Adult stem cells are activated to proliferate and differentiate during normal 
tissue homeostasis as well as in disease states and injury. This activation is a 
vital component in the restoration of function to damaged tissue via either 
complete or partial regeneration. When regeneration does not fully occur, 
reparative processes involving an overproduction of stromal components ensure 
the continuity of tissue at the expense of its normal structure and function, 
resulting in a "reparative disorder". Adult stem cells from multiple organs have 
been identified as being involved in this process and their role in tissue 
repair is being investigated. Evidence for the participation of mesenchymal 
stromal cells (MSCs) in the tissue repair process across multiple tissues is 
overwhelming and their role in reparative disorders is clearly demonstrated, as 
is the involvement of a number of specific signaling pathways. Transforming 
growth factor beta, bone morphogenic protein and Wnt pathways interact to form a 
complex signaling network that is critical in regulating the fate choices of 
both stromal and tissue-specific resident stem cells (TSCs), determining whether 
functional regeneration or the formation of scar tissue follows an injury. A 
growing understanding of both TSCs, MSCs and the complex cascade of signals 
regulating both cell populations have, therefore, emerged as potential 
therapeutic targets to treat reparative disorders. This review focuses on recent 
advances on the role of these cells in skeletal muscle, heart and lung tissues.