BME Seminar Series: Dr. Brandon Macias

Senior Scientist, Cardiovascular and Vision Laboratory, KBRwyle / NASA Johnson Space Center

Abstract: 

​"Spaceflight associated neuro-ocular syndrome during exploration missions"

As the spaceflight community prepares for long-duration exploration class mis­sions of distant objects beyond low Earth orbit, a new and perplexing spaceflight-associated neuro-ocular syndrome (SANS) has emerged. Vestibular dysfunction, loss of mechanical weight bearing, subjective sensation of a headward fluid shift, reduc­tion in muscle volume, and bone loss were intensely studied in the past five decades. These spaceflight adaptations are obvious to most of us now, reduced muscle activity results in muscle atrophy, and reduced mechanical loading of bone results in bone loss. Body fluid redistribution and cardiovascular adaptations dur­ing spaceflight result in postflight orthostatic intolerance, but are now mostly met with effective countermeasure strategies. SANS is characterized by changes in astronauts’ vision (hyperopic shifts) and eye structure (optic disc edema, choroidal folds, globe flattening, and optic nerve sheath distention). More than 50% of International Space Station (ISS) astronauts have decrements in their visual acuity or changes in their ocular structures during or after spaceflight. Our understanding of the SANS has progressed from initial hypotheses related to pathologically-elevated intracranial pressure, to a more complex phenomenon likely related to the chronic headward fluid shift that occurs in weightlessness. This talk will discuss approaches utilized to mitigate spaceflight induced physiological deconditioning, recent data of a ground-based model of SANS, as well as an update on findings from astronauts flying long-duration missions to the International Space Station.

Bio:

Brandon R. Macias, PhD., is a Senior Scientist and the Human Health and Performance Contract Technical Lead of the Cardiovascular and Vision Laboratory, at NASA-Johnson Space Center.  Dr. Macias completed his B.A. in Molecular and Cell Biology at University of California, Berkeley in 2002.  Prior to entering graduate school, Dr. Macias worked as a staff research associate for Dr. Alan Hargens at the University of California, San Diego (UCSD) supporting NASA funded human spaceflight analog countermeasure studies.  He matriculated to Texas A&M University where he obtained his Ph.D. in Exercise Physiology with National Space Biomedical Research Institute (NSBRI) Certificate in Space Life Sciences.  He completed his dissertation under the mentorship of Dr. Susan Bloomfield, studying Sclerostin-Wnt signaling responses to mechanical loading of bone.  Dr. Macias conducted pre-doctoral research as part of a National Science Foundation Nordic Award with Dr. Per Aspenberg’s experimental medicine laboratory at Linköping University, Sweden, studying mechanotransduction in bone during disuse and fracture healing.  Following his graduate career at Texas A&M University, Dr. Macias was awarded the NSBRI First Award to conduct postdoctoral research studying spaceflight associated neuro-ocular syndrome, with Drs. Alan Hargens and John Liu at UCSD.  Currently, Dr. Macias is principal investigator of the International Space Station “Ocular Health Study,” and co-investigator of the “Fluid Shifts” experiment, and is working with his team to determine why spaceflight induces vision change in some astronauts.  Over the course of his career he has published over 60 peer-reviewed journal articles on space life science topics in the fields of orthopedic surgery and ophthalmology.