Three-dimensional Multicellular Tumor Spheroids Research Articles

A novel approach to producing uniform 3-D tumor spheroid constructs using ultrasound treatment

Producing three-dimensional (3-D) multicellular tumor spheroids (TSs) is valuable for characterizing anticancer drugs since they provide a more representative model of the 3-D in vivo tumor than conventional two-dimensional (2-D) monolayer culture. The interaction of tumor cells with the extracellular matrix (ECM) in a 3-D culture environment is more similar to a tumor in vivo than in a 2-D environment; cell-cell and cell-ECM interaction can influence cell behaviour, such as in response to drug treatment. In vitro tumor spheroid models have been developed using microfluidic systems to generate 3-D hydrogel beads containing components of alginate and ECM protein, such as collagen, with high uniformity and throughput. Cell-laden hydrogel droplets are formed using a flow focusing process wherein the hydrogel precursors should be a homogeneous mixture. During gelation of the droplets into beads, the alginate acts as a fast gelling component helping to maintain the spherical shape of beads and preventing coalescence as the temperature-sensitive collagen I component gels more slowly. To produce uniform hydrogel droplets using the microfluidic flow focusing system, the mixtures must be homogeneous. However, collagen's sensitivity to temperature can lead to formation of chunks of collagen gel inside of the mixture, causing the mixture to become non-uniform and risking chip clogging. In order to overcome this limitation, previous approaches have used a cooling system during bead encapsulation while tumor cells were also present in the mixture, but this procedure can contribute to a delay in cell proliferation. Here a novel yet simple method is developed to prepare homogeneous pre-bead-encapsulation-mixtures containing collagen type I through ultrasonication. This method allows the cultivation of homogenous TS cultures with high uniformity and compact structure, and not only maintains cell viability but also the proliferation of cells in alginate/collagen hydrogel bead cultures. Depending on the sonication parameters, time and temperature, collagen can form small sized fibrils to thick fibers. Here, the mixtures containing collagen are assessed for morphology of collagen fibers/fibrils, cell viability, and proliferation. Human source Michigan Cancer Foundation-7 (MCF-7) breast cancer cells are successfully incorporated into alginate/collagen mixtures, followed by sonication, and then bead production. After bead gelation, the encapsulated MCF-7 cells remained viable and proliferated to form uniform TSs when the beads contained alginate and collagen. Results indicate that ultrasound treatment (UST) provides a powerful technique to change the structure of collagen from fiber to fibril, and to disperse collagen fibers in the mixture homogeneously for an application to generate uniform hydrogel beads and spheroids while not inhibiting cell proliferation.

Chemo-photothermal effects of doxorubicin/silica-carbon hollow spheres on liver cancer.

Chemo-photothermal therapy, which exhibits synergistic effects, is more effective than either of the treatments administered alone because of its superior ability to target and destroy cancer cells. An anti-cancer compound (doxorubicin, DOX) was embedded in silica–carbon hollow spheres (SCHSs) using heat and vacuum to integrate multi-therapeutic effects onto one platform and subsequently improve the anti-cancer efficacy. SCHSs were synthesized via a surface activation method and its highly porous surface enhanced the loading content of the desired drug. SCHSs are an infrared photothermal material that can destroy targeted cells by heating under near-infrared (NIR) laser illumination at 808 nm. NIR laser illumination also enhances DOX release from SCHSs to increase the anti-cancer efficiency of DOX–loaded SCHSs (DOX–SCHSs) in both two-dimensional and three-dimensional multicellular tumor spheroid cultures. SCHSs exhibited high heat-generating ability and pH-responsive drug delivery. In conclusion, this study demonstrated that DOX–SCHSs represent a potential tool for chemo-photothermal therapy due to its photothermal effects. Thus, our findings imply that the high cancer cell killing efficiency of DOX–SCHSs induced by NIR illumination can be used for the treatment of tumors.

CuS-Based Theranostic Micelles for NIR-Controlled Combination Chemotherapy and Photothermal Therapy and Photoacoustic Imaging.

