Pigs make human pigment.

Genetic engineers have created the first pigs carrying the human gene for hemoglobin, the oxygen-carrying pigment in red blood cells. The feat may help scientists create an inexpensive, disease-free substitute for human blood, say researchers at DNX Corp. of Princeton, N.J., the biotechnology firm that developed the transgenic swine.

John Logan of DNX presented data on one of the three pigs this week at the World Congress on Cell and Tissue Culture, held in Anaheim, Calif. Ten to 20 percent of this pig's hemoglobin is the human variety, he says.

Logan also outlined a simple method for breaking open red blood cells and separating the swine and human hemoglobins -- a crucial step toward producing a human blood substitute.

DNX President Paul Schmitt notes that isolated hemoglobin stores at room temperature for six months to a year, significantly longer than whole blood. The company plans to pasteurize the hemoglobin, a process that reduces the risk that a blood substitute will harbor disease-causing microbes.

DNX must complete animal testing and conduct human trials before the pig-produced pigment can obtain federal approval, Schmitt adds.