June 2001 News

Hopkins Student Wins Fellowship for Human Cell Research

June 28, 2001 By Nakita Lewis

A Johns Hopkins University graduate student has received the Lasker Graduate Fellowship Award to support an innovative approach to lead research.

The Lasker Graduate Fellowship Award is presented annually by the Johns Hopkins Center for Alternatives to Animal Testing (CAAT) and the American Society for the Prevention of Cruelty to Animals (ASPCA) to a Hopkins graduate student whose research involves the Three Rs: replacement, reduction, or refinement.

This year, the award was presented to Desmond Bannon, a doctoral student in the Department of Environmental Health Sciences. Bannon is using human cells to study the absorption of lead in the intestine. Lead poisoning, especially among children, is the number one preventable disease in the United States.

Bannon worked for 10 years as a laboratory supervisor in a lead poisoning clinic before entering Hopkins as a part-time graduate student in 1996. As a result of his of background in lead poisoning, Bannon decided to become a full-time student in 1998.

Bannon's research focuses on metal transporters in the body that control the absorption of lead by the intestine. He wants to figure out how this happens. While studying lead in human cells, he came across a protein known as Divalent Metal Transporter (DMT1). Bannon said DMT1, which is found in the intestine, is affected by the amount of iron in a person's diet. Children and others who don't eat enough iron-rich foods have more of this protein.

What makes Bannon research unique is the replacement of the rat cells with the human intestinal Caco-2 cell line. Typically, researchers study lead absorption in live rats. Because of the complexity of the absorption process, scientists have needed to follow each step in a living animal. However, Bannon has developed a process with the Caco-2 cell line that closely mimics what happens in the human body. He grows the cell line on a small disc with an upper and a lower chamber. The upper and lower chamber represent the outside and inside of the duodenum, or first part of the small intestine. The cells provide the barrier between the two chambers so that absorption can be studied when lead is applied to the upper chamber.

People, particularly children, injest lead after getting it on their hands, toys, or even pacifiers. Lead is found in older homes, where the use of lead paint was common. Bannon's work may provide valuable information for physicians and parents alike. "My work is not intended as a test for lead poisoning, but it may shed light on the reasons why nutritional deficiency is a risk factor for lead poisoning," he said.

Bannon is the second Hopkins student to receive the Lasker Fellowship. CAAT and ASPCA present the award each spring to a student interested in developing new alternative methods.