Worms may spin silk fit for skin. (Technology).

Silk cocoons could become puffs of valuable human proteins if a new bioengineering method developed by Japanese scientists pans out.

In the past few decades, various biotechnology research teams have devised ways to mass-produce medically or industrially useful proteins by modifying the DNA of organisms. The animals create the proteins in their cells, milk, urine, or eggs (SN: 4/6/02, p. 213).

Now, Katsutoshi Yoshizato of Hiroshima University and his colleagues have genetically altered silkworms to produce a partial form of human collagen in their silk. Collagen is the structural protein in skin, cartilage, tendons, ligaments, and bones.

Given that silkworms worldwide annually spin about 60,000 tons of silk, the technique could lead to inexpensive, high-volume manufacture of collagen for artificial skin grafts. The method might also produce the blood-serum component albumin and other proteins, the scientists say.

In the January Nature Biotechnology, Yoshizato and his team report attaining concentrations of 0.8 percent collagen in the altered silkworms' cocoons. "If we raised the yield to 10 percent per total protein weight, we could produce it cheaply enough," Yoshizato predicts.--P.W.