Comparable calcium handling of human iPSC-derived cardiomyocytes generated by multiple laboratories.

Cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are being increasingly used to model human heart diseases. hiPSC-CMs generated by earlier aggregation-based methods (i.e., embryoid body) often lack functional sarcoplasmic reticulum (SR) Ca stores characteristic of mature mammalian CMs. Newer monolayer-based cardiac differentiation methods (i.e., Matrigel sandwich or small molecule-based differentiation) produce hiPSC-CMs of high purity and yield, but their Ca handling has not been comprehensively investigated. Here, we studied Ca handling and cytosolic Ca buffering properties of hiPSC-CMs generated independently from multiple hiPSC lines at Stanford University, Vanderbilt University and University of Wisconsin-Madison. hiPSC-CMs were cryopreserved at each university. Frozen aliquots were shipped, recovered from cryopreservation, plated at low density and compared 3-5days after plating with acutely-isolated adult rabbit and mouse ventricular CMs. Although hiPSC-CM cell volume was significantly smaller, cell capacitance to cell volume ratio and cytoplasmic Ca buffering were not different from rabbit-CMs. hiPSC-CMs from all three laboratories exhibited robust L-type Ca currents, twitch Ca transients and caffeine-releasable SR Ca stores comparable to adult CMs. Ca transport by sarcoendoplasmic reticulum Ca ATPase (SERCA) and Na/Ca exchanger (NCX) was similar in all hiPSC-CM lines, but slower compared to rabbit-CMs. However, the relative contribution of SERCA and NCX to Ca transport of hiPSC-CMs was comparable to rabbit-CMs. Ca handling maturity of hiPSC-CMs increased from 15 to 21days post-induction. We conclude that hiPSC-CMs generated independently from multiple iPSC lines using monolayer-based methods can be reproducibly recovered from cryopreservation and exhibit comparable and functional SR Ca handling.

Effects of l-amphetamine sulfate on cognitive function in multiple sclerosis patients.

We evaluated the effects of the levo (l) enantiomer of amphetamine sulfate on cognitive function in multiple sclerosis (MS) patients. Using a counterbalanced within-subjects design, 19 MS patients received four single-dose administrations of placebo, 15 mg, 30 mg, or 45 mg of l-amphetamine. Neuropsychological tests measuring processing speed and memory served as the primary outcomes. Performance on tests of processing speed were improved following the 45 mg condition and the largest effects were observed on the Symbol Digit Modalities Test, which measures visual processing speed and working memory. While episodic memory test effects were in the expected direction, the findings were not statistically significant. These preliminary findings show promise for the use of l-amphetamine for the symptomatic treatment of slowed mental processing in MS. Further placebo-controlled trials are needed to confirm these findings.