Cancer remains a major threat to human health due to low therapeutic efficacies of currently available cancer treatment options. Nanotheranostics, capable of simultaneous therapy and diagnosis/monitoring of diseases, has attracted increasing amounts of attention, particularly for cancer treatment. In this study, CuS-based theranostic micelles capable of simultaneous combination chemotherapy and photothermal therapy (PTT), as well as photoacoustic imaging, were developed for targeted cancer therapy. The micelle was formed by a CuS nanoparticle (NP) functionalized by thermosensitive amphiphilic poly(acrylamide-acrylonitrile)-poly(ethylene glycol) block copolymers. CuS NPs under near-infrared (NIR) irradiation induced a significant temperature elevation, thereby enabling NIR-triggered PTT. Moreover, the hydrophobic core formed by poly(acrylamide-acrylonitrile) segments used for drug encapsulation exhibited an upper critical solution temperature (UCST; ∼38 °C), which underwent a hydrophobic-to-hydrophilic transition once the temperature rose above the UCST induced by NIR-irradiated CuS NPs, thereby triggering a rapid drug release and enabling NIR-controlled chemotherapy. The CuS-based micelles conjugated with GE11 peptides were tested in an epidermal growth factor receptor-overexpressing triple-negative breast cancer model. In both two-dimensional monolayer cell and three-dimensional multicellular tumor spheroid models, GE11-tagged CuS-based micelles under NIR irradiation, enabling the combination chemotherapy and PTT, exhibited the best therapeutic outcome due to a synergistic effect. These CuS-based micelles also displayed a good photoacoustic imaging ability under NIR illumination. Taken together, this multifunctional CuS-based micelle could be a promising nanoplatform for targeted cancer nanotheranostics.

PH-sensitive nanogels with ortho ester linkages prepared via thiol-ene click chemistry for efficient intracellular drug release

pH-sensitive nanogels with ortho ester linkages were conveniently prepared through reaction of thiol-ene click chemistry. Through adjusting feed reactant ratios and concentrations of ortho ester diacrylamide (OEAM), pentaerythritol tetra(3-mercaptopropionate) (PT), and methoxyl poly(ethyleneglycol) acrylate (mPEGA), the size of the nanogels could be controlled at 100–200nm with relatively narrow size distributions. The nanogels with size of 149.1±17.7nm (designed as NG) were verified by proton nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), dynamic laser scattering (DLS) and transmission electron microscopy (TEM). Doxorubicin (DOX) was loaded into NG with high drug loading efficiency up to 73.7%. In vitro drug release studies showed that up to 75.9% DOX from NG was released in 24h at pH 5.0 because of hydrolysis of ortho ester. Cellular uptake studies confirmed that DOX-loaded NG (NG/DOX) could be readily internalized by two-dimensional cells, resulting in efficient antitumor efficiency of cancer cells. Three-dimensional (3D) multicellular tumor spheroids (MCTS) as in vitro tumor model was used to further evaluate the antitumor effect of NG/DOX. The results demonstrated that NG/DOX showed a significantly enhanced penetration and growth inhibition in 3D multicellular tumor spheroids (MCTS), compared to free DOX.

PH-sensitive poly(ortho ester urethanes) copolymers with controlled degradation kinetic: Synthesis, characterization, and in vitro evaluation as drug carriers

Poly(ortho ester urethanes) (POEUs) copolymers were synthesized via polycondensation between the new ortho ester-based diols and hexamethylene diisocyanate (HDI) or dicyclohexylmethane 4,4′-diisocyanate (HMDI) with flexible or rigid chain, which was introduced to regulate the degradation kinetic of POEUs, and designed as POEU1 or POEU2, respectively. POEU1 and POEU2 could form nanoparticles using an oil-in-water single emulsion, which is named as NP1 and NP2, respectively. In vitro degradation experiment shows that NP1 prepared from POEU1 with flexible chains has a degradation half-life of 5.0h at pH 5.0 whereas NP2 prepared from POEU2 with rigid chains has a degradation half-life of 16.2h. Doxorubicin (DOX) was then loaded into these nanoparticles and designed as NP1/DOX and NP2/DOX for evaluating the antitumor effect. NP1/DOX with faster acid-triggered drug release can be more efficiently internalized by two-dimensional (2D) cells and three-dimensional (3D) multicellular tumor spheroids (MCTS), and lead to improved antitumor efficiency.

