Building stronger bones, one stem cell at a time

Mesenchymal stem cells (MSCs) are bone marrow-derived cells that are capable of giving rise to various cell types through a process known as differentiation.

Although it has been proposed that drugs targeting the in vivo differentiation of these cells might provide a new strategy for regenerative medicine, identifying drugs that are capable of specifically targeting MSCs and that can also regulate their differentiation has proven an enormous obstacle.

In a new study, David Scadden and colleagues at Massachusetts General Hospital, Boston, have determined that the antitumor drug bortezomib (Bzb) targets MSCs and leads to bone cell–specific differentiation. Human and mouse MSCs treated with Bzb effectively differentiated into osteoblasts, the cell type responsible for bone formation.

Bzb treatment increased bone formation in normal mice and recovered bone loss in mice with an induced form of osteoporosis.

The authors therefore concluded that Bzb might be a novel therapy for bone loss in individuals with some types of cancer as well as those with osteoporosis.

The clinical importance of these data for the treatment of patients with cancer accompanied by severe bone disease, such as often occurs in individuals with myeloma, is further highlighted in an accompanying commentary by David Roodman at the VA Pittsburgh Healthcare System.