The skin is the body's first line of defense against infection. And when this barrier is broken, or an internal organ is ruptured, it is the process of coagulation, or clotting, which relies largely on blood cells called platelets, that seals the breach and stems the flow of blood. Researchers at UC Santa Barbara (UCSB) have now synthesized nanoparticles that mimic the form and function of platelets, but can do more than just accelerate the body's natural healing processes.

Platelets are nucleus-free blood cells that are essentially the building blocks for any blood clot, binding together at the edge of a wound as well as changing shape and secreting chemical messengers to call more platelets to the scene of the injury to assist in the healing process. However, coagulation can be hampered if an injury is too severe, or if the injured person is taking anti-coagulation medication or suffers from a platelet disorder.

In such cases, the platelet-like nanoparticles (PLNs) synthesized at UCSB could save the day. Developed by researchers in UCSB's Department of Chemical Engineering and its Center for Bioengineering, the synthetic platelets behave just like their naturally-occurring counterparts, mimicking their shape, flexibility and surface biology.

In this way, their creators say they could be added to a patient's own natural blood supply or augment the patient's own platelet supply and accelerate the healing process for both internal and external injuries. Not only will the PLNs congregate at the site of an injury, but like natural platelets, they'll also call other platelets to the site and bind to them. Then, once their task has been completed and the wound has been plugged, the PLNs will dissolve into the blood.

Furthermore, the researchers claim to have improved on nature, with their nanoscale synthetic platelets outperforming micron-sized natural ones in tests. The synthetic platelets are also able to be customized with medications that match the needs of patients with a specific condition. They could also be used to carry antibiotics to certain parts of the body, such as across the blood-brain barrier, to provide targeted therapy and improved diagnostics.

"This technology could address a plethora of clinical challenges," said Dr. Scott Hammond, director of UCSB’s Translational Medicine Research Laboratories. "One of the biggest challenges in clinical medicine right now – which also costs a lot of money – is that we’re living longer and people are more likely to end up on blood thinners." The researchers say PLNs would help in the treatment of such elderly patients, allowing the PLNs to be targeted at the site of an injury without triggering unwanted bleeding.

Importantly, the researchers say the synthetic platelets have a longer shelf life and are cheaper relatively speaking than another person's platelets – both important factors at times of emergencies and natural disasters when blood products are in highest demand.

These aren't the first synthetic platelets we’ve seen that improve on nature. In 2009, researchers at Case Western University reported the development of artificial platelets made of biodegradable polymers that reduced clotting times in animal models and attracted the interest of the military.

The team will now look at how well the production of the PLNs scales up and asses practical clinical concerns, such as manufacturing, storage, sterility ahead of pre-clinical and clinical testing.

Results of the researchers’ current findings appear in the journal ACS Nano.

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