Synthetic platelets mimic natural functions and open door to new treatments

Researchers from the University of California, Santa Barbara, along with Scripps Research Institute and Sanford-Burnham Institute, have developed synthetic blood platelets that mimic natural ones. These synthetic platelets are seen as a step forward in mimicking human blood function. However, these platelets do not simply mimic natural platelets; the researchers believe these new cells might also be useful in transporting imaging agents to damaged areas and dissolving blood clots.

Platelets are tiny (2-4 micrometers), disk-shaped cells that clot together to stop bleeding and heal wounds. Their small size has made it difficult to replicate them in the lab, so most platelets used in medical treatment are isolated from donor blood. Unfortunately, these natural platelets have a brief shelf life that causes shortages and several complications, like thrombosis.

The researchers at the University of California, Santa Barbara wanted to create a synthetic platelet that mimicked natural platelets’ small size and overall flexibility. The researchers started with a tiny polymeric template, but most polymers are too rigid to fully mimic platelet functions. So several, interlocking layers of proteins and polyelectrolytes were used to cover the polymer, and then the polymer template was dissolved away. This created a small, flexible cell. Afterwards, the cells were covered with a layer of proteins found on the surface of natural platelets.

Of course, this is not the first platelet like synthetic cell to be created. Erin Lavik of Case Western University created synthetic blood platelets in 2009 by using an already FDA approved polymer that dissolves in the body. Lavik's research has also gone a step further by conducting studies to demonstrate that her polymeric, synthetic platelet stops bleeding.

Both of these synthetic platelets should have a longer shelf life than natural donor platelets, and both synthetic platelets should be capable of being injected into the circulatory system. This means that these synthetic platelets should be capable of stopping internal bleeding, making the synthetic platelets of particular interest to the Department of Defense, which has developed wonderful treatments to stop external bleeding but has few methods of safely treat internal bleeds. Moreover, the longer shelf life should allow these platelets to be carried onto the battlefield, unlike donor platelets.

Yet, this remains to be seen. The researchers from the University of California, Santa Barbara have developed a synthetic platelet that more closely mimics natural platelets and is more flexible, but the verdict is still out on whether these advances will make the synthetic platelet more effective in combating internal and external bleeding or whether the platelets from the University of California, Santa Barbara will have more uses than a blood clotting agent.

Both synthetic platelets are advancements over traditional blood clotting agents, like Coagulation Factor VIIa (recombinant) or Recothrom. Coagulation Factor VIIa (recombinant) is a protein that simply promotes coagulation of the blood and is used to stop bleeding in hemophilia patients and sometimes off label use during surgery. Recothrom also promotes blood clotting in small capillaries, but it can only be applied topically. These new synthetic platelets do not simply promote blood coagulation, but they bind and help build the blooding clotting structure that stop bleeding and heals wounds

While further research is necessary to determine whether these two synthetic platelets will get widespread use, both of them overcome several problems that hindered platelet development. The scientists were able to replicate the small size of natural platelets. Moreover, both synthetic cells are dissolvable within the human body. Without the ability to dissolve into harmless materials the body can handle, the new synthetic platelets could case numerous problems and could require extraction. Overcoming these two issues should allow scientists to use these models to develop numerous other tiny cells or even improve upon these platelet designs.