Tropoelastin: The quest for innovative materials for wound care treatment and management

Modern wound dressings support the body to promote wound healing and shorten treatment time. Physicians have a multitude of products at their disposal.

In a joint research project that ended at the end of 2021, the Fraunhofer Institute for Microstructure of Materials and Systems, the Martin Luther University Halle-Wittenberg, and Skinomics GmbH examined whether a structural protein is suitable as a wound dressing material.

In this COMPAMED-tradefair.com interview, Dr. Christian Schmelzer from the Fraunhofer IMWS talks about the potential benefits of using human tropoelastin and details the progress the researchers have made in their endeavor.

Dr. Schmelzer, what exactly is tropoelastin?

Dr. Christian Schmelzer: Tropoelastin is formed in our cells but is merely a kind of intermediate stage. It is the precursor to elastin. It forms outside the cell, in the so-called extracellular matrix, by cross-linking the tropoelastin molecules into a network. The resulting fibers are only between two to three microns in diameter and are assembled in different ways in our body. In the skin, the fibrous structure is two-dimensional and relatively random. Three-dimensional, lamellar structures can be found in the blood vessels. Meanwhile, cartilage features honeycomb structures - depending on the mechanical deformations the corresponding organs and tissues must undergo. After all, the role of elastin is to provide human tissue with elasticity and resilience. The project idea was to use the intermediate product - tropoelastin - to get a product we can modify to achieve an individual and customized application.

What are the benefits of human tropoelastin in wound treatment?

Dr. Schmelzer: Injuries lead to damages of elastin, which cannot be recreated by the body. Meanwhile, the body does not recognize human tropoelastin as a foreign substance and does not produce an immunological rejection.

Our material is degradable, which means something could be fed back into the body. You could conceivably use it as a carrier of drugs or active substances, meaning you could embed painkillers or anti-inflammatory substances for controlled release.

We also consider the mechanical properties carefully. The wound dressing should exhibit a certain deformability.

Since we use recombinant methods to produce the tropoelastin (editor’s note: biotechnological production), we can subsequently influence the mechanical properties and the enzyme stability. It means we have a material that can both be customized to the position of the wound and mechanical requirements and the specific type of wound.

What were the steps in the project to produce this biomedically applicable material?

Schmelzer: First, we had to create a process that would allow us to produce and purify a recombinant tropoelastin. In our case, we produced the protein using an E. coli bacterial system. We have optimized this production process to get the largest possible quantity with a high level of purity. In a subsequent step, we wanted to modify the product. Our goal was hydroxylation, which also occurs in native tropoelastin. Although this is a very difficult endeavor, we succeeded towards the end of the project.

This was a joint research project. The Martin Luther University Halle-Wittenberg (MLU) developed the biotechnological process for modifying the recombinant tropoelastin. Our task at IMWS was to identify the specific modifications and where in the material they occur. There are a series of modifications before elastin is created.

This was followed by some further processing at the Fraunhofer Institute. We used electrospinning to produce semi-finished products. The process facilitates the production of fibers with a very small diameter. We are talking about dimensions in the sub-micrometer range, i.e., in the order of several 100 nanometers. It enabled us to replicate the natural fibers in the body effectively.

We then characterized the resulting material as it pertains to pore size, fiber diameter, biocompatibility, and mechanical properties. Skinomics GmbH conducted preclinical tests and developed demonstrators from the produced materials.

The project has been completed. What insights did you gain during the project period?

Schmelzer: We have achieved a multitude of exciting results. We could show the feasibility in this project. For the first time, we have succeeded in integrating these types of natural modifications in a synthetically made material. This is not always an easy feat when it comes to biotechnologically produced products. The resulting nonwovens and hydrogels can definitely be processed as wound dressing when applied to the respective carrier material. That being said, we are still a long way from a finished product. The high manufacturing costs currently put a limit on things. The best wound dressing product is useless if it costs too much.

While we are still planning to work on using tropoelastin for wound dressings, we must consider scaling and the cost factors. We also intend to hone the modifications since we think there is still great untapped potential in this area - not just as it pertains to better wound dressings, but also with regard to understanding the general function and mechanism of elastin throughout the body.