The human body knows 3 types of cartilage. Hyaline cartilage, which you can find on joint surfaces, fibrocartilage, which can be found in intervertebral disks, and elastic cartilage which is most comparable to hyaline cartilage but more flexible, and which can be found in the ear. This last one is what we will mainly be focussing on during this project, since we will ultimately try to find a solution for printing cartilage to reconstruct burned ears.
First of all focussing on the structure of cartilage, you can find two types of cells in there: chrondroblasts and chrondocytes. The chrondroblasts, which produce the ground substance while their fibroblasts add fibres to the matrix. While the matrix accumulates, the chondroblasts become trapped in the matrix’ so called “lacunae” and that’s when they change into chondrocytes. Cartilage does not consist chondroclast, in contrary to bone, which causes that nothing stops the growth of cartilage. That’s why elderly have such big ears, because they keep on growing. Also, the absence of these chondroclasts cause that you can’t remodel cartilage and you can’t take cartilage away.
Cartilage is in contrary to bone avascular, which means that there are no blood vessels running through the cartilage. This causes that cartilage grows very slowly, because there aren’t a lot of resources. That’s why the ear has a perichondrium. The perichondrium functions in the growth and repair of cartilage because it helps to get the cartilage what it needs even though there are no blood vessels.
So what happens for burning victims? If the burning wounds take away too much of the ear, causing the perichondrium to be damaged, the burned cartilage can’t reconstruct itself, and infections force the removal of the burned piece. Since cartilage is essential for the form as well as the function of the ear, and donor cartilage is limited, there have been designed multiple reconstructing softwares to rebuild the ear from scrap. However, even though it’s proven that stamcells in combination with cartilage cells can rebuild cartilage, getting the cartilage in the right form with the right properties is challenging. And this is when the so called “scaffold” plays an important part. A scaffold is a sort of temporary supportive material. During this project we will try to find an universal scaffold, which can be printed on any kind of shape. The cells need to be attracted to this universal scaffold, so that the ear can continue to re-build itself again.