Self-boosting vaccines: An MIT invention could solve one of healthcare’s biggest problems

“Imagine that you’re living in a place where it is very hard to provide health care services, for example, in a developing country. It’s a huge issue to provide the first shot to someone and then make sure they receive the second shot, too,” mechanical engineer Morteza Sarmadi, one of the researchers behind the new technology, told IE.

But it’s not just limited to vaccines. “This is a platform that can be broadly applicable to all types of vaccines, including recombinant protein-based vaccines, DNA-based vaccines, even RNA-based vaccines, says research“, said Ana Jaklene, another researcher on the project. The breakthrough could enable other kinds of therapies, too. The new technology is described in an article published Wednesday in the peer-reviewed journal Science Advances.

Interesting Engineering sat down with Sarmadi to learn more about how the new technology works, how his team developed it, and what it could be used for in the future. 

This interview has been edited for length and clarity.

Interesting Engineering: What’s so exciting about these particles?

Morteza Sarmadi: These particles are really tiny — they are as small as a grain of salt — and can be injected into the body safely. They have a very interesting structure. Imagine a coffee cup. So, we have a container, we pour coffee inside, and then put a lid on top to protect the contents. It’s similar to this concept. The microparticles are also made from two layers: the coffee cup layer and the lid layer. We use micro-fabrication to fabricate the first layer. Then, we dispense the vaccine or other therapeutic cargoes into the core of the first layer, and then we align a second layer — the lid — with the first layer. Then we basically fuse the two layers together. 

IE: Once the particle has been inserted into a patient, how does it make its way out of the capsule and into the patient’s body.

These particles start to degrade once they are exposed to the body’s moisture and high temperature. Over time, they start to dissolve. At some point, they dissolve so much that these particles allow the cargo to rapidly leave this encapsulated container. That’s basically what causes the delayed release. 

IE: How long does it take for that process to occur?

We can program these particles to release the cargo at a certain time point. When you think about vaccine delivery — for example, for the Covid-19 vaccine — that means we can provide the first shot and simultaneously inject particles that will release the second dose after four weeks. 

IE: What are the particles doing during that four-week period? Are they floating around the body, or do they remain in one place?

The size of these particles is such that they stay stationary at the injection site. It could be subcutaneously in the fat of the stomach, or it could be in a muscle. It depends on which administration route is more helpful for that specific vaccine.

IE: What are the particles made of?

We use a safe and non-toxic material called poly(lactic-co-glycolic) acid, or PLGA. It’s a type of polymer or plastic that has been used for several decades. It’s approved by the FDA. We really didn’t want to deal with toxic particles or toxic material, so these particles are made from something which has already been used in industry for a good amount of time.

IE: What challenges did you face in developing this new biomedical technology?

We faced a lot of different types of challenges. Obviously, the size of these particles is really tiny, so we needed to make sure we used methods that were compatible with tiny structures and systems. We worked with individual particles, so it was important to make sure the way we picked them up and analyzed them was consistent. We tested a good number of particles, and all the methods we used had to be sensitive and non-invasive. 

IE: Have you tested these particles in living organisms?

Yes, we have done extensive studies in different animal models and also have ongoing experiments and studies on more complicated, more realistic animal models.

IE: Which animal models have you used so far?

We tested in mice, rats, and pigs. We have ongoing studies with non-human primates.

IE: For you, as a micro- and nano-scale mechanical engineer, what’s most interesting about this new technology?

When I first saw these particles under the microscope, I just fell in love with them. The structure is very nice. The level of precision we can get at the micro- and nano-scales with current tools and technologies blew my mind. The interesting thing is that these particles are highly tunable, so the range of possible applications is very broad. 

IE: It sounds like tunability is an important attribute of this technology. What does that mean, and why is it such a big deal? 

So tunability is defined by two aspects. One is the design, meaning that you’re able to fabricate these particles in many different shapes, geometries, and sizes. Let’s say you want to inject these particles with a smaller needle gauge: you have to make them smaller, so they don’t block the needle. Since this technology is highly tunable, we are able to make these particles smaller. If you want to increase the deliverable dose, you have to increase the size of the core to encapsulate more therapeutic cargo into individual particles. 

The second aspect is the composition and the material’s properties. Those properties are the factor that determines the release time point when the therapeutic cargo gets out of the particle. This is also highly tunable, meaning that we are able to fabricate particles that release the cargo after just a couple of hours. Or we can fine-tune the material and make it really, really slow, so it releases after, let’s say, six months.

IE: Does that mean vaccines are just the start?

It’s not just vaccination that these particles are useful for. It’s also cancer therapies, hormone therapies, and even therapies for autoimmune diseases. A broad range of diseases could be treated using this technology because of its tunability and its compatibility with the various needs of different medications.