**9. Limitations of organoids**

Generation of organoids from epithelial cells may lead to contamination or overgrowth of normal cells [58]. Generally, the organoids developed from cancer cells will have less growth than organoids developed from normal cells which result in overgrowth of normal cells in the medium which can be overcome by limiting the use of growth factors in the medium [106]. Upon analyzing the efficiency of various organoids on drug development in-vitro, a positive predictive value of 88% and a negative predictive value of 100% were endorsed upon numerous studies [107, 108]. The organoids developed *in-vitro* lack the native microenvironment like stromal cells, immune cells [109]. This limitation can be overcome by culturing the tissues with required cellular elements for proper differentiation but this may end up in more cost [110]. In a study by [111], a high-throughput screening accompanied with patient-derived 3D organoids has been successfully utilized to overcome the limitations of organoids in drug screening. In another study, an organ-on-a-chip platform has been devised which contains hollow microchannels filled with living cells resembling human organs and organoids which can be utilized effectively for drug screening [112]. Another major limitation in organoid development is lack of reproducibility, laborious and costly method [113].
