Study of links between bone health and cardiovascular status in women a molecular biology approach

India in the past two decades witnessed a dramatic epidemiological transition from

infectious, diseases of undernutrition, and maternal and childhood diseases to

noncommunicable diseases (NCDs). These diseases mainly include cardiovascular

diseases (CVD), cancers, respiratory diseases, diabetes, skeletal disorders 1 .

Amongst these diseases, osteoporosis, a disease of bone and CVD constitute a

considerable burden of NCD as these two share common risk factors and often

occur simultaneously. A need therefore exists to investigate the link between these

seemingly unrelated diseases of bone and cardiovascular systems.

1. Bone biology

Bone is a vascularized and metabolically active connective tissue that exerts

numerous functions in the body such as provision of mechanical support to the body

and protection of internal vital organs such as brain, spinal cord and heart. It is a

storehouse for calcium and phosphorous, the major site for metabolic pathways

associated with mineral homeostasis and provide site for ligaments and muscles

attachment. The process of skeletal development during early stages of life is called

bone modeling which involves the deposition of mineralized tissue at

developmentally determined sites. Once skeleton achieves maturity, the processes

of bone resorption and bone formation equally balance each other in a healthy

skeleton. This continuous process, termed as bone remodelling is essential for the

maintenance of bone structure and its strength 2 . It involves replacement of

old/damaged bone through the combined action of the osteoclasts, the bone

resorbing cells and osteoblasts, the bone forming cells. Bone remodelling cycle

comprises of three phases: 1) initiation of bone resorption by osteoclasts 2) the

transition (or reversal period) from resorption to new bone formation and 3) bone

formation by osteoblasts3, 4. This remodelling is necessary to maintain the structural

integrity of the skeleton. Normal bone remodelling cycle involves bone resorption

and formation in a co-ordinated fashion.