A local renin-angiotensin system in the bone marrow.

The renin-angiotensin system has been considered to be a circulating system that controls blood pressure and electrolyte homeostasis. It is now clear, however, that the renin-angiotensin system must also be regarded as a local tissue system within many organs. Renin-angiotensin system peptides are capable of producing the hyperplasia and growth of cells. The haematopoietic bone-marrow system is characterized by turnover, proliferation and differentiation of cells. We propose that there exists a locally active renin-angiotensin system that is intrinsic to bone marrow and that might affect the growth of haematopoietic colonies, and the production, proliferation and differentiation of cells. The local synthesis of a particular protein can be deduced from the presence of the corresponding messenger ribonucleic acid. To prove our hypothesis, we propose that attempts be made to quantitatively analyse messenger ribonucleic acids for components of the renin-angiotensin system in tissues from bone marrow biopsies. Demonstration of an endogenous renin-angiotension system in bone marrow might lead us to a better understanding of the production of haematopoietic cells and of the excessive cell-growth associated with neoplastic diseases of the blood.