Monday, June 29, 2015

Tumor spheroids for representative cancer therapy testing

One of the new product categories to come out of PolySciTech is 3DCellMaker ( which is a thermogelling media modifier that allows for easy and convenient growth of tumor spheroids. The importance of growing tumors in a spheroid pattern for chemotherapy testing has been described in a recent research paper. In traditional research methods, potential cancer therapies are tested on cancer cells grown as a flat-layer in the bottom of a petri dish or other container (2D cells). In the 2D growth pattern, practically every therapy tested works well against the cancer cells because all cells are exposed simultaneously to the drug and there is limited potential for drug-resistant properties to be observed. This does not match up with clinical pharmacology because, in the human body, cancer cells do not grow flat but rather into clumps/spheroids/tumors in which the outer layer of cells acts to create a unique environment for the inner cells. This growth pattern leads to a variety of drug-transport barriers and other changes which can make the tumor resistant to chemotherapeutic treatments. For this reason, in order to accurately assay treatment regimens, it is important to test the proposed therapy against a more realistic tumor spheroid rather than flat cells. Read more about tumor spheroids here: Giannattasio, Ariane, Sandra Weil, Stephan Kloess, Nariman Ansari, Ernst HK Stelzer, Adelheid Cerwenka, Alexander Steinle, Ulrike Koehl, and Joachim Koch. "Cytotoxicity and infiltration of human NK cells in in vivo-like tumor spheroids." BMC cancer 15, no. 1 (2015): 351.

“Abstract: Background: The complex cellular networks within tumors, the cytokine milieu, and tumor immune escape mechanisms affecting infiltration and anti-tumor activity of immune cells are of great interest to understand tumor formation and to decipher novel access points for cancer therapy. However, cellular in vitro assays, which rely on monolayer cultures of mammalian cell lines, neglect the three-dimensional architecture of a tumor, thus limiting their validity for the in vivo situation. Methods: Three-dimensional in vivo-like tumor spheroid were established from human cervical carcinoma cell lines as proof of concept to investigate infiltration and cytotoxicity of NK cells in a 96-well plate format, which is applicable for high-throughput screening. Tumor spheroids were monitored for NK cell infiltration and cytotoxicity by flow cytometry. Infiltrated NK cells, could be recovered by magnetic cell separation. Results: The tumor spheroids were stable over several days with minor alterations in phenotypic appearance. The tumor spheroids expressed high levels of cellular ligands for the natural killer (NK) group 2D receptor (NKG2D), mediating spheroid destruction by primary human NK cells. Interestingly, destruction of a three-dimensional tumor spheroid took much longer when compared to the parental monolayer cultures. Moreover, destruction of tumor spheroids was accompanied by infiltration of a fraction of NK cells, which could be recovered at high purity. Conclusion: Tumor spheroids represent a versatile in vivo-like model system to study cytotoxicity and infiltration of immune cells in high-throughput screening. This system might proof useful for the investigation of the modulatory potential of soluble factors and cells of the tumor microenvironment on immune cell activity as well as profiling of patient-/donor-derived immune cells to personalize cellular immunotherapy. Keywords: NK cell; tumor immune escape; tumor infiltration; tumor spheroid; 3D culture; innate immune system; NKG2D; ligand shedding”
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