Towards Lasting Therapeutic Manufactories that Operate Inside the Body

Gene therapies involve delivering instructions into cells to ensure that specific proteins are manufactured, either temporarily or permanently. This is effectively a hijacking or programming of cellular mechanisms. There is another approach, which is to deliver suitable DNA machinery into the body, capable of manufacturing the desired proteins outside cells. This isn't helpful for all types of protein, but in many cases it is. That machinery needs protection, however: naked, it would be quickly removed by the immune system or otherwise broken down. One possibility is to employ engineered bacteria, which removes the need to introduce changes into a patient's cells, but adds a sizable set of other complications. Another approach is to build a suitable structure from scratch, such as a membrane that will not alert the immune system, containing a carefully limited set of DNA machinery that will turn out the desired proteins for a lengthy period of time, but is incapable of any other activity. These constructs would in many ways resemble extracellular vesicles more than cells, and the research community has been capable of building such things for a few years now.

Researchers have successfully treated a cancerous tumor using a "nanofactory" - a synthetic cell that produces anti-cancer proteins within the tumor tissue. The research combines synthetic biology, to artificially produce proteins, and targeted drug delivery, to direct the synthetic cell to abnormal tissues. The synthetic cells are artificial systems with capacities similar to, and, at times, superior to those of natural cells. Just as human cells can generate a variety of biological molecules, the synthetic cell can produce a wide range of proteins. Such systems bear vast potential in the tissue engineering discipline, in production of artificial organs and in studying the origins of life. Design of artificial cells is a considerably complex engineering challenge being pursued by many research groups across the globe.

The researchers integrated molecular machines within lipid-based particles resembling the natural membrane of biological cells. They engineered the particles such that when they "sense" the biological tissue, they are activated and produce therapeutic proteins, dictated by an integrated synthetic DNA template. The particles recruit the energy sources and building blocks necessary for their continued activity, from the external microenvironment (e.g., the tumor tissue).

After experiments in cell cultures in the lab, the novel technology was also tested in mice. When the engineered particles reached the tumor, they produced a protein that eradicated the cancer cells. The particles and their activity were monitored using a green fluorescent protein (GFP), generated by the particles. This protein can be viewed in real-time, using a fluorescence microscope. "By coding the integrated DNA template, the particles we developed can produce a variety of protein medicines. They are modular, meaning they allow for activation of protein production in accordance with the environmental conditions. Therefore, the artificial cells we've developed may take an important part in the personalized medicine trend - adjustment of treatment to the genetic and medical profile of a specific patient."



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