Science in Images: Tissue Mimics

If you ask most people, they have an opinion on the use of animals in research. Despite the need for animals in some situations, there are many scenarios where viable alternatives do exist.

Imaged below are hydrogels: soft-solids consisting of over 90% water. Hydrogels are already heavily utilised in research, from tissue engineering to drug delivery.


Hydrogels are great candidates for tissue mimics and in turn, the replacement of animals in some experiments. The properties of the gel can be individually tailored and designed such that the strength, charge and other characteristics are similar to a tissue sample.

In this case the hydogel is comprised of agarose, a polysacharide (carbohydrate), whose long chains make up the framework around which the water resides.

Hydrogels with similar properties to brain tissue were fabricated and used to test a large number of MRI contrast agents: the final therapeutic use is as an agent for labelling stem cells, for implantation into the brain, for cell therapy.

For cellular therapy to be effective, we need to know if cells remain in the correct location and are performing the correct function. One way to do is to label them before implantation, so we can image them with an MRI.

Samples of contrast agent are prepared and injected into the gel, before they are imaged. By using hydogels in this way, we can test many combinations of contrast agents quickly, cost-effectively and without the use of animals.