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Forty Years Amidst the Bones

October 15, 2020
by Matt O'Rourke

This month marks 40 years of service for Professor Mark Horowitz, who started his career in the department as a postdoctoral graduate. In the following interview, Horowitz reflects on his time in the department and his research contributions to the study of bone.

“I’d like to thank Dr. Horowitz on behalf of the department for all of his years of service and congratulate him on a long and successful career,” said Lisa L. Lattanza, Chair of the Department of Orthopaedics and Rehabilitation.

What made you decide to pursue a path as a research scientist and, more specifically, looking into bone function and growth?

I’ve always been interested in nature and the outdoors. For me, the spark came in sixth grade with my teacher. He did all of these very cool demonstrations in my class. He used to let me help him set up these experiments that I loved. It set me on the path, all through high school, college, and then graduate school.

I am an immunologist by training. When I came to Yale as a post-doc, I met Roland Baron, an assistant professor at Yale at the time who had done all of this work with bone. He had worked on something called Osteoclast Activating Factor, and that was something that interested me. I said to him that I was interested in this, and sure enough, we connected and published a paper on it together. This important introduction set me on the path for my career to look into bone and the cross-section of immunology and bone tissues.

What has been the primary focus of your research during your 40-year career here at Yale?

Over my entire time here at Yale, I’ve benefited from supportive chairs in our department. Dr. Gary Friedlaender, Dr. Ted Blaine, Dr. Jonathan Grauer, and now Dr. Lisa Lattanza always supported my work.

My current research is focused on bone marrow fat. So marrow fat is different than the other types of fats that you have in your body. And it develops as you get older: you have more and more fat in your bones. We're very interested in how that occurs, where the marrow fat occurs within the skeleton and its functional aspects. What does it do as it relates to your skeleton and the immune response?

My earlier work was more osteoimmunology. It was a relationship between osteoblasts and osteoclasts, although osteoclasts are in the macrophage lineage, so they're already immune cells. So how osteoblasts and osteoclasts interact with the immune system and vice versa.

What's the advice you give to young scientists interested in a career like yours?

Years ago I had an orthopaedic surgeon who worked in my lab. One of the best things that came out of that was for me because talking to an orthopaedic surgeon was extremely valuable. He had a completely different view of the work, and it made my science better and hopefully, it made his science better. So I would certainly encourage having clinicians in the lab but I've learned that in practical terms, it is very difficult to do. So my advice is to talk to the types of people your research might benefit because you, too, will benefit from the perspective.

How do you feel your work fits into Orthopaedics as a whole?

In our department, I've been fortunate to work alongside so many different types of people involved in this field in one way or another. There aren't as many physician-scientists as there used to be, and our department is a great training ground for people looking to become orthopaedic surgeons. That said, when we do cross paths, it's a beautiful thing. It helps expand my field of vision: on the one hand, you're working with surgeons who are thinking about immediate patient outcomes. On the other, they see your research and an issue where they might meld well together.

Take, for instance, a condition like post-menopausal osteoporosis. This is something that will eventually impact many, many women in their lifetime. Now let's say I'm working with a trauma surgeon. They want to be sure to fix the bone and adequately make sure it heals – or that there's a union, quickly. Many of the osteoporosis drugs on the market today are focused on preventing or slowing bone loss. Some have the secondary impact of growing new bone, but that's not their primary use. We're working on research that looks into that and asks questions like, what if we can combine this research with something that could potentially speed up the healing/union process by 50 percent? You can't tell me that's something a trauma surgeon wouldn't want. I think that's the path we're on. Our orthopedic surgeons in the clinic are the first line of people who identify women with fractures, which can be a very insidious disease. We want to be the ones who can find a way to increase bone density and work alongside surgeons to keep that perspective.

Tell me something you enjoy doing when you’re not in the lab or publishing papers.

I enjoy exercising and getting out for walks in nature. It's one of the best things I can do. I also like trying my hand at investing.

Submitted by Matt O'Rourke on October 15, 2020