Real-time viability and apoptosis kinetic detection method of 3D multicellular tumor spheroids using the Celigo Image Cytometer.

The development of three-dimensional (3D) multicellular tumor spheroid models for cancer drug discovery research has increased in the recent years. The use of 3D tumor spheroid models may be more representative of the complex in vivo tumor microenvironments in comparison to two-dimensional (2D) assays. Currently, viability of 3D multicellular tumor spheroids has been commonly measured on standard plate-readers using metabolic reagents such as CellTiter-Glo® for end point analysis. Alternatively, high content image cytometers have been used to measure drug effects on spheroid size and viability. Previously, we have demonstrated a novel end point drug screening method for 3D multicellular tumor spheroids using the Celigo Image Cytometer. To better characterize the cancer drug effects, it is important to also measure the kinetic cytotoxic and apoptotic effects on 3D multicellular tumor spheroids. In this work, we demonstrate the use of PI and caspase 3/7 stains to measure viability and apoptosis for 3D multicellular tumor spheroids in real-time. The method was first validated by staining different types of tumor spheroids with PI and caspase 3/7 and monitoring the fluorescent intensities for 16 and 21 days. Next, PI-stained and nonstained control tumor spheroids were digested into single cell suspension to directly measure viability in a 2D assay to determine the potential toxicity of PI. Finally, extensive data analysis was performed on correlating the time-dependent PI and caspase 3/7 fluorescent intensities to the spheroid size and necrotic core formation to determine an optimal starting time point for cancer drug testing. The ability to measure real-time viability and apoptosis is highly important for developing a proper 3D model for screening tumor spheroids, which can allow researchers to determine time-dependent drug effects that usually are not captured by end point assays. This would improve the current tumor spheroid analysis method to potentially better identify more qualified cancer drug candidates for drug discovery research. © 2017 International Society for Advancement of Cytometry.

Control of Liposomal Penetration into Three-Dimensional Multicellular Tumor Spheroids by Modulating Liposomal Membrane Rigidity.

Effective penetration of drug-carrying nanoparticles into solid tumors is a major challenge in cancer therapy. Exploration of the physicochemical properties of nanoparticles that affect penetration efficiency is required to achieve maximum therapeutic effects. Here, we used confocal laser scanning microscopy to evaluate the efficiencies of penetration of fluorescently labeled liposomes into three-dimensional spheroids composed of HeLa cells. The prepared liposomes were composed of phosphatidylcholines and varying contents of cholesterol and/or a polyethylene glycol-modified phospholipid. We demonstrated that the efficiency of penetration into spheroids increased with the bending modulus (i.e., membrane rigidity) of the liposome, as determined by atomic force microscopy (correlation coefficient, 0.84). To clarify the mechanism by which membrane rigidity contributes to the penetration behavior of liposomes, we also analyzed the cellular uptake using monolayer cells. We showed that penetration efficiency was explained partially by cellular uptake efficiency, but that other factors such as liposome diffusion efficiency in the intercellular space of tumor spheroids contributed. Our results quantitatively demonstrate that the bending modulus of the liposomal membrane is a major determinant of liposomal penetration into three-dimensional spheroids. The present study will contribute to the understanding and control of tumor penetration of liposomal formulations.

