Characterization and evaluation of chitosan matrix for in vitro growth of MCF-7 breast cancer cell lines

Biodegradable polymer scaffolds were prepared from chitosan with varying degree of deacetylation for in vitro culture of human breast cancer MCF-7 cell lines. These polymers were characterized in terms of functional groups by FTIR and swelling properties. Polymers having high degree of deacetylation showed better swelling properties irrespective of the molecular weight. These polymers were biocompatible and non-toxic towards human epithelial MCF-7 cell lines. Attachment kinetics of MCF-7 cell lines on to polymer scaffold was investigated and it was observed that polymer having high degree of deacetylation favored better cell attachment. In CPIII polymer scaffold having 80% degree of deacetylation, a maximum of 1 millions cells per mg pf polymer were adsorbed within 1h. It appears that high swelling and high degree of deacetylation of chitosan helped in better adsorption of cancer cell lines. The cellular morphology of the attached cells on chitosan matrix was similar to that observed with regular plastic culture with the difference that, cells grew as three-dimensional clumps on chitosan matrix. Polymer having high degree of deacetylation not only favored better adsorption but also showed improved cell growth kinetics. Maximum cell concentration of 6.5 x 10(5) cells/ml was achieved in 5 days culture on CPIII polymer scaffold. The glucose consumption and lactate production pattern of the MCF-7 cell lines on chitosan polymer matrix were similar to that observed on cell growth on tissue culture flask. These results indicate that chitosan scaffold having high degree of deacetylation can be used for three-dimensional growth of MCF-7 cancer cell lines. Such in vitro 3D culture of cancer cells can thus be used as a model for the cytotoxic evaluation of anticancer drugs.     

体外构建三维肝肿瘤模型及药物筛选

背景：体外构建三维肿瘤模型替代现有二维平面肿瘤细胞模型用于药物筛选是肿瘤药筛技术发展的必然趋势。 目的：体外构建三维肝肿瘤模型体系,并用于抗肿瘤药物的敏感性研究。 方法：以人肝癌细胞HepG2作为模型细胞,以壳聚糖/胶原混合材料制备水凝胶支架,体外构建肝(肿瘤)细胞的三维培养体系,表征三维肝(肿瘤)细胞聚集体的形态、生长、细胞骨架分布等,并以二维平面培养的肝肿瘤细胞为对照,研究三维肝肿瘤模型对临床常用的化疗药物的敏感性。 结果与结论：①肝细胞在壳聚糖/胶原水凝胶支架中培养10 d后形成三维的聚集细胞团。②肝细胞在水凝胶支架中生长速度略慢于二维平面培养,但在三维体系下肝细胞能长时间保持细胞活性。③在水凝胶支架中肝细胞三维生长后,纤维蛋白骨架发生重排,结构与在体肝组织更接近。④在水凝胶支架中的三维肝肿瘤细胞模型对化疗药物的敏感性降低。由此可见,在壳聚糖/胶原水凝胶支架中形成的三维肝(肿瘤)模型,其细胞骨架结构更接近体内肝组织,因此可用于体外药筛模型研究。 中国组织工程研究杂志出版内容重点：肾移植;肝移植;移植;心脏移植;组织移植;皮肤移植;皮瓣移植;血管移植;器官移植;组织工程全文链接：     

