An Indian-origin scientist-led team has for the first time demonstrated how the brain's own stem cells and precursor cells control growth of glioblastomas - the most common and most aggressive tumour.

Dr Sridhar Reddy Chirasani of Max Delbrenter for Molecular Medicine Berlin-Buch, Germany, and his colleagues have shown in cell culture and mouse model experiments just how the body's own protective mechanism they identified in an earlier study, actually works, the 'Brain' journal reported.

Glioblastomas are brain tumours that are most common in adults in their mid-fifties or early sixties. The causes for developing the disease are not yet known.

In their research, the scientists showed that the neural stem cells and neural precursor cells release a protein that belongs to the family of the bone morphogenetic protein.

This protein received its name for its ability to induce bone and cartilage tissue formation. However, BMP is active in the entire organism - even in the brain.

Neural stem cells release BMP-7 in the brain in the vicinity of the glioblastoma cells. The protein influences a small population of cancer cells, the so-called tumour stem cells.

A small quantity of these cells is sufficient to form new tumours again even after surgery. BMP-7 induces signalling in the tumour stem cells, causing them to differentiate. This means that they are no longer tumour stem cells.

However, the activity of stem cells in the brain and thus of the body's own protective mechanism against glioblastomas diminishes with increasing age. This could explain why the tumours usually develop in older adults and not in children and young people.

The discovery of the tumour stem cells has led to new concepts in the therapy of glioblastomas.