Mesenchymal transition (MT) is required for the formation of several tissue and organs during development. Indeed, cells change their specific phenotype to a mesenchymal-like one, involving a complex cell and genetic program that leads to the loss of cell-cell interactions and cell polarity with concomitant acquisition of mesenchymal markers and a distinct migratory behavior. Evidence progressively accumulates that MT is not confined to the embryonic development but is an important mechanism reactivated at the onset of several pathologies. MT is at the basis of the metastatic dissemination of solid tumor cells, a complex process that requires active migration and intra/extravasation. Importantly MT is the general mechanism that triggers and worsens diseases with a fibrotic component being primary cause of morbidity and a major cause of comorbidity of a broad spectrum of diseases including severe blood and vascular disorders and several complex diseases such as diabetes, for which there is a critical need to develop new and more optimized therapeutic approaches.

The network of cellular interactions and signaling pathways underlying MT in physiological and pathological conditions is extremely complex. A crescent number of studies are providing more and more information on the signaling pathways leading to this change of cell identity and ultimately to the onset/exacerbation of the pathological features of these diseases. However how the overall process is regulated is still far from being fully elucidated and many open questions need to be answered to better understand the underlying mechanisms and develop new and specific diagnostic and therapeutic tools.

The main focus of this special issue will be to put together studies that use different experimental approaches and in vivo or in vitro models to in-depth dissection of the dynamic changes of identity of different progenitors, their crosstalk with the tissue microenvironment, and their contribution to normal tissue remodeling versus onset of pathological condition.

Manuscripts reporting translation of basic cell and developmental biology to therapeutic approaches will be welcome, as well as reviews summarizing the most recent developments and ideas in the field.

Potential topics include, but are not limited to:

• MT and embryonic development
• Signaling pathways in MT
• Physiological and pathological MT in selected adult tissues: skin, lung, kidney, muscle, vasculature, central nervous system, and so on
• MT and tumor progression
• The immune system and MT
• Emerging therapeutic options