**Author details**

Three-dimensional cell culture models have been shown to be more accurate in assessing drug screening, selection and efficacy than 2D models of the diseases [115, 124]. For instance, spheroids obtained from patients were used to identify an effective therapy for 120 patients with HER2-negative breast cancer of all stages. The results indicated that spheroid 3D culture models display present guideline treatment recommendation for breast cancer [113]. In addition, 3D cell culture models are very powerful in analyzing drug induced toxicity. Organ buds of heart, liver, brain and kidney can be used to identify drug toxicity [83]. For instance, liver cell spheroid 3D culture used for investigating drug induced liver injury, function and diseases. Spheroids generated from human primary hepatocyte found to be phenotypically stable and retained morphology and viability for almost 5 weeks, providing toxicity analysis of drug molecules [115]. Liver spheroids and organoids also have been used to understand

However, many challenges remain in 3D cell culture technologies in the drug discovery process. Three-dimensional culture are different in terms of size, morphology, complexity and protocol for assaying compared to 2D cell culture, which can lead to challenges in systematic assessment, culture and assay protocol standardization. It also has complexity of identifying specific phenotypes for drug screening [125]. Moreover, some 3D models have limited permeability, which can impact cell viability and functions thus making it difficult to have accurate automated system for HTS. A summary of the differences between 2D and 3D cell cultures is

Two-dimensional and 3D cell culture models have been widely used for improving the productivity of pharmaceutical research and development. It is evident that 3D culture systems hold great potential as a tool for drug discovery compared to 2D cell culture. This is due to the improved cell-cell and cell-ECM interactions, cell populations and structures that similar to *in vivo*. However, there are still hurdles to overcome before 3D systems can be widely used in industry. More studies are needed to promise reproducibility, high throughput analysis and compatibility to demonstrate standardized and validated 3D culture models. In future, development of screening compatible 3D models would help to identify early physiological

the metabolism of drug molecules.

relevant efficacy and toxicity data in drug discovery.

DDDR drug discovery and development research

CaCo-2 human colon carcinoma

CO2 carbon dioxide

ADMETox absorption, distribution, metabolism, excretion and toxicity

given in **Table 5**.

32 Cell Culture

**4. Conclusion**

**List of abbreviations**

Jitcy Saji Joseph, Sibusiso Tebogo Malindisa and Monde Ntwasa\*

\*Address all correspondence to: ntwasmm@unisa.ac.za

Department of Life and Consumer Sciences, College of Agriculture and Environmental Sciences, University of South Africa, South Africa
