Insulin is a hormone that allows blood glucose (blood sugar) to enter the cells of the body to be used for energy. The technique, known as ultrasound-targeted microbubble destruction (UTMD), delivers these insulin genes to the organ via microscopic "bubbles." Once the bubbles reach their target, they are burst with ultrasound releasing the insulin genes into the pancreas.
Using UTMD, researchers delivered the bubbles containing human insulin genes into the pancreas of rats and later found that the rat's blood sugar had been subsequently lowered. Another gene that regulates insulin production, known as hexokinase I, was successfully delivered using UTMD as well, and resulted in increased blood insulin and decreased blood sugar in the rats.
"Not only was their blood sugar lowered, but there was no evidence of any damage to the pancreas," says Paul Grayburn, M.D., principal investigator of the study. "Other forms of gene therapy are usually invasive and unlike the UTMD technique, do not target the tissues and organs specifically."
Currently, patients with Type I (juvenile onset) diabetes must inject themselves with insulin daily to keep their blood sugar levels balanced in addition to following strict nutritional guidelines. Dr. Grayburn says that the UTMD technique is one of the most important steps in the development of a successful treatment of diabetes without the need for daily insulin injections.
"Now that we have successfully delivered insulin genes to the pancreas, our ultimate goal is to research the regeneration of insulin-producing cells in patients with diabetes," says Dr. Grayburn.
In the future, Dr. Grayburn says that the UTMD technique for gene delivery can be used to deliver therapeutic agents to other organs as well.
Nationwide, more than one million people have Type 1 (juvenile onset) diabetes. Diabetes – the fifth deadliest disease in the United States – affects the body's ability to produce or respond to insulin. People with Type I diabetes are at increased risk for many serious complications, including heart disease, blindness, nerve damage and kidney damage.
Dr. Grayburn's research was supported by a grant from the National Institutes of Health and by the Mary Alice M. and Mark Shepherd, Jr. Endowment Fund in Cardiology and Cardiovascular Surgery and Research. The study was also held in conjunction with researchers from Duke University and UT Southwestern Medical Center.
Baylor University Medical Center at Dallas, a 997-bed not-for-profit academic hospital, is a major patient care and research center in the southwest. In 2005, U.S. News & World Report recognized Baylor Dallas for the 13th consecutive year in its "America's Best Hospitals" guide in several medical specialties. Baylor Dallas serves as the flagship hospital of Baylor Health Care System.
The Baylor Research Institute, an affiliate of Baylor Health Care System, promotes and supports clinically relevant research, bringing innovative treatments from the laboratory workbench to the patient bedside. Investigators at Baylor are conducting more than 500 active research protocols spanning more than 20 medical specialties.
For fiscal year 2005, Baylor Health Care System reported $314 million in community benefit to the Texas Department of State Health Services. For more information about Baylor, visit www.BaylorHealth.com.
Journal
Proceedings of the National Academy of Sciences