Engineered silk fibroin protein 3D matrices for in vitro tumor model

3D in vitro model systems that are able to mimic the in vivo microenvironment are now highly sought after in cancer research. Antheraea mylitta silk fibroin protein matrices were investigated as potential biomaterial for in vitro tumor modeling. We compared the characteristics of MDA-MB-231 cells on A. mylitta, Bombyx mori silk matrices, Matrigel, and tissue culture plates. The attachment and morphology of the MDA-MB-231 cell line on A. mylitta silk matrices was found to be better than on B. mori matrices and comparable to Matrigel and tissue culture plates. The cells grown in all 3D cultures showed more MMP-9 activity, indicating a more invasive potential. In comparison to B. mori fibroin, A. mylitta fibroin not only provided better cell adhesion, but also improved cell viability and proliferation. Yield coefficient of glucose consumed to lactate produced by cells on 3D A. mylitta fibroin was found to be similar to that of cancer cells in vivo. LNCaP prostate cancer cells were also cultured on 3D A. mylitta fibroin and they grew as clumps in long term culture. The results indicate that A. mylitta fibroin scaffold can provide an easily manipulated microenvironment system to investigate individual factors such as growth factors and signaling peptides, as well as evaluation of anticancer drugs.     

Western immunoblotting and enzymatic activity analysis of cathepsin D in human breast cancer cell lines of different invasive potential. Regulation by 17β-estradiol, tamoxifen and ICI 182,780

We used enzymatic activity and immunochemical quantifications to analyse the expression and secretion of cathepsin D by human breast cancer cell lines of different invasive potentials (MCF-7/6, MCF-7/AZ, MDA-MB-231). This study does not directly prove that cathepsin D or procathepsin D is involved in human breast cancer cell invasion and metastasis but it shows that the proportion of procathepsin D (activity and antigen) secreted by the human breast cancer cell lines tested correlates with their invasive potential. In the estrogen receptor-positive MCF-7 subclones, this proportion is increased by estradiol only in the invasive MCF-7/6 variant. The cell content in procathepsin D is increased by estrogens to a greater extent in MCF-7/6 cells as compared to non-invasive MCF-7/AZ cells. Tamoxifen appears to be an estrogen agonist concerning cathepsin D regulation, whereas ICI 182,780 is a true antagonist. Our results suggest that synthesis and secretion of cathepsin D are regulated at two distinct levels and differentially affected by estrogens. Synthesis only seems to be affected in non-invasive MCF-7/AZ cells, whereas in invasive MCF-7/6 cells, both synthesis and the efficiency of secretion are increased by estrogens. Our results also confirm that the key site of regulation leading to lysosomal enzyme oversecretion is the Golgi apparatus insulin-like growth factor-II/mannose 6-phosphate receptor.     

Chitosan-alginate as scaffolding material for cartilage tissue engineering

Tissue compatibility of chitosan-alginate scaffolds was studied in vitro in terms of cell morphology, proliferation, and functionality using HTB-94 cells. The scaffold has an interconnected 3D porous structure, and was fabricated by thermally induced phase separation followed by freeze drying. Cell proliferation on the chitosan-alginate scaffold was found to be faster than on a pure chitosan scaffold. After cell culture for 2 weeks in vitro, the cells on the chitosan scaffold gradually assumed a fibroblast-like morphology while the cells on the chitosan-alginate scaffold retained their spherical morphology throughout the period of study. SDS-PAGE electrophoresis and Western blot assays for proteins extracted from cells grown on scaffolds indicated that production of cartilage-specific collagen type II, a marker for chondrocytic phenotype, increased from week 2 to week 3 on the chitosan-alginate scaffold but decreased on the chitosan scaffold. This study suggested that chitosan-alginate scaffolds promote cell proliferation, enhance phenotype expression of HTB-94 chondrocytes, and may potentially serve as an improved alternative to chitosan scaffolds for cartilage tissue engineering.     

