US Research And Development Of New Human Tissue Replacement Materials Can Preserve Athletic Ability For Patients With Tendon Injuries.

The research team of Massachusetts Institute of Technology (MIT) has developed a new type of human tissue replacement material, which is made up of nanofibrous lines coated with living stem cells. It is expected to help the damaged tissue recover quickly when maintaining normal or partial motor function.

As we all know, people who are keen on running fitness are very concerned about the health of their knees.

Once the key parts of the knee are injured, the motion function of the human body will be greatly reduced. Surgical repair, convalescent and complete healing will take a short period of time for weeks and long periods. Only limited activity can be performed during the period, or there will be two injuries.

The new materials developed look like a string of twisted threads.

Each strand contains hundreds of thousands of biocompatible nanofibers, which are twisted together in a special spiral way. It looks a bit like the handle line of a telephone. Even stretching and bending will not damage the surface fragile cells for many times, and the reason why the stem cells are coated on the material surface is that they can arrange and grow along the nanofiber line and eventually form corresponding human tissues, such as muscles and tendons.

The study is published in the proceedings of the National Academy of Sciences (PNAS).

Flexible materials inspired by lobsters

Guo Ming, assistant professor of mechanical engineering at Massachusetts Institute of Technology, said he was inspired by the lobster belly film and invented the new nanofiber rope.

Guo Ming's previous research has pointed out that lobsters have unique abdominal tissues. The films are not only resilient but also highly elastic. They can even be compared with rubber tires.

After careful observation, his team found that the tissue membrane after cutting appeared layered structure, similar to the plywood structure made by man.

Professor Guo believes that if we can develop flexible materials with similar strength and toughness, they may be applied to parts of the body that are often stretched, such as shoulders and knees.

Generally speaking, hydrogel is a hot research field in this field, such as muscle tissue.

But consider further that if you want to put muscle or other stem cells on it to help restore human tissue, hydrogel alone is hard to achieve.

Although hydrogels are highly malleable, it also breaks the connection between the surface cells and leads to cell death.

The relationship between them is similar to gum sticking to paper towels, and a gum will tear off a small piece of paper and destroy the paper towel.

Therefore, if we want to design a material to help muscles and tendons recover, we should not only consider the ductility of materials, but also consider how to protect cells during vigorous stretching.

Tight spiral structure

In humans, the real tendon tissue is made up of well arranged protein bundles, which spiral together, and the muscle cells grow along the spiral structure.

If the protein fiber is stretched, the cells will rotate along the helix, clinging to it without breaking or damaging.

This is the inspiration that the research team needs.

They then began to try to replicate this structure with artificial materials to protect cells.

First, the researchers used electrospinning technology to create hundreds of thousands of aligned nanofibers.

This technology can produce ultra-fine fiber thread through polymer solution under the action of high voltage electrostatic.

They use materials such as cellulose (cellulose) which have good biocompatibility and are suitable for implantation into human body.

Later, the researchers tied these neat fibers together and twisted them slowly into a spiral shape. They once again fastened the whole body to form a yarn like product with a width of about 0.5 millimeters.

These yarns were finally "wrapped" on a lot of live cells, including muscle cells and mesenchymal stem cells.

Preparation and characterization of spiral yarn

Professor Guo's team found that most of the cells could still survive after stretching each spiral (twined filament line) to 6 times the original length.

Interestingly, when cells are placed on the same material, but with a looser fiber structure, cells are less likely to survive.

This means that the tight spiral structure plays a role in protecting cells, and the closer the protective effect is, the better.

Under strong tensile force, spiral scaffolds protect cells from injury.

Effect of spiral scaffold on myocyte production

In the future, the research team plans to use other biocompatible materials to produce similar yarn, and may try to implant it into human damaged tissue under skin.

Compared with hydrogel technology, the advantage of this technology is that the elastic fiber can be used as a temporary scaffold for the growth of new cells. Therefore, in the process of muscle tissue recovery, the injured part can be guaranteed to have some motor function, and after the tissue is repaired, these materials will be dissolved, leaving only new cells and tissues.