The unified hypothesis of interactions among the bone, adipose and vascular systems: 'osteo-lipo-vascular interactions'.

Epidemiological evidence has established a link among hyperlipidemia, visceral obesity, osteoporosis, and cardiovascular diseases (CVD). We here propose the hypothesis that the associations of those disorders are based on interaction of the three organs, i.e. the bone, adipose, and vascular tissues, possibly through multiple interactions among several humoral factors and/or transcription factors. The unified hypothesis of three organs, which we call 'osteo-lipo-vascular interactions', may be explained by the common origin of the cells in each organ. The mesenchymal stem cells are capable of differentiating into osteoblasts, vascular smooth muscle cells, and adipocytes. Alternatively, macrophages may evolve into osteoclasts or infiltrate both the vascular and adipose tissues, thereby leading to chronic inflammation. This unified concept of three organs may provide insights into the development of a new drug for the treatment of osteoporosis, obesity, hyperlipidemia or CVD.