Gravity, Mechanical Loading Critical for Cartilage Development

What happens to cartilage development if there is no pressure such as gravity or mechanical loading?

University of Missouri bioengineers have found out.

According to their new study, “Comparison of Simulated Microgravity and Hydrostatic Pressure for Chondrogenesis of hASC,” microgravity may inhibit cartilage formation. Their work was published in Aerospace Medicine and Human Performance.

“Cartilage tissue engineering is a growing field because cartilage does not regenerate,” said Elizabeth Loboa, Ph.D., dean of the MU College of Engineering and a professor of bioengineering, in the August 22, 2017 news release.

“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.”

As MU College of Engineering wrote in the news release, “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. Researchers found 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,” Dr. 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.”

Dr. Loboa told OTW, “From an orthopedic surgeon’s standpoint, our study shows the benefits of physiological loading to stimulate chondrogenesis. So, if a patient is on prolonged bed rest with a broken leg and no mechanical loading is occurring at the fracture site, then chondrogenesis (cartilage formation) could be delayed or inhibited. In normal secondary fracture healing, cartilage usually forms at the fracture site and that cartilage is then replaced by bone through the process of endochondral ossification. So, if cartilage formation is inhibited and/or delayed, fracture healing could be compromised.”