Ex Vivo Tumor Culture Systems for Functional Drug Testing and Therapy Response Prediction

Figures & data

Figure 1.  Comparison of ex vivo tumor culture techniques.

Fresh viable tumor tissue can be preserved and cultured ex vivo in several ways, each having its own advantages and disadvantages. A tumor sample can be dissociated using enzymatic and/or mechanical methods and subsequently cultured either as a 2D monolayer or in a 3D tumor spheroid culture. To mimic the in vivo situation as much as possible, dissected tumor samples can be implanted in immunodeficient mice to generate patient-derived xenograft models. Organotypic tumor tissue slices can be generated by precision slicing of a tumor specimen, keeping general tumor/tissue architecture intact.

+: Advantages of the method; -: Disadvantages of the method.

Figure 2.  Main applications of different ex vivo model systems.

An ex vivo model system should be chosen according to the purpose of the specific research. Each ex vivo model system has its own benefits and disadvantages, making one more applicable for a specific research endeavor than the others.

Table 1. Comparison of various reports on organotypic tumor slices.

Study (year)	Tissue	Slicing method	Specific culture condition	Validation tool for culture conditions/assay read-out	Duration of successful culture	Investigated compound	Study size	Ref.
Van der Kuip et al. (2006)	Breast	Krumdieck	- Composite medium – Rotation (150 rpm) – 200 μm slices	– TMRM/SYTO-63/picogreen three-color assay	4 days	– Taxol	22	[72]
Vaira et al. (2010)	Colon Lung Prostate	Vibratome	– Culture plate inserts – No rotation – 400 μm slices	– Ki-67 staining – MTT assay – TUNEL assay (apoptosis) – BrdU incorporation – p-Akt and p-S6RP protein levels	5 days	– LY294002 (PI3K inhibitor)	42	[68]
Davies et al. (2015)	Breast Prostate Lung	Vibratome	– Composite medium – No rotation – Culture plate inserts – 200–300 μm slices -High/low oxygen	– Ki-67 staining – CICK18 stainig (apoptosis) – Cleaved caspase 3 staining – qPCR and IHC analysis of several other biomarkers – Morphologic examination	4 days	NA	No cohort	[65]
Holliday et al. (2013)	Breast	Vibratome	– Regular medium – No rotation – 250 μm slices	– MIB1 staining (proliferation) – M30 staining (apoptosis) – Morphological examination	7 days (no quantification)	– Doxorubicin – Tamoxifen	10	[82]
Naipal et al. (2016)	Breast	Vibratome	– Composite medium – Rotation (60 rpm) – 300 μm slices	– EdU incorporation – TUNEL assay (apoptosis) – Morphologic examination	7 days	– FAC (5-FU, doxorubicin, cyclophosphamide)	15	[69]
Gerlach et al. 2014	Head and neck	Both vibratome and Krumdieck	– Composite medium – Culture plate inserts – 350 μm slices	– Ki-67 staining – Cleaved caspase 3 staining – Morphologic examination	6 days (no quantification)	– Cisplatin – Cetuximab – Docetaxel	No cohort	[66]
Koerfer et al. (2016)	Gastric and esophageal	Krumdieck	– Regular medium – Culture plate inserts – No rotation – 400 μm slices	– Cytokeratin – Ki-67 staining – Cleaved caspase 3 staining – Morphologic examination	6 days	– 5-FU – Cisplatin	8	[67]
Carranza et al. (2015)	Breast	Krumdieck	– Composite medium – Rotation (25 rpm) – 250–300 μm slices	– Alamar Blue assay – LDH release – Morphologic examination – KI67 staining	3–4 days	– Paclitaxel – Caffeic acid – Ursolic acid – Rosmarinic acid	9	[62]

Many different methods for cultivation of organotypic tissue slices exist and the optimal system remains to be selected. Various reports on organotypic tumor tissue slices used different methods for slice cultivation. Moreover, assays and quality standards differ between reports, making it difficult to draw conclusions.

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