Researchers from MIT and Lincoln Laboratory are developing innovative bioabsorbable fabrics that replicate how soft tissues naturally stretch, providing a better environment for cell growth and tissue repair.

Severe or chronic soft tissue injuries, such as damage to skin and muscle, present significant challenges in healthcare. Current treatment methods are often expensive and ineffective. With chronic wounds becoming more common due to conditions like diabetes and vascular disease, along with an aging population, the demand for better healing solutions is growing.

One promising approach involves implanting biocompatible materials embedded with living cells—called microtissues—into wounds. These materials act as scaffolds, allowing stem cells or precursor cells to grow and repair damaged tissue. However, traditional scaffold materials struggle to mimic the way human tissue flexes and moves. If these scaffolds stretch too much, they can also stretch and damage the embedded cells, which slows healing and may trigger an immune response.

MIT Lincoln Laboratory researcher Steve Gillmer explains that human tissue doesn’t stretch in a simple way but rather unfolds or "uncrimps" before extending. This unique characteristic prevents cells from being damaged during movement. Replicating this process in engineered materials is key to improving soft tissue repair.

Gillmer, along with MIT Professor Ming Guo and the Defense Fabric Discovery Center (DFDC), is working to design knitted fabrics that mimic this natural movement. The collaboration began when Guo, who was researching how stem cells grow on flexible materials, encountered difficulties scaling up his electrospun nanofiber structures for larger tissue repair applications. Gillmer suggested using industrial knitting machines available at Lincoln Laboratory to develop larger-scale fabric structures.

The team experimented with three basic knit patterns: jersey, ribbed, and interlock. Jersey knits, like those found in T-shirts, stretch by extending their yarn loops. Ribbed knits, similar to sweater cuffs, stretch in an accordion-like manner. Interlock knits, a denser variation of ribbed fabric, contain more yarn per inch, providing additional surface area for cell embedding.

Initially aimed at treating skin and muscle injuries, the project has broader implications, with the potential to mimic various soft tissues such as cartilage and fat. The team has recently filed a provisional patent outlining how to create these specialized knit patterns and select suitable yarn materials. This research provides a "toolbox" for tailoring knitted structures to match the mechanical properties of different types of injured tissue.