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Today on The Physics Factor I have the pleasure of interviewing Professor Larry Bonassar here
at Cornell, and Larry you're not actually a physics professor are you? I'm not. So I'm
a professor of biomedical engineering and mechanical and aerospace engineering. Ok,
so related to physics. Yes. And I'm actually kind of curious how physics influences your
work. What role does physics play in the research that you're interested in? Sure. So my lab
spends a lot of time thinking about the physics of cartilage - the mechanics of cartilage.
So cartilage is this very primitive connective tissue that's found all over our bodies. Like
on the end of your nose, right? It's in your nose, it's in your ears, it's in your windpipe.
Oh I didn't know that one! It's in the spine - it's the flexible motion segments of your
spine. And it's in all your joints as well, it's one of the things that allows your joints
to move freely and without much friction. Friction is a good physics word. Friction
is is a great physics word. In fact this is something that my lab started doing maybe
about a decade ago and cartilage friction has become one of the really prominent areas
of investigation. And I think what you're most known for, at least according to your
group website - you have a beautiful demonstration of the ear - the 3D printing that you do,
where you're printing an ear out of living cells, is that correct? That's right. And
I'm kind of curious how you got interested in that particular research project. I know
your background is in materials science; I think there's also some biomedical background
as well. Right. So did you come at it more from this 3D printing/engineering side, or
more from an interest in biomedicine, or both just kind of came together in your head and
you're like "Aha!" Yeah it was more the latter, right. It was more kind of...this was a more
real condensation, if you will, of a bunch of different areas of my knowledge. As you
said, my PhD's in materials science, and from there I did a postdoc in a hospital - Massachusetts
General Hospital - in a lab that was focused on cartilage cell biology. And so in many
ways these tissue engineering studies are an intersection of how to use materials and
cells together to try to regrow tissues. And what are some of the things you have to think
about if you're printing with a cell versus - apart from keeping it alive of course - Well
but that's a big one right? So keeping it alive is the real challenge, right? So if
you think about this idea of printing, what makes a material printable is some combination
of critical values of viscosity of the fluid that you're printing and surface tension.
The analogy I use is you can't print with water because the viscosity's too low and
the surface tension is not high enough, so you print with water and it spreads on a surface,
right? And so you also can't print with marbles, right? The marbles roll relative to each other
- And they don't really gel together - And they don't stick together, that's right. So
you need some sticky marbles or you need really thick water or you need something that's at
the intersection of sticky marbles and thick water. Ok. So there's the whole physics of
printability which is really interesting by itself and then you have this other set of
constraints, meaning that everything you have to print with - if inside that droplet are
cells, now both the chemistry and the physics of that material have to be compatible with
things being alive. My group really spends a lot of time thinking not about the kind
of electronics or robotics aspects of printing, but really, if you will, the designing of
the inks. we spend a lot of our time thinking about the development of living inks for printing
living tissues. What materials can we use, what cells can we use? Once we have that how
can we put cells and materials together to make tissues that kind of mimic the structure
and function of native tissues. So the ears that you guys have printed, for example, are
those cells the same sorts of cells that I would find in my ear? They are, they are.
So the experiments that we've done actually start out with cow ear cells because it's
actually relatively easy to get cow ear cells. It's harder to get human ear cells. Although
we actually do have experiments in the lab going on right now that are using human ear
cells. We get tissue shipped up from our medical school. We isolate the cells from the human
ear tissue and we have human ear cells growing in the lab kind of as we speak. So apart from
research, what sorts of things do you like to do when you're not thinking about the human
ear or 3D printing? So you know I have three small kids. I have twin daughters who are
eight and a son who's six. And so they occupy a lot of my free time and that's great. So
we spend a lot of time doing things like going to Little League games and going to swimming
lessons and that kind of thing. Mostly this time of year I've gotten into gardening a
lot lately. It's very nice outside and that's also been a great - it's beautiful for gardening.
And it's actually not all that different than tissue engineering. It both requires a lot
of patience, it requires kind of a lot of planning and watching things change over time
and mature over time. So it's also been a great activity with the kids too - it's a
great chance for science lessons. Not so much in the physics lessons, more biology lessons,
but it's been great. I really...that's what relaxes me when I spend my free time doing
during the summer. And that actually makes me think back to the 3D printing. Have you
played around with plant tissue or plant cells at all? I never have, you know, it's something
that the technology is so new and the area is so new that these things are all kind of
cropping up. Ok. So plant - engineering plant tissue is something that I've heard proposed.
My lab certainly doesn't do any of it. Ok. Both the physical infrastructure and the knowledge
infrastructure for plant cell culture and mammalian cell culture are very very different,
so I know practically nothing about how to culture plants. From the little I remember
about biology, I know that animal cells and plant cells are very different from each other.
They are very different - that's right. But certainly this kind of technology has really
interesting possibilities for basic science both on the mammalian cell biology side and
on the plant cell biology side. Well thank you so much Larry. Thank you! It's been really
fun. Great. Thanks so much. So she used to be a news correspondent for MTV. Like I remember
her when I was in college. She was doing the MTV news. Ok. So the whole time during this
interview I was having this flashback of her saying "Hey. This is Serena. Green Day is
going to be on tour." But I was really struck at - so we were having a conversation we were
just kind of talking and then the camera rolled and, like, the smile, like just went, like
- exactly. Yes. I was like, "Wow. I don't know if I can do that!"