indirect. While direct interaction involves cells being in direct contact with each other in the same culture media or matrix, indirect interaction involves different environments, allowing signaling and soluble factors to participate. Cell differentiation in tissue models during interaction between cells can be studied using the Co-Cultured System to simulate cancer tumors, to assess the effect of drugs on therapeutic trials, and to study the effect of drugs on therapeutic trials. The co-culture system in 3D models can predict the response to chemotherapy and endocrine therapy if the microenvironment defines biological tissue for the cells. A co-culture method is used in tissue engineering to generate tissue formation with multiple cells interacting directly. Cell culture in microfluidic device Microfluidics technique is developed systems that can perform a process in a flow which are usually in a scale of micron. Microfluidics chip are also known as Lab-on-a-chip and they are able to have continuous procedure and reaction steps with spare amount of reactants and space. Such systems enable the identification and isolation of individual cells and molecules when combined with appropriate biological assays and high-sensitivity detection techniques. Organ-on-a-chip OoC systems mimic and control the microenvironment of the cells by growing tissues in microfluidics. Combining tissue engineering, biomaterials fabrication, and cell biology, it offers the possibility of establishing a biomimetic model for studying human diseases in the laboratory. In recent years, 3D cell culture science has made significant progress, leading to the development of OoC. OoC is considered as a preclinical step that benefits pharmaceutical studies, drug development and disease modeling. OoC is an important technology that can bridge the gap between animal testing and clinical studies and also by the advances that the science has achieved could be a replace for in vivo studies for drug delivery and pathophysiological studies. Culture of non-mammalian cells Besides the culture of well-established immortalised cell lines, cells from primary explants of a plethora of organisms can be cultured for a limited period of time before senescence occurs (see Hayflick's limit). Cultured primary cells have been extensively used in research, as is the case of fish keratocytes in cell migration studies. Plant cell culture methods Plant cell cultures are typically grown as cell suspension cultures in a liquid medium or as callus cultures on a solid medium. The culturing of undifferentiated plant cells and calli requires the proper balance of the plant growth hormones auxin and cytokinin.