Encyclopedia
Three-dimensional (3D) cultures of cancer cells that better recapitulate in vivo cell environments emerged as scientifically accurate and low cost cancer models for preclinical screening and testing of new drug candidates before moving to expensive and time-consuming animal models.
- 3D cultures
- tumor microenvironment
- tumor spheroids
- efficacy analysis
- drug resistance
- cancer therapy
The following contents are excerpts from your papers. They are editable. The entry will better spread your research and findings. We'll help to correct the format after your submission
1. Introduction
Significant investments are made in cancer research for drug discovery and development. Yet, the approval rate (≤5%) of drugs that reach the clinic remains very low [1,2]. Typically, anticancer compounds are tested in two dimensional (2D) cell culture models, that involve a panel of cancer cell lines, such as those used by the US National Cancer Institute [3]. Drugs that show promising cytotoxicity in 2D in vitro system progress to animal models of human cancers (mainly mice) for anti-tumor efficacy testing [4]. Unfortunately, most of the promising preclinical drugs have no or weak efficacy in real patients with tumors, resulting in a significant delay of anticancer drug development [5]. One of the main factors underlying this poor success is the inadequacy of the preclinical 2D cultures and animal models to recapitulate the human tumor microenvironment (TME). TME is a complex and heterogeneous structure made of cellular (e.g., transformed epithelial cells, fibroblasts, infiltrating lymphocytes, mesenchymal stem cells, endothelial cells) and non-cellular (e.g., extracellular matrix—ECM, growth factors, cytokines and chemokines) components, with a critical role in cancer development and progression [6,7]. The 2D culture systems lack the structural architecture and the microenvironment of the tumor, and display altered gene expression and activation of cell signaling pathways, compared to the in vivo tumor tissues (Table 1) [8,9,10]. Besides the associated higher cost and ethical issues, animal models also display significant limitations and poorly reflect the proprieties of human tumors. For instance, the stromal component of the xenograft is not of human origin, the rate of growth is higher in xenografts (doubling time of a few days) than in primary human tumors (doubling time of a few months), and, thus, they often tend to respond better to anticancer drugs [11].
Table 1. Differences between conventional 2D monolayer and 3D spheroid cultures
| Cell Culture System | Advantages | Disadvantages |
|---|---|---|
| 2D cultures |
|
|
| 3D cultures |
|
|
Therefore, the development of preclinical models that better recapitulate patient tumor and microenvironment represents a promising challenge to improve the success rates in anticancer drug development. Since the discovery of the importance of the extracellular matrix (ECM) in cell behavior, it became clear that three-dimensional (3D) cell culture systems offer an excellent opportunity to recapitulate the real avascular tumor, by allowing cancer cells to be cultured, either alone or in co-culture with other cell types, in a spatial manner reminiscent of the structural architecture of the tumor that provides cell–cell and cell–ECM interactions, thereby mimicking the native tumor microenvironment (Table 1) [12,13,14,15]. Hopefully, besides circumventing the barriers and limitations imposed by 2D monolayer cultures, 3D cell culture models could reduce or, ideally, replace the use of animal models, thereby resolving the associated ethical and cost issues [16,17]. Here, common 3D cell culture methods are highlighted, the characterization tools for the evaluation of the targeted effect are reviewed, with focus on multicellular tumor spheroids (MCTS) and their applicability in cancer research.
2. Application of 3D Cultures in Anti-Cancer Drug Discovery and Delivery
The capacity to reproduce the in vivo 3D tumor environment such as cellular heterogeneity, gene expression patterns, cell differentiation, generation of hypoxia, activation of cell signaling pathways, and cell–cell and cell–ECM adhesions, are amongst the many advantages that prompted the use of spheroids for in vitro evaluation of chemoresistance, migration and invasion, and other aspects of tumor biology (e.g., cancer stem cells/tumorigenicity, hypoxia and tumor metabolism). We will focus on chemoresistance and migration/invasion, and provide a brief overview on the use of spheroids to study drug delivery. Details of the other aspects were reviewed elsewhere [64,70,212,213].
