A new 3-D pen uses a healing ink to deliver immune system fluids directly to cuts and wounds. 

The ink, developed by researchers in China, can be spread into a cut of any shape. It has been shown to bring wounds in mice close to closure in 12 days, the developers reported in ACS Applied Materials & Interfaces. 

The PAINT, or “portable bioactive ink for tissue healing,” system uses white blood cells, or extracellular vesicles, combined with sodium alginate. The ingredients mix at the pen’s tip and form a sturdy gel at the site of an injury within three minutes of being applied. 

The extracellular vesicles promote blood vessel formation and reduce inflammatory markers in human epithelial cells, shifting them into the “proliferative,” or growth, phase of healing, researchers said.

PAINT (pictured above) also promoted collagen fiber formation in mice, the researchers noted. They reported the tool could help heal a wide variety of skin injuries quickly and easily, without the need for complex procedures.