What are in vivo and in vitro?

While the terms in vivo and in vitro sound very similar, their meanings are not. In vivo is Latin for “within the living.” It is a study model used for a process or procedure that is conducted “on” a living being rather than in cell samples. The in vivo method simulates biological conditions found in a living subject. In vivo studies may be conducted in animals and humans.
In vitro is Latin for “in the glass.” It is a study model in which a procedure is conducted in labs. Interventions may be done on a specific cell culture to grow a virus, bacterium, or fungus, or to test a new drug. Because we look at specific cells during an “in vitro” procedure and not the whole organism, these experiments are more suited for research and analysis.
Given that an in vivo model involves the internal environment of a living being, the results of in vivo studies are considered more reliable or more relevant than those of in vitro studies. This does not mean that an in vitro model is in any way less valuable.
For cases in which normal conception or in vivo fertilization fails, the doctor may advise the couple to try in vitro fertilization (IVF). In vitro fertilization happens when the ovum (female egg cell) and sperm (male reproductive cell) are united outside the body or in a “glass” petri dish.
In the world of research, “in vivo” and “in vitro” models are used in clinical trials, scientific studies, and up-and-coming medical procedures. Scientists use both these models to understand the way a drug (or intervention) affects the body (pharmacodynamic profile) and the way the body affects/breaks down the drug (pharmacokinetic profile). Both these studies serve to create a safer and effective drug profile before they are approved for use by the general population.
Let us look at an example. Suppose scientists want to study a new anti-epilepsy drug. This study goes through various stages. Initially, in vitro studies are conducted in specialized acute seizure models that only need slices of the brain tissue. These models create electroencephalography (EEG) signals (brain signals) that are identical to those seen in a patient having a seizure.
During initial testing of the drug, scientists prefer acute seizure models (in vitro) over time-consuming human trials that often involve high levels of individual variation and ethical concerns. Only those drug molecules that show promising results in the in vitro stage will be tested in human clinical trials (in vivo). Here, scientists will see if trends observed in preclinical data (in vitro model) still hold in human volunteers consistently and if the results are reproducible. Thus, drug development needs both in vivo and in vitro models before it is U.S. Food and Drug Administration (FDA)-approved.
Both in vitro and in vivo studies have their own set of advantages and disadvantages, which are explained in the table below.
Category | In vivo method | In vitro model |
---|---|---|
Cost and preparation |
|
|
Time |
|
|
Result |
|
|
Testing regulations |
|
|
Applications |
|
|
In vitro models do not put live subjects at risk. However, they cannot capture the inherent complexity of organ systems and the internal environment of the human body. For example, in vitro cell culture may not account for interactions between various body procedures and cellular biochemistry. Therefore, in vitro studies are often followed by animal studies (in vivo).
Drugs may be tested on animals such as rabbits, hamsters, mice, rats, guinea pigs, dogs, and primates (including monkeys, gibbons, and chimpanzees). Scientists can better evaluate the safety, toxicity, and efficacy of a drug candidate in a complex model (animal). The majority of animals in laboratories are purpose-bred (bred specifically to be used in experiments).
Besides ethical concerns over the use of animals for experiments, the problem of translatability persists because there are considerable physiological differences between humans and animals, and drug absorption, distribution, and excretion may differ.
Only those drugs that appear safe and effective in the in vitro stage eventually go on to the clinical trial stage or in vivo stage.
https://www.humanesociety.org/resources/animals-used-biomedical-research-faq
Top Why Is In Vivo Better Than In Vitro Related Articles
Early Pregnancy Symptoms Before Missed Period
Pregnancy symptoms vary from one woman to another. Women could have none of the symptoms but can still go on to have a perfectly healthy pregnancy. Usually missing a period after conception is considered a sign of pregnancy.16 Early Signs & Symptoms of Pregnancy: Could You Be Pregnant?
What are the early signs and symptoms of pregnancy? Can you know before your missed period? Read about nausea and vomiting (morning sickness), bloating, tender breasts, and more. Explore first trimester symptoms of pregnancy and learn what week pregnancy symptoms start.Am I Pregnant Quiz
What are early pregnancy symptoms? In some women, symptoms range from a missed period to feeling lightheaded. Others may experience typical "morning sickness" and food cravings. Could you be pregnant? Take the quiz!Exercise & Pregnancy
Pregnancy exercises and workouts for moms-to-be include Kegel exercises and prenatal yoga. A prenatal workout is an important part of healthy living. Try these safe exercises for pregnancy.How Soon Can You Get Symptoms of Pregnancy?
Early symptoms of pregnancy are usually different for every woman. Some women might experience the first symptoms a week or two after conceiving, whereas others don’t feel anything for months. Many women may tell if they are pregnant within two or three weeks of conceiving, and some women know a lot sooner, even within a few daysOvulation & Fertility
Boost fertility and increase your chances to conceive. Learn about ovulation calendars, diet, aging and other factors that can affect pregnancy.Pregnancy Myths and Facts Quiz
Being pregnant is a delicate time for both mother and baby. Take this pregnancy myths and facts quiz to separate the myths and facts about being pregnant, and learn the truth behind healthy pregnancies!Pregnancy Planning (Tips)
Pregnancy planning is an important step in preparation for starting or expanding a family. Planning for a pregnancy includes taking prenatal vitamins, eating healthy for you and your baby, disease prevention (for both parents and baby) to prevent birth defects and infections, avoiding certain medications that may be harmful to your baby, how much weight gain is healthy exercise safety and pregnancy, travel during pregnancy.Stages of Pregnancy: Week by Week
See pictures on the various stages of pregnancy. See and learn what changes a woman's body goes through and view fetal images of how her baby grows during the 1st, 2nd and 3rd trimesters.Pregnancy: 7 Common Third Trimester Tests
Testing is often recommended during the third trimester of pregnancy. These tests are designed to ensure the health and safety of both the child and mother. Common tests during the third trimester of a woman's pregnancy include:- group B streptococcus screening,
- electronic fetal heart monitoring,
- nonstress test,
- contraction stress test, and
- a biophysical profile.