慢性缺氧应激可能通过EMT增强乳腺癌MCF-7细胞恶性生物学行为

目的:探讨慢性缺氧应激对人乳腺癌MCF-7细胞恶性生物学行为的影响及可能机制。方法:将人乳腺癌MCF-7细胞分为缺氧组(1%O_2、5%CO_2和94%N_2)和正常对照组(常氧)进行培养。利用MTT法、CCK-8实验、细胞直接计数法及细胞侵袭和迁移实验对MCF-7细胞活力、增殖及侵袭和迁移能力进行检测;用软琼脂集落形成实验及Matrigel 3D培养技术检测MCF-7细胞非锚定生长能力及极性改变情况;利用MCF-7细胞构建裸鼠皮下种植瘤模型,检测慢性缺氧应激对体内肿瘤生长及肺转移的影响;利用倒置显微镜观察MCF-7细胞形态改变;Western blot检测低氧诱导因子1(hypoxia-inducible factor-1,HIF-1)和磷酸化的糖原合成酶激酶3β(glycogen synthase kinase-3β,GSK-3β)在缺氧环境下表达水平的改变,以及E-钙黏连蛋白(E-cadherin)、N-钙黏连蛋白(Ncadherin)、波形蛋白(vimentin)、基质金属蛋白酶3(matrix metalloproteinase-3,MMP-3)、MMP-9等上皮-间充质转化(epithelial-mesenchymal transition,EMT)相关蛋白的表达水平。结果:与正常对照组相比较,慢性缺氧组MCF-7细胞活力、增殖能力及侵袭迁移能力增强,细胞非锚定生长能力提高且在3D培养系统更容易发生极性改变,呈现侵袭样生长,体内生长及转移能力增强;除了HIF-1被缺氧诱导表达升高外,GSK-3β呈现活化趋势,且上皮样标志物E-cadherin蛋白表达水平明显下降,而间充质样标志物N-cadherin、vimentin、MMP-3和MMP-9蛋白表达水平明显升高。结论:慢性缺氧应激促进了乳腺癌细胞恶性生物学行为,且其机制可能与EMT有关。     

Biochemical and immunohistological identification of thymosin alpha-1 in MCF-7 breast cancer cells

Growth of normal and malignant cells is controlled by the interplay of several hormones and growth factors present in the body. The growth of the human breast cancer cell line MCF-7 is stimulated in vitro by estradiol which has been shown to induce the release of numerous polypeptide growth factors into the culture media. In a search to identify polypeptide growth factors for MCF-7 breast cancer cells we have detected the thymic hormone, thymosin alpha one (TA1) in culture supernatants and cytosol preparations of MCF-7 cells grown in TA1 free media. TA1 was identified by reverse phase-high performance liquid chromatography (RP-HPLC) followed by a specific radioimmunoassay for TA1 (TA1-RIA). Indirect immune fluorescence localized TA1 on, or within, the cytoplasm of MCF-7 cells grown in TA1 free media. The results of this data along with our previously published findings fulfills three of the four criteria needed to establish thymosin alpha-1 as an autocrine growth factor for MCF-7 cells in culture.     

Cancer of the breast, mechanism of action of anti-estrogens

Estrone sulfate (E1-S) is quantitatively the main estrogen in human breast cancer tissue. This sulfate is converted with a great yield into estradiol (E2) in different hormone-dependent mammary cancer cell lines (MCF-7, R-27, T-47D). In opposition, there is small or no conversion in the hormone-independent cell lines (MDA-231 and MDA-436). The anti-estrogen tamoxifen blocks the conversion of E1-S to E2 in the MCF-7 and R-27 lines but not in the T-47D cell line. A new anti-estrogen: ICI 164,384 is also very active to block this conversion. In conclusion, the most probable way of action of the antiestrogen in through the competitive binding to the estrogen receptor; however recent date suggests other possible pathways.     

Developing an alginate/chitosan hybrid fiber scaffold for annulus fibrosus cells

A fibrous scaffold made of alginate or alginate/chitosan was fabricated for annulus fibrosus (AF) cell culture using a wet-spinning and lyophilization technique. The scaffolds were evaluated using several in vitro tests. Scanning electron microscopy showed the scaffold fibers generally aligned in one direction with individual fiber diameters varying between 40-100 microm. The alginate/chitosan hybrid scaffold exhibited a slower degradation rate, while both scaffold types did not display any cyto-toxicity to 3T3 fibroblasts and could maintain canine AF cell growth. The AF cells retained their spherical shape within the fibrous scaffold at the beginning of the culture period and formed into cell clusters at later times. Specific extracellular matrix molecules, including collagen I, collagen II, and aggrecan, could be detected in the AF cell clusters. These results demonstrate the feasibility of using this hybrid alginate/chitosan scaffold for AF cell culture, and the potential application for intervertebral disc tissue engineering.     

