We may be on our way to a new treatment for osteoarthritis.
A team of engineers from Penn State has used strands of cow cartilage in a 3D bioprinting process that could potentially be used to create patches of cartilage for patients suffering from osteoarthritis or worn out joints.
"Our goal is to create tissue that can be used to replace large amounts of worn out tissue or design patches," Ibrahim T. Ozbolat, associate professor of engineering science and mechanics, said in a press statement. "Those who have osteoarthritis in their joints suffer a lot. We need a new alternative treatment for this."
According to the press release, once cartilage is damaged, it remains damaged and the tissue cannot repair itself. However, it makes a good tissue for bioprinting since it contains no blood vessels and is only made up of one cell type.
In the past, researchers have attempted to grow cartilage using hydrogel, which is a substance made of about 90 percent water as well as polymer chains (chains of simple molecules).
However, the problem with hydrogel is that it doesn’t allow the cells to grow normally. Instead, it “confines the cells and doesn't allow them to communicate as they do in native tissues,” explains Ozbolat.
Further, degradation of the hydrogel can create toxic compounds that have the potential to harm cell growth.
In the new study, which appears in the journal Scientific Reports, the research team created tiny tubes (with diameters from three to five one hundredths of an inch) from an algae extract called alginate. Cartilage cells don’t stick to alginate, so the researchers can inject them into the tubes and leave them to grow and adhere to each other for about a week. Then, the tube can be removed and a strand of cartilage will be left behind.
Further, the researchers use a specially designed prototype nozzle that enables them to lay down the rows of cartilage strands in any pattern they choose.
"We can manufacture the strands in any length we want," said Ozbolat. "Because there is no scaffolding, the process of printing the cartilage is scalable, so the patches can be made bigger as well. We can mimic real articular cartilage by printing strands vertically and then horizontally to mimic the natural architecture."
The researchers say that their artificially produced cartilage is similar to native cow cartilage, but the mechanical properties are inferior. However, Ozbolat suspects that putting mechanical pressure on the artificial cartilage would improve the mechanical properties, since natural cartilage forms with pressure from the joints.
If the process is applied to human cartilage in the future, the process would likely require each individual to supply their own cells to avoid tissue rejection — either existing cartilage or stem cells.
To see the process in action, check out the video below.
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