Connexin 43 knockout (Cx43␣1KO) mice have conotruncal heart defects that are associated with a reduction in the abundance of cardiac neural crest cells (CNCs) targeted to the heart. In this study, we show CNCs can respond to changing fibronectin matrix density by adjusting their migratory behavior, with directionality increasing and speed decreasing with increasing fibronectin density. However, compared with wild-type CNCs, Cx43␣1KO CNCs show reduced directionality and speed, while CNCs overexpressing Cx43␣1 from the CMV43 transgenic mice show increased directionality and speed. Altered integrin signaling was indicated by changes in the distribution of vinculin containing focal contacts, and altered temporal response of Cx43␣1KO and CMV43 CNCs to ␤1 integrin function blocking antibody treatment. High resolution motion analysis showed Cx43␣1KO CNCs have increased cell protrusive activity accompanied by the loss of polarized cell movement. They exhibited an unusual polygonal arrangement of actin stress fibers that indicated a profound change in cytoskeletal organization. Semaphorin 3A, a chemorepellent known to inhibit integrin activation, was found to inhibit CNC motility, but in the Cx43␣1KO and CMV43 CNCs, cell processes failed to retract with semaphorin 3A treatment. Immunohistochemical and biochemical analyses suggested close interactions between Cx43␣1, vinculin and other actin-binding proteins. However, dye coupling analysis showed no correlation between gap junction communication level and fibronectin plating density. Overall, these findings indicate Cx43␣1 may have a novel function in mediating crosstalk with cell signaling pathways that regulate polarized cell movement essential for the directional migration of CNCs.

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder associated with ciliary defects and situs inversus totalis, the complete mirror image reversal of internal organ situs (positioning). A variable incidence of heterotaxy, or irregular organ situs, also has been reported in PCD patients, but it is not known whether this is elicited by the PCD-causing genetic lesion. We studied a mouse model of PCD with a recessive mutation in Dnahc5, a dynein gene commonly mutated in PCD. Analysis of homozygous mutant embryos from 18 litters yielded 25% with normal organ situs, 35% with situs inversus totalis, and 40% with heterotaxy. Embryos with heterotaxy had complex structural heart defects that included discordant atrioventricular and ventricular outflow situs and atrial/pulmonary isomerisms. Variable combinations of a distinct set of cardiovascular anomalies were observed, including superior-inferior ventricles, great artery alignment defects, and interrupted inferior vena cava with azygos continuation. The surprisingly high incidence of heterotaxy led us to evaluate the diagnosis of PCD. PCD was confirmed by EM, which revealed missing outer dynein arms in the respiratory cilia. Ciliary dyskinesia was observed by videomicroscopy. These findings show that Dnahc5 is required for the specification of left-right asymmetry and suggest that the PCD-causing Dnahc5 mutation may also be associated with heterotaxy.

Factors limiting the adoption of iPSC technology include the cost of developing lines and the time period that it takes to characterize and bank them, particularly when integration free, feeder free, and Xeno-free components are used. In this manuscript we describe our optimization procedure that enables a single technician to make 20–40 lines at a time in a 24–96 well format in a reliable and reproducible fashion. Improvements spanned the entire workflow and included using RNA virus, reducing cytotoxicity of reagents, developing improved transfection and freezing efficiencies, modifying the manual colony picking steps, enhancing passaging efficiency and developing early criteria of success. These modifications allowed us to make more than two hundred well-characterized lines per year.

Cardiomyocytes can be differentiated from human pluripotent stem cells (hPSCs) in defined conditions, but efficient and consistent cardiomyocyte differentiation often requires expensive reagents such as B27 supplement or recombinant albumin. Using a chemically defined albumin‐free (E8 basal) medium, we identified heparin as a novel factor that significantly promotes cardiomyocyte differentiation efficiency, and developed an efficient method to differentiate hPSCs into cardiomyocytes. The treatment with heparin helped cardiomyocyte differentiation consistently reach at least 80% purity (up to 95%) from more than 10 different hPSC lines in chemically defined Dulbecco's modified Eagle's medium/F‐12‐based medium on either Matrigel or defined matrices like vitronectin and Synthemax. One of heparin's main functions was to act as a Wnt modulator that helped promote robust and consistent cardiomyocyte production. Our study provides an efficient, reliable, and cost‐effective method for cardiomyocyte derivation from hPSCs that can be used for potential large‐scale drug screening, disease modeling, and future cellular therapies. Stem Cells Translational Medicine 2017;6:527–538