Synthetic platelets built to treat bleeding


"The synthetic platelets can have profound implications in wound-healing problems for trauma and wounds arising in both battlefield situations and during surgery," says Frank Doyle. (Credit: "blood test" image via Shutterstock)

UC SANTA BA

Synthetic platelets built to treat bleeding

RBARA (US) — Scientists have created synthetic platelets—the blood components that prevent excessive bleeding and heal wounds.





University of California, Santa Barbara researchers, in collaboration with researchers at Scripps Research Institute and Sanford-Burnham Institute in La Jolla, California, report their findings in the journal Advanced Materials.


An artist’s rendering of artificial platelets and artificial red blood cells alongside their natural counterparts. (Credit: Peter Allen, UCSB)

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Read the original study

DOI: 10.1002/adma.201200607

The unique physical and biochemical properties of platelets play an important role in performing complex biological tasks. Smaller than red blood cells, platelets are flexible, disk-shaped cells that are 2-4 micrometers in size.

“Upon further optimization and exhaustive testing, the synthetic platelets could be used for various biomedical applications,” says the paper’s first author Nishit Doshi, a researcher from the department of chemical engineering.

The challenge Doshi and colleagues faced was to develop a comparably sized particle—roughly 1/50th of the diameter of a strand of hair—that had key structural properties of real platelets.

“In order to mimic the size, shape, and surface functionality of natural platelets synthetically, polymeric particles are particularly attractive,” says Doshi. “However, polymeric particles are orders of magnitude more rigid than platelets.”

To solve the problem of flexibility, researchers at UC Santa Barbara used a polymeric “template”—a core upon which layers of proteins and polyelectrolytes were deposited, layered, and cross-linked to create a stable synthetic platelet-shaped particle.

The rigid polymeric core was then dissolved to give the particle the desired flexibility. The particle was then coated with proteins found on the surface of activated natural platelets or damaged blood vessels, a procedure performed by the researchers at Scripps Research Institute.

These synthetic platelets may be used to not only perform the typical functions of human platelets but also may be used to carry imaging agents to identify damaged blood vessels or to deliver drugs that dissolve blood clots.

The synthetic platelets represent the latest and one of the most advanced in a line of efforts over the last century to mimic platelet function. While clotting factors and platelets from outside donors are used widely to halt bleeding, immune system responses and thrombosis have been issues.

Non-platelet-derived substitutes have also received attention. However, Doshi says, these do not physically resemble the physical features of natural platelets.

“This development is a significant milestone in the field of biomimetic materials,” says Samir Mitragotri, professor of chemical engineering and director of UC Santa Barbara’s Center for Bioengineering, and an author of the paper.

“By capitalizing on our capabilities in engineering materials, with the expertise in platelet biology that exists in Professor Ruggeri’s laboratory, our synthetic platelets combine unique physical and biological attributes that mimic natural platelets.”

In 2009, Doshi and colleagues in the Mitragotri laboratory developed synthetic red blood cells.

“This work is a marvelous demonstration of the power of material synthesis applied to medical problems. The synthetic platelets can have profound implications in wound-healing problems for trauma and wounds arising in both battlefield situations and during surgery,” says Frank Doyle, director of UCSB’s Institute of Collaborative Biotechnologies and the Associate Dean of Research in the College of Engineering.

Additional authors from Scripps Research Institute and Sanford-Burnham Medical Research Institute contributed to the study, which was funded by the Institute for Collaborative Biotechnologies through a grant from the U.S. Army Research Office and the National Institutes of Health.

More news from UC Santa Barbara: www.ucsb.edu/news-topics

A blood test to monitor cancer treatment

LONDON: Scientists have devised a new simpleblood test that can clearly show whether treatments to reduce tumours is working, a breakthrough which could soon revolutionize cancer care.

British researchers, who developed the new blood test, said can closely monitor the progress of tumours without the need for surgery or scans.

In a world first, they used the blood analysis to detect deadly mutations in 20 of 38 patients studied with breast and ovarian cancer.

They even managed to build up a picture of how one woman's breast cancer responded to different treatments over 16 months.

The new test, expected to be available to patients within five years, uses sequencing — a technique to read genetic code — to look for tiny pieces of DNA that cancer tumours shed into the bloodstream and are not picked up by current screening methods, the Daily Mail reported. This could alert doctors when a treatment is not working, allowing them to try alternatives , as well as potentially sparing the patient unnecessary side effects. Currently cancer patients often need to have tissue samples surgically removed for analysis.

In the study, published in journal Science Translational Medicine, the researchers took blood samples from women either before, during or after chemotherapy at Addenbrooke's Hospital in Cambridge. Dr Nitzan Rosenfeld, who led the study at the Cancer Research UK Cambridge Research Institute, said, "This type of blood test has the potential to revolutionize the way we diagnose and treat cancer. The great advantage is that it can be used to identify cancer mutations without surgery or a biopsy, making it safer and cheaper."

DNA sequencing is widely used, but Rosenfeld's team found a way to home in on key genes known to be "cancer hot spots" and analyse them in detail. This is the first time entire genes have been analysed from a blood test, which enabled the researchers to examine 20,000 possible mutations in six cancer-related genes. Using a blood sample from a 56-year-old woman with breast cancer, the researchers were able to see in retrospect that the first type of treatment she was given had not worked.

Rosenfeld said, "We could see in a blood test what the doctors could only see using extensive imaging. If we had looked at a different time, we may have been able to spot it earlier. Doctors could try different types of chemotherapy or refer patients to a specific clinical trial. It broadens the scope for more personalized medicine."