Acid-degradable poly(ortho ester urethanes) copolymers for potential drug carriers: Preparation, characterization, in vitro and in vivo evaluation

Herein, acid-degradable poly(ortho ester urethanes) (POEUs) were synthesized via polycondensation between an acid-labile ortho ester diamine and active esters of poly(ε-caprolactone) (PCL) diols with different molecular weights. The POEUs nanoparticles were easily fabricated using an oil-in-water emulsion technique, whose ortho ester bonds in main-chains could be degraded at different rate in acidic pHs. DOX was loaded into the nanoparticles with high drug loading efficiency. In vitro release studies demonstrate that DOX is released in a pH-dependent manner. In vitro cellular uptake confirms that DOX-loaded POEUs nanoparticles can be more readily internalized by two-dimensional (2D) cells and three-dimensional (3D) multicellular tumor spheroids (MCTS), resulting in efficient antitumor efficiency of cancer cells. In vivo biodistribution and antitumor effect were evaluated by H22 tumor-bearing mice. The results demonstrate that DOX-loaded POEUs nanoparticles show a prolonged blood circulation time and improved accumulation in solid tumor, leading to enhanced therapeutic efficacy.

Folic acid-conjugated soybean protein-based nanoparticles mediate efficient antitumor ability invitro.

In this study, soy protein isolate was hydrolyzed by compound enzymes to give aqueous soy protein with low molecular weights. Folic acid modified and free soy protein nanoparticles were successfully prepared by a desolvation method as target-specific drug delivery, respectively. Ultraviolet spectrophotometry demonstrated that folic acid was successfully grafted onto soy protein. The shape and size of folic acid modified soy protein nanoparticles were detected by transmission electron microscopy, scanning electron microscope, and dynamic light scattering. In addition, a series of characteristics including kinetic stability, pH stability, and time stability were also performed. Doxorubicin was successfully loaded into folic acid modified soy protein nanoparticles, and the encapsulation and loading efficiencies were 96.7% and 23%, respectively. Doxorubicin-loaded folic acid modified soy protein nanoparticles exhibited faster drug release rate than soy protein nanoparticles in PBS solution (pH = 5). The tumor penetration and antitumor experiments were done using three-dimensional multicellular tumor spheroids as the invitro model. The results proved that folic acid modified soy protein nanoparticles display higher penetration and accumulation than soy protein nanoparticles, therefore possessing efficient growth inhibitory ability against multicellular tumor spheroids.

IRGD peptide as effective transporter of CuInZnxS2 + x quantum dots into human cancer cells

In this paper, iRGD peptide-mediated quantum dots (QDs) delivery was studied. In the first step, dodecanethiol-capped CuInZnxS2+x (ZCIS) QDs were prepared and subsequently transferred into water using a standard and facile ligand exchange approach involving 3-mercaptopropionic acid (MPA). ZCIS@MPA nanocrystals possess a photoluminescence quantum yield (PL QY) of 25%, a PL emission centered at ca. 640nm and low distributions in size and shape. Next, the iRGD peptide was electrostatically associated to ZCIS@MPA QDs. After cytotoxicity evaluation, the tumor-targeting and penetrating activities of the iRGD/QD assembly were investigated by confocal microscopy. The experiments performed on various cancer cell lines revealed a high penetration ability of the assembly, while the bare QDs were not internalized. Additionally, imaging experiments were conducted on three-dimensional multicellular tumor spheroids in order to mimic the tumor microenvironment in vivo. iRGD/QD assemblies were found to be evenly distributed throughout the whole HeLa spheroid contrary to normal cells where they were not present. Therefore, iRGD/QD assemblies have a great potential to be used as targeted imaging agents and/or nanocarriers specific to cancer cells.

Anti-metastatic effects of RAPTA-C conjugated polymeric micelles on two-dimensional (2D) breast tumor cells and three-dimensional (3D) multicellular tumor spheroids

