A living medicine is a type of biologic that consists of a living organism that is used to treat a disease. This usually takes the form of a cell (animal, bacterial, or fungal) or a virus that has been

genetically engineered Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...

to possess

therapeutic A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many different ...

properties that is injected into a patient. Perhaps the oldest use of a living medicine is the use of leeches for

bloodletting Bloodletting (or blood-letting) is the withdrawal of blood from a patient to prevent or cure illness and disease. Bloodletting, whether by a physician or by leeches, was based on an ancient system of medicine in which blood and other bodily flu ...

, though living medicines have advanced tremendously since this time. Examples of living medicines include cellular therapeutics (including immunotherapeutics), phage therapeutics, and bacterial therapeutics, a subset of the latter being

probiotic Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria-host i ...

Development of living medicines

Development of living medicines is an extremely active research area in the fields of

synthetic biology Synthetic biology (SynBio) is a multidisciplinary area of research that seeks to create new biological parts, devices, and systems, or to redesign systems that are already found in nature. It is a branch of science that encompasses a broad ran ...

and

microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, prot ...

. Currently, there is a large focus on: 1) identifying microbes that naturally produce therapeutic effects (for example, probiotic bacteria), and 2) genetically programming organisms to produce therapeutic effects.

Applications

Cancer therapy

Schematic of therapeutic bacteria strategies against hypoxic tumors

Mechanisms by which bacteria target tumors

There is tremendous interest in using bacteria as a therapy to treat tumors. In particular,

tumor-homing bacteria Tumor-homing bacteria are facultative or obligate anaerobic bacteria (capable of producing ATP when oxygen is absent or is destroyed in normal oxygen levels) that are able to target cancerous cells in the body, suppress tumor growth and survive i ...

that thrive in

hypoxic Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the t ...

environments are particularly attractive for this purpose, as they will tend to migrate to, invade (through the leaky vasculature in the

tumor microenvironment The tumor microenvironment (TME) is the environment around a tumor, including the surrounding blood vessels, immune cells, fibroblasts, signaling molecules and the extracellular matrix (ECM). The tumor and the surrounding microenvironment are ...

) and

colonize Colonization, or colonisation, constitutes large-scale population movements wherein migrants maintain strong links with their, or their ancestors', former country – by such links, gain advantage over other inhabitants of the territory. When ...

tumors. This property tends to increase their residence time in the tumor, giving them longer to exert their therapeutic effects, in contrast to other bacteria that would be quickly cleared by the immune system.

References

{{reflist, 30em Bacteria and humans Biological engineering Biotechnology Biotechnology products Biopharmaceuticals Pharmaceutical industry Life sciences industry Specialty drugs Pharmacy