Asking the Pro | Kevin Jahnke

24th Week


Hello! First of all, I want to thank you for accepting my request and answering my questions.

Before going into details with your research, can you please tell us about yourself?

Hello! Thank you for giving me the chance to be here. My name is Kevin and I am a PhD student in the Lab of Kerstin Göpfrich at the Max Planck Institute for Medical Research in Heidelberg. I studied physics at Heidelberg University with a research stay at Cambridge University and currently work in the field of in the field of biophysics, or more specifically on bottom-up synthetic cell assembly. To put it short: I try to build artificial cells from natural and synthetic components.

How your studies had affected from the quarantine period due to COVID-19 pandemic? Working from home surely should be a different experience; do you have any tips & tricks to stay in the road during this time?

The pandemic strongly affected our everyday life at the institute. At first, the institute was shut down for weeks before we were allowed to conduct only the most important experiments. Right now, we do homeoffice whenever possible but at least we returned to a more or less regular working routine. During the shutdown, we implemented daily coffee meetings via an online platform. This was great because it gave you a sense of normality and allowed you to stay in touch with your colleagues. Apart from that, I tried to follow a routine (as much as possible 🙂 ), to follow many online conferences or talks as well as tried not to lose track and stay focused. The latter was actually the hardest!

adfm201808647-fig-0003-m.jpg
Water-in-oil droplets aka artificial cell compartments – Source

You are studying about artifical cells, and we mostly talk about living cells in tissue engineering applications. In my opinion, even if it is not a main topic for now, these 2 subjects will merge in future, and the use of artifical cells in tissue engineering applications will have a huge impact on the area. What is your opinion about that?

I could not agree more. I think synthetic biology can greatly enrich these well-established fields by providing compartments that are programmable and easy-to-handle. Currently, a “living” synthetic cell is still a distant goal for the future but there are already many groups trying to investigate the behavior of vesicle collectives as well as droplet populations or even the interaction of synthetic with natural cells. This, I foresee, will lay the foundation for future endeavors in tissue engineering applications. However, it will be difficult to elucidate the mechanisms and interactions that are at play when natural and synthetic cells coexist.

Your studies are shaping on bottom-up engineering of artificial cells. Do you think these engineered mimics can help us to understand the cell – extracellular matrix dynamics within traditional top-down approach for tissue engineering applications?

Yes, I think so. Synthetic cells are very beneficial as model system. In bottom-up synthetic biology, we usually start by creating a cell-sized compartment e.g. enclosed by a lipid bilayer that can then subsequently be loaded or modified to the custom needs. Thus, you could for example build synthetic cell that specifically degrade a certain scaffold, while the natural cells proliferate. It will be exciting to see how the field further develops!

Figure 1
Cell mimic production via microfluidic approach – Source

Microfluidics is one of the most exciting tools for organ-on-chip applications right now. Although, you are using these in a different way than we use. You have a couple of published work (1, 2), and you used an interesting approach in one of your recent studies (3, 5). You simply encapsulated living cells into a chamber which you generally use to produce aritificial cells. What type of problems were the ones you encountered mainly, and how have you solved these issues?

Generally speaking, I would say there are two main challenges: On the one hand, you don’t want the cells to clog the microfluidic channels or tubings and on the other you don’t want them to interact with a second fluid, which in my case contained DNA linkers, before the encapsulation. Microfluidics is great at dealing with the minimal amount of solutions but it also comes at a cost, if you for example want to encapsulate a high cell density. Because the channels are very narrow – typically ranging from 10-100µm – highly concentrated cells get stuck easily and also settle on the bottom after some time. For this reason, one needs to work fast and at high pressures from the inlets. However, this is difficult with a two-inlet device, where two channels meet before a flow-focusing T-junction, and you neatly need to adjust the fluid flows. Therefore, one needs to find the right balance between fluid velocity and fine-tuning of the applied pressures. Moreover, it is difficult to maintain an environment which is optimal for the cells after the encapsulation. In the droplet-based confinement, for instance, the continuous supply of nutrients can be a challenge.

image
DNA nanotechnology‐mediated link between the actomyosin network and the compartment periphery – Source

Although there is an increasing trend in interdisciplinary topics, it is hard to change some strictly placed concepts for some people. You have graduated from physics department, and your studies might be interesting for some when they hear your bachelor’s degree background. Because in addition to the topics we discussed, you are also using DNA nanotechnology for your studies (2, 4), which might be considered as a topic for biology/biochemistry -originated studies. Have you always seen yourself in bio-related topics, or is that something developed through your academic journey? How did you decide to study in biophysics?

That is an interesting question! I actually have to admit that my affection for biophysics and bio-related studies definitely arose during my studies at the university. I was always drawn to chemistry, biology and physics when I was still in school but the moment I started at the university I actually wanted to become a theoretical physicist. I honestly don’t know, where this idea came from and I also changed my mind rather quickly. I wanted to do something hands-on, something that is more tangible! Thus, I attended many interdisciplinary lectures making bridges and closing gaps in between the different fields. After that I was hooked, and followed the path of biophysics and still find myself at the interface of biology, chemistry and physics even though physics is where my home is.

Deformation-of-GUVs-with-pH-sensitive-DNA-origami-a-Schematic-illustration-of-the-DNA_W640
Cell mimic deformation with DNA origami – Source

And lastly, do you have any advice for people who want to study in your area?

I think enthusiasm, motivation and open-mindedness are key! The field of synthetic cell assembly is highly interdisciplinary and this is what makes it so interesting. A broad knowledge across fields is always advantageous but not strictly necessary. The ability to listen and trying to understand the person in front of you even though you have completely different backgrounds is much more important. Therefore, I would say if you are interested in the field of biophysics, just get in touch with a group you like and do an internship or your bachelor thesis there. This way you get to know how it is like working in this environment and if it is something for you. I can only encourage everybody to try it!

Thank you for your time, and I am wishing you the best for your studies!


More on Giant Unilamellar Vesicles:

Giant unilamellar vesicles (GUVs) are simple model membrane systems of cell-size, which are instrumental to study the function of more complex biological membranes involving heterogeneities in lipid composition, shape, mechanical properties, and chemical properties. – Source


Kevin Jahnke Google Scholar Profile, ORCID Profile, Group Page


References

1- An Integrated Microfluidic Platform for Quantifying Drug Permeation across Biomimetic Vesicle Membranes https://doi.org/10.1021/acs.molpharmaceut.9b00086

2- Programmable Functionalization of Surfactant‐Stabilized Microfluidic Droplets via DNA‐Tags https://doi.org/10.1002/adfm.201808647

3- Droplet‐Based Combinatorial Assay for Cell Cytotoxicity and Cytokine Release Evaluation https://doi.org/10.1002/adfm.202003479

4- Engineering Light‐Responsive Contractile Actomyosin Networks with DNA Nanotechnology https://doi.org/10.1002/adbi.202000102

5- Autonomous Directional Motion of Actin-Containing Cell-Sized Droplets https://doi.org/10.1002/aisy.202000190

 

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