Macromolecular ruthenium (Ru) complexes are a promising avenue to better, and more selective, chemotherapeutics to treat metastatic cancers. In our previous research, amphiphilic block copolymeric micelles carrying RAPTA-C (RuCl2(p-cymene)(PTA)) were demonstrated to improve the cellular uptake and cytotoxicity of RAPTA-C (Blunden et al., 2013). However, the anti-metastatic effect of RAPTA-C conjugated polymeric micelles is yet to be established. In this work, we investigated the anti-metastatic effects of RAPTA-C conjugated micelles in both 2D and 3D in vitro breast tumor cell models in comparison with free RAPTA-C. RAPTA-C conjugated micelles showed an improved anti-metastatic effect compared with RAPTA-C for 2D cultured breast tumor cells. RAPTA-C micelles selectively targeted the metastatic tumor cells over the nontumorigenic CHO cells. 3D MCTS assays showed that RAPTA-C conjugated micelles showed a cell growth inhibition similar to that of ten times of the free drug. Further improvement of the RAPTA-C delivery vehicle may provide useful tools to harness ruthenium compounds for metastatic cancer therapy. Statement of SignificanceThe interest in ruthenium drugs stem from their anti-metastatic effect. In contrast to other metal-based drugs that inhibit the growth of tumor cells, ruthenium drugs seem less toxic, but have a pronounce effect on the migration of cancer cells. The ruthenium drug chosen here, RAPTA-C, is capable of inhibiting migration as shown in various assays here. In this publication, we could show for the first time that this effect is enhanced when the drug is delivered using micelles. Important in particular is that the effect is more pronounced in cancerous breast cancer cells while RAPTA-C delivered in micelles does not seem to show any effect on healthy cells.We believe that the presented micelles are suitable carriers for this anti-metastatic drug. The design of the micelle would also allow the encapsulation of other drugs in future studies creating a potentially powerful bullet.

Three-dimensional tumor spheroids for in vitro analysis of bacteria as gene delivery vectors in tumor therapy.

BackgroundSeveral studies in animal models demonstrated that obligate and facultative anaerobic bacteria of the genera Bifidobacterium, Salmonella, or Clostridium specifically colonize solid tumors. Consequently, these and other bacteria are discussed as live vectors to deliver therapeutic genes to inhibit tumor growth. Therapeutic approaches for cancer treatment using anaerobic bacteria have been investigated in different mouse models. In the present study, solid three-dimensional (3D) multicellular tumor spheroids (MCTS) of the colorectal adenocarcinoma cell line HT-29 were generated and tested for their potential to study prodrug-converting enzyme therapies using bacterial vectors in vitro.ResultsHT-29 MCTS resembled solid tumors displaying all relevant features with an outer zone of proliferating cells and hypoxic and apoptotic regions in the core. Upon incubation with HT-29 MCTS, Bifidobacterium bifidum S17 and Salmonella typhimurium YB1 selectively localized, survived and replicated in hypoxic areas inside MCTS. Furthermore, spores of the obligate anaerobe Clostridium sporogenes germinated in these hypoxic areas. To further evaluate the potential of MCTS to investigate therapeutic approaches using bacteria as gene delivery vectors, recombinant bifidobacteria expressing prodrug-converting enzymes were used. Expression of a secreted cytosine deaminase in combination with 5-fluorocytosine had no effect on growth of MCTS due to an intrinsic resistance of HT-29 cells to 5-fluorouracil, i.e. the converted drug. However, a combination of the prodrug CB1954 and a strain expressing a secreted chromate reductase effectively inhibited MCTS growth.ConclusionsCollectively, the presented results indicate that MCTS are a suitable and reliable model to investigate live bacteria as gene delivery vectors for cancer therapy in vitro.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-015-0383-5) contains supplementary material, which is available to authorized users.

Noncovalent Ruthenium(II) Complexes-Single-Walled Carbon Nanotube Composites for Bimodal Photothermal and Photodynamic Therapy with Near-Infrared Irradiation.

