Mechanisms of Plasticity Remodeling and Recovery

The brain has limited repair capacity and some degree of functional recovery is evident in nearly all stroke patients. Spontaneous repair and recovery processes are multifaceted and include angiogenesis, neurogenesis, axonal remodeling, oligodendrogenesis, synaptogenesis, and inflammatory response after stroke. Stroke also affects brain and circulating microRNA (miR) levels. The affected miRs further regulate the repair processes after stroke. Exosomes are nanosized vesicles that carry and deliver complex cargos of biomolecules (nucleic acids such as DNAs, ribosomal RNAs, circular RNAs, long noncoding RNAs and miRs, proteins, and lipids). Exosomes, by transferring select RNAs and proteins, are mediators of intercellular communication, and their generation and molecular cargo are affected by stroke. New therapies, such as cell reprogramming, modification and targeting of cellular miRs, or engineering exosomes to deliver enriched exosomal content of miRs have potential for promoting brain repair and neurologic recovery after stroke. In this chapter, we will review post-stroke endogenous brain repair mechanisms as well as cell-based, including exosome and miR, and pharmacologic therapies which amplify brain repair processes and lead to improvement of neurologic function after stroke.