Role of microbiota in epithelial homeostasis: Germ-free mice and organoids as model systems

what is EdU?

EdU (5-ethynyl-2 -deoxyuridine) staining′ = IMPROVED version of traditional BrdU

How do you study the effect of microbiota on a biological process in vivo?

Use animals devoid of microorganisms – either:

- Animals treated with specific antibiotics

- Germ-free animals

Approach 1: Use animals devoid of microorganisms – either:

• antibiotic treatment:

• germ free conditions: model organism is bread and and kept in a sterile environment isolator to prevent their exposure to microorganisms

How do you study the effect of a specific niche factor on tissue development or homeostasis?

Use organoids

• Ex vivo, reductionist

method (i.e. in the absence

of other signals)

• To study how individual

niche components regulate

SC behaviour

- e.g. individual bacterial

preparations

• Complementary to in vivo

animal studies

Approach 2 (ex vivo)

Culture organoids with specific factors

Organoids = recapitulate much of the cell

composition and architecture of the in vivo organ

from which they derive

How do you identify a specific type of cell among various cells?

Detection of specific cell-surface or intracellular protein markers

- Immunohistochemistry

- Flow cytometry