Effect of tamoxifen and estrogens on breast cancer cell lines: MCF-7 and R-27, and on the uterus and vagina of fetal and newborn guinea-pigs

The action of tamoxifen was studied in two models: in breast cancer cell lines MCF-7 and R-27. The latter is resistant to tamoxifen; 2) in the uterus and vagina of guinea pig during the perinatal period. In the breast cancer cell line MCF-7 tamoxifen blocks the proliferation of the cells and in the R-27 it does not antagonize the effects provoked by estrogens. However, in this cell line tamoxifen provokes a significant alteration of the ultrastructures. In the uterus and vagina of guinea pig (fetal and newborn) tamoxifen acts as a real estrogen and it does not block the effects provoked by estrogens.     

Superior survival and durability of neurons and astrocytes on 3-dimensional aragonite biomatrices

Current needs of central nervous system therapy urge for the identification of scaffolds supporting the generation and long-term maintenance of healthy and functional neuronal tissue. We compared for the first time the viability of hippocampal neurons and astrocytes grown on conventional 2-dimensional (2D) conditions with that of cells grown on an aragonite bioactive 3-dimensional (3D) scaffold prepared from coralline exoskeleton. Cultures in 3D showed significantly lower mortality rate and higher neurons/astrocytes ratio than 2D cultures. Moreover, whereas cell survival in 2D was arrested in the absence of the supporting substrates poly-D-lysine and laminin, these substrates had negligible effect on the 3D cultures. Furthermore, aragonite matrices supported cell survival and growth under conditions of calcium and nutrients deprivation, whereas in 2D such treatments led to death of all neurons and of almost all astrocytes. To show that the aragonite matrices are permissive for neural cells also in vivo, aragonite matrices having no substrate coating grafted into postnatal rat cortex were invaded by neurons growing on the surface and in multilayer structures resembling those seen in the 3D culture in vitro. Hence, culture of neurons and astrocytes on 3D aragonite coralline matrices is a novel mean for production of stable neuronal tissue, with significant implication to the field of neuronal tissue restoration.     

A healing method of tympanic membrane perforations using three-dimensional porous chitosan scaffolds

Both surgical tympanoplasty and paper patch grafts are frequently procedured to heal tympanic membrane (TM) perforation or chronic otitis media, despite their many disadvantages. In this study, we report a new healing method of TM perforation by using three-dimensional (3D) porous chitosan scaffolds (3D chitosan scaffolds) as an alternative method to surgical treatment or paper patch graft. Various 3D chitosan scaffolds were prepared; and the structural characteristics, mechanical property, in vitro biocompatibility, and healing effects of the 3D chitosan scaffolds as an artificial TM in in vivo animal studies were investigated. A 3D chitosan scaffold of 5 wt.% chitosan concentration showed good proliferation of TM cells in an in vitro study, as well as suitable structural characteristics and mechanical property, as compared with either 1% or 3% chitosan. In in vivo animal studies, 3D chitosan scaffold were able to migrate through the pores and surfaces of TM cells, thus leading to more effective TM regeneration than paper patch technique. Histological observations demonstrated that the regenerated TM with the 3D chitosan scaffold consisted of three (epidermal, connective tissue, and mucosal) layers and were thicker than normal TMs. The 3D chitosan scaffold technique may be an optimal healing method used in lieu of surgical tympanoplasty in certain cases to heal perforated TMs.     

