Identity and function of the tongue satellite cells.

Abstract

The tongue is an interesting organ, singled out by the traditional developmental biological studies, as a sole muscular organ derived from the occipital somite which is a head portion of the paraxial mesoderm. Separating the tongue from all other head muscles, which were thought to be related to the cranial mesoderm that contains progenitors of the cardiomyocytes. However, more recent evidence and findings from our laboratory show that tongue progenitors not only belong to the cranial mesoderm but also are a closer cousin of the cardiomyocyte. Since, the first pharyngeal arches originate from a close location of the cardiac field progenitors called pharyngeal mesoderm. Therefore, may possess overlapping anatomical and molecular characteristic during early pharyngeal arch development. The first arches are the confirmed source for the tongue development, and it could be hypothesized that the cardiac field cells engross the arches and arrive at the tongue. Indeed, the tongue has been recognised as the biggest extracardiac muscular organ to express the cardinal cardiac transcription factor NKX2-5.

The tongue muscle, however, seem to possess many characteristics of the cardiomyocytes, and the muscle contain a precious type of cells that the heart has long lost - the muscle progenitors, satellite cells. If the origin of the tongue is close to the heart, perhaps, these cells would be the closest donor to regenerate the heart tissue when damaged due to myocardial infarction.

Although many studies need to be done to ascertain many questions related to the development of the tongue and orofacial muscle, the current report indicates that the tongue as the central organ of the face and oral cavity may have close relationship to the heart. Elucidating the origin and molecular pathways may provide answers to syndromic congenital malformations of cardiac and facial structure. Moreover, tongue satellite cells may provide an alternative stem cell source for the cardiac repair.