Is Fracture Healing in Space Problematic?

A team of bioengineers led by the University of Missouri have been thinking a lot about what would happen if an astronaut broke a leg or injured a knee while in space. Can a fracture heal just as well in space as it would on Earth?

In a recent study, Elizabeth Loboa, Ph.D., dean of the College of Engineering at the university and her team that includes researchers from the University of North Carolina and North Carolina State found that the key to that answer is gravity or ‘mechanical loading’.

Mechanical loading or forces that stimulate cellular growth for development, is required for creating cartilage that is then turned to bone but little is known about how cartilage develops in the absence of gravity or mechanical loads.

According to their study findings, microgravity may actually inhibit cartilage formation, complicating the healing process for astronauts who experience a fracture while in space as well as for patients on bed rest or who are paralyzed due to trauma.

“Because these tissues cannot renew themselves, bioreactors, or devices that support tissue and cell development, are used in many cartilage tissue engineering applications. Some studies suggest that microgravity bioreactors are ideal for the process to take place, while others show that bioreactors that mimic the hydrostatic pressure needed to produce cartilage might be more ideal. Our first-of-its-kind study was designed to test both theories,” Loboa said in a release.

The process through which cartilage is developed is called chondrogenic differentiation. Using human adipose, or fat cells (hASC) obtained from women, Loboa and her team tested chondrogenic differentiation in bioreactors that simulated either microgravity or hydrostatic pressure, which is the pressure that is exerted by a fluid.

The results showed that cyclic hydrostatic pressure, which has been shown to be beneficial for cartilage formation, caused a threefold increase in cartilage production and resulted in stronger tissues. Microgravity, in turn, decreased chondrogenic differentiation.

“Our study provides insight showing that mechanical loading plays a critical role during cartilage development,” Loboa said. “The study also shows that microgravity, which is experienced in space and is similar to patients on prolonged bed rest or those who are paralyzed, may inhibit cartilage and bone formation. Bioengineers and flight surgeons involved with astronauts’ health should consider this as they make decisions for regenerating cartilage in patients and during space travel.”

The study, “Comparison of Simulated Microgravity and Hydrostatic Pressure for Chondrogenesis of hASC,” was published in Aerospace Medicine and Human Performance.