PLACENTAL GROWTH FACTOR LEVELS IN POPULATIONS WITH 1 HIGH VERSUS LOW RISK FOR CARDIAC DISEASE AND STRESSFUL 2 PHYSIOLOGICAL ENVIRONMENTS SUCH AS MICROGRAVITY: A 3 PILOT STUDY

29 This pilot study compared placental growth factor (PlGf) levels in populations with 30 high versus low risk for cardiac disease. Previous experiments from our laboratory 31 (Sundaresan et al. 2005; 2009) revealed that the angiogenic factor PlGf was up- 32 regulated in modeled microgravity conditions in human lymphocytes leading to 33 possible atherogenesis and pathogenesis in microgravity. Since the findings came 34 from simulated microgravity experiments, there is a strong link to its usefulness in 35 the microgravity field as a biomarker. The relevance is enhanced because in life on 36 earth, it is a cardiovascular inflammatory marker. Studies on the levels of PIGF 37 would help to give a hint about the risk of heart failures in astronauts. 38 The investigations here to confirm that in a cardiovascular stressed 40 population such CAD ACS patients, PlGf overexpressed. a other than ACS and in thirty-three low-risk asymptomatic subjects. Additional data 47 on traditional cardiac risk factors for both populations were also compiled and 48 compared. We found that PlGf levels were significantly higher in the high-risk 49 than low-risk population and correlated inversely with HDL-cholesterol but 50 directly with the triglyceride levels. With further validation, PlGf may prove a 51 useful addition to the armamentarium of noninvasive biomarkers for cardiac 52 disease including a new area of stressful physiological conditions such as 53 microgravity. 54 55