BioTime products, Hextend and PentaLyte, presented at medical and scientific meetings.

BERKELEY, Calif.--(BUSINESS WIRE)--May 1, 1996--BioTime Inc. (NASDAQ: BTIM) Wednesday announced that Dr. George V. Letsou presented the results of his research on ice-cold blood substitution with Hextend, BioTime's blood plasma volume expander and hypothermic blood substitute.

In this study, whole body perfusion with cold, oxygenated Hextend was shown to protect the heart and brain of laboratory animals during four hours of deep hypothermia. The presentation was made yesterday by Letsou at the 76th Annual Meeting of the American Association For Thoracic Surgery, held at the San Diego Convention Center. Letsou is associate professor of surgery at the Baylor College of Medicine in Houston.

Letsou said, "chilled blood substitution with Hextend can potentially allow extended periods of time for surgery on the heart and brain, during which circulation can be substantially reduced, or even arrested. When adapted to clinical surgery, these techniques should prove valuable in the repair of ancurysms of the aorta and the cerebral circulation, and in reducing the body temperature of transplant donors prior to removal and transplantation of vital organs."

Letsou's talk follows a series of presentations describing research with Hextend made at the Experimental Biology '96 meeting held in April at the Washington Convention Center in Washington, D.C. Dr. Roger Jacobs, director of the Surgical Research Laboratory at New York's Metropolitan Hospital Center, reported on studies in which Hextend, and PentaLyte (a physiologically balanced pentastarch-based solution recently developed by BioTime for indications which require the replacement of lesser volumes of blood compared with Hextend) were substituted for more than 3/4 of the circulating blood of rats. Results indicated that both solutions could adequately replace blood volume, but that blood albumin and total protein levels returned faster in the PentaLyte-hemodiluted animals compared with those whose blood was diluted with Hextend.

Jacobs said "these findings suggest that PentaLyte may be eliminated from the blood more quickly than Hextend. Since overall survival of rats in which a large amount of their blood volume was replaced by Hextend was slightly better than when the replacement was with PentaLyte, PentaLyte may prove to be more ideal for clinical use when smaller volumes of blood are lost, as patients may more quickly restore smaller amounts of blood constituents. However, when replacement of large amounts of blood volume is necessary, it may be better to use a product such as Hextend, which can endure longer in the circulation."

Stephen Kehrer, director of BioTime's Surgical Research Laboratory, also presented data at this conference which showed that rats subjected to partial blood substitution after fasting and severe cold stress were much more likely to survive if their blood volume was maintained with Hextend than with a commercially used plasma expander. Dr. Paul Segall, BioTime president and chief executive officer, said "better survival in Hextend-treated animals may be related to the higher blood glucose levels observed. Hextend provides glucose whereas the commercially available product does not. BioTime has submitted an Investigational New Drug Application to the Food and Drug Administration and is currently planning Phase III clinical trials of Hextend for use in surgery in which large volumes of blood are lost."

Additional research on the use of Hextend supplemented with cold-protective agents was presented by Dr. Hal Sternberg, BioTime's research vice president. He described experiments in which hamsters were completely blood substituted at hypothermic temperatures with BioTime solutions, and then placed in sub-zero freezing baths for periods of up to 2 hours. These animals reached deep body temperatures as low as -4 C, and then were revived to consciousness and reactivity. An analysis of brain tissue immediately following revival indicated that substantial freezing and thawing of the tissues of the brain had occurred. Sternberg said "these experiments reveal that mammals can survive - at least for short periods - partial freezing of vital organs, if their blood is replaced with solutions which guard against some of the damage caused by ice crystallization. These studies suggest that techniques for maintaining a wide variety of tissues and organs in frozen or partially frozen states for extended time periods may be achievable when adequate solutions and protocols are developed. This breakthrough could lead to long term organ and tissue banking for transplantation."

BioTime, with headquarters in Berkeley, is engaged in the research and development of synthetic blood plasma volume expanders and low temperature blood substitute solutions and technology for use in surgery, emergency trauma treatment, the preservation of organs awaiting transplant, and other applications.

CONTACT: BioTime Inc.

Victoria Bellport, 510/845-9535

or

The Spindler Organization

Paul Spindler, 213/930-0811