Invisible Pink Unicorn writes "Researchers at MIT have found a way to induce cells to form parallel tube-like structures that could one day lead to tiny engineered blood vessels. The researchers found that they can control the cells' development by growing them on a surface with nano-scale patterning. The work focuses on vascular tissue, which includes capillaries, the tiniest blood vessels. The team has created a surface that can serve as a template to grow capillary tubes aligned in a specific direction. The cells, known as endothelial progenitor cells, not only elongate in the direction of the grooves, but also align themselves along the grooves. That results in a multicellular structure with defined edges — a band structure. Once the band structures form, the researchers apply a commonly used gel that induces cells to form three-dimensional tubes."