ABSTRACT
The aging process is characterized by alterations in the functions of many organ systems. Changes occur in the cardiovascular, endocrine and immune systems, and have been studied extensively. Changes in bone marrow function are also evident, but the physiologic basis for these alterations is less well understood. Clearly, the bone marrow plays an important role in normal homeostasis, producing cells responsible for maintenance of oxygen delivery, hemostasis, and host defense against infection. The bulk of evidence favors preservation of normal homeostatic bone marrow function with aging in healthy individuals, although functional deficits are apparent under conditions of hematopoietic stress. The question of which of these observed cellular alterations are normal physiologic responses and which are consequences of coexistent disease processes remains under debate. In order to place published experimental data in perspective, an understanding of the regulation of normal hematopoiesis is essential.
