Table 1.

Minimum requirements for live-MPS.

Tissue	Standard existing evaluation system	Required Profile	Evaluation target	Measurement item
		• Has sufficient drug metabolic activity.	Expression of phase I enzyme activityExpression of phase II enzyme activity	CYP, AO, FMO, MAO, CES UGT, SULT, GST
		• Has sufficient transporter activity.	Functional expression of transporter	ABC, SLC
		• Has the ability to induce the drug metabolizing enzymes.	Induction of CYPs	CYP1A2, CYP2B6, CYP3A4, nuclear receptor
Liver	Human cryo-preserved hepatocyte	• Capable of long-term culture.	Cellular function	MTT, albumin, urea metabolism
		• The structure of a micro bile duct can be confirmed.	Bile pocket formation	Localization of the biliary transporterBile excretion capability
		• Has the ability to excrete bile.	Biliary transporter expression	BSEP, MRP2, BCRP, PGP
		• Long-term repeated exposure that mimics the ling body.	Zonation	Functional gradient
		• Covering various toxicity mechanisms.	Liver fibrosis	aSMA, collagen

CYP: Cytochrome; AO: Amine oxidase; FMO: Flavin-containing monooxygenase; MAO: Monoamine oxidase; CES: Carboxylesterase; UGT: Bilirubin uridine diphosphate glucuronosyl transferase; SULT: Sulfotransferases; CYP1A2: One of the monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids; CYP2B6: One of the monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids; CYP3A4: One of the monooxygenases which oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs; MTT: A colorimetric assay for assessing cell metabolic activity; Albumin: Colorimetric high-throughput assay that detects Albumin concentration in serum; Urea metabolism: Renal nitrogen metabolism primarily involves urea and ammonia metabolism and is essential to normal health; BSEP: The major transporter responsible for the secretion of bile salts from liver hepatocytes into the bile; MRP2: Efflux transporter that serves to facilitate the biliary excretion of substrates; BCRP: Efflux transporter that restricts the distribution of its substrates into organs such as the brain, testes, placenta, and across the gastrointestinal tract; PGP: A P-glycoprotein ATP-powered efflux pump which can transport hundreds of structurally unrelated hydrophobic amphipathic compounds, including therapeutic drugs, peptides and lipid-like compounds; aSMA: In the human liver, α-smooth muscle actin (ASMA) is present in smooth muscle of the vasculature, perisinusoidal cell (Ito cells), and myofibroblasts derived from perisinusoidal cells; Collagen: The collagen superfamily of proteins plays a dominant role in maintaining the integrity of various tissues.