Recombinant spider silk protein hydrogels show promise for cell culture and tissue engineering

In a groundbreaking study, scientists at the Karolinska Institutet have revealed the remarkable qualities of recombinant spider silk protein hydrogels. These hydrogels exhibit numerous attractive characteristics, making them highly desirable for various applications. By simply incubating them at a temperature of 37°C, cells and bioactive molecules can be easily encapsulated within the hydrogels. Additionally, their transparent nature allows for convenient monitoring of the encapsulated cells, while the fibrillar network closely resembles that of the extracellular matrix. The mechanical properties of these hydrogels can be tailored to match different tissues, and they can even be utilized for sustained drug release.

The potential of artificial spider silk, produced from proteins generated in alternative hosts, is extremely promising as a biomaterial. Researchers at the Karolinska Institutet’s Department of Biosciences and Nutrition have already developed a biomimetic method for producing spider silk proteins and fibers, eliminating the need for harsh organic solvents.

This remarkable achievement was made possible through the creation of a small spider silk protein known as spidroin. One significant advantage of this mini-spindroin is its ability to be mass-produced, with an impressive yield of 14.5 grams of purified protein per liter of culture in bioreactors. Furthermore, the purification process can be semi-automated, streamlining production.

Recently, the research team made another exciting discovery: recombinant mini-spindroins can spontaneously form hydrogels within minutes when incubated at 37°C, without the need for crosslinkers. This gelation process occurs within a temperature and time range that is compatible with most bioactive agents and living cells. The resulting hydrogels possess a nano-sized fibrillar network structure, paving the way for the development of a novel hydrogel system for applications in cell culture and tissue engineering.

Tunable to match different tissues

In an exciting new publication in Advanced Functional Materials, researchers Tina Arndt and Urmimala Chatterjee demonstrate the remarkable capabilities of recombinant spider silk protein hydrogels. Their study reveals that these hydrogels can successfully encapsulate human fetal mesenchymal stem cells, resulting in their excellent survival and viability. Notably, the mechanical properties of the hydrogels can be finely adjusted by modifying the protein concentration, allowing them to mimic the characteristics of different tissues, such as muscles and cartilage.

Additionally, the researchers have discovered that mixtures of recombinant spider silk proteins and green fluorescent protein (GFP) can form gels. Importantly, functional GFP is gradually released from these gels, indicating that bioactive molecules incorporated into the hydrogels retain their activity and can diffuse throughout the gel matrix. This exciting finding suggests that the hydrogels hold significant potential for applications in drug delivery.

Continuing along the same line of investigation, the team successfully encapsulated ARPE-19 cells within the hydrogels. These encapsulated cells exhibited sustained viability and were found to continuously produce the growth factor progranulin. The released progranulin diffused through the hydrogel structure and was detectable in the cell culture medium throughout the entire 31-day study period. This observation further highlights the versatility and potential of the hydrogels for various biomedical applications.

Source: Karolinska Institutet

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