversed by Batimastat, a broad-spectrum MMP inhibitor, and subsequent analyses showed BMP4 to induce the expression of MMP3 and MMP14, that are thus likely to be responsible for the stellate phenotype.ConclusionsTaken together, our results show that Matrigel provides a more physiological environment for breast epithelial cells than PEG gel. Moreover, BMP4 partly recapitulates in 3D culture the growth suppressive abilities previously seen in 2D culture and induces an MMP-dependent migratory phenotype in MDA-MB-231 cells.

Abstract 1397: BMP4 inhibits the proliferation of breast cancer cells in 3D and induces a migratory phenotype in MDA-MB-231 cells.

Abstract Bone morphogenetic protein 4 (BMP4) is an extracellular signaling molecule that belongs to the bone morphogenetic protein (BMP) family, which in turn is part of the transforming growth factor β (TGF-β) -superfamily. BMPs regulate cell proliferation, differentiation and motility, and have also been shown to be involved in cancer pathogenesis. We have previously shown that BMP4 is able to consistently reduce breast cancer cell proliferation through G1 cell cycle arrest and simultaneously to induce the migration in a subset of these cell lines. In order to study the effects of BMP4 in a more physiological setting, we used two different 3D culture systems: Matrigel, a basement membrane extract from mouse sarcoma cells, and a synthetic polyethylene glycol (PEG) gel with matrix metalloproteinase (MMP) degradable cross-links and RGD peptides. MCF-10A normal breast epithelial cells formed round acini with a hollow lumen and correct apicobasal localization of α-6 integrin in Matrigel whereas irregular structures without lumen formation or apicobasal integrin localization were seen in PEG gel. Thus the two matrices do not provide identical 3D environments. In Matrigel, BMP4 treatment reduced the proliferation of MCF-10A cells and T-47D breast cancer cells. In PEG gel, reduced growth was also seen in two other breast cancer cell lines, MDA-MB-231 and MDA-MB-361. To clarify the mechanisms behind the growth suppressive effects of BMP4, we first examined the expression levels of 11 known cell cycle regulators in T-47D and MDA-MB-361cells grown in 2D culture using Western blot. Based on its consistent upregulation in both cell lines, p21 was selected for detailed analyses. In 2D culture, BMP4 induced the expression of p21 in all three breast cancer cell lines but not in MCF-10A cells. Unexpectedly, there was no correlation between p21 expression and the BMP4 induced growth suppression in 3D. These data seem to indicate that different mechanisms are involved in BMP4 mediated cell growth regulation in 2D and 3D environments. Finally, in response to BMP4 treatment MDA-MB-231 cells formed large branching, stellate structures in Matrigel, suggestive of increased cell migration. This effect was not seen in PEG gel. Gremlin, a BMP antagonist, reversed the stellate phenotype, confirming that the effect was indeed dependent on BMP4. Similarly, a broad-spectrum MMP inhibitor, Batimastat, was also able to reverse the stellate appearance. These results imply that the actions of MMPs are required for this migratory phenotype. Taken together, our results show that BMP4 reduced the growth of breast epithelial cells and breast cancer cells in 3D culture. In addition, the highly metastatic breast cancer cell line MDA-MB-231 formed stellate, branching structures upon BMP4 treatment in Matrigel. Further research is needed to elucidate the molecular mechanisms behind these BMP4 induced phenotypes and their clinical relevance. Citation Format: Minna E. Ampuja, Riikka Jokimäki, Emma-Leena Alarmo, Kati Juuti-Uusitalo, Anne Kallioniemi. BMP4 inhibits the proliferation of breast cancer cells in 3D and induces a migratory phenotype in MDA-MB-231 cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1397. doi:10.1158/1538-7445.AM2013-1397

Debinding behaviour of a water soluble PEG/PMMA binder for Ti metal injection moulding

Polyethylene glycol (PEG) has been becoming a common component in the design of water soluble binder systems for metal injection moulding. Similar to solvent debinding, PEG can be leached out by water and the mechanism of debinding was proposed in the literature with somehow misleading information about the debinding mechanism, particularly about the formation of PEG gel. This work investigates the debinding behaviours of a PEG-based binder in titanium compacts. Titanium powder is formulated with PEG, poly(methyl methacrylate) (PMMA) and stearic acid (SA) to formulate titanium feedstock. To determine the debinding kinetics, the PEG removal percentages are measured at three different temperatures and for various specimen thicknesses. A mathematic model based on diffusion-controlled debinding process is established. The evolution of porous microstructure during the water debinding process is observed using scanning electron microscopy. Based on these observations, a water debinding mechanism for titanium alloy compacts formulated with PEG-based binders is proposed.