Heal Thyself

The self-healing abilities of the bodies of living organisms are truly impressive.

Have you ever had a toy break, or seen a crack in the pavement? You may have noticed that when you break a bone or cut your skin, your body can repair itself over time. What if the things people make – toys, cars, roads, bridges, etc. – didn’t have to stay broken, but could fix themselves, just like our bodies can?

You will need to do some preparation in advance. A few weeks/months (depends on the size of the wound) before the demonstration, cut a small branch (leaf) of a houseplant in the classroom. The experiment can of course be suitably modified using a tree or shrub in the vicinity of the school or if you find a plant injury that has already healed over.

1. Cut a similar twig in front of your pupils and ask them what they think will happen to the injury.
2. Ask pupils to observe and compare the fresh and already healed wounds on the plants. Discuss together what you observe. What happened first? What followed? How is this ability beneficial to the plant? How will it continue? Will a replacement twig (leaf) sprout?
3. Ask pupils if they have any cuts or scars on their skin and note how it has healed.
4. Next, take out a piece of building material, for example a brick. Ask for one volunteer among your pupils to break the brick with a hammer.
5. Ask pupils what will happen to the brick in the next few days? The answer is clear and so we ask further if they would like buildings, roads or toys that could 'heal' themselves as living nature can do? How might self-healing human things be useful?

How is it that living organisms are able to repair themselves? And how do they actually do it? Is it realistic for people to be inspired by them, for example, when developing modern building materials?

Simple explanation

In living organisms, the seat of wisdom is not only the brain, but every part of their body. For example, our entire body is full of various receptors that constantly detect what is happening to us. Every minor injury is therefore discovered and the remedial process begins immediately.

Everyone has probably experienced a case where they cut theirself and the wound gradually healed on its own. For such a repair process, the body has various specialized cells that work as a well-coordinated team taking turns in their actions to repair the body. Part of this team is tasked with preventing blood from flowing by plugging broken vessels. Part of the team removes the damaged cells and tissues, another unit sends defenders to the site to prevent infection. Another unit begins to bind the disturbed site, etc. until healing is complete.

More detailed explanation

In a little more detail, we can see the ability of self-healing that takes place after a bone is broken. In the body, such a situation sets off an alarm that starts a series of steps that lead to healing. The text below describes the individual steps involved in the various specialized cells of the body. It is incredible how the body can perfectly coordinate the entire complex process:

“Within hours of the bone fracture, a blood clot forms around the fracture containing special immune cells that remove bone fragments and any unwanted microbes that enter the site. Next, a soft protective callus is formed. Then comes the time for special cells capable of producing bone mass. These deposit calcium and phosphate crystals in the soft collagen callus, thereby strengthening the substance into new bone tissue. At the same time, they are able to coordinate with each other incredibly effectively. Eventually, the cells clean and remove any unwanted bone around the fracture site until the repaired bone acquires a shape similar to its pre-injury appearance.” (Source: AskNature)

The self-healing mechanisms of living organisms have evolved for an incredibly long time. As a result, they are very efficient. It's different with human buildings. If people were inspired by nature, it would bring incredible savings of money, materials and energy, and it would increase the safety of buildings many times over. By the way, do you know how long the road leading to your school (plaster on your school, etc.) will last without repairs?

Let's look at one example. Concrete may seem like an permanent material, but the opposite is true. Small microcracks gradually appear in it, which slowly grow until the concrete completely disintegrates. In recent years, scientists have been inspired by nature and its self-healing abilities to develop self-healing concrete. Thanks to the addition of bacteria, concrete has been developed which can repair its own cracks. The microorganisms eagerly absorb light and produce calcium carbonate, which gradually fills the gaps in the concrete. The  service life of such material is thus many times longer (see more here).

Another useful invention is a method of repairing leaky pipes that mimics the way platelets seal the holes of a broken blood vessel (read more here).

Some STEAM opportunities include:

• Identify and compare suitability of everyday materials.
• Asking questions and making observations.
• Consider how the properties of different materials makes them suitable for different tasks.
• Discuss how changes to materials have an impact on our lives.
• Carrying out simple tests.
• Making predictions.
• Apply learning to real world problems.

Learn more about how bones heal themselves (find out more).

Self-healing concrete is inspired by nature (find out more).