To enhance the efficacy and optimize the treatment of cancers, the integration of multimodal treatment strategies leading to synergistic effects is a promising approach. The coassembly of multifunctional agents for systematic therapies has received considerable interest in cancer treatment. Herein, Ru(II) complex-functionalized single-walled carbon nanotubes (Ru@SWCNTs) are developed as nanotemplates for bimodal photothermal and two-photon photodynamic therapy (PTT-TPPDT). SWCNTs have the ability to load a great amount of Ru(II) complexes (Ru1 or Ru2) via noncovalent π-π interactions. The loaded Ru(II) complexes are efficiently released by the photothermal effect of irradiation from an 808 nm diode laser (0.25 W/cm(2)). The released Ru(II) complexes produce singlet oxygen species ((1)O2) upon two-photon laser irradiation (808 nm, 0.25 W/cm(2)) and can be used as a two-photon photodynamic therapy (TPPDT) agent. Based on the combination of photothermal therapy and two-photon photodynamic therapy, Ru@SWCNTs have greater anticancer efficacies than either PDT using Ru(II) complexes or PTT using SWCNTs in two-dimensional (2D) cancer cell and three-dimensional (3D) multicellular tumor spheroid (MCTS) models. Furthermore, in vivo tumor ablation is achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.25 W/cm(2) for 5 min. This study examines an efficacious bimodal PTT and TPPDT nanoplat form for the development of cancer therapeutics.

Treatment Efficiency of Free and Nanoparticle-Loaded Mitoxantrone for Magnetic Drug Targeting in Multicellular Tumor Spheroids.

Major problems of cancer treatment using systemic chemotherapy are severe side effects. Magnetic drug targeting (MDT) employing superparamagnetic iron oxide nanoparticles (SPION) loaded with chemotherapeutic agents may overcome this dilemma by increasing drug accumulation in the tumor and reducing toxic side effects in the healthy tissue. For translation of nanomedicine from bench to bedside, nanoparticle-mediated effects have to be studied carefully. In this study, we compare the effect of SPION, unloaded or loaded with the cytotoxic drug mitoxantrone (MTO) with the effect of free MTO, on the viability and proliferation of HT-29 cells within three-dimensional multicellular tumor spheroids. Fluorescence microscopy and flow cytometry showed that both free MTO, as well as SPION-loaded MTO (SPIONMTO) are able to penetrate into tumor spheroids and thereby kill tumor cells, whereas unloaded SPION did not affect cellular viability. Since SPIONMTO has herewith proven its effectivity also in complex multicellular tumor structures with its surrounding microenvironment, we conclude that it is a promising candidate for further use in magnetic drug targeting in vivo.

Nonspecifically enhanced therapeutic effects of vincristine on multidrug-resistant cancers when coencapsulated with quinine in liposomes.

The use of vincristine (VCR) to treat cancer has been limited by its dose-dependent toxicity and development of drug resistance after repeated administrations. In this study, we investigated the mechanism by which quinine hydrochloride (QN) acts as a sensitizer for VCR. Our experiments used three kinds of multidrug-resistant cancer cells and demonstrated that QN worked by inducing intracellular depletion of adenosine triphosphate, increasing adenosine triphosphatase activity, and decreasing P-glycoprotein expression. Based on these results, we designed and prepared a VCR and QN codelivery liposome (VQL) and investigated the effect of coencapsulated QN on the in vitro cytotoxicity of VCR in cells and three-dimensional multicellular tumor spheroids. The antitumor effects of the formulation were also evaluated in multidrug-resistant tumor-bearing mice. The results of this in vivo study indicated that VQL could reverse VCR resistance. In addition, it reduced tumor volume 5.4-fold when compared with other test groups. The data suggest that VQL could be a promising nanoscaled therapeutic agent to overcome multidrug resistance, and may have important clinical implications for the treatment of cancer.

Quantitative determination of irinotecan and the metabolite SN-38 by nanoflow liquid chromatography-tandem mass spectrometry in different regions of multicellular tumor spheroids.

A new and simple method was developed to evaluate the distribution of therapeutics in three-dimensional multicellular tumor spheroids (MCTS) by combining serial trypsinization and nanoflow liquid chromatography-tandem mass spectrometry (nLC-MS/MS). This methodology was validated with quantitative measurements of irinotecan and its bioactive metabolite, SN-38, in distinct spatial regions of HCT 116 MCTS. Irinotecan showed a time-dependent permeability into MCTS with most of the drug accumulating in the core after 24h of treatment. The amount of SN-38 detected was 30 times lower than that of the parent drug, and was more abundant in the outer rim and intermediate regions of MCTS where proliferating cells were present. This method can be used to investigate novel and established drugs. It enables investigation of drug penetration properties and identification of metabolites with spatial specificity in MCTS. The new approach has great value in facilitating the drug evaluation process.

