animal models have shown promise in vitro or in human cell models. It indicated that

in vitro models can be used in conjunction with more traditional in vivo toxicologi-

cal and pharmacokinetic evaluations throughout the drug development process.

These validated in vitro models can be classified as in vitro screens. The utility of

these screens for drug research process is evaluated in terms of their standardization,

validation, human tissue uses, iteration level with in vivo studies, regulatory status,

and cost-effectiveness (Kačarević et al. 2018).

6.3

Organ-on-a-Chip as Novel In Vitro Disease Model

Different organs have been built using on-a-chip technology in recent years. One of

the most recent advancements in in vitro disease models is ‘organ-on-a-chip tech-

nology’, which uses microfabrication techniques (Derakhshanfar et al. 2018; Zhang

et al. 2019). This technique is becoming more popular as a tool for studying drug

metabolism (Mengus et al. 2017). Due to this ‘human-on-a-chip’ technology,

researchers will gain a better understanding of drug metabolism, pharmacokinetics,

and toxicity in humans. Additionally, researchers have been able to detect metabolic

changes associated with the disease in humans. Organ-on-chip systems require only

a small amount of patient tissue to replicate the organ, implying that the development

of personalized medicine may be possible (Kimura et al. 2018).

In several of these models, living cells resulting from tumours and tissues are

refined in conditions designed to mimic disease states and processes. However, since

every structure is only as powerful as the cells it is made with, choosing the right

cells to form the model’s base is a major challenge. Increasingly, human primary

cells are being used to build physiologically relevant in vitro cell model systems.

Primary cells carefully extracted from human blood and tissue closely resemble the

functions and processes of the tissues from which they were derived.

On the other hand, efficiently isolating and purifying primary cells is a challeng-

ing task that necessitates a thorough understanding of cell and tissue biology. Given

the complexities, many laboratories would profit from working with vendors to

acquire primary cells that have already been characterized, enabling them to con-

struct the right model more confidently for their needs. After being isolated, cells

must be checked for viability and functionality, as well as for the presence of

common laboratory pathogens. Tissues must also be collected in an ethical manner

from donors who have filled out the required paperwork and given their permission

(Cooley et al. 2002; Rodriguez-Garcia et al. 2020).

To characterise the safety of lead drug compounds by predicting how the drug

will interact with an organ in vivo, ‘organ-on-chip’ microfluidic procedures are

increasingly being used. While assay robustness and model sophistication appear

to be impeding progress towards wider acceptance, these sophisticated models have

the potential to increase predictivity, allowing for more confident drug candidate

selection.

6

Organ-on-a-Chip: Novel In Vitro Model for Drug Discovery

77