Phosphorus compounds that deliver proteins directly to bones could be used to combat skeletal disease.

Bone tissue contains a massive mineral phase that makes it unique from the rest of our tissues. Now researchers are using this as an opportunity to develop a 'magic bullet' for bone diseases - an ideal drug that will act specifically on diseased bone without affecting the surrounding tissues.

A 'magic bullet' for bone disease will act specifically on diseased bones and not the surrounding tissues. © iStockphotos

Hasan Uludag and colleagues at the University of Alberta, Canada, have focused on the development of bone-seeking proteins as medicines. 'Natural proteins are powerful drugs capable of effective bone repair,' said Uludag. 'Due to their significant side-effects in the body, however, they must be delivered only to bones, and not to other organs.' 

Bisphosphonates are one class of a limited number of molecules that show a strong affinity for bone. By linking these bone-seeking bisphosphonates to proteins Uludag and colleagues have shown that the targeting efficiency can be improved by increasing the number of bisphosphonates attached per protein. 

So far, experiments have involved model proteins that cannot repair bone. Future research will explore specific classes of proteins that can stimulate bone healing. 'The critical challenge is to formulate a drug delivery system that delivers the proteins to bones in a pharmacologically active form,' said Uludag. 
 
'Given the promise of the bone targeting approach, more concerted focus on this area is expected in the near future,' said Uludag. The aim is to 'generate novel pharmaceutical agents specifically for musculoskeletal diseases.'

Sarah Dixon