PLAN B AND RETURN TO THE MOON    
SPACEFLIGHT 49:358, 2007

 

When large complex ventures are planned by nations it seems appropriate to have a plan B. The potential cardiovascular hazards complicating a lunar venture before the end of the next decade clearly require an alternative plan to offset the lack of availability of pharmaceuticals; this is because pharmaceuticals are contraindicated in space stemming from invariable malabsorption necessitating parenteral administration, deterioration of some (no longer meeting U.S.P. standards) and potential impairment in their hepatic metabolism and renal excretion.(1)

In addition to the vascular complications of space flight there are those vascular complications resulting from the inhalation of moon dust – particularly ultra-fine particles ( < 100 nm.)- brought into the lunar habitats on the space suits.(2)  On earth there has been growing concern regarding the industrial exposure to these “ nanotechnology products “ with  inhalation of these particles and then circulating throughout the body. (3)

 Similarly Apollo 17 astronaut Schmitt emphasized  his concern  with his statement : “ NASA has made no attempt to learn whether the Apollo astronauts’ limited exposure to this dust has had any lasting effects “ ----(4) During the recent  Rutgers Symposium on Lunar Settlements (June 3-8, 2007) (www.lunarbase.rutgers.edu ) Schmitt  indicated  however his confidence that the problems with exposure in the lunar habitats of this ultra-fine dust could be solved  ultimately  perhaps by  the combination of electrostatic processes and development of the technology to remove the space suits before entering the lunar habitat and leaving the space suits outside the habitat.

But in case of failure of these options is there a plan B? Should NASA begin NOW looking for a substitute for pharmaceuticals which can’t be utilized in space?  With promising studies in experimental animals it appears that gene therapy may provide for lunar explorers an option which might offset a few of the vascular complications.

For example a major vascular complication in space appears to be the reduction in circulating platelets because they can adhere to the injured lining of the blood vessels    (endothelium) or aggregate.  Since platelets are the primary source of a vital  growth factor ( vascular endothelial growth factor )( VEGF) and  platelets have been shown to be reduced both with space flight (5) and with exposure to dust ( 6), the studies in experimental animals of  gene therapy to enhance the supply of VEGF  appears promising.(7)  VEGF is necessary for endothelial ( the lining of blood vessels) function, repair and the development of collateral circulation . (1,2)

Another  preliminary  study in experimental animals ( rats ) has shown that gene therapy with  a peptide (atrial natriuretic peptide) ANP  (8)  may conceivably offset the invariable reduction in ANP complicating space flight.(1) This reduction in ANP  may be a partial  explanation for  Apollo 15 Astronaut Irwin’s  extraordinary elevations of stress test –related blood pressures (> 275/125) after his  mission ,which I postulated was secondary to inhalation of ultra-fine dust in the lunar module(2). Such blood pressure levels have not been reported – to my knowledge- from dust inhalation on earth. It is important to keep in mind however that inhalation of urban dust- superimposed upon vascular disease- does not always precipitate hypertension. The explanation may be because on earth the presence of ANP in sufficient quantities prevents this from occurring because ANP counteracts the effects of vessel constrictors, and by another mechanism also enhances vasodilatation. ( 1,2,9)

If we indeed are serious about exploring and ultimately colonizing the moon and then on to Mars now is the time to explore as well the opportunities gene therapy may provide.

William J. Rowe M.D. FBIS
1485 Bremerton La.
Keswick, Virginia 22947
U.S.A.

 

References

1. WJ Rowe. The case for a subcutaneous magnesium product and delivery device for space missions. J Am Coll Nutr 23, pp 525 S-528S, 2004

2 WJ Rowe. Moon dust may simulate vascular hazards of urban pollution. JBIS 60 pp. 133-136,2007

3 BJ.Feder.  New rules expected on safety of nanotechnology products.  New York Times, June 21, 2007

4 HH.Schmitt. Return to the moon. Copernicus Books , New York, P 317,  2006

5  E.Gunsillius , AL Petzer , G Gastl. Space flight and growth factors. Lancet 353 : p 1529, 1999

6. K Donaldson, V Stone, A Seaton, W MacNee.  Ambient particle inhalation and the cardiovascular system : potential mechanisms . Environ. Health perspect S 109 , S4,  pp 523-527 ,2001

7. MM Gaffney ,  SO Hynes , F Barry , T O’Brien.  Cardiovascular gene therapy ; current status and therapeutic potential.  Brit.  J. Pharmacol , 11 June,  pp1-14, 2007

8. KF Lin, J Chao, L Chao. Human atrial natriuretic peptide gene delivery reduces blood pressure in hypertensive rats. Hypertension 26, pp.847-853,1995.

9. MA Costa, LV Gonzales Bosc, MP Majowicz et al.  Atrial natriuretic peptide modifies arterial blood pressure through nitric oxide pathway in rats. Hypertension  35 pp. 1119-1123,  2000