Knockdown of BMP7 induced oligodendrocyte apoptosis, demyelination and motor function loss.

Background: Demyelinating diseases, including multiple sclerosis (MS) and spinal cord injury (SCI), lead to significant neurological deficits primarily due to the loss of oligodendrocytes (OLs). Bone Morphogenetic Protein 7 (BMP7) is expressed abundantly in the central nervous system and previous studies showed its protective effect in reducing OL loss. In this study, we aim to explore BMP7's potential as a biomarker and therapeutic target for demyelinating diseases by investigating its expression and effects on OLs and myelin sheath integrity.

Method: We analyzed multiple Gene Expression Omnibus datasets for BMP7 expression profiles in demyelinating conditions such as MS and SCI. Experimentally, we employed a BMP7 knockdown model in rat spinal cords using adeno-associated virus8 vectors to specifically reduce BMP7 expression. Western blotting, immunofluorescence, and Nissl staining were used to assess the effect on OL and other types of cells. The structure of myelin sheath and locomotor function were evaluated using transmission electron microscopy and BBB scores, and statistical analysis included ROC curves and ANOVA to evaluate BMP7's diagnostic and therapeutic potential.

Results: BMP7 expression consistently decreased across various demyelinating models, and BMP7 knockdown led to increased OL apoptosis through the Smad1/5/9 pathway, with no apparent effect on other cell types. This reduction in OLs was associated with myelin degeneration, axonal damage, and impaired motor function.

Conclusion: The study confirms BMP7's significant involvement in the pathophysiology of demyelinating diseases and supports its potential as a therapeutic target or biomarker. Future research should focus on therapeutic strategies to enhance BMP7 function and further investigate the mechanisms by which BMP7 supports myelin integrity.