2.1. Chemoresistance
Drug resistance is a major concern responsible for the failure of the current chemotherapeutics and their ability to fight cancer, especially in aggressive and highly metastatic tumors. It is now well established that cancer cells, grown in vitro as 3D spheroids, more accurately mimic the drug behavior in terms of sensibility and resistance than cells grown as 2D monolayers [214]. This difference is probably due to the TME and the spatial organization of the spheroids [215]. Increased cell–cell and cell–matrix adhesions may lead to changes in gene expression. Upregulation of cell–adhesion molecules, such as lumican, SNED1, DARP32, and miR-146a, was reported to increase chemotherapeutic resistance in pancreatic tumor spheroids as compared to 2D monolayers [59]. Fibronectin protected DU145 prostate cancer cell spheroids against ceramide and docetaxel-induced apoptosis through interaction with Insulin like growth factor-1 receptor [216]. A variety of apoptotic stimuli, including combinations of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), ribotoxic stressors, histone deacetylase, and proteasome inhibitors, were reported to be highly effective against mesothelioma cells when grown as monolayers than when grown as multicellular spheroids [214].
Increased resistance to chemotherapeutic drugs in spheroids is attributed to many factors associated with their constitution and organization, such as hypoxia, altered cellular energy metabolism, the acidic microenvironment, the cellular heterogeneity including the presence of cancer stem cells, and cell–cell and cell–ECM interactions [215,217,218,219,220,221,222]. The mechanisms by which these factors confer chemoresistance to spheroids were nicely reviewed in [223]. While most studies showed that cells in spheroids are more chemoresistant than cells in 2D monolayers, some studies reported that cells in MCTS are equally or even more sensitive to anticancer agents than their 2D monolayer counterparts. For example, the proteasome inhibitor PS-341 was shown to be equally effective in killing ovarian and prostate tumor cells grown in the form of multicellular spheroids, and tumor cells grown in monolayer cell culture [224].
A number of studies reported that spheroids are also more radioresistant than 2D monolayers. For instance, increased cell compaction increased the resistance of human colon adenocarcinoma spheroids to ionizing radiation [225]. Besides the aforementioned factors, radioresistance may be due to decreased radiation-induced DNA damage as a consequence of lack of oxygen in the spheroids, given that oxygen seems to be required to stabilize DNA damage upon radiation [226,227,228].
2.2. Migration and Invasion
The acquisition of motility and migratory ability is an important hallmark of malignant tumors. Common characteristics of solid tumors, such as hypoxia and soluble mediators-mediated interactions with stromal cells, drive tumor cell migration and invasion, through essential steps that involve, amongst others, actin cytoskeleton remodeling, changes in cell–cell and cell–ECM adhesion, and protein degradation of the surrounding ECM [229,230]. Therefore, the success of studying the multistep process of metastasis relies on a 3D microenvironment through which tumor cells can move and disseminate. In this sense, tumor spheroids are viewed as relevant in vitro models for studying invasion and migration processes [70,166,231,232]. For instance, 3D spheroids display adhesion and ECM molecule expression pattern similar to that of the tumor in vivo, and can also induce expression of proteins associated with metastasis [70,231,233]. Importantly, non-tumor cells are also present in the TME and continuously interact, through paracrine signaling, with cancer cells. For instance, fibroblasts were shown to promote contact-dependent cancer cell motility and invasion of 3D spheroids in co-culture with colorectal cancer cells, a finding validated in vivo [234]. Therefore, ideal migration/invasion assays should be performed in 3D co-cultures that also include non-tumor cells, such as macrophages, dendritic cells, endothelial cells, CAFs and immune cells, in order to better simulate the migration and invasion process found in tumor tissues. CAFs, through the release of cytokines and growth factors, together with the other stromal cells, promote the epithelial-mesenchymal transition in heterotypic 3D cell cultures, resulting in tumor development and metastasis [111,234,235,236]. At the same time, endothelial cells in 3D co-cultures tend to accumulate in the peripheral layer, facilitating the adhesion and infiltration of immune cells [28]. In fact, immune cells can secrete interleukin 6 and MMP-9, which cause inflammation, angiogenesis and ECM degradation, thereby promoting tumor invasion and metastasis [237].
