Monoclonal antibodies for the S2 subunit of spike of SARS-CoV-1 cross-react with the newly-emerged SARS-CoV-2.

BackgroundA novel coronavirus, SARS-CoV-2, which emerged at the end of 2019 and causes COVID-19, has resulted in worldwide human infections. While genetically distinct, SARS-CoV-1, the aetiological agent responsible for an outbreak of severe acute respiratory syndrome (SARS) in 2002-2003, utilises the same host cell receptor as SARS-CoV-2 for entry: angiotensin-converting enzyme 2 (ACE2). Parts of the SARS-CoV-1 spike glycoprotein (S protein), which interacts with ACE2, appear conserved in SARS-CoV-2.AimThe cross-reactivity with SARS-CoV-2 of monoclonal antibodies (mAbs) previously generated against the S protein of SARS-CoV-1 was assessed.MethodsThe SARS-CoV-2 S protein sequence was aligned to those of SARS-CoV-1, Middle East respiratory syndrome (MERS) and common-cold coronaviruses. Abilities of mAbs generated against SARS-CoV-1 S protein to bind SARS-CoV-2 or its S protein were tested with SARS-CoV-2 infected cells as well as cells expressing either the full length protein or a fragment of its S2 subunit. Quantitative ELISA was also performed to compare binding of mAbs to recombinant S protein.ResultsAn immunogenic domain in the S2 subunit of SARS-CoV-1 S protein is highly conserved in SARS-CoV-2 but not in MERS and human common-cold coronaviruses. Four murine mAbs raised against this immunogenic fragment could recognise SARS-CoV-2 S protein expressed in mammalian cell lines. In particular, mAb 1A9 was demonstrated to detect S protein in SARS-CoV-2-infected cells and is suitable for use in a sandwich ELISA format.ConclusionThe cross-reactive mAbs may serve as useful tools for SARS-CoV-2 research and for the development of diagnostic assays for COVID-19.

Human Wharton's jelly stem cell conditioned medium and cell-free lysate inhibit human osteosarcoma and mammary carcinoma cell growth in vitro and in xenograft mice.

Human Wharton's jelly stem cells (hWJSCs) were shown to inhibit the growth of human mammary carcinomas. It is not known whether cell-free secretions or lysates of hWJSCs do the same on different cancers. They may be less controversial than cells to regulatory bodies for clinical application. We examined the influence of hWJSC conditioned medium (hWJSC-CM) and cell-free lysate (hWJSC-CL) on two osteosarcoma cell lines (MG-63, SKES-1) in vitro and on human mammary carcinomas in immunodeficient mice. When exposed to hWJSC-CL, increased vacuolations in MG-63 and increased membrane fragmentation in SKES-1 cells were observed, with greater cell death in SKES-1. Exposure of SKES-1 and MG-63 cells to hWJSC-CL showed significant decreases in cell proliferation of 46.48 ± 6.66% and 24.32 ± 5.67% respectively compared to controls. MG-63 and SKES-1 cells were annexin V-FITC positive and SKES-1 TUNEL positive following treatment with hWJSC-CM and hWJSC-CL. MG-63 cells were positive and SKES-1 cells negative for anti-BECLIN-1 and anti-LC3B following treatment with hWJSC-CM and hWJSC-CL. RT-PCR showed that the pro-apoptotic BAX gene and the autophagy-related ATG-5 and BECLIN-1 genes were up-regulated while the anti-apoptotic BCL2 and SURVIVIN genes were down-regulated in MG-63 and SKES-1 cells treated with hWJSC-CM and hWJSC-CL. Injections of hWJSCs and hWJSC-CM into mammary carcinomas in immunodeficient mice resulted in decreased tumor sizes and weights of 24.86 ± 6.05% to 37.03 ± 5.91% and 47.14 ± 7.36% to 55.09 ± 5.87% respectively at 6 weeks compared to controls. hWJSC-CM and hWJSC-CL inhibit mammary carcinoma and osteosarcoma cells via apoptosis and autophagy.

Contribution of Fc-dependent cell-mediated activity of a vestigial esterase-targeting antibody against H5N6 virus infection.

The highly pathogenic avian influenza A (H5N6) virus has caused sporadic human infections with a high case fatality rate. Due to the continuous evolution of this virus subtype and its ability to transmit to humans, there is an urgent need to develop effective antiviral therapeutics. In this study, a murine monoclonal antibody 9F4 was shown to display broad binding affinity against H5Nx viruses. Furthermore, 9F4 can neutralize H5N6 pseudotyped particles and prevent entry into host cells. Additionally, ADCC/ADCP deficient L234A, L235A (LALA) and CDC deficient K322A mutants were generated and displayed comparable binding affinity and neutralizing activity as wild type 9F4 (9F4-WT). Notably, 9F4-WT, 9F4-LALA and 9F4-K322A exhibit in vivo protective efficacies against H5N6 infections in that they were able to reduce viral loads in mice. However, only 9F4-WT and 9F4-K322A but not 9F4-LALA were able to reduce viral pathogenesis in H5N6 challenged mice. Furthermore, depletion of phagocytic cells in mice lungs nullifies 9F4-WT's protection against H5N6 infections, suggesting a crucial role of the host's immune cells in 9F4 antiviral activity. Collectively, these findings reveal the importance of ADCC/ADCP function for 9F4-WT protection against HPAIV H5N6 and demonstrate the potential of 9F4 to confer protection against the reassortant H5-subtype HPAIVs.

On-pump transapical cardioscopic mitral valve