A freeze-dried blood product that could be stored for years on ambulances or in remote emergency departments is showing promise at treating traumatic brain injuries.
The news comes from a mouse study done by researchers at UC San Francisco. If it pans out in people, it could answer a huge unmet need for therapies that treat these injuries, which are the leading cause of death in people under 44 years old.
In addition to the immediate bleeding, traumatic brain injury (TBI) also causes dangerous brain swelling days later, as blood vessels begin to leak. Even if a person is rushed to the hospital, doctors have few options, aside from surgery, to stop the bleeding or the brain swelling.
"In some cases, surgeons will remove part of the skull to relieve the pressure — but there's no drug that effectively treats swelling, or cerebral edema, directly," said Shibani Pati , MD, PhD, director of the UCSF Center for Research Transfusion Medicine and Cell Therapies and senior author of the paper, which published March 17 in Blood . "We were excited to see how readily this product reinforced damaged blood vessels in the brain."
The product, called "Thrombosomes," was originally developed to control bleeding in battlefield settings. It is derived from platelets that have been freeze-dried with a sugar called trehalose, which helps preserve some of their beneficial contents. It has a shelf life of up to 5 years — far longer than the 7-day shelf life of fresh platelets from human blood donors.
Fresh platelets, which must be stored in refrigerators, are used to treat hemorrhage and some cancer patients and to prevent bleeding during surgery. But they have not been shown to be effective against TBI.
Scientists have only learned how to preserve platelets in the last 30 years, hoping to address an ongoing global shortage of fresh platelets, but no preserved platelet product has been approved for human use, let alone TBI.
The team tested Thrombosomes on the blood vessel cells in petri dishes and in 3D organoid models of blood vessels. The product made both the cell layers and vessels resilient to damage.
Mice that received the product either an hour or a day after a brain injury had less hemorrhage and their blood vessels were not as leaky. They also had less brain inflammation, which can lead to swelling.
The scientists found that the product contained high amounts of a protein that activates a receptor on blood vessel cells, helping to stabilize them. This may explain how the product makes them less leaky.
So far, that protein is the first of what the researchers say could be a cocktail of beneficial molecules.
"Platelets carry many potent factors that go beyond clotting," Pati said. "In our mouse model of TBI, we saw hints that this product concentrates these factors, making it more effective than platelets themselves."
The product is in Phase II clinical trials for bleeding disorders, which means it has already been shown to be safe for people. This could hasten trials that test it for TBI.
Authors: Other UCSF authors are Alpa Trivedi, PhD; Byron Miyazawa; Haoqian Zhang, PhD; Longhui Qiu, PhD; Daniel Potter; Austin Edwards; Lindsay Vivona; Maximillian Lin; Callie Keane; Huimin Geng, PhD; Simon J. Cleary, PhD; Alison Nair, MD; and Mark R. Looney, MD. For all authors, see the paper.
Funding: This work was supported by the Department of Defense (W81XWH‐19‐1‐0462 BA180248). For all funding see the paper.
About UCSF: The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health , which serves as UCSF's primary academic medical center, includes among the nation's top specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. UCSF School of Medicine also has a regional campus in Fresno. Learn more at ucsf.edu or see our Fact Sheet .