Several assays are available to determine the invasion and migration potential of cells in spheroids [70,232]. In the transwell-based or Boyden chamber assays, the spheroids are seeded on the top of a filter coated with a thick layer of ECM-derived components, usually collagen I, and invasion, in response to a chemo-attractant such as growth factors, can be measured by determining the number of cells that move from the top chamber to the lower chamber [70,232,238]. Additionally, the ability of the cells to invade cellular barriers can be determined by adding a layer of fibroblasts or endothelial cells on top of the matrix [70]. This latter is particularly relevant to mimic the ability of cancer cells to cross the blood vessel barrier and to invade deeply the tissues. Alternatively, spheroids can be completely embedded into different matrices, usually between two layers of ECM gel, where cells leave the spheroids and invade the surrounding matrix [96,239]. Sophisticated techniques combined with computerized quantification are now available to reproducibly perform optimized experimental conditions and to calculate the invasive index of cells [70,239,240,241]. For instance, the extent and rate of tumor spheroid invasion, using the 3D spheroid invasion assay, was rapidly and reproducibly measured using imaging cytometer [238]. Spheroid invasion assays can also be used as a metric to measure drug efficacy [96]. For example, lower concentrations of the adjuvant gamma-linolenic acid caused an increase in glioma spheroid invasion, but increased the apoptotic index at higher concentrations [242]. In sum, spheroids have been widely utilized to study the role of mechanisms involved in cellular invasion, and represent a valuable tool for preclinical evaluation of therapeutic agents targeting invasion [96,166,232].
2.3. Spheroids and Nanomedicines
Systemic drug toxicity and poor efficacy remain a major concern in cancer therapy due to the lack of selective drug delivery to tumor tissues, stressing the need to improve tumor targeting [243]. Nanomedicines have thus emerged as promising approach to (actively) target tumor and improve drug delivery. These nanostructures are biocompatible, biodegradable, non-toxic, can be prepared on a large scale, can provide controlled drug release, and enhance tissue/cell-specific targeting, in addition to reducing side effects [244,245,246,247,248]. However, despite the promising preclinical outcome that was reported for a significant number of nanotherapeutics, only few nanodrugs reached the clinic and achieved the expected results in patients [243]. Many barriers influence the efficiency of nanomedicine delivery to the target tumor, that are not recapitulated by the 2D monolayer cultures.
Tissue penetration of nanoparticles (NPs) relies on their diffusion capacity through the ECM, which varies in density and size, and is also influenced by cell–cell interactions, necrotic core, hypoxia, and by the intravascular pressure irregularities due to vessel compressions applied by growing tumors [249,250,251]. In this sense, as outlined above, spheroids have gained in popularity over traditional 2D culture systems because their pathophysiological features are close to those of the native tumors, being an excellent model to evaluate nanodrugs and to better predict their clinical outcomes [101,197,212,252]. Consequently, spheroids have been used as valuable tool to study different physico-chemical proprieties of nanocarriers such as chemical composition, size, shape and surface properties, which are crucial for their penetration and antitumor efficacy [197,253,254].
A general observation from studies that used spheroids is that nanoparticles (NPs) penetration is inversely correlated to the particle size [159,254,255,256]. NPs with small size (<100 nm) penetrate deeply and faster in the spheroids and distribute homogeneously, as compared to larger NPs (>100 nm) which remain confined to the superficial layers [159,257,258,259]. However, NPs <50 nm were reported to interact with liver cells, and to be poorly retained in the tumor [260].
The surface charge of NPs also influences their penetration in the spheroids: negatively charged NPs penetrate deeply while their positive counterparts remain at the outer layers [56,199]. Yet, more effective drug delivery is warranted by NPs with positive surface charge due to electrostatic interactions with negatively charged cell membranes. To overcome this issue, it has been proposed the use of pH-responsive negatively charged NPs that can turn to positively charged ones once in contact with acidic conditions (e.g., tumor microenvironment), so that negative surface charge ensures deep penetration in the spheroids, while positive surface charge enables more effective drug delivery [199,261].
Although little information exists on the influence of NP shape on penetration and accumulation in the spheroid, the existing literature indicates that nanorods seem to diffuse more rapidly in spheroids compared to nanospheres, and that short nanorods (400 nm in length) accumulate more rapidly and are better internalized than long nanorods (<2000 nm in length) [262,263,264].
Interestingly, NP penetration into spheroids has been enhanced by modification of the surface coating. For instance, ECM-degrading enzymes such as collagenases have been used to coat NPs of up to 100 nm in size, which demonstrated superior (4-fold increase) penetration over control NPs [258]. Drug efficacy is the most important endpoint of any formulation, and it depends greatly on the penetration and accumulation into the spheroids [254]. In general, nanocarrier formulations with high penetration and accumulation in the spheroids exhibited better antitumor activity [159].