Multifunctional albumin nanoparticles as combination drug carriers for intra-tumoral chemotherapy.

Current cancer therapies are challenged by weakly soluble drugs and by drug combinations that exhibit non-uniform biodistribution and poor bioavailability. In this study, we have presented a new platform of advanced healthcare materials based on albumin nanoparticles (ANPs) engineered as tumor penetrating, delivery vehicles of combinatorially applied factors to solid tumors. These materials were designed to overcome three sequential key barriers: tissue level transport across solid tumor matrix; uptake kinetics into individual cancer cells; therapeutic resistance to single chemotherapeutic drugs. The ANPs were designed to penetrate deeper into solid tumor matrices using collagenase decoration and evaluated using a three-dimensional multicellular melanoma tumor spheroid model. Collagenase modified ANPs exhibited 1-2 orders of magnitude greater tumor penetration than unmodified ANPs into the spheroid mass after 96 hours, and showed preferential uptake into individual cancer cells for smaller sized ANPs (<100 nm). For enhanced efficacy, collagenase coated ANPs were modified with two therapeutic agents, curcumin and riluzole, with complementary mechanisms of action for combined cell cycle arrest and apoptosis in melanoma. The collagenase coated, drug loaded nanoparticles induced significantly more cell death within 3-D tumor models than the unmodified, dual drug loaded ANP particles and the kinetics of cytotoxicity was further influenced by the ANP size. Thus, multifunctional nanoparticles can be imbued with complementary size and protease activity features that allow them to penetrate solid tumors and deliver combinatorial therapeutic payload with enhanced cancer cytotoxicity but minimal collateral damage to healthy primary cells.

Cell behavior observation and gene expression analysis of melanoma associated with stromal fibroblasts in a three‐dimensional magnetic cell culture array

A three-dimensional (3D) multicellular tumor spheroid culture array has been fabricated using a magnetic force-based cell patterning method, analyzing the effect of stromal fibroblast on the invasive capacity of melanoma. Formation of spheroids was observed when array-like multicellular patterns of melanoma were developed using a pin-holder device made of magnetic soft iron and an external magnet, which enables the assembly of the magnetically labeled cells on the collagen gel-coated surface as array-like cell patterns. The interaction of fibroblast on the invasion of melanoma was investigated using three types of cell interaction models: (i) fibroblasts were magnetically labeled and patterned together in array with melanoma spheroids (direct-interaction model), (ii) fibroblasts coexisting in the upper collagen gel (indirect-interaction model) of melanoma spheroids, and (iii) fibroblast-sheets coexisting under melanoma spheroids (fibroblast-sheet model). The fibroblast-sheet model has largely increased the invasive capacity of melanoma, and the promotion of adhesion, migration, and invasion were also observed. In the fibroblast-sheet model, the expression of IL-8 and MMP-2 increased by 24-fold and 2-fold, respectively, in real time RT-PCR compared to the absence of fibroblasts. The results presented in this study demonstrate the importance of fibroblast interaction to invasive capacity of melanoma in the 3D in vitro bioengineered tumor microenvironment.

