Eight years after he began a surgical residency through Mayo Clinic School of Graduate Medical Education, Johnathon Aho, M.D., Ph.D., is nearing completion. What took him so long? In between, he put surgery on hold to become a scientist. He earned a doctorate in biomedical engineering and physiology from Mayo Clinic Graduate School of Biomedical Sciences.

"I like machines," says Dr. Aho, who spent his youth fixing anything with moving parts. "The heart and lungs move. They're the major machinery of the body."

The art of surgery and the science of engineering, he figured, would prepare him to develop practical solutions to real-world problems. 

"I see problems every day - small inefficiencies that could be made better with a different solution," he says. His name already has appeared on more than 80 articles and 20 patent applications involving research projects aiming to improve treatment for hernias, rib fractures, tension pneumothorax, small-bowel tumors and obstructions, appendicitis, gallbladder inflammation, perforated peptic ulcer and more. 

Back to School

For more than 100 years, Mayo Clinic has been known for its physician-scientists. Mayo has built on that tradition with medical education that offers ample opportunities for research. Medical students at Mayo Clinic Alix School of Medicine spend a full quarter learning the principles and process of biomedical research and working on a research project. Most residencies and fellowships through Mayo Clinic School of Graduate Medical Education also include dedicated time for basic, translational and clinical research projects.

Mayo offers medical trainees many options for additional research training. However, only a few enroll in the Ph.D. program at Mayo Clinic Graduate School of Biomedical Sciences. Mayo launched its Medical Scientist Training Program in 1986, combining M.D. and Ph.D. training, to prepare graduates to be leaders in clinical medicine and scientific research. 

In recent years, a growing number of physicians have chosen to go back to school for a Ph.D. in biomedical research, separate from the Medical Scientist Training Program. 

"Students in the Medical Scientist Training Program typically decide to pursue this route by their junior or senior year of college," says Bruce Horazdovsky, Ph.D., the graduate school's associate dean for Academic Affairs. "Others complete their medical school training and realize that they want to pursue a Ph.D. to make research a larger part of their career."

Dr. Horazdovsky says the trend involves two groups: Mayo residents and fellows who, like Dr. Aho, put their medical training on hold to complete a Ph.D.; and non-Mayo trainees who want to pursue research under a leading authority in their areas of interest. Of the six M.D.s currently working toward a Ph.D., four are international students from Ireland, Pakistan, Germany and Uruguay.

Customized Training

After graduating from Chicago Medical School in 2012, Dr. Aho returned to his hometown of Rochester, Minnesota, for his surgical residency. Two years later, he entered Mayo's Clinician-Investigator Training Program, a two-year program of uninterrupted research training incorporated into a residency or fellowship, but he wanted more. The next year, he put residency on hold.

"For a unique individual like John, who wants a career in academic medicine, the Ph.D. is a critical piece of being set up to be successful," says Dennis Wigle, M.D., Ph.D., chair of the Division of Thoracic Surgery. "We were putting him in an environment with protected time to become proficient at research in a specific subject area."

As with all Ph.D. candidates, the graduate school tailored Dr. Aho's training to fit his interests and provided mentoring under world-renowned faculty. He worked with Daniel Tschumperlin, Ph.D., director of the Tissue Repair and Mechanobiology Laboratory, which investigates diseases of the respiratory system; Dr. Wigle, head of the Thoracic Oncology Laboratory; and Matthew Urban, Ph.D., who is developing ultrasound-based imaging methods to noninvasively evaluate the state of human kidneys and other organs.

Dr. Aho chose to focus on reconstruction and mechanical assessment of hollow structures through tissue engineering approaches, including the necessary instrumentation, imaging and devices. For his thesis, he led a team that demonstrated the safety and efficacy of a tissue-engineered implant that regenerates a replacement segment of an esophagus. As described in Nature Scientific Reports, the team used an artificial scaffold and a special type of stem cells to regrow esophageal tissue in a large-animal model. 

"It's encouraging," Dr. Aho says. "It seems to work well in animal models and in preliminary clinical study. It's possible we could extend a similar approach to replacement of other hollow tubes in the body."

Meeting the Needs of Clinical Departments

All Ph.D. students ultimately choose a track based on their area of interest. Several physicians going for a doctorate have opted for the Ph.D. track in clinical and translational science, which focuses on speeding scientific discoveries into advances in patient care.

"That's frequently a good match for these individuals," Dr. Horazdovsky says. Because of close ties to clinical practice, Ph.D. tracks in biomedical engineering and immunology also have been popular. 

Mayo residents and fellows who complete a Ph.D. in biomedical research tend to stay at Mayo Clinic. 

"This is one way the graduate school supports Mayo's clinical practice," Dr. Horazdovsky says. "Those select residents and fellows that become physician-scientists are poised to make new discoveries that lead to better patient care in the future." 

At the end of 2017, Mayo Clinic named Dr. Aho an assistant professor of biomedical engineering - a rare title for a physician midway through a residency ¾ in recognition of his innovation and accomplishments.

"For the physician who is truly driven to know more and learn more," Dr. Wigle says a Ph.D. offers great value. "Most importantly, it gives you the tools to not just ask questions, but follow through on them."

Mayo's Department of Surgery invested in concentrated research time for Dr. Aho to build his expertise at tissue engineering and his ability to navigate the never-ending quest for advances in patient care.

"He has a very strong engineering and mathematical mindset," Dr. Wigle says. "People who have exposure to other disciplines and can think on the fringe are the ones who can see new things. John is uniquely in that position."

Solving Problems

Dr. Aho, who will complete his residency in mid-2020 and start a fellowship in thoracic surgery, agrees that Ph.D. training was critical to his problem-solving and his career plans. 

"I want to do something to solve surgical patients' clinical problems. To make that contribution, I wanted to learn a different skill set. The engineering way of thinking helps me break down a problem into different components." 

Dr. Aho already has developed surgical devices and protocols for tissue engineering and stem cell therapies, but one mentor foresees still greater accomplishments ahead as he continues to challenge current practices.

"He has a strong interest in regenerative technologies and different ways to treat a clinical problem," Dr. Wigle says. "A lot of this technology is in its infancy. John's constant questioning and thinking is going to lead to some advances. You know something interesting is going to happen, and I can't wait to see it." 

- Jon Holten, January 2020

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