In vivo vs in vitro systems
The etymological origins of in vivo and in vitro comes from Latin, in vivo describes something within a living organism while in vitro describes something in glass such as a test tube or petri dish. An in vivo study involves living organism such as animals or plants. In vitro experiments refer to work carried out with cells, tissues or other biological components that have been removed from the living organism of interest. While in vivo and in vitro are both essential for biological research, they present their own advantages and challenges (1).
Before an experimental drug is studied in vivo, it is important for its mechanism of action and complexity to be thoroughly evaluated by in vitro models. In vitro models provide a starting point for researchers to gather insights into how cells response to a new drug in a controlled and isolated environment (2).
In vitro testing systems
In vitro testing is an essential component of biological research that provides a way to study the response of human, animal, or microbial cells in culture. An organ-on-a chip is a three-dimensional, microfluidic device that combines cell culture with biomedical engineering to simulate the physiological environment of an entire organ in vitro. This method has emerged as a promising platform for advanced drug development studies and are currently being applied to better understand the molecular mechanisms of liver, kidney, heart, lung, and brain diseases (3).
In vivo testing systems
In vivo testing plays a vital role in drug discovery involving animal testing and clinical trials. Before a drug candidate is tested in human subjects, it must undergo animal testing to further evaluate its toxicity, metabolism and over efficacy. Vertebrate animal models such as primates, dogs and rabbits are commonly used for pre-clinical studies. Mice are the most used vertebrate species due to factors such as size, ease of handling, fast reproduction, and low cost. Mice also share 95% of their genes with humans, which makes them very attractive models for studying human diseases (4).
1. Lorian V. Differences between in vitro and in vivo studies. Antimicrob Agents Chemother. 1988
2. Gillette JR. Problems in correlating In vitro and In vivo studies of drug metabolism. In: Benet L.Z., Levy G., Ferraiolo B.L. (eds) Pharmacokinetics. Springer, Boston, MA. 1984.
3. Miwa T, Kanda M, Umeda S, et al. Establishment of peritoneal and hepatic metastasis mouse xenograft models using gastric cancer cell lines. In Vivo. 2019;33(6):1785-1792.
4. Lee J, Kim S. Kidney-on-a-Chip: A new technology for predicting drug efficacy, interactions, and drug-induced nephrotoxicity. Curr Drug Metab. 2018;19(7):577-583.