Human ISL1 blocking peptide

The esophagus links the oral cavity to the stomach and facilitates the transfer of bolus. Using genetic tracing and mouse mutants, we demonstrate that esophagus striated muscles (ESMs) are not derived from somites but are of cranial origin. Tbx1 and Isl1 act as key regulators of ESMs, which we now identify as a third derivative of cardiopharyngeal mesoderm that contributes to second heart field derivatives and head muscles. Isl1-derived ESM progenitors colonize the mouse esophagus in an anterior-posterior direction but are absent in the developing chick esophagus, thus providing evolutionary insight into the lack of ESMs in avians. Strikingly, different from other myogenic regions, in which embryonic myogenesis establishes a scaffold for fetal fiber formation, ESMs are established directly by fetal myofibers. We propose that ESM progenitors use smooth muscle as a scaffold, thereby bypassing the embryonic program. These findings have important implications in understanding esophageal dysfunctions, including dysphagia, and congenital disorders, such as DiGeorge syndrome.

Cardiac stem cell therapy has been proposed as a therapy option to treat the diseased myocardium. However, the low retention rate of transplanted single-cell suspensions remains a major issue of current therapy strategies. Therefore, the concept of scaffold-free cellular self-assembly into three-dimensional microtissues (3D-MTs) prior to transplantation may be beneficial to enhance retention and survival. We compared clinically relevant, human stem cell sources for their ability to generate 3D-MTs with particular regards to formation characteristics, proliferation-activity, viability and extracellular-matrix production. Single-cell suspensions of human bone marrow- and adipose tissue-derived mesenchymal stem cells (hBMMSCs and hATMSCs), Isl1(+) cardiac progenitors derived from human embryonic stem cells (hESC-Isl1(+) cells), and undifferentiated human induced pluripotent cells (hiPSCs) were characterized before to generate 3D-MTs using a hanging-drop culture. Besides the principal feasibility of cell-specific 3D-MT formation, a detailed head-to-head comparison between cell sources was performed using histology, immunocyto- and histo-chemistry as well as flow cytometry. Round-oval shaped and uniform 3D-MTs could be successfully generated from all cell types starting with a loose formation within the first 24 h that fully stabilized after 3 days and resulting in a mean 3D-MT diameter of 194.56 +/- 18.01 mu m (hBMMSCs), 194.56 +/- 16.30 mu m (hATMSCs), 159.73 +/- 19.20 mu m (hESC-Isl1(+) cells) and 120.95 +/- 7.97 mu m (hiPSCs). While all 3D-MTs showed a homogenous cell distribution, hiPSC-derived 3D-MTs displayed a compact cell formation primarily located at the outer margin. hESC-Isl1(+) and hiPSC-derived 3D-MTs maintained their proliferation-activity which was rather limited in the MSC-based 3D-MTs. All four 3D-MT types revealed a comparable viability in excess of 70% and showed a cell-specific expression profile being comparable to their single-cell counterparts. Extracellular matrix (ECM) production during 3D-MT formation was observed for all cell-specific 3D-MTs, with hiPSC-derived 3D-MTs being the fastest one. Interestingly, ECM distribution was homogenous for hATMSC- and hiPSC-based 3D-MTs, while it appeared to be primarily concentrated within in the center of hESC-Isl1(+) and hBMMSC-based 3D-MTs. The results of this head-to-head comparative study indicated that 3D-MTs can be successfully generated from hESC-derived Isl1(+) cells, hiPSCs and MSC lines upon hanging drop culture. Cell-specific 3D-MTs displayed sufficient viability and instant ECM formation. The concept of 3D-MT in vitro generation prior to cell transplantation may represent a promising delivery format for future strategies to enhance cellular engraftment and survival. (C) 2013 Elsevier Ltd. All rights reserved.