reticuloendothelial cell is involved in both homeostasis and immunity regulation of

the liver. Instead of primary cells, the immortalized liver cell lines HepG2 and

HepG2B can be used for drug screening and toxicological tests. p53 and Nrf2

proteins, which are nuclear transcription factors required for drug metabolism, are

found in hepatocellular carcinoma cells, which are frequently employed to measure

drug toxicity (Deng et al. 2019; Rodriguez-Garcia et al. 2020).

The HepaRG is the best cell line for studying a slowly excreted able drug and

uncovering xenobiotic exposure mechanisms. Acute liver injury, which results in the

withdrawal of approved drugs from the market, is another toxicity concept that

should be included in the drug assessment. Promising advancements in molecular

pharmacology and toxicology have created more relevant cell interactions within

their own environment, which allow for a more enabling long-term culture of livers

and better re-creation of cellular responses to toxicants (Maschmeyer et al. 2015;

Gori et al. 2016).

In research conducted by Bavli et al., the mitochondria and the sensor helped the

liver respond to impairment. To monitor the levels of glucose and lactate over time,

the sensor was designed. The world’s first micro-liver-on-a-chip was also created to

determine the effects of opioids on the liver. The objective of the study was to try to

reconstruct the 3D cellular arrangement of the hepatic sinus. The hepatocyte culture

was conducted for an additional 4 weeks and permitted the assessment of new drugs

for potential toxicity (Bavli et al. 2016).

6.6.3

Kidney-on-a-Chip

Filtration and preservation of essential combinations, as well as blood pressure, can

all be used to regulate kidney function. Additionally, the kidneys function as a waste

disposal system, metabolizing drugs and excess materials. Due to these functions,

drug testing is typically conducted in the kidneys. As kidney function declines in the

elderly, glomerulonephritis, pyelonephrosis, and high cholesterol crystal disease can

occur. Most people suffer from problems with their ability to excrete (Paoli and

Samitier 2016). The primary goal of kidney chip studies is to identify nephrotoxicity,

which occurs when various treatments/drug products are administered.

The kidney integrates several different tissues with the proper environmental

conditions, making it difficult to model. Interstitial, glomerulotubular, proximal,

ascending, distal tubule, and renal endothelial cells make up the kidney. Using

four different co-cultures instead of a single kidney model allows both morphology

and biochemical conditions to be utilized as well as the proximal, distal, and distal

tubules. This is a simplified procedure to study drug toxicity, which mimics the renal

nephrons on the chip. This model aids in drug filtration and understanding of the rate

of molecules’ reabsorption. The chip serves as the basis for the convoluted proximal

tubule, the ‘nephron’s glomerulus’, and the ‘loop of Henle’. A single silicon chip

was rumoured to contain a three-component artificial nephron function. Numerous

factors preclude the use of [kidney] pods in the fabrication of kidney-on-chips,

including the absence of human podocytes, the primary element of the glomerulus.

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