Cellular Dynamics International (United States)

Recent in vitro cardiac safety studies demonstrate the ability of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to detect electrophysiologic effects of drugs. However, variability contributed by unique approaches, procedures, cell lines, and reagents across laboratories makes comparisons of results difficult, leading to uncertainty about the role of hiPSC-CMs in defining proarrhythmic risk in drug discovery and regulatory submissions. A blinded pilot study was conducted to evaluate the electrophysiologic effects of 8 well-characterized drugs on 4 cardiomyocyte lines using a standardized protocol across 3 microelectrode array platforms (18 individual studies). Drugs were selected to define assay sensitivity of prominent repolarizing currents (E-4031 for IKr, JNJ303 for IKs) and depolarizing currents (nifedipine for ICaL, mexiletine for INa) as well as drugs affecting multichannel block (flecainide, moxifloxacin, quinidine, and ranolazine). Inclusion criteria for final analysis was based on demonstrated sensitivity to IKr block (20% prolongation with E-4031) and L-type calcium current block (20% shortening with nifedipine). Despite differences in baseline characteristics across cardiomyocyte lines, multiple sites, and instrument platforms, 10 of 18 studies demonstrated adequate sensitivity to IKr block with E-4031 and ICaL block with nifedipine for inclusion in the final analysis. Concentration-dependent effects on repolarization were observed with this qualified data set consistent with known ionic mechanisms of single and multichannel blocking drugs. hiPSC-CMs can detect repolarization effects elicited by single and multichannel blocking drugs after defining pharmacologic sensitivity to IKr and ICaL block, supporting further validation efforts using hiPSC-CMs for cardiac safety studies.

Feasibility, tolerance, and safety of intravenous infusions of allogeneic mesenchymal stem cell (MSC) therapy in lung transplant recipients with bronchiolitis obliterans syndrome (BOS) are not well established. MSCs were manufactured, cryopreserved, transported to our facility, thawed, and infused into nine recipients with moderate BOS (average drop in forced expiratory volume in 1 second was 56.8% ± 3.2% from post‐transplant peak) who were refractory to standard therapy and not candidates for retransplant. Cells were viable and sterile prior to infusion. Patients received a single infusion of either 1 (n = 3), 2 (n = 3), or 4 (n = 3) million MSCs per kg. Patients were medically evaluated before; during; and at 24 hours, 1 week, and 1 month after infusion for evidence of infusion‐related adverse events and tolerance of therapy. Vital signs, pulmonary function test results, Borg Dyspnea Index, and routine laboratory data were recorded. Vital signs and O2 saturation did not significantly change during or up to 2 hours after MSC infusion. There were no significant changes in gas exchange variables, pulmonary function test results, or laboratory values at 1, 7, and 30 days postinfusion compared with preinfusion values. Infusion of MSCs in patients with BOS was feasible, safe, and well tolerated and did not produce any significant adverse changes in clinical, functional, or laboratory variables during or up to 30 days after infusion. Manufacturing, transport, and administration of intravenous, allogeneic bone marrow‐derived MSCs in doses from 1 to 4 million MSCs per kg is safe in lung transplant recipients with BOS. Stem Cells Translational Medicine2018;7:161–167

The development in 2006 of reprogramming technology has allowed the production of induced pluripotent stem cells (iPSC) from post-natal cell sources. The ability to generate stem cells, and more importantly their differentiated progeny, from individuals with known diseases has the potential to revolutionise and re-energise phenotypic screening efforts by biopharmaceutical companies. For the first time not only it is possible to screen against almost all human somatic cell types, but in some cases these cells express a disease-relevant phenotype. The iPSC technology holds the promise of improving compound screening, safety assessment, and candidate selection by permitting the evaluation of lead molecules on batteries of genetically diverse human cells prior to formal entry into human studies.

Abstract Human induced pluripotent stem cells (hiPSCs) have been shown to differentiate along the retinal lineage in a manner that mimics normal mammalian development. Under certain culture conditions, hiPSCs form optic vesicle-like structures (OVs), which contain proliferating progenitors capable of yielding all neural retina (NR) cell types over time. Such observations imply conserved roles for regulators of retinogenesis in hiPSC-derived cultures and the developing embryo. However, whether and to what extent this assumption holds true has remained largely uninvestigated. We examined the role of a key NR transcription factor, visual system homeobox 2 (VSX2), using hiPSCs derived from a patient with microphthalmia caused by an R200Q mutation in the VSX2 homeodomain region. No differences were noted between (R200Q)VSX2 and sibling control hiPSCs prior to OV generation. Thereafter, (R200Q)VSX2 hiPSC-OVs displayed a significant growth deficit compared to control hiPSC-OVs, as well as increased production of retinal pigmented epithelium at the expense of NR cell derivatives. Furthermore, (R200Q)VSX2 hiPSC-OVs failed to produce bipolar cells, a distinctive feature previously observed in Vsx2 mutant mice. (R200Q)VSX2 hiPSC-OVs also demonstrated delayed photoreceptor maturation, which could be overcome via exogenous expression of wild-type VSX2 at early stages of retinal differentiation. Finally, RNAseq analysis on isolated hiPSC-OVs implicated key transcription factors and extracellular signaling pathways as potential downstream effectors of VSX2-mediated gene regulation. Our results establish hiPSC-OVs as versatile model systems to study retinal development at stages not previously accessible in humans and support the bona fide nature of hiPSC-OV-derived retinal progeny. Stem Cells 2014;32:1480–1492