Effect of cathepsin D and prostate specific antigen on latent transforming growth factor-beta in breast cancer cell lines

Transforming growth factor-beta (TGFbeta) is present, predominantly in latent forms, in normal and malignant breast tissue. The mechanisms by which latent TGFbeta is activated physiologically remain largely an enigma. The objective of this study was to assess whether the proteases, cathepsin D and prostate specific antigen (PSA) could activate latent TGFbeta1 and TGFbeta2 in conditioned media of the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 human breast cancer cell lines, newly purchased from ATCC. Both of the cell lines were seeded in 6-well plates 2 days prior to treatment with varying concentrations of cathepsin D and PSA. Active TGFbeta1 and TGFbeta2 in the media were then measured by ELISA after 4, 8, 24 and 72 hours of treatment. TGFbeta1 and TGFbeta2 mRNA expression of both cell lines were measured by RT-PCR to determine whether any increase in level of active TGFbeta1 and TGFbeta2 was due to increased production. There was a significant increase in only active TGFbeta2 levels in the MDA-MB-231 cell line with both treatments. Cathepsin D and PSA did not have any effect on TGFbeta1 and TGFbeta2 mRNA expression. Cathepsin D and PSA were unable to activate latent TGFbeta1 and TGFbeta2 in these two breast cancer cell lines. A constant level of TGFbeta2 mRNA in the control and treated MDA-MB-231 cells suggests that the increase in level of active TGFbeta2 was not a result of increased production but was likely to be due to activation by a mechanism independent of cathepsin D and PSA.     

MCF-7 cells as a three-dimensional model for the study of human breast cancer

The increasing use of three-dimensional (3D) cell culture is because it reproduces in vitro results similar to in vivo results. Multicellular tumor spheroids generated in vitro exhibit important characteristics of avascular tumors, mainly with respect to tumor physiology and microenvironment. The interaction among cells in a tridimensional culture environment enhances cell differentiation and leads to luminal formation in some breast-derived cell cultures. The present work describes a method that permits luminal formation in breast adenocarcinoma cell (MCF-7)-derived spheroids in a 3D environment. In the proposed model, several relevant parameters, such as cell survival, apoptosis, autophagy, and E-cadherin expression, were analyzed to understand the organization of MCF-7 cells during different culture phases, including luminal and bud formation.     

Significance of mitochondrial calcium and nitric oxide for apoptosis of human breast cancer cells induced by tamoxifen and etoposide

In the present study, we tested the significance of mitochondria for apoptosis upon exposure to tamoxifen and etoposide using two human breast cancer cell lines, MCF-7 and MDA-MB-231. We showed that both tamoxifen and etoposide induced apoptosis, increased intramitochondrial calcium and nitric oxide, and decreased mitochondrial transmembrane potential in both cell lines. Both drugs increased mitochondrial protein tyrosine nitration and caused release of cytochrome c from the mitochondria of both cell lines. This study suggests that tamoxifen and etoposide utilize a common mechanism to induce apoptosis in MCF-7 and MDA-MB-231 cells.     

淫羊藿颗粒剂联合三苯氧胺对乳腺癌MCF-7细胞增殖的调节作用

目的探讨补肾中药淫羊藿或与三苯氧胺(TAM)合用是否有促人乳腺癌MCF-7细胞增殖的作用。方法设立空白、E2及TAM对照组,观察淫羊藿颗粒剂单用及联合TAM在不同剂量和作用时间下对MCF-7细胞的生长的影响。应用MTT法观察细胞增殖情况。结果淫羊藿对乳腺癌MCF-7细胞生长的影响因浓度的不同而不同:低浓度的淫羊藿颗粒剂对乳腺癌细胞MCF-7的促增殖作用不明显(P>0.05)。淫羊藿与TAM联合作用于MCF-7细胞,无明显促细胞增殖的作用(P>0.05),而中等剂量的淫羊藿颗粒有弱雌激素样作用(P<0.05),但可被TAM拮抗。结论淫羊藿联合TAM作用于乳腺癌MCF-7细胞,无促癌细胞生长的作用。但单独应用淫羊藿治疗乳腺癌患者,其使用剂量及持续时间尚需进一步探索。     

负载木通皂苷D的纳米羟基磷灰石/壳聚糖支架修复骨缺损北大核心

背景:木通皂苷D具有促进成骨细胞的增殖与分化、提高成骨细胞活性与数量、促进基质钙化与骨痂生长等诸多作用,主要被用于治疗骨质疏松与促进骨折愈合,将其应用于骨缺损修复的研究较少见。目的:以纳米羟基磷灰石/壳聚糖支架为载体,将包裹木通皂苷D的缓释微球负载于其中,观察其骨缺损修复作用。方法:采用W/O/W方法制作包裹木通皂苷D的缓释微球,采用冷冻干燥方法制备负载包裹木通皂苷D缓释微球的纳米羟基磷灰石/壳聚糖支架(以下简称缓释支架)与单纯的纳米羟基磷灰石/壳聚糖支架(以下简称空白支架),检测缓释微球与缓释支架的体外释药能力。将小鼠来源前成骨细胞MC3T3-E1分别接种于两种支架上,以单独培养的细胞为对照,分析细胞的黏附、增殖与分化情况。在24只成年新西兰大白兔双侧桡骨中段制造1.5 cm的骨缺损,分别植入空白支架与缓释支架,术后4,12周时进行大体观察、Micro-CT扫描影像学检查及组织学观察。结果与结论:①包裹木通皂苷D的缓释微球与缓释支架均具有缓释作用,其中缓释支架的药物释放速率更加平稳、持久;②CCK-8实验显示,缓释支架上的细胞增殖速率快于空白支架、对照组(P<0.05);扫描电镜下可见,小鼠来源前成骨细胞MC3T3-E1覆盖在两组支架表面,其中缓释支架上的细胞数量要多于空白支架;③培养7,14 d时,缓释支架组的碱性磷酸酶活性、Runx2 mRNA表达高于空白支架组(P<0.05);培养第21天时,缓释支架组的骨桥蛋白、骨钙素蛋白表达量高于空白支架组(P<0.05);④影像学检查与组织学观察结果显示,术后4周时,缓释支架组材料周围可见大量的新生骨,其新生骨量明显多于空白支架组;术后12周时,缓释支架内部也可见大量的新生骨长入,空白支架内部仅见少量的新生骨长入,并且缓释支架组的材料残余明显少于空白支架组(P<0.05);⑤结果表明,负载木通皂苷D缓释微球的纳米羟基磷灰石/壳聚糖支架可提升体外成骨细胞的黏附、增殖与分化能力,提升纳米羟基磷灰石/壳聚糖支架的体内骨诱导能力。     

Collagen-chitosan polymeric scaffolds for the in vitro culture of human epidermoid carcinoma cells.

A biodegradable polymer scaffold was developed using collagen and chitosan, in the form of interpenetrating polymeric network (IPN), for in vitro culture of human epidermoid carcinoma cells (HEp-2, Cincinnati). Glutaraldehyde was used as cross-linking agent for the development of scaffold. Various types of scaffolds were prepared using different proportionate mixtures of collagen and chitosan solutions in the ratio of 3:7, 4:6, 5:5, 6:4 and 7:3 (collagen:chitosan). These scaffolds were fully characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA). Equilibrium swelling studies were carried out in phosphate buffer of physiological pH (7.4) to study its swelling characteristics at slightly alkaline pH. The scaffold that showed optimum swelling property was selected as the best scaffold for performing in vitro culture studies. In vitro culture studies were carried out using HEp-2 cells, over the selected scaffold and its growth morphology was determined through optical photographs taken at different magnifications at various days of culture. The results of the above studies suggest that the scaffolds prepared from collagen and chitosan can be utilized as a substrate to culture HEp-2 cells and can also be used as an in vitro model to test anticancerous drugs.