Comparison between NP delivery and efficacy between 3D tumor spheroids and animal models revealed key similarities between the two systems. For instance, the photosensitizer verteporfin encapsulated into lipid nanocarriers strongly reduced tumor cell viability of ovarian spheroid cancer cells, and also inhibited tumor growth in an orthotopic murine ovarian cancer model, when compared to free drug [265]. Similar to in vivo tissues, HepG2 cells in 3D hydrogels were more resistant to biotin-conjugated pullulan acetate nanoparticles (Bio-PA NPs) treatments compared to the 2D system [266]. Moreover, Bio-PA NPs exhibited similar anti-tumor activity in 3D culture cells and in in vivo xenografted hepatic tumor model [266]. Studies also observed that iRGD-conjugated nanoparticles with doxorubicin were able to accumulate with more efficacy and penetrate deeply into tumor in both SH-SY5Y spheroids and H22 tumor-bearing mice, restraining tumor growth in both systems [267]. Overall, this highlights the predictive power of spheroids for in vivo therapeutic efficacy, and their potential as promising alternative to animal models for cancer study, hopefully resolving high cost and ethical issues associated with animal use.
Reference (we'll rearrange the references after you submitted it)
- Hait, W.N. Anticancer drug development: The grand challenges. Nat. Rev. Drug. Discov. 2010, 9, 253–254.
- Hutchinson, L.; Kirk, R. High drug attrition rates—Where are we going wrong? Nat. Rev. Clin. Oncol. 2011, 8, 189–190.
- Rubinstein, L.V.; Shoemaker, R.H.; Paull, K.D.; Simon, R.M.; Tosini, S.; Skehan, P.; Scudiero, D.A.; Monks, A.; Boyd, M.R. Comparison of In Vitro Anticancer-Drug-Screening Data Generated With a Tetrazolium Assay Versus a Protein Assay Against a Diverse Panel of Human Tumor Cell Lines. JNCI J. Natl. Cancer Inst. 1990, 82, 1113–1117.
- Ocana, A.; Pandiella, A.; Siu, L.L.; Tannock, I.F. Preclinical development of molecular-targeted agents for cancer. Nat. Rev. Clin. Oncol. 2011, 8, 200–209.
- van der Worp, H.B.; Howells, D.W.; Sena, E.S.; Porritt, M.J.; Rewell, S.; O’Collins, V.; Macleod, M.R. Can animal models of disease reliably inform human studies? PLoS Med. 2010, 7, e1000245.
- Quail, D.F.; Joyce, J.A. Microenvironmental regulation of tumor progression and metastasis. Nat. Med. 2013, 19, 1423–1437.
- Belli, C.; Trapani, D.; Viale, G.; D’Amico, P.; Duso, B.A.; Della Vigna, P.; Orsi, F.; Curigliano, G. Targeting the microenvironment in solid tumors. Cancer Treat. Rev. 2018, 65, 22–32.
- Imamura, Y.; Mukohara, T.; Shimono, Y.; Funakoshi, Y.; Chayahara, N.; Toyoda, M.; Kiyota, N.; Takao, S.; Kono, S.; Nakatsura, T.; et al. Comparison of 2D- and 3D-culture models as drug-testing platforms in breast cancer. Oncol. Rep. 2015, 33, 1837–1843.
- Birgersdotter, A.; Sandberg, R.; Ernberg, I. Gene expression perturbation in vitro--a growing case for three-dimensional (3D) culture systems. Semin. Cancer Biol. 2005, 15, 405–412.
- Souza, A.G.; Silva, I.B.B.; Campos-Fernandez, E.; Barcelos, L.S.; Souza, J.B.; Marangoni, K.; Goulart, L.R.; Alonso-Goulart, V. Comparative Assay of 2D and 3D Cell Culture Models, Proliferation, Gene Expression and Anticancer Drug Response. Curr. Pharm. Des. 2018, 24, 1689–1694.
- Teicher, B.A. Tumor models for efficacy determination. Mol. Cancer Ther. 2006, 5, 2435–2443.
- Bissell, M.J. Architecture Is the Message, The role of extracellular matrix and 3-D structure in tissue-specific gene expression and breast cancer. Pezcoller Found J. 2007, 16, 2–17.
- Ravi, M.; Paramesh, V.; Kaviya, S.R.; Anuradha, E.; Solomon, F.P. 3D cell culture systems: Advantages and applications. J. Cell Physiol. 2015, 230, 16–26.
