TB4 is Essential for Coronary Vessel Development Report U.K. and U.S. Scientists.

Findings with T[eth]4 Demonstrate Blood Vessel Regeneration Possible in Adult Hearts

BETHESDA, Md. -- REGENERX BIOPHARMACEUTICALS, INC. (AMEX: RGN) (www.regenerx.com) reported today that a study published in the advanced online edition of the journal Nature supported and elaborated T[eth]4's significant effects in the damaged hearts of mice and highlighted its therapeutic potential for the treatment of heart attacks and heart failure in humans.

"T[eth]4 is presented here as a single factor that can potentially couple myocardial [heart] and coronary vascular regeneration in failing mouse hearts," according to researchers from the University College London's Institute of Child Health, London, UK; Baylor College of Medicine, Houston, TX; Massachusetts General Cardiovascular Research Center, Boston, MA; and Harvard Medical School and Harvard Stem Cell Institute, Cambridge, MA.

"A major shortcoming of current angiogenic therapy in response to myocardial ischemia in humans is that the outcome may be limited to capillary growth without concomitant collateral support of arterioles [terminal branches of arteries]. Our findings that, in mice, T[eth]4 can promote vessel formation and collateral growth not only during development but also critically from adult epicardium, suggest T[eth]4 has considerable therapeutic potential in humans," stated the researchers.

"These results are very exciting because most humans suffering from ischemic cardiac events, either acutely or chronically, do not develop the collateral vessel growth necessary to preserve and restore heart tissue. If, in humans, we see the same effects as seen in mice, T[eth]4 would be the first drug to prevent loss of [heart] muscle cells and restore blood flow in this manner and provide a new and much needed treatment modality for these patients," commented Deepak Srivastava, M.D., Professor and Director, Gladstone Institute of Cardiovascular Disease, University of California San Francisco, CA. Dr. Srivastava and his colleagues published the first paper on T[eth]4's effects on myocardial infarction in Nature in November 2004.

The study was funded by the British Heart Foundation and the Medical Research Council.

Over 105,000 people die from heart disease in the UK each year. Heart attacks occur in over one million people annually in the United States and over thirteen million suffer from coronary artery disease, making it the single largest cause of death in the Western world.

The RegeneRx Technology Platform

Thymosin beta 4 (T[eth]4) is a synthetic version of a naturally occurring peptide present in virtually all human cells. It is a first-in-class drug candidate that promotes endothelial cell differentiation, angiogenesis in dermal tissues, keratinocyte migration, collagen deposition, and down-regulates inflammation. One of T[eth]4's key mechanisms of action is its ability to regulate the cell-building protein, actin, a vital component of cell structure and movement. Of the thousands of proteins in cells, actin represents up to 10% of the total protein and, thus, plays a major role in the physiology of the cell. RegeneRx has identified several molecular variations of T[eth]4 that may affect the aging of skin, among other properties, and could be important candidates as active ingredients in pharmaceutical and consumer products. Researchers at the National Institutes of Health, and at other academic institutions throughout the U.S., have published numerous scientific articles indicating that T[eth]4 is effective in accelerating dermal and corneal wound healing in several animal models, under a variety of conditions. In two articles published in the scientific journal, Nature, researchers found that T[eth]4 protects heart tissue following a myocardial infarction (heart attack) and can regenerate coronary vessels in laboratory animals. Abstracts of scientific papers related to T[eth]4's mechanisms of action may be viewed at RegeneRx's web page: www.regenerx.com.

About RegeneRx Biopharmaceuticals, Inc.

RegeneRx is focused on the discovery and development of novel molecules to accelerate tissue and organ repair. Currently, RegeneRx is developing T[eth]4, a 43 amino acid peptide, in part, under an exclusive world-wide license from the National Institutes of Health. Preliminary research suggests that T[eth]4 may prove efficacious for multiple indications; therefore, RegeneRx is developing T[eth]4 as a therapeutic platform. RegeneRx holds nearly 60 world-wide patents and patent applications related to dermal, ocular, and internal wounds and tissue repair, cardiac and neurological injuries, and septic shock. RegeneRx is currently sponsoring three Phase II chronic dermal wound healing clinical trials and has additionally targeted ophthalmic and cardiac trials in 2007 as part of its ongoing clinical development program.