Sibley School of Mechanical & Aerospace Engineering
Cornell University

Postdoc, UC Berkeley
Postdoc, Mount Sinai School of Medicine
MS, Ph.D. Mechanical Engineering, Stanford University
SB, Engineering Sciences, Harvard University

Specific Area of Interest
The Microbiome and Musculoskeletal Disease

What are you currently working on?
My lab focuses on the effects of the gut microbiome on musculoskeletal tissues and orthopaedic surgery. Our main focus right now is to understand how the constituents of the gut microbiome regulate bone structure and mechanical performance. We have been encouraged by recent findings that modifications to the constituents of the gut microbiome can impair the mechanical properties of the bone tissue itself. These findings are exciting since existing therapies focus on increasing the amount of bone (“bone quantity”); the microbiome may be one of the few ways to improve bone tissue quality. A second ongoing project in the laboratory is to understand how the constituents of the gut microbiome influence the response to bacterial challenge at the surface of an orthopaedic implant. Our preclinical studies have shown that a history of a “poor” gut microbiota can impair the immune response to bacterial challenge, making it as much as 50% more likely that the bacteria will colonize the implant surface. I think one day we may look to modifications of the gut microbiome – something I call a “microbiome-based therapeutic” that can be used to address chronic musculoskeletal diseases and to achieve better responses after orthopaedic surgery. I also have an ongoing project that isn’t related to orthopaedics at all; we made materials testing machines for individual bacteria and have been studying their mechanical properties and how they respond to mechanical stimulation.

What has been the biggest challenge/issue for you lately in your research?
Teasing out the links between the gut microbiome and organ far from the gut lining is challenging. There are multiple potential mechanistic pathways that touch on immunology, nutritional sciences, microbiology and, of course, musculoskeletal biology. It’s hard to identify the pathways that are potentially most important.

What project(s) are you looking forward to in the near future?
We just had a big surprise in a mouse study we were doing. We have been studying ways in which the gut microbiome can lead to impaired bone tissue strength so we can find preventive approaches. We did a study with that had a control group in which the microbiome was modified only by a non-influential dietary additive (like a “vehicle” group in a drug study). To our surprise the changes in the gut microbiome generated in the control group led to increases in bone tissue strength. The idea that we could actually increase the strength of bone matrix by manipulating the gut microbiome was totally unexpected and opens up the possibility of novel therapies. We can’t wait to figure out how this happened.

What advice would you give investigators who are just starting out in the field?
When I started my lab, I focused on finding the answers I had wanted as graduate student and postdoc. It wasn’t until sometime later that I realized that it was much more fun to instead focus on finding the important new questions. To really do that you have to step outside your comfort zone and learning something new.

Is there anything in your career/research that, if you had it to do over, you would change?
Oh, I have a list 😉 but I think what I’ve been doing has really been right for me.

What is your most memorable moment in your career?
My former student, Marysol Luna (see her in the ) earned her PhD last year. It turns out she was the first Latina to earn a PhD in Cornell’s Mechanical Engineering program. Her  about graduating went viral (and even mentioned me!).

We spend a lot of time dreaming about how our work might change science, but it’s even more satisfying to see how we, as scientists, can change the world.

Watch the video interview with Dr. Hernandez.