The technology of generation and development of organoids and organs-on-a-chip (OOC) contributes to the in vitro study of tissues and organ-like structures capable of mimicking organ structures of living beings. Recently there has been a considerable advance in studies for the differentiation of stem cells - the main building blocks of organoids and OOC – to generate structures with higher rates and heterogeneity that contain the collection of cells prevalent in certain organs [1], [2], [3], [4], [5], [6].

The dynamics of structural and functional development and the maintenance of organs in living beings are coordinated by the cells physical and spatial interaction associated with epigenetic control and specific gene expression regarding the external environment in organisms [7], [8], [9]. Such advances were used to initiate the engineering and structure-organization processes, resulting in eminence in studies and initiatives for modeling various organs. In particular, OOC and organoids mimic organ physiology and can be used to screen for responses to pathogenic or pharmacological agents [2], [10], [11].

Organoids are multicellular structures that self-organize three-dimensionally and are generated using bioengineering scaffolding manufactured by bioprinting. This organization occurs autonomously by stem and progenitor cells during their differentiation, mimicking the tissue maturation at the beginning of development. In turn, OOCs are microfluidic devices with microchambers developed by bioengineering. A specific set of an organ or tissue is contained, functionally recreating miniaturized versions of organs [1], [3], [4], [5], [6], [10], [12].

Until a few years ago, the study of physiology, pathology, and biological responses was based on traditional 2D cell cultures or animal models. Both approaches have critical limitations regarding compatibility between in vitro and in vivo events. These limitations are now alleviated with these 3D multicellular structures [10], [12].

The key challenges in constructing organoids and OOCs are related to the scale, blood vessel network, and the temporal and spatial ability to reproduce the tissue-specific architecture [13]. Therefore, this review will elucidate and update the main topics regarding development strategies, generation, and applicability of organoids and OOCs.