Effects of bone morphogenic proteins on neural precursor cells and regulation during central nervous system injury

Bone morphogenic proteins (BMPs) are well known for their influence on cell fate determination, proliferation and differentiation during early embryogenesis. Here, we review evidence for BMPs playing an additional, ongoing role in the proliferation and differentiation of neural precursor and progenitor cells in postnatal and adult central nervous system (CNS) and in CNS injury. The effects of BMPs on CNS cells have been studied using primary cultures of neural precursor and oligodendrocyte lineage cells. In addition, transgenic mice have been used to investigate in vivo effects of altering BMP pathway activation, and rodent models of CNS injury have been used to examine endogenous regulation of BMPs. These results have shown that BMPs promote production of astrocytes and inhibit production and maturation of oligodendroglia. The effects of BMPs on neurogenesis could be dependent on the origin of precursor cells or on the specifics of the microenvironment of the cell niche, as there are reports of inhibition and promotion of neurogenesis by BMPs. There is emerging evidence that BMPs are upregulated in several models of CNS injury; however, the effects of this regulation have not been well characterised. Understanding of the function of endogenous BMP regulation is important for determining how modulation of BMP signalling could improve repair following CNS injury.