New shrinking gel could help repair damaged teeth or bones

Scientists from the Harvard School of Engineering and Applied Sciences (SEAS) have developed a new gel-based material that could allow stem cells to fill in the gaps in teeth and bones. This advance in tissue engineering comes from an examination of embryonic development. The researchers have essentially created a material that mimics the physical conditions under which tissue forms naturally specifically, the gel shrinks.

Tissue engineers have been wrestling with the difficulties of coaxing human cells to form three-dimensional structures in the lab, but the combination of growth factors and artificial gene activation cant quite get us there. The bio-inspired gel developed at SEAS could be the first step in solving those problems. This is the first approach that has taken a process called mesenchymal condensation into account.

Mesenchymal condensation is a process involving two tissue layers in embryos where organ formation takes place. A layer of undifferentiated connective tissue cells (mesenchyme) and an epithelium exchange biochemical signals, which causes the mesenchymal cells to contract and form a small knot right where the new organ tissue is supposed to develop (see the image at the top). Mesenchymal cells are a type of stem cell that can develop into bone, enamel, fat, and other mature cells.

The gel developed at SEAS simulates the compressionthat mesenchymal cells would experience naturally in mesenchymal condensation. A modified form of PNIPAAm polymer forms the base of the gel. It normally contracts when warmed slightly, but was tweaked in this experiment to activate at body temperature. The loose matrix of the gel is impregnated with mesenchymal cells, which are compressed as it warms. Thats how theyre encouraged to start differentiating into the appropriate types of cells and lay down new tissues, in this case teeth composed of dentin and enamel.

In embryonic development, mesenchymal cells cant form complete teeth without that extra epithelial layer. The team hopes to test its shrinking gel with both tissue layers to see if it can form a full tooth all on its own. Other tissue types could follow if the team finds that its shrinking gel works.

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New shrinking gel could help repair damaged teeth or bones