Sperm binding within the oviductal sperm reservoir plays an important role for reproductive success by enabling sperm survival and maintaining fertilizing capacity. To date, numerous in vitro technologies have been established to measure sperm binding capacity to cultured oviductal cells or oviductal explants. However, these methods do not accurately represent the microenvironment and complex multi-molecular nature of the oviduct. In this paper, we describe a novel protocol for assessing sperm binding capacity in the tubal sperm reservoir using an ex vivo oviduct culture in the bovine model. This protocol includes the staining of frozen-thawed bovine spermatozoa with the DNA-binding dye Hoechst 33342, the co-incubation of stained sperm in closed segments of the oviduct and the visualization and quantification of bound spermatozoa by fluorescence microscopy. By generating overlays of multiple Z-stacks of randomly selected regions of interest (ROIs), spermatozoa bound in the sperm reservoir can be visualized and quantified within the 3D arrangement of the oviductal folds. This method, which is applicable to multiple species, can be used to assess individual sperm binding capacity in males for prognostic purposes as well as to assess the impact of diseases and medications on the formation of the sperm reservoir in the oviduct in humans and animals.

Recombinant Adeno-associated virus (rAAV) is a popular vector for treating genetic diseases caused by absent or defective genes. rAAVs can be produced that contain a therapeutic transgene, i.e., a correct copy of the affected gene, which is then delivered into target cells. A further application of rAAV is to deliver pro-apoptotic genes such as TNF-related apoptosis-inducing ligand (TRAIL) into cancer cells, leading to tumor regression. However, rAAV production is expensive and insufficient yields may hinder wide-spread adoption especially in systemic conditions. During rAAV production, the therapeutic transgene may be expressed in the producer cell line, and in the case of an oncolytic gene, this would likely lead to cell death thus reducing rAAV yields. Here we demonstrate that expression of TRAIL during rAAV production in HEK293F cells negatively impacts rAAV yield. A shRNA-based strategy was developed to suppress the expression of TRAIL in rAAV-producing cells specifically during the production process. Incorporating a TRAIL-targeting shRNA expression cassette within the backbone of the rAAV genome-encoding plasmid during triple-transfection of HEK293F cells reduced transgene expression and led to a 60% increase in the yield of rAAV-TRAIL compared to controls.

Introduction: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major health emergency since its emergence in late 2019. Endothelial dysfunction is a hallmark of COVID-19, leading to severe illness, i.e. coagulopathy, multi-organ failure. FX06, a fibrin-derived peptide naturally occurring in the human body, formerly known as Bβ_15-42, is a promising therapeutic candidate for endothelial complications like capillary leakage in COVID-19 and other forms of acute respiratory disorders. The aim of this project is to investigate whether FX06 can attenuate COVID-19 cytokine-triggered inflammatory processes in vitro.Methods: To mimic the inflammatory status of COVID-19, a human pulmonary microvascular endothelial cell line (ECs) – HULEC-5a, was treated with a cytokine cocktail comprised of ten different cytokines or chemokines at concentrations found in serum profiles of COVID-19 patients with severe illness, further referred to as the severe cytokine cocktail. ECs were treated with the severe cytokine cocktail for 24 h, in the absence or presence of FX06 for 2 h.Results: The severe cytokine cocktail enhanced peripheral blood mononuclear cell (PBMC)-endothelial adhesion and monolayer transmigration. This deleterious effect was significantly reduced by FX06. FX06 was also shown to mitigate the cytotoxic activity of allogeneic CD8⁺ T cells, which increased upon cytokine treatment. FX06 restored continuous vascular endothelial (VE)-cadherin/CD144 distribution on the EC surface and reversed morphological changes mediated by the severe cytokine cocktail, such as the elongation of F-actin stress fibers. FX06 reduced capillary-like structure formation of the severe cytokine cocktail treated-ECs, indicating FX06 down-regulated the pro-inflammatory angiogenic activity caused by the severe cytokine cocktail. Additionally, FX06 might assist in maintaining the normal barrier function of ECs by altering the surface expression of Syndecan-1 (SDC1/CD138). Proteomics and phosphoproteomics analyses demonstrated that FX06 in the presence of the severe cytokine cocktail inactivated RhoGTPase, which was confirmed by western blotting that FX06 attenuated RhoA, a member of RhoGTPase, enhanced by the severe cytokine cocktail and down-regulated the expression of the phosphorylated downstream protein, ROCK1.Conclusion: Overall, FX06 shows promising potential in normalizing ECs and reducing vascular leakage to protect the endothelium against the proinflammatory effect of COVID-19-triggered cytokines.

Lentiviral transduction remains the gold standard in adoptive modified cellular therapy, such as CAR-T; however, genome integration is not always desirable, such as when treating non-fatal autoimmune disease or for additional editing steps using CRISPR to produce allogeneic CAR-modified cells. Delivering in vitro-transcribed (IVT) mRNA represents an alternative solution but the labile nature of mRNA has led to efforts to improve half-life and translation efficiencies using a range of approaches including chemical and structural modifications. In this study, we explore the role of N⁶–methyladenosine (m6A) in a CD19-CAR sequence when delivered to T cells as an IVT mRNA. In silico analysis predicted the presence of four m6A consensus (DRACH) motifs in the CAR coding sequence and treating T cells with an inhibitor of the m6A methyltransferase (METTL3) resulted in a significant reduction in CAR protein expression. RNA analysis confirmed m6A bases at three of the predicted sites, indicating that the modification occurs independently of nuclear transcription. Synonymous mutation of the DRACH sites reduced the levels of CAR protein from 15 to >50% depending on the T cell donor. We also tested a panel of CAR transcripts with different UTRs, some containing m6A consensus motifs, and identified those which further improved protein expression. Furthermore, we found that the methylation of consensus m6A sites seems to be somewhat sequence-context-dependent. These findings demonstrate the importance of the m6A modification in stabilising and enhancing expression from IVT-derived mRNA and that this occurs within the cell, meaning targeted in vitro chemical modification during mRNA manufacturing may not be necessary.