Stem-cell-loaded silk scaffolds speed healing of injured tendons
Tendon injuries are painful and don’t always heal properly. Researchers at the Terasaki Institute have now shown that silk scaffolds loaded with stem cells can help tendons regenerate more effectively.
Tendons are the crucial tissues that connect muscle to bone, but they can be torn or ruptured by movements during sport or other physical activity. These injuries can take weeks or months to heal, and even then they usually don’t recover fully, leading to weaker tendons and an increased risk of another injury.
In recent years researchers have experimented with ways to aid the regeneration of injured tendons. That includes hydrogel scaffolds with the same consistency as natural tendons to help speed up the healing process, or a two-faced material that can firmly hold two sections of a tendon together while allowing it to glide against other tissues. Others use scaffolds loaded with stem cells.
For the new study, the Terasaki researchers developed their own scaffold that could support the tendon while it healed. This scaffold was made of silk fibroin paired with a hydrogel known as GelMA – the former gave the scaffold strength and stretchability, while the latter is biocompatible and encourages cells to attach and grow.
After experimenting to get the right ratios of ingredients, the team fabricated nanofiber sheets of their silk fibroin and GelMA (SG) material. Then the sheets are seeded with mesenchymal stem cells (MSCs), which can not only differentiate into several cell types, but also aid regeneration by producing signaling molecules that summon immune cells to the area and encourage new blood vessels to form.
The team tested these stem-cell-loaded SG sheets in rats with injuries to their Achilles tendons. Compared to other scaffolds loaded with stem cells, those made of SG healed the tendons the fastest, while also forming densely packed tendon fibers, reducing injury sites, and remodeling the muscle components.
“The synergistic effects of GelMA’s capacity for supporting regenerative tissue formation and the structural advantages of silk fibroin make our composite material well suited for tendon repair,” said HanJun Kim, lead researcher on the study.
The team hopes that with further work, the stem-cell-loaded scaffolds could eventually lead to new therapies for tendon injuries.
The research was published in the journal Small.
Source: Terasaki Institute