**8. Technological developments of organoids**

The existing *in-vitro* and *in-vivo* platforms used for cancer therapy were proved to be not much effective and hence there is a need to derive many new platforms for cancer treatment [81]. In a study conducted by Majumder et al., 2015 [82], an

#### *Evolution of Organoids in Oncology DOI: http://dx.doi.org/10.5772/intechopen.104251*

attempt has been carried out to overcome the tumor heterogeneity with the help of the CANScriptTM platform designed by their team. In 2013, Radhakrishnana and his coworkers [83] attempted to design a drug PAT-1102 that acts as a HDAC (Histone deacetylase) inhibitor and hence can be utilized for cancer treatment. The utilization of Light-screening fluorescence microscopy, confocal microscopy, and multiphoton laser screening microscopy in organoid development can be used to visualize the 3D image of polarized and nonpolarized cells based on the individual organoid model [84]. Organoids have been utilized effectively to understand human brain development and also about various diseases elaborately [85]. Apart from cancer research organoids were also used to study various infectious diseases [86], genetic diseases by combing with CRISPER technology [87], to study the gene function [88] and cell development [89].

The development of organoids paved the way for 3D imaging technology which can be used to visualize complex organizations that were not possible using 2D imaging technology [90]. The 3D imaging technology helped scientists to visualize cellular components, intracellular processes, and architecture of cells in a detailed manner [91]. Lungs were considered as one of the most complex organs in the human body with numerous types of cells and the development of lung organoids had a significant impact on the treatment of lung cancer, asthma, cystic fibrosis, and pulmonary fibrosis [92]. Based on 3D imaging technology major therapeutic drugs were developed that can be used successfully in lung cancer treatment [93]. The 3D models increased the predictability and reliability of preclinical assays and decreased the use of animal models [94]. The quantitative analysis of the organization of various cell types in aggregates uses 3D imaging technology for detailed analysis [95].

Another technological up-gradation seen in organoid technology is Organson-a-chip which is used to model various functional groups of organs for detailed study [96]. Initially, the anatomy of the particular organ was studied, and then its basic elements were investigated that can be used to study organ-specific physical and biochemical applications [97]. Retinal diseases were one of the major causes of vision loss in humans worldwide while the complexity of neuro-retinal organization and complex blood supply causes side effects by the use of therapeutic drugs in the treatment of retinal diseases [98]. The development of retinal organoids improved the treatment methods of retinal diseases and also organs-on-a-chip technology paved the way to study cell types in detail that can further enhance the treatment methodology of retinal disease [99]. In case the focus of cancer research is based on a particular cell type or organ miniature types of organoids can be developed by utilizing organ-on-a-chip technology [100]. The organoid development and organoid-on-a-chip technology has their unique characteristics and limitations and based on research requirement the suitable technology is to be utilized [101]. The usage of organoid-on-a-chip technology on brain organoids paved the way to cure many neurological diseases [102].

In earlier days, tumor spheroids were developed to analyze the capability of antitumor therapeutic drugs, and recently tissue-specific organoids were utilized effectively to model various organs that can be used in cancer treatment by overcoming the limitations of ethical concerns caused by tumor spheroids [103]. The use of brain organoids to study neural diseases has proven that the brain organoids developed in 3D cultures express a large number of genes entangled in neurological problems and hence make the study process feasible compared to 2D technology [104]. In recent areas of research organoid technology is being implemented extensively in image-based phenotypic high throughput screening [105].
