Human Nasal Septal Cartilage: Analysis of Intracellular Enzyme Activities, Glycogen Content, Cell Density and Clonal Proliferation of Septal Chondrocytes of Healthy Adults and Acromegalic Patients

Abstract

The human septal cartilage is of ectodermal origin and contributes to midfacial growth and development. Acromegaly is an endocrine disease due to growth hormone (Gh) excess originating from a somatotrophic adenoma of the pituitary gland. Excessive Gh levels lead to high insulin-like growth factor I (IGF I) concentrations, which are known to stimulate cartilage growth in vivo and in vitro. One of the salient clinical pictures is coarsening of the midface and enlargement of the septal cartilage.

Septal cartilage was obtained from 8 acromegalic patients during transnasal hypophysectomy and from 10 healthy adults during septoplasty to analyse the following aspects of cartilage biochemistry, metabolism and growth.

1. Intracellular glycogen, the major source of energy of chondrocytes, was determined enzymatically and found to be drastically reduced in acromegaly.

2. Several intracellular enzymes, related to biomatrix degradation, showed a strict local pattern of distribution. Cathepsin B activity, a neutral proteinase degrading both the helical and nonhelical region of the collagen molecule was significantly increased in acromegaly, whereas alkaline phosphatase activity, an enzyme related to mineralization of the cartilage at the chondroosseous junction was depressed in acromegaly.

3. The cell density in some areas of the septal cartilage was increased in acromegaly, whereas the clonal proliferation rate of its chondrocytes in response to serum and growth factors was decreased. Chondrocytes both of healthy adults and acromegalic patients could be effectively stimulated by insulin-like growth factor I and II and to a lesser extent by epidermal growth factor.

Key Words:

• Human septal cartilage
• acromegaly
• enzyme activity
• glycogen content
• proliferation of chondrocytes