Scalable downstream purification of recombinant adeno-associated viral vectors

Scalable manufacturing technologies are essential for ensuring modern medicines can be produced to meet the needs of clinical trials, process development, and commercial manufacture. Recent advances in in vivo gene therapies have resulted in multiple regulatory approvals of rAAV vectors for gene transfer in humans. These vectors can be produced using transient transfection of mammalian cells, baculovirus infection of insect cells or produced via engineered stable producer cells. These production methods are performed in single-use bioreactors and utilize other scalable technologies as used in commercial monoclonal antibody manufacture. In this work, we evaluated the use of existing single-use filtration and separation technologies for downstream purification of an rAAV5 viral vector. rAAV5 vector was produced by transient transfection of HEK293 cells in the Pall iCELLis® Nano bioreactor. Bioreactor harvest lysis material was clarified using direct flow filtration with both depth and sterilizing grade filters. The product was concentrated 10x using 100kD OmegaTM flat-sheet tangential flow-filtration (TFF) before primary purification using affinity chromatography. The rAAV5 vector was then polished using Mustang® Q membrane chromatography to enrich for full capsids. A second TFF step was performed to concentrate and buffer exchange with flat sheet TFF with the same 100KD Omega membrane. Final sterile filtration was performed using Supor® EKV validated sterilizing grade filters. All downstream unit operations resulted in acceptable performance. Feasibility of a complete downstream process was established with a theoretical whole process yield of ~25%. This process results in a very low contaminant profile as host cell protein (HCP) and host cell DNA were reduced to near and below the assays’ limits of quantitation during purification. Of particular interest, Mustang Q polishing resulted in retention of only ~10% of total capsids, while recovering ~50% of full capsids enriching the ratio of full capsids to empty capsids by 4.5 fold

Selective targeting of microglia by quantum dots

<p>Abstract</p> <p>Background</p> <p>Microglia, the resident immune cells of the brain, have been implicated in brain injury and various neurological disorders. However, their precise roles in different pathophysiological situations remain enigmatic and may range from detrimental to protective. Targeting the delivery of biologically active compounds to microglia could help elucidate these roles and facilitate the therapeutic modulation of microglial functions in neurological diseases.</p> <p>Methods</p> <p>Here we employ primary cell cultures and stereotaxic injections into mouse brain to investigate the cell type specific localization of semiconductor quantum dots (QDs) in vitro and in vivo. Two potential receptors for QDs are identified using pharmacological inhibitors and neutralizing antibodies.</p> <p>Results</p> <p>In mixed primary cortical cultures, QDs were selectively taken up by microglia; this uptake was decreased by inhibitors of clathrin-dependent endocytosis, implicating the endosomal pathway as the major route of entry for QDs into microglia. Furthermore, inhibiting mannose receptors and macrophage scavenger receptors blocked the uptake of QDs by microglia, indicating that QD uptake occurs through microglia-specific receptor endocytosis. When injected into the brain, QDs were taken up primarily by microglia and with high efficiency. In primary cortical cultures, QDs conjugated to the toxin saporin depleted microglia in mixed primary cortical cultures, protecting neurons in these cultures against amyloid beta-induced neurotoxicity.</p> <p>Conclusions</p> <p>These findings demonstrate that QDs can be used to specifically label and modulate microglia in primary cortical cultures and in brain and may allow for the selective delivery of therapeutic agents to these cells.</p

Rare and low-frequency coding variants alter human adult height

Height is a highly heritable, classic polygenic trait with ~700 common associated variants identified so far through genome - wide association studies . Here , we report 83 height - associated coding variants with lower minor allele frequenc ies ( range of 0.1 - 4.8% ) and effects of up to 2 16 cm /allele ( e.g. in IHH , STC2 , AR and CRISPLD2 ) , >10 times the average effect of common variants . In functional follow - up studies, rare height - increasing alleles of STC2 (+1 - 2 cm/allele) compromise d proteolytic inhibition of PAPP - A and increased cleavage of IGFBP - 4 in vitro , resulting in higher bioavailability of insulin - like growth factors . The se 83 height - associated variants overlap genes mutated in monogenic growth disorders and highlight new biological candidates ( e.g. ADAMTS3, IL11RA, NOX4 ) and pathways ( e.g . proteoglycan/ glycosaminoglycan synthesis ) involved in growth . Our results demonstrate that sufficiently large sample sizes can uncover rare and low - frequency variants of moderate to large effect associated with polygenic human phenotypes , and that these variants implicate relevant genes and pathways

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The challenge of sustaining the research and innovation process

Sustaining the research and innovation process in the 21st century is a complex task. With research budgets under scrutiny, a huge increase in the volume of research publications, mounting patent applications and increased litigation, a successful participant--whether an individual researcher, institution, company or government--needs to be equipped with the right tools and information to make good strategic decisions. Sustainable research is illustrated here as a "cycle" leading from pure research to applied innovations onto patenting through to commercial wealth creation, which can then be returned as further research and development. Using case studies and examples from the fields of biotechnology and nanotechnology, critical stages of this cycle are identified and illustrated with data, tools and analysis.Research process Innovation cycle Strategic decisions EuroCRIS Biotechnology Nanotechnology Database use

Dissection of Combinatorial Control by the Met4 Transcriptional Complex

Loss of Met31 and Met32 abolishes all Met4-activated transcription, while only certain target genes, such as sulfate assimilation genes, depend on Cbf1 and Met28 for expression. Unlike Met4 and the other cofactors, Cbf1 remains promoter-bound under inducing and repressing conditions and helps to stabilize Met32, the main platform for Met4, at promoters