Multicellular Tumor Spheroids as an in Vivo–Like Tumor Model for Three-Dimensional Imaging of Chemotherapeutic and Nano Material Cellular Penetration

We present a flexible and highly reproducible method using three-dimensional (3D) multicellular tumor spheroids to quantify chemotherapeutic and nanoparticle penetration properties in vitro. We generated HeLa cell-derived spheroids using the liquid overlay method. To properly characterize HeLa spheroids, scanning electron microscopy, transmission electron microscopy, and multiphoton microscopy were used to obtain high-resolution 3D images of HeLa spheroids. Next, pairing high-resolution optical characterization techniques with flow cytometry, we quantitatively compared the penetration of doxorubicin, quantum dots, and synthetic micelles into 3D HeLa spheroid versus HeLa cells grown in a traditional two-dimensional culturing system. Our data revealed that 3D cultured HeLa cells acquired several clinically relevant morphologic and cellular characteristics (such as resistance to chemotherapeutics) often found in human solid tumors. These characteristic, however, could not be captured using conventional two-dimensional cell culture techniques. This study demonstrated the remarkable versatility of HeLa spheroid 3D imaging. In addition, our results revealed the capability of HeLa spheroids to function as a screening tool for nanoparticles or synthetic micelles that, due to their inherent size, charge, and hydrophobicity, can penetrate into solid tumors and act as delivery vehicles for chemotherapeutics. The development of this image-based, reproducible, and quantifiable in vitro HeLa spheroid screening tool will greatly aid future exploration of chemotherapeutics and nanoparticle delivery into solid tumors.

MCF-7 MTS에서 sodium salicylate과 genistein 복합처리는 불완전한 세포사멸과 세포괴사를 유도한다

아스피린과 아스피린의 deacetylated form인 sodium salicylate (NaSal)은 대장암, 폐암 및 유방암을 비롯한 다양한 암의 항암제 활성을 나타내는 것으로 잘 알려져 있다. A549 폐암 세포주에 저농도의 NaSal과 genistein을 함께 복합 처리시 상승작용에 의해 세포사멸을 증가시켜서 NaSal에 의한 암억제 효과를 증대시킴을 이미 밝힌바 있다. 본 연구에서는 A549가 아닌 다른 암세포주와 in vitro solid tumor model인 multicellular spheroids (MTS)을 이용하여 NaSal과 genistein 복합처리 효과를 조사하였다. NaSal/genistein 복합 처리시 A549 세포주와 마찬가지로 HCT116 세포주에서도 세포사멸이 유도되었지만, MCF-7 세포주에서는 유도되지 않았다. 흥미롭게도, MCF-7 세포주는 MTS로 배양되는 동안 NaSal/genistein 복합 처리에 의해 세포 죽음을 나타내었다. 세포 죽음의 형태는 MCF-7 MTS의 발달 단계에 따라 세포사멸 또는 세포괴사로 나타났다. MCF-7 MTS에서의 세포사멸은 불완전한 양상을 보였다. 즉 염색체가 응축되고 쪼개지지만, 핵막은 여전히 관찰되었다. 이상의 연구 결과 NaSal/genistein 복합처리는 MCF-7 MTS 배양 system에서 불완전한 세포사멸과 세포괴사를 일으킴을 알 수 있었다. Aspirin and its deacetylated form, sodium salicylate (NaSal), have been shown to exert chemopreventive activities against many human cancers including those of the colon, lung, and breast. Previously, we showed that combined treatment of NaSal and genistein synergistically induced apoptosis in A549 lung cancer cells, indicating that these two natural chemicals could be used in combination for cancer therapy. In this study, we examined effects of NaSal/genistein combined treatment on other cancer cells and in three-dimensional multicellular tumor spheroid (MTS) and in an in vitro solid tumor model. We found that the combined treatment induces apoptosis in the HCT116 cells and the A549 cells, but not in the MCF-7 cells. Interestingly, the MCF-7 cells responded to the NaSal/genistein combined treatment by undergoing cell death when they were cultivated as MTS. The combined treatment induced apoptosis at an earlier stage in the MCF-7 MTS culture. However, when the MCF-7 MTS was cultivated for a longer period, it induced necrosis rather than apoptosis. We further found that the apoptotic pattern observed in MCF-7 MTS was incomplete: the chromatins were condensed and fragmented, but the nuclear membrane was still intact. Taken together, these results demonstrate that the NaSal/genistein combined treatment induces incomplete apoptosis and necrosis in the MCF-7 MTS culture system.