Disease & implant models
Human tumour cells or patient-derived tumour fragments implanted subcutaneously (or orthotopically) in immunodeficient mice, randomised to treatment when tumours are established, and measured with callipers against a burden limit.
Our ruleSimulations prepare you for the bench but don't replace hands-on practice.
Xenografts
Human tumour cells or patient-derived tumour fragments implanted subcutaneously (or orthotopically) in immunodeficient mice, randomised to treatment when tumours are established, and measured with callipers against a burden limit.
How it differs from the standard method
- Immunodeficient hosts: nude, SCID, NSG.
- Randomise at about 100–150 mm³.
- Volume = length × width² / 2; endpoint at 12 mm mean diameter or ulceration.
1A disease, a material or a wound in a living animal
Some questions only have answers in a whole organism: whether a compound slows a tumour that has its own blood supply, how the body walls off an implanted material, or how skin closes a wound with blood flow, immune cells and mechanical tension all acting at once. Disease and implant models create that situation in a controlled way, and they carry an ethical cost that has to be justified, minimised and watched every day.
Tumour xenograft
Human tumour cells grown under the skin of immunodeficient mice; volume from callipers tracks treatment.
Subcutaneous implant
A material placed in a dorsal pocket; the fibrous capsule around it measures the foreign-body response.
Excisional wound
Full-thickness skin wounds under anaesthesia and analgesia, splinted so they heal by re-epithelialisation.
2What makes these models interpretable
The host has to suit the model: human cells are rejected by an intact immune system, so xenografts need immunodeficient mice. Groups must start equal, so tumour studies randomise once tumours are established rather than on the day of injection, and outcomes are measured blind.
3Welfare is part of the design
Surgery is aseptic and done under general anaesthesia with analgesia started before the incision and continued afterwards. Every model has humane endpoints written in advance: a tumour burden limit (commonly a mean diameter of 12 mm in mice), ulceration, wound breakdown, infection or weight loss of around 20%.
4The 3Rs in these models
Use a non-animal model first
Organoids, spheroids, tumour-on-chip and in vitro cytotoxicity and endotoxin tests answer many questions without animals; an animal model is used only for what needs a whole organism.
As few animals as answer the question
Group size comes from a power analysis on pilot variability; randomising established tumours, paired wounds on one mouse and longitudinal imaging all cut the numbers needed.
Least suffering for every animal used
Pre-emptive and continued analgesia, aseptic surgery, nesting material and enrichment, tunnel handling, the smallest tumours, implants and wounds that work, and humane endpoints applied daily.
Key terms
Practise these as flashcards →Tissue or cells from one species grown in another, typically human tumour cells in immunodeficient mice.
The fraction of injected animals in which a tumour establishes.
How much smaller treated tumours are than vehicle tumours at a set time, usually compared on log volume.
The maximum tumour size allowed before the humane endpoint; commonly 12 mm mean diameter in mice.
The inflammatory and fibrotic reaction to an implant, ending in a collagen capsule around it.
A rodent excisional wound held open by a sutured ring so that it heals by re-epithelialisation rather than contraction.
The thin muscle layer under rodent skin that drives rapid wound contraction; humans largely lack it.
When to use it
- Testing whether a treatment slows the growth of an established tumour with its own stroma and blood supply.
- Assessing the local tissue response to a biomaterial before clinical use, as standards such as ISO 10993-6 require.
- Measuring how a treatment changes wound re-epithelialisation in tissue with circulation and immune cells.
Compared with alternatives
Patient-derived organoids and spheroids answer many drug-response questions without animals; use them first and keep animal models for what needs a whole organism.
Bioluminescent tumour lines and micro-CT follow disease and implants in the same animals over time, often reducing the numbers needed.
How the implanted materials are made; in vitro cytotoxicity and endotoxin testing come before any implantation.
Sub-techniques
Choosing one here switches the whole page, including the protocol and the lab, to it.
Human tumour cells or patient-derived tumour fragments implanted subcutaneously (or orthotopically) in immunodeficient mice, randomised to treatment when tumours are established, and measured with callipers against a burden limit.
- Immunodeficient hosts: nude, SCID, NSG.
- Randomise at about 100–150 mm³.
- Volume = length × width² / 2; endpoint at 12 mm mean diameter or ulceration.