For generations, the journey into space has been a primary focus of those who escape the gravity well of planet Earth. We have a good idea about the health effects of low gravity in low earth orbit (LEO), but what about the effects of living on a new planet? 

A pair of Temple University researchers are pursuing that very question, and their work just may have good bones.

Laura H. Carnell Professor and Bioengineering Department chair Peter Lelkes and newly-minted PhD Justin Braveboy-Wagner ecently published their joint work, studying how partial gravity conditions—such as those found on the Moon and Mars—may impact bone health. Their paper was published in June in the prestigious journal npj nature Microgravity. It is the first comprehensive study comparing the effects of different simulated partial gravities and microgravity on the function of cultured animal cells. 

"Previous studies have shown that bone formation and maintenance is impaired under microgravity conditions of orbital space flight (< 10-3 G )," Dr. Lelkes said. "Since we cannot easily go to space, the experiments were performed using bone precursor cells (osteoblasts) that were cultured in a 'random position machine' that can accurately simulate extraterrestrial partial gravity/microgravity conditions. The differentiation and maturation of these bone precursor cells is a model for studying bone health."

The results may be predictive of what to expect when humans will land and live on Mars and Moon. 

As Dr. Lelkes cautions, one important conclusion is that the differential effects of partial gravity on cell function cannot be generalized and need further careful, case-by-case evaluation. Of particular relevance will be to determine individual thresholds for specific partial gravity effects.  

The Temple researchers hypothesized that the expression of bone-cell specific markers would be inhibited by reduced gravity in a dose-dependent manner: i.e. the lower the reduced gravity, the more the impairment. While certain results, such as the rate of cell proliferation and mineralization, bore this out, other parameters, such as bone-specific gene expression, responded in a stepwise manner. In other words, maximal inhibition was observed once a particular partial gravity level was achieved (e.g.. Mars or Moon). In these cases, further reduction in the partial gravity levels beyond a particular threshold did not result in a further decrease in the expression of these parameters.

The work was part of Braveboy-Wagner's PhD thesis. "We were privileged enough to have a random positioning machine built by a Dutch aerospace company for this," said Dr. Braveboy-Wagner. "In addition to having the equipment, there was and is great excitement about continued advances in commercial space lift, spurred by SpaceX's Falcon, Falcon Heavy, and Starship, and a renewed interest in human activities in space and, eventually, on Mars and the Moon. We can simulate artificial gravity in space via rotation, if need be, but on a planet or moon, we need to adapt."

Other recent microgravity studies, looking to determine how the adverse effects of microgravity can be mitigated by food-derived antioxidants, were conducted in the Lelkes lab in collaboration with Prof. Yoav Sharoni, Ben Gurion University, Beersheva, Israel. 

Click here to view the full publication. Click here to learn more about Prof. Lelkes and his research interests and click here to learn more about the Integrated Laboratory for Cellular Tissue Engineering and Regenerative Medicine lab.