way. The organ-on-a-chip as in vitro model will prove to be a potential platform

in the development of personalized medicines in future.

Keywords

In vitro model · Liver model · Kidney model · Lung model · Bioprinting · Human-

on-a-chip

6.1

Introduction

The pharmaceutical’s industry is the most demanding, and the most challenging

aspect is drug discovery that involves development, identification, characterization,

and optimization of new drug chemical entity (Hughes et al. 2011; Harper and Topol

2012). Several problems continually faced by drug developers related to adverse

effects of novel lead molecules and then to carry new drug candidate/entity on to the

market in a systematic and progressive manner (Bhusnure et al. 2017). In vitro

conventional cell models are generally used to examine and observe a variety of

signal molecules, viz., enzymes, receptors, and ligands, which are associated with

biological and physiological processes (Booth and Kim 2012). Nevertheless, there

are several drawbacks of conventional in vitro models like they do not mimic the

complexity of interactions of cells within the body. They do not detect the time-

changing signalling molecules (mechanical or chemical) due to its static conditions

and require excessive quantity of nutrients, which are vital for the normal cellular

functions (Frohlich et al. 2013; Griep et al. 2013; Polini et al. 2019). Further, these

models do not imitate the extracellular mechanical environment (Bhusnure et al.

2017).

Due to the poor predictive power of existing animal models used in preclinical

research, several proposed drug molecules fail in clinical studies during the new drug

research and discovery process. This problem arises due to the use of conventional

animal testing models that only detect the investigational drugs in animals and in

human cells. In addition, another complexity comes from the genetic variability

among patients that can change the pharmacokinetic and pharmacodynamic

behaviour to a drug.

Thus, there is always an urgent demand by the pharmaceutical companies in the

development of novel testing approaches, to produce the authentic and reliable

information of drug candidate w.r.t. its safety and toxicity profile clinically in

human beings. To overcome these challenges, microfabrication and microfluidics

based on micro-engineered cell culture models are used nowadays. Development of

advanced cell culture models opens a new era in the drug discovery, i.e. organ-on-a-

chip, which is a more reliable and precise approach in the human biological

processes and can transfigure the outlook of drug development process and methods

(Esch et al. 2015). This advanced technique when compared to conventional models

assist for the selection of right drug molecule and its concentrations in a time

efficient manner (Booth and Kim 2012). Moreover, they can generate different

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