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Background Non-therapeutic interventions such as practicing good hand hygiene continue to be the mainstay of protection from SARS-CoV-2 and other emerging respiratory viruses. Methods We have evaluated a range of commercially available personal care products including soaps, handwash liquids and alcohol-based hand sanitizers for antiviral efficacy against a clinical isolate of SARS-CoV-2 using internationally accepted standardized protocols at user-relevant contact time-points and product dilutions. Results All the tested products resulted in 3 to 4 log reduction of SARS-CoV-2 titer. Conclusion Our data re-affirms recommendations by global public health authorities that proper hand hygiene can reduce SARS-CoV-2 viral load significantly which should likely limit spread of the contagion.

Substantial progress has been made in the past decade in treating several primary immunodeficiency disorders (PIDs) with gene therapy. Current approaches are based on ex-vivo transfer of therapeutic transgene via viral vectors to patient-derived autologous hematopoietic stem cells (HSCs) followed by transplantation back to the patient with or without conditioning. The overall outcome from all the clinical trials targeting different PIDs has been extremely encouraging but not without caveats. Malignant outcomes from insertional mutagenesis have featured prominently in the adverse events associated with these trials and have warranted intense pre-clinical investigation into defining the tendencies of different viral vectors for genomic integration. Coupled with issues pertaining to transgene expression, the therapeutic landscape has undergone a paradigm shift in determining safety, stability and efficacy of gene therapy approaches. In this review, we aim to summarize the progress made in the gene therapy trials targeting ADA-SCID, SCID-X1, CGD and WAS, review the pitfalls, and outline the recent advancements which are expected to further enhance favourable risk benefit ratios for gene therapeutic approaches in the future., Highlights • PID gene therapy is a promising alternative to HSCT in absence of suitable donors. • Gene therapy clinical trials targeting various PIDs have shown significant efficacy. • Retroviral and lentiviral vectors are presently the mainstay of gene delivery. • Insertional mutagenesis and vector silencing constitute the main concerns. • Novel gene delivery approaches are currently being investigated and validated.

Retinitis pigmentosa, other inherited retinal diseases, and age-related macular degeneration lead to untreatable blindness because of the loss of photoreceptors. We have recently shown that transplantation of mouse photoreceptors can result in improved vision. It is therefore timely to develop protocols for efficient derivation of photoreceptors from human pluripotent stem (hPS) cells. Current methods for photoreceptor derivation from hPS cells require long periods of culture and are rather inefficient. Here, we report that formation of a transient self-organized neuroepithelium from human embryonic stem cells cultured together with extracellular matrix is sufficient to induce a rapid conversion into retinal progenitors in 5 days. These retinal progenitors have the ability to differentiate very efficiently into Crx(+) photoreceptor precursors after only 10 days and subsequently acquire rod photoreceptor identity within 4 weeks. Directed differentiation into photoreceptors using this protocol is also possible with human-induced pluripotent stem (hiPS) cells, facilitating the use of patient-specific hiPS cell lines for regenerative medicine and disease modeling. ispartof: STEM CELLS vol:31 issue:2 pages:408-414 ispartof: location:England status: published

Induced pluripotent stem cells (iPSCs) with potential for therapeutic applications can be derived from somatic cells via ectopic expression of a set of limited and defined transcription factors. However, due to risks of random integration of the reprogramming transgenes into the host genome, the low efficiency of the process, and the potential risk of virally induced tumorigenicity, alternative methods have been developed to generate pluripotent cells using nonintegrating systems, albeit with limited success. Here, we show that c-KIT+ human first-trimester amniotic fluid stem cells (AFSCs) can be fully reprogrammed to pluripotency without ectopic factors, by culture on Matrigel in human embryonic stem cell (hESC) medium supplemented with the histone deacetylase inhibitor (HDACi) valproic acid (VPA). The cells share 82% transcriptome identity with hESCs and are capable of forming embryoid bodies (EBs) in vitro and teratomas in vivo. After long-term expansion, they maintain genetic stability, protein level expression of key pluripotency factors, high cell-division kinetics, telomerase activity, repression of X-inactivation, and capacity to differentiate into lineages of the three germ layers, such as definitive endoderm, hepatocytes, bone, fat, cartilage, neurons, and oligodendrocytes. We conclude that AFSC can be utilized for cell banking of patient-specific pluripotent cells for potential applications in allogeneic cellular replacement therapies, pharmaceutical screening, and disease modeling. ispartof: Molecular Therapy vol:20 issue:10 pages:1953-1967 ispartof: location:United States status: published

lthough gammaretroviruses have been hugely im-portant for proof-of-principle demonstrations of efficacyin several specific clinical applications, other retroviral clas-ses, lentiviruses in particular, are emerging as promisingalternatives. Of the on-going 35 trials using lentivirus-basedvectors (LVs), 24 are in phase I, 9 in phase I/II, and 1 each inphases II and III (source: http://clinicaltrials.gov/). In ad-dition to their ability to stably integrate into the genome oftarget cells for long-term expression of the gene of interest,LVs enjoy a few significant advantages through their abilityto transduce nondividing cells and also to allow robusttransgene expression in cells where there is a high proba-bility of epigenetic silencing or position-related variation ofactivity (Trono, 2000; Schambach and Baum, 2008). Early-generation gammaretroviral vectors have been shown to beparticularly prone to insertional mutagenesis through inad-vertent long terminal repeat (LTR)-mediated upregulationof proto-oncogene expression (Ott et al., 2006; Hacein-Bey-Abina et al., 2008; Howe et al., 2008; Stein et al., 2010). Inpart, this risk may be enhanced by the intrinsic preference ofthese vectors to integrate in and around gene regulatoryregions. LVs may therefore have an overall safer integrationprofile, although both exhibit a semirandom pattern of in-sertion into the human genome, and this type of risk stillcannot be ignored (Bushman et al., 2005; Cavazzana-Calvoet al., 2010). The safety of LVs has been enhanced in severalways including self-inactivating (SIN) vector design, tat in-dependence, use of insulators, and employment of internaltissue- or lineage-specific promoter and enhancer sequences,thereby reducing risks of insertional mutagenesis and vectormobilization (Matrai et al., 2010). Even so, longer term ob-servations in the clinical arena will be needed to define therisk for newer integrating vectors with more clarity. Con-currently, the development of a stable packaging cell line toensure useful batch consistency and size during large-scaleclinical vector production and purification under strict GoodManufacturing Practice (GMP) conditions has been at-tempted by various groups. Inducible systems for generatingstable cell lines have been developed to eliminate cytotox-icity from viral gene products required for packaging, suchas the HIV-1-derived protease and Rev, and the heter-ologous VSV-G envelope protein (Xu et al., 2001; Ikeda et al.,2003; Cockrell et al., 2006; Broussau et al., 2008; Kutner et al.,2009; Throm et al., 2009). It is also noteworthy thatreplication-competent LVs (generated by homologous re-combination between packaging and vector constructs) havenot been detected in large-scale production batches based onlatest generation packaging systems and vector design(Merten et al., 2011). In this commentary, we comment on sixoriginal research articles addressing three separate areasrelating to continuing efforts in improving retroviral design,production, and application for preclinical research andclinical applications.In this issue of Human Gene Therapy, Marc Giry-Laterrie`reand colleagues describe a modified tetracycline (TET)-inducible, polycistronic vector system encoding a selectablemarker and allowing for simple transgene cloning. As notedin their paper, the individual features incorporated in the‘‘polyswitch vector’’ have been previously described byseveral groups. The novelty lies in the combination of thesein a single vector to facilitate stable, inducible, and reversibletransgene expression from a single integration event. Sincethe description of the first tetracycline-inducible system byGossen and Bujard (1992), various small-molecule inducersystems have been employed to control the levels and timingof transgene expression both in vitro and in vivo (Vigna et al.,2002; Sirin and Park, 2003; Galimi et al., 2005). However,many have suffered from either low levels of inducibility orleakiness in the absence of the specific inducer. The modifiedpTF promoter used in this current study was shown to havelow basal activity and high inducibility. The authors alsoseparated a selectable marker (regulated by a ubiquitoushuman elongation factor-1a promoter) from the inducibletransgene cassette for enrichment of transduced cells beforeactivating the transgene of interest, and were able to dem-onstrate regulated expression from their vector in cell lines aswell as primary human cells. Of course, it will now beimportant to evaluate the performance of this vector inpreclinical animal models, especially in terms of drug in-ducibility and reversibility on withdrawal. Although this islikely to be useful for a number of applications, there willalso be restrictions on the nature of the transgene dictated

bsenceofeffectiveandreliableanimaland cellularmodels for studying neurodevelopmental and neurode-generative disorders such as Parkinson’s disease, Alzhei-mer’s disease (AD), Huntington’s disease, amyotropic lateralsclerosis, spinal muscular atrophy, and many others has se-verely compromised both basic and translational research inthe arena of such complex disorders. However, recent ad-vancements in the field of cellular reprogramming haveprovided an effective tool to study such disorders utilizingpatient-derived cells. Through ectopic overexpression of aFIG. 1. Immunophenotypic characterization of neuronal precursors and progenitors emerging out of trisomy 21 amnioticfluid–derived induced pluripotent stem cells (iPSCs). Nes, nestin; Tuj1, tubulin beta-III.