The effects of smokeless tobacco extract on bone nodule formation and mineralization by chick osteoblasts in vitro

Abstract

Short-term exposure to smokeless tobacco extracts (STE) reportedly inhibits osteoblast metabolism. The objective of this study was to determine the effects of serial dilutions of a water-soluble extract of smokeless tobacco on osteoblast proliferation and their potential to form and mineralize bone nodules. STE significantly stimulated cell proliferation when diluted 10 2–10 4 times; 10 3 and 10 4 dilutions produced the greatest effect. 10 2–10 4 STE dilutions significantly increased alkaline phosphatase activity at day 7 but 10 6 STE dilutions significantly decreased it. 10 3 and 10 4 dilutions significantly increased bone nodule formation, but inhibited their mineralization. In contrast, 10 5 and 10 6 dilutions significantly decreased bone nodule formation, but increased their mineralization. Stimulation of in vitro bone nodule formation by STE was similar to that produced by 10 −7 M insulin-like growth factor 1 (IGF-1) in vivo. Heat and acid treatment of STE significantly reduced its beneficial effect on cell proliferation, suggesting that a peptide within STE may be responsible for enhancement of osteogenic cell proliferation. Thus, STE may contain a peptide capable of significantly stimulating osteoblast proliferation, differentiation and metabolism, similar to the effects of IGF-1. This peptide could have potential therapeutic benefits.