- Białkowska, K.; Komorowski, P.; Bryszewska, M.; Miłowska, K. Spheroids as a Type of Three-Dimensional Cell Cultures-Examples of Methods of Preparation and the Most Important Application. Int. J. Mol. Sci. 2020, 21, 6225.
- Shehzad, A.; Ravinayagam, V.; AlRumaih, H.; Aljafary, M.; Almohazey, D.; Almofty, S.; Al-Rashid, N.A.; Al-Suhaimi, E.A. Application of Three-dimensional (3D) Tumor Cell Culture Systems and Mechanism of Drug Resistance. Curr. Pharm. Des. 2019, 25, 3599–3607.
- Park, J.I.; Lee, J.; Kwon, J.L.; Park, H.B.; Lee, S.Y.; Kim, J.Y.; Sung, J.; Kim, J.M.; Song, K.S.; Kim, K.H. Scaffold-Free Coculture Spheroids of Human Colonic Adenocarcinoma Cells and Normal Colonic Fibroblasts Promote Tumorigenicity in Nude Mice. Transl. Oncol. 2016, 9, 79–88.
- Szade, K.; Zukowska, M.; Szade, A.; Collet, G.; Kloska, D.; Kieda, C.; Jozkowicz, A.; Dulak, J. Spheroid-plug model as a tool to study tumor development, angiogenesis, and heterogeneity in vivo. Tumour Biol. J. Int. Soc. Oncodev. Biol. Med. 2016, 37, 2481–2496.
- Khaitan, D.; Dwarakanath, B.S. Multicellular spheroids as an in vitro model in experimental oncology: Applications in translational medicine. Expert Opin. Drug Discov. 2006, 1, 663–675.
- Sacks, D.; Baxter, B.; Campbell, B.C.; Carpenter, J.S.; Cognard, C.; Dippel, D.; Eesa, M.; Fischer, U.; Hausegger, K.; Hirsch, J.A. Multisociety Consensus Quality Improvement Revised Consensus Statement for Endovascular Therapy of Acute Ischemic Stroke. Int. J. Stroke 2018, 13, 612–632.
- Barbone, D.; Yang, T.M.; Morgan, J.; Gaudino, G.; Broaddus, V.C. Mammalian target of rapamycin contributes to the acquired apoptotic resistance of human mesothelioma multicellular spheroids. J. Biol. Chem. 2008, 283, 13021–13030.
- Huanwen, W.; Zhiyong, L.; Xiaohua, S.; Xinyu, R.; Kai, W.; Tonghua, L. Intrinsic chemoresistance to gemcitabine is associated with constitutive and laminin-induced phosphorylation of FAK in pancreatic cancer cell lines. Mol. Cancer 2009, 8, 125.
- Thomas, F.; Holly, J.M.; Persad, R.; Bahl, A.; Perks, C.M. Fibronectin confers survival against chemotherapeutic agents but not against radiotherapy in DU145 prostate cancer cells: Involvement of the insulin like growth factor-1 receptor. Prostate 2010, 70, 856–865.
- Weigelt, B.; Lo, A.T.; Park, C.C.; Gray, J.W.; Bissell, M.J. HER2 signaling pathway activation and response of breast cancer cells to HER2-targeting agents is dependent strongly on the 3D microenvironment. Breast Cancer Res. Treat. 2010, 122, 35–43.
- Liao, J.; Qian, F.; Tchabo, N.; Mhawech-Fauceglia, P.; Beck, A.; Qian, Z.; Wang, X.; Huss, W.J.; Lele, S.B.; Morrison, C.D.; et al. Ovarian cancer spheroid cells with stem cell-like properties contribute to tumor generation, metastasis and chemotherapy resistance through hypoxia-resistant metabolism. PLoS ONE 2014, 9, e84941.
- Wartenberg, M.; Hoffmann, E.; Schwindt, H.; Grünheck, F.; Petros, J.; Arnold, J.R.S.; Hescheler, J.; Sauer, H. Reactive oxygen species-linked regulation of the multidrug resistance transporter P-glycoprotein in Nox-1 overexpressing prostate tumor spheroids. FEBS Lett. 2005, 579, 4541–4549.
- Hoffmann, O.; Ilmberger, C.; Magosch, S.; Joka, M.; Jauch, K.-W.; Mayer, B. Impact of the spheroid model complexity on drug response. J. Biotechnol. 2015, 205, 14–23.
