Am J Stem Cells 2013;2(3):137-154

Review Article
Therapeutic potential of Pnmt+ primer cells for neuro/myocardial regeneration

Aaron Owji, Namita Varudkar, Steven N Ebert

Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL 32827, USA

Received April 2, 2013; Accepted October 5, 2013; Epub December 22, 2013; Published December 30, 2013

Abstract: Phenylethanolamine n-methyltransferase (Pnmt) catalyzes the conversion of norepinephrine into epinephrine, and thus serves
as a marker of adrenergic cells. In adults, adrenergic cells are present in the adrenal medullae and the central and peripheral
(sympathetic) nervous systems where they play key roles in stress responses and a variety of other functions. During early embryonic
development, however, Pnmt first appears in the heart where it is associated with specialized myocytes in the pacemaking and
conduction system. There is a transient surge in cardiac Pnmt expression beginning when the first myocardial contractions occur, before
any nerve-like or neural crest cells appear in the heart. This early expression of Pnmt denotes a mesodermal origin of these “Instrinsic
Cardiac Adrenergic” (ICA) cells. Interestingly, Pnmt+ cells are found in all four chambers of the developing heart, but by adult stages, are
found primarily concentrated on the left side of the heart. This regionalized expression occurs in the left atrium and in specific regions of
the left ventricle roughly corresponding to basal, mid, and apical sections. A second distinct population of Pnmt-expressing (Pnmt+) cells
enters the embryonic heart from invading neural crest, and these “Neural Crest-Derived” (NCD) Pnmt+ cells appear to give rise to a
subpopulation(s) of cardiac neurons. Pnmt expression thus serves as a marker not only for adrenergic cells, but also for precursor or
“primer” cells destined to become specialized myocytes and neurons in the heart. This review discusses the distribution of Pnmt in the
heart during development, including the types of cells where it is expressed, and their potential use for regenerative medicine therapies
for cardiovascular disease. (AJSC1304001).

Keywords: Phenylethanolamine n-methyltransferase (Pnmt), Pnmt+ primer cells, neuroregeneration, myocardial regeneration

Address correspondence to: Dr. Steven N Ebert, Burnett School of Biomedical Sciences, College of Medicine, University of Central
Florida, 6900 Lake Nona Blvd, Orlando, FL 32827. Tel: 01-407-266-7047; Fax: 01-407-266-7002; E-mail:
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