Clot science: from lab to life. “I have seen the devastating impact that stroke can have – so knowing that our devices are helping people really drives me.” Sarah Johnson, PhD.

sarah johnson holding award

“I have seen the devastating impact that stroke can have – so knowing that our devices are helping people really drives me.”

Meet Sarah Johnson, our research and development engineer within the CERENOVUS Neuro Thromboembolic Initiative (NTI) team in Galway, Ireland. Sarah joined us after completing her PhD on stroke science at the National University of Ireland, Galway and has been essential in our efforts to advance research in stroke and clot science. 

We spoke to Sarah about why she’s passionate about what she does, what her day-to-day job entails, and why she’s excited about being a woman in science and engineering. 

What sparked your interest in this field? 
I’ve been interested in stroke since a young age. My dad works with the local Heart and Stroke charity in Galway and I used to volunteer for them. The experience opened my eyes to the effect of stroke on individuals and their families. 

croi runners photo
Taking part in the annual Croí night run in 2019, with her parents, Neil and Ríóna and sister Emma.

How would you describe what you do as a biomedical engineer within the NTI team at CERENOVUS? 
As part of the NTI team, I research the basic mechanism of stroke –  how they occur, what happens during a stroke, and what are the factors that can impact treatment. We do this by modelling stroke on the bench in the most realistic ways possible, we then feed this research back into the R&D team so they can develop the best devices to treat the condition. 

Can you describe your day-to-day work in the NTI lab? 
We work in collaboration with various institutes here in Ireland and abroad, who provide us with patient scans that we use to recreate realistic blood vessels. We then introduce our novel blood clot analogues to replicate vessel occlusions. By altering the different properties of the clots, we can emulate different patient-specific stroke conditions and increase or decrease the challenge to treatment. These stroke models are adaptable so that we can challenge devices in different scenarios by altering variables such as the vessels’ tortuosity, the vessel and clot material properties, the pressure and flow conditions, and more.  

We believe that our latest model is one of the most sophisticated systems available – it allows us to accurately control the pressures and flows in the model and simulate acute ischemic stroke ‘on the bench’. It’s a huge advantage when it comes to early-stage product development, as well as testing established devices in more challenging conditions. 

dr sarah johnson working with team on the flow model in the new nti lab
Dr Sarah Power working on the flow model in the new NTI lab during the first physician site visit since COVID. From left to right: Sarah, Mahmood Mirza (Principal Research Engineer, NTI) and Dr. Sarah Power, Interventional Neuroradiologist, Beaumont Hospital, Dublin.

Tell us about your team and the people you work closely with.
The immediate team I work with in the lab is a small one. There are five of us in total: we have our lab manager, another research engineer, a lab technician, and a senior clinical research engineer who is both a qualified engineer and a doctor, so he has the best of both worlds. 

We also have bi-weekly meetings with the field team to update them on the research we’re working on in the lab. It’s a good opportunity for them to share any questions or findings from their visits with physicians too, so we can incorporate any new information into our research. 

Then there’s our global NTI meeting every year, where we come together to share our latest research and findings from the field in detail. Our  external collaborators are also invited to share the work they’re doing. This includes any interesting results from their research, or new data from relevant publications. 

Why is it so important to invest in clot science, and what sets CERENOVUS apart? 
No two clots are the same. You’ll rarely find two occlusions that behave in the same way, which means they will more than likely have different treatment outcomes. The devices we create to treat stroke  need to work with a whole range of clots that can be found in patients. That’s why it’s so important to invest time and energy in creating the most realistic models of all these different clots, so we can develop the most effective solutions. 

At CERENOVUS, we go the extra mile when creating these clot models. Rather than using printed polymer or hydrogels to mimic the clots, we make our own clots from blood so they are as realistic as possible. Then, we look at the various properties of the clots and how those variables affect the clot’s behaviour in order to propose the most appropriate treatment. 

“We take the time and energy to really understand the problem so we can design solutions to effectively address the problem. I believe that’s what sets us apart”. 

Tell us about the wider stroke research community. Why is it important to maintain strong relationships within the community? 
The stroke research community is a tight-knit group – you see the same names popping up all the time, and everyone is happy to share their findings and learn from each other. These collaborations are really important as stroke science is a relatively new area. It goes beyond researchers too – we also have physicians reaching out to us about projects and our devices. 

It’s great to have that open dialogue. The more we learn about the disease itself, the more  wellequipped we are to design and develop appropriate treatment device that will hopefully improve outcomes. 

sarah johnson holding award
Team photo during a recent physician site visit. From left to right: Karl Keating (Senior R&D Engineer), Sarah, Ray McCarthy (NTI Scientific Affairs Manager), Dr Patrick Brouwer (Senior Medical Director, CERENOVUS), Dr Sarah Power (Interventional Neuroradiologist, Beaumont Hospital, Dublin), Michael Gilvarry (General Manager Cerenovus Galway), Mahmood Mirza (Principal Research Engineer, NTI).

How has the team’s work made a difference in clot science? 
Our team’s research was key in the development of a device designed to tackle tough clots, specifically fragmenting clots. We were able to simulate these types of clots and use them in our models, and this data helped inform the design of the device. 

Another example is of a collaboration we had was with a professor from Paris, who came to us with an interesting problem. There are instances where calcified clots form around fragments from other procedures like valve replacements or even from actual bone. They are easy to see on imaging as the calcification causes them to glow brightly, but they are very, very difficult to remove. 

So, we developed a calcified clot model in our lab and used it to test different procedures and techniques to investigate the best methods for retrieving those clots. 

What do you enjoy most about your role? 
I love what I do. I enjoy the cutting-edge research we’re doing as there aren’t many people doing what we’re doing. I have also seen the devastating impact that stroke can have – so knowing that our devices are helping people and making a difference really drives me. 

“I love what I do. I enjoy the cutting-edge research we’re doing as there aren’t many people doing what we’re doing”.

What excites you most about being a woman in science and engineering? 
Traditionally, there weren’t many females in my position, so I’m proud of where I am and what I’ve achieved. It excites me that I can be a role model for other young girls who are considering studying a STEM subject. Hopefully someday we will have a 50/50 gender balance in this field. 

sarah johnson visiting local school
Sarah during a visit to a local primary school, speaking to 5th and 6th class students about biomedical engineering during engineers week in 2019.

What are your personal highlights or achievements? 
I had the opportunity to work in Professor Matthew Gounis’ lab at the New England Center for Stroke Research for six months, as part of my PhD. The lab is linked with the UMass hospital which meant that we were involved in case reviews and were able to hear about the live cases, treatments and testing. It was a huge learning experience. 

members of prof. matt gounis’ lab after completing a local 6k run during sarah’s visit to umass in 2018
Members of Prof. Matt Gounis’ lab after completing a local 6k run during Sarah’s visit to UMass in 2018. From left to right: Jildaz Caroff- Fulbright fellow at NECStR, PH, Neuroradiologie Interventionnelle, Hôpital Bicêtre, Paris, France, Matt Gounis, Director of NECStR and Professor of Radiology, UMM, Sarah Johnson, Robert King, PhD Candidate at NECStR, Miklos Marosfoi, Assistant Professor, Department of Radiology, UMAS, Chris Raskett, Sr Research Associate at NECStR, UMASS.