- Sethi, T.; Rintoul, R.C.; Moore, S.M.; MacKinnon, A.C.; Salter, D.; Choo, C.; Chilvers, E.R.; Dransfield, I.; Donnelly, S.C.; Strieter, R.M.; et al. Extracellular matrix proteins protect small cell lung cancer cells against apoptosis: A mechanism for small cell lung cancer growth and drug resistance in vivo. Nat. Med. 1999, 5, 662–668.
- Aoudjit, F.; Vuori, K. Integrin signaling inhibits paclitaxel-induced apoptosis in breast cancer cells. Oncogene 2001, 20, 4995–5004.
- Nunes, A.S.; Barros, A.S.; Costa, E.C.; Moreira, A.F.; Correia, I.J. 3D tumor spheroids as in vitro models to mimic in vivo human solid tumors resistance to therapeutic drugs. Biotechnol. Bioeng. 2019, 116, 206–226.
- Frankel, A.; Man, S.; Elliott, P.; Adams, J.; Kerbel, R.S. Lack of multicellular drug resistance observed in human ovarian and prostate carcinoma treated with the proteasome inhibitor PS-341. Clin. Cancer Res. 2000, 6, 3719–3728.
- Ferrante, A.; Rainaldi, G.; Indovina, P.; Indovina, P.L.; Santini, M.T. Increased cell compaction can augment the resistance of HT-29 human colon adenocarcinoma spheroids to ionizing radiation. Int. J. Oncol. 2006, 28, 111–118.
- Olive, P.L.; Durand, R.E. Drug and radiation resistance in spheroids: Cell contact and kinetics. Cancer Metastasis Rev. 1994, 13, 121–138.
- Robert Grimes, D.; Partridge, M. A mechanistic investigation of the oxygen fixation hypothesis and oxygen enhancement ratio. Biomed. Phys. Eng. Express 2015, 1, 045209.
- Horan, A.D.; Giandomenico, A.R.; Koch, C.J. Effect of oxygen on radiation-induced DNA damage in isolated nuclei. Radiat. Res. 1999, 152, 144–153.
- Lefranc, F.; Brotchi, J.; Kiss, R. Possible future issues in the treatment of glioblastomas: Special emphasis on cell migration and the resistance of migrating glioblastoma cells to apoptosis. J. Clin. Oncol. 2005, 23, 2411–2422.
- Erler, J.T.; Weaver, V.M. Three-dimensional context regulation of metastasis. Clin. Exp. Metastasis 2009, 26, 35–49.
- Jessup, J.M.; Brown, D.; Fitzgerald, W.; Ford, R.D.; Nachman, A.; Goodwin, T.J.; Spaulding, G. Induction of carcinoembryonic antigen expression in a three-dimensional culture system. In Vitro Cell Dev. Biol. Anim. 1997, 33, 352–357.
- Vinci, M.; Box, C.; Zimmermann, M.; Eccles, S.A. Tumor spheroid-based migration assays for evaluation of therapeutic agents. Methods Mol. Biol. 2013, 986, 253–266.
- Weiswald, L.B.; Bellet, D.; Dangles-Marie, V. Spherical cancer models in tumor biology. Neoplasia 2015, 17, 1–15.
- Cattin, S.; Ramont, L.; Rüegg, C. Characterization and In Vivo Validation of a Three-Dimensional Multi-Cellular Culture Model to Study Heterotypic Interactions in Colorectal Cancer Cell Growth, Invasion and Metastasis. Front. Bioeng. Biotechnol. 2018, 6, 97.
- Almahmoudi, R.; Salem, A.; Murshid, S.; Dourado, M.R.; Apu, E.H.; Salo, T.; Al-Samadi, A. Interleukin-17F Has Anti-Tumor Effects in Oral Tongue Cancer. Cancers 2019, 11, 650.
- Gao, Q.; Yang, Z.; Xu, S.; Li, X.; Yang, X.; Jin, P.; Liu, Y.; Zhou, X.; Zhang, T.; Gong, C.; et al. Heterotypic CAF-tumor spheroids promote early peritoneal metastatis of ovarian cancer. J. Exp. Med. 2019, 216, 688–703.
- Yamamoto, S.; Hotta, M.M.; Okochi, M.; Honda, H. Effect of vascular formed endothelial cell network on the invasive capacity of melanoma using the in vitro 3D co-culture patterning model. PLoS ONE 2014, 9, e103502.
- Vinci, M.; Box, C.; Eccles, S.A. Three-dimensional (3D) tumor spheroid invasion assay. J. Vis. Exp. 2015, e52686.
- Berens, E.B.; Holy, J.M.; Riegel, A.T.; Wellstein, A. A Cancer Cell Spheroid Assay to Assess Invasion in a 3D Setting. J. Vis. Exp. 2015, e53409.
- De Wever, O.; Hendrix, A.; De Boeck, A.; Eertmans, F.; Westbroek, W.; Braems, G.; Bracke, M.E. Single cell and spheroid collagen type I invasion assay. Methods Mol. Biol. 2014, 1070, 13–35.
- Febles, N.K.; Ferrie, A.M.; Fang, Y. Label-free single cell kinetics of the invasion of spheroidal colon cancer cells through 3D Matrigel. Anal. Chem. 2014, 86, 8842–8849.
- Bell, H.S.; Wharton, S.B.; Leaver, H.A.; Whittle, I.R. Effects of N-6 essential fatty acids on glioma invasion and growth: Experimental studies with glioma spheroids in collagen gels. J. Neurosurg. 1999, 91, 989–996.
- Marchal, S.; El Hor, A.; Millard, M.; Gillon, V.; Bezdetnaya, L. Anticancer Drug Delivery, An Update on Clinically Applied Nanotherapeutics. Drugs 2015, 75, 1601–1611.
- Aldawsari, H.M.; Singh, S. Rapid Microwave-Assisted Cisplatin-Loaded Solid Lipid Nanoparticles, Synthesis, Characterization and Anticancer Study. Nanomaterials 2020, 10, 510.
- Wang, H.; Li, L.; Ye, J.; Wang, R.; Wang, R.; Hu, J.; Wang, Y.; Dong, W.; Xia, X.; Yang, Y.; et al. Improving the Oral Bioavailability of an Anti-Glioma Prodrug CAT3 Using Novel Solid Lipid Nanoparticles Containing Oleic Acid-CAT3 Conjugates. Pharmaceutics 2020, 12, 126.
- Zielińska, A.; Ferreira, N.R.; Durazzo, A.; Lucarini, M.; Cicero, N.; Mamouni, S.E.; Silva, A.M.; Nowak, I.; Santini, A.; Souto, E.B. Development and Optimization of Alpha-Pinene-Loaded Solid Lipid Nanoparticles (SLN) Using Experimental Factorial Design and Dispersion Analysis. Molecules 2019, 24, 2683.
- Lukowski, J.K.; Hummon, A.B. Quantitative evaluation of liposomal doxorubicin and its metabolites in spheroids. Anal. Bioanal. Chem. 2019, 411, 7087–7094.
- Yang, S.; Gao, H. Nanoparticles for modulating tumor microenvironment to improve drug delivery and tumor therapy. Pharmacol. Res. 2017, 126, 97–108.
- Davies Cde, L.; Berk, D.A.; Pluen, A.; Jain, R.K. Comparison of IgG diffusion and extracellular matrix composition in rhabdomyosarcomas grown in mice versus in vitro as spheroids reveals the role of host stromal cells. Br. J. Cancer 2002, 86, 1639–1644.
- Hobbs, S.K.; Monsky, W.L.; Yuan, F.; Roberts, W.G.; Griffith, L.; Torchilin, V.P.; Jain, R.K. Regulation of transport pathways in tumor vessels: Role of tumor type and microenvironment. Proc Natl Acad Sci USA 1998, 95, 4607–4612.
- Prabhakar, U.; Maeda, H.; Jain, R.K.; Sevick-Muraca, E.M.; Zamboni, W.; Farokhzad, O.C.; Barry, S.T.; Gabizon, A.; Grodzinski, P.; Blakey, D.C. Challenges and key considerations of the enhanced permeability and retention effect for nanomedicine drug delivery in oncology. Cancer Res. 2013, 73, 2412–2417.
- Patel, N.R.; Aryasomayajula, B.; Abouzeid, A.H.; Torchilin, V.P. Cancer cell spheroids for screening of chemotherapeutics and drug-delivery systems. Ther. Deliv. 2015, 6, 509–520.
- Jin, H.; Gui, R.; Sun, J.; Wang, Y. RETRACTED, Facilely self-assembled magnetic nanoparticles/aptamer/carbon dots nanocomposites for highly sensitive up-conversion fluorescence turn-on detection of tetrodotoxin. Talanta 2018, 176, 277–283.
- Millard, M.; Yakavets, I.; Zorin, V.; Kulmukhamedova, A.; Marchal, S.; Bezdetnaya, L. Drug delivery to solid tumors: The predictive value of the multicellular tumor spheroid model for nanomedicine screening. Int. J. Nanomed. 2017, 12, 7993–8007.
- Bugno, J.; Hsu, H.-J.; Pearson, R.M.; Noh, H.; Hong, S. Size and Surface Charge of Engineered Poly(amidoamine) Dendrimers Modulate Tumor Accumulation and Penetration, A Model Study Using Multicellular Tumor Spheroids. Mol. Pharm. 2016, 13, 2155–2163.
- Ni, D.; Ding, H.; Liu, S.; Yue, H.; Bao, Y.; Wang, Z.; Su, Z.; Wei, W.; Ma, G. Superior intratumoral penetration of paclitaxel nanodots strengthens tumor restriction and metastasis prevention. Small 2015, 11, 2518–2526.
- Agarwal, R.; Jurney, P.; Raythatha, M.; Singh, V.; Sreenivasan, S.V.; Shi, L.; Roy, K. Effect of shape, size, and aspect ratio on nanoparticle penetration and distribution inside solid tissues using 3D spheroid models. Adv. Healthc. Mater. 2015, 4, 2269–2280.
- Goodman, T.T.; Olive, P.L.; Pun, S.H. Increased nanoparticle penetration in collagenase-treated multicellular spheroids. Int. J. Nanomed. 2007, 2, 265–274.
- Hinger, D.; Navarro, F.P.; Käch, A.; Thomann, J.-S.; Mittler, F.; Couffin, A.-C.; Maake, C. Photoinduced effects of m-tetrahydroxyphenylchlorin loaded lipid nanoemulsions on multicellular tumor spheroids. J. Nanobiotechnology 2016, 14, 68.
- Ernsting, M.J.; Murakami, M.; Roy, A.; Li, S.D. Factors controlling the pharmacokinetics, biodistribution and intratumoral penetration of nanoparticles. J Control. Release 2013, 172, 782–794.
- Kim, B.; Han, G.; Toley, B.J.; Kim, C.; Rotello, V.M.; Forbes, N.S. Tuning payload delivery in tumour cylindroids using gold nanoparticles. Nat. Nanotechnol. 2010, 5, 465–472.
- Chauhan, V.P.; Popović, Z.; Chen, O.; Cui, J.; Fukumura, D.; Bawendi, M.G.; Jain, R.K. Fluorescent nanorods and nanospheres for real-time in vivo probing of nanoparticle shape-dependent tumor penetration. Angew. Chem. Int. Ed. Engl. 2011, 50, 11417–11420.
- Wang, Y.; Kibbe, M.R.; Ameer, G.A. Photo-crosslinked Biodegradable Elastomers for Controlled Nitric Oxide Delivery. Biomater. Sci. 2013, 1, 625–632.
- Zhao, J.; Lu, H.; Xiao, P.; Stenzel, M.H. Cellular Uptake and Movement in 2D and 3D Multicellular Breast Cancer Models of Fructose-Based Cylindrical Micelles That Is Dependent on the Rod Length. ACS Appl. Mater. Interfaces 2016, 8, 16622–16630.
- Michy, T.; Massias, T.; Bernard, C.; VanWonterghem, L.; Henry, M.; Guidetti, M.; Royal, G.; Coll, J.-L.; Texier, I.; Josserand, V.; et al. Verteporfin-Loaded Lipid Nanoparticles Improve Ovarian Cancer Photodynamic Therapy In Vitro and In Vivo. Cancers 2019, 11, 1760.
- Chen, H.; Wei, X.; Chen, H.; Wei, H.; Wang, Y.; Nan, W.; Zhang, Q.; Wen, X. The study of establishment of an in vivo tumor model by three-dimensional cells culture systems methods and evaluation of antitumor effect of biotin-conjugated pullulan acetate nanoparticles. Artif. Cells Nanomed. Biotechnol. 2019, 47, 123–131.
- Wang, X.; Zhen, X.; Wang, J.; Zhang, J.; Wu, W.; Jiang, X. Doxorubicin delivery to 3D multicellular spheroids and tumors based on boronic acid-rich chitosan nanoparticles. Biomaterials 2013, 34, 4667–4679.
This entry is adapted from the peer-reviewed paper 10.3390/pharmaceutics12121186
