A collaborative research team led by scientists at Houston Methodist is one step closer to developing technologies that could help mend broken bones faster. The Department of Defense (DoD) awarded close to $6 million to the Houston Methodist Research Institute for an initiative aimed at studying two new materials to repair complex fractures in long bones.
Major injuries to long bones, such as the shinbone, typically require multiple surgeries involving the placement of plates, screws, rods, external fixators and in some cases, amputation. In 2008, Defense Advanced Research Projects Agency (DARPA), the Pentagon's research agency, initiated the Fracture Putty Program to tackle the challenges associated with healing these complex fractures.
Mauro Ferrari, Ph.D., president & CEO of the Houston Methodist Research Institute, and Ennio Tasciotti, Ph.D., director of the Center for Biomimetic Medicine and scientific director of the Surgical Advanced Technology Laboratory at Houston Methodist, led a multi-institutional team of researchers who developed a groundbreaking approach to regenerate large segments of missing bone in a single surgery, without the use of any supporting hardware.
By 2014, this team developed two platforms that could radically change the fundamentals of orthopedic care. These two biomaterials work together to create a biomimetic scaffold that acts like a bridge between the ends of the broken bone. When implanted into the injury site, the scaffold supports, regrows and heals fractured bone without the need of standard metallic devices traditionally used to hold bones together. The scaffold is composed of a load-bearing shell -- a synthetic, non-toxic, biodegradable polymer (L-phenylalanine-based poly(ester urea)s - PEU) -- and of another shell made of natural biomineralized collagen that promotes the growth of bone cells and accelerates the healing process.
The Houston Methodist team demonstrated the scaffold's structural integrity and mechanical stability (PEU shell) as well as its ability to induce accelerated bone tissue regeneration around the defect (collagen shell). No additional growth factors, bioactive molecules or mesenchymal stem cells were implanted, establishing the unique properties of these scaffolds. Within six weeks, the implant promoted enough bone growth to heal the fracture and allow full weight-bearing activities, including walking.
"We designed the materials to mimic natural, healthy tissues, so the scaffolds are not rejected by the body's immune system and guide the injured tissues to heal better and faster," said Tasciotti, the principal investigator for this grant. "Over the next three years, we will lead our biomimetic scaffolds through the arduous process of moving from the lab to first-in-human clinical trials."
Orthopedic surgeons, especially those treating patients in military conflicts, see massive trauma and high morbidity in soldiers injured by high-energy blasts.
"While surgical advances in the treatment of these severe injuries have been made, far too often the end result is significant disability or amputation. Novel approaches to the problem are warranted and our solution, based upon biomimetic tissue engineering, appears promising," said Houston Methodist Vice Chairman of Orthopedics Bradley Weiner, M.D., clinical lead investigator of this study.
Tasciotti said the Houston Methodist team will continue to advance the development of the PEU and collagen shells, with the final goal of making them a viable treatment option. Cardiovascular diseases, osteoporosis, diabetes, and spinal cord injuries are among the dozens of other medical ailments likely to benefit from advances in regenerative medical technologies.
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