Bone-boosting milk protein offers future

25 November 2004

Bone-boosting milk protein offers future hope for osteoporosis sufferers

The discovery of the bone-boosting properties of a component of milk may offer hope in the future to the millions of sufferers worldwide of the debilitating bone-wasting condition, osteoporosis.

Research by The University of Auckland’s Osteoporosis Research Group has found that a milk protein, lactoferrin, not only inhibits bone breakdown, but also boosts bone growth four times faster than normal when injected directly into bone.

Associate Professor Jill Cornish in the University’s Faculty of Medical and Health Sciences, who heads the project, says incorporating lactoferrin into a pill or an enriched beverage may prevent the onset of osteoporosis in those at risk, but this is some time away as more research is needed.

Local injection of lactoferrin has resulted in such “phenomenal bone growth”, she says, that it could be applied directly to a fracture site to promote faster healing than growth factor treatments currently available.

“It is a goody molecule. It’s good for bones, it’s good for the immune system, It’s an anti-bacterial, anti-viral and anti-fungal. Interestingly, when white blood cells in the body respond to infection they spurt out lactoferrin naturally. This is the body’s first line of defence.”

The research is a LactoPharma project. LactoPharma, established to discover and commercialise novel bioactive components from milk and colostrum, is a joint venture involving Fonterra Co-operative Group, and Auckland UniServices Ltd, the commercial arm of The University of Auckland, with investment from the Foundation for Research, Science and Technology (FORST).

Osteoporosis, an increasing global health burden affecting some 200 million people, costs New Zealand an estimated $200 million a year in health care and related costs.

Sixty per cent of women and 30 per cent of men in New Zealand over the age of 60 years suffer osteoporotic fractures. Seventeen per cent of post-menopausal women suffer a hip fracture, with one third dying within a year, and half unable to walk again unassisted.

Dr Cornish, who delivered a paper on her findings today (November 24) at the Global Dairy Summit Conference in Melbourne, says a lot of research has been done on the development of treatments to inhibit bone resorption, but little is known about how to build bone.

“This is what differentiates lactoferrin and makes it so exciting – it’s a double whammy if you like – inhibiting the formation of cells that resorb bone and stimulating the cells that form bone.”

While bone has a “static limestone cave appearance”, says Dr Cornish, it is in fact a dynamic, complex living tissue, with the human skeleton completely renewing itself every ten years.

Healthy bone depends on continual replacement, which is accomplished by the action of two main types of bone cell - osteoclasts which break down old bone, and osteoblasts, which form new bone. Osteoporosis occurs when there is an imbalance in this process.

“This regular turnover of bone is critical and without it the old bone develops fine fractures a bit like metal fatigue and eventually breaks,” says Dr Cornish.

Lactoferrin is a naturally occurring protein in cows’ and human milk and is particularly concentrated in colostrum, the rich substance newborns receive at birth before breast milk is fully established.

Dr Cornish says it is not surprising that milk contains a number of growth factors but this is the first time that lactoferrin has received this attention. The team of cell and molecular biologists are now looking at how lactoferrin works.

“This is the other really intriguing thing. We have discovered two new receptors on the bone-forming cells and lactoferrin is working through at least one of these to promote bone growth. So we think we have discovered a new anabolic (cell growth and differentiation) pathway in bone.

“This is significant because other molecules may be working through these receptors leading to new treatment options.”

Receptors and molecules travelling around the body have a “lock and key” relationship, says Dr Cornish, with receptors on the bone cells rather like the “lock”, waiting for the lactoferrin to make contact. This activates the process which makes new bone.

Dr Cornish, whose findings were published in September issues of “Endocrinology” and “Molecular Endocrinology” says although lactoferrin is present in various secretions in the body, it is not in sufficient concentration to prevent osteoporosis in later life.

LactoPharma’s Head Dr Kannan Subramaniam says LactoPharma has filed patent applications for lactoferrin as a bone growth factor as well as the two new receptors on the osteoblasts.

“These findings by Dr Cornish and her team are extremely exciting, paving the way for development of new value-add, therapeutic applications which are beneficial to human health as well as commercially viable,” he said.

The work of the University’s Osteoporosis Research Group is also supported by funding from the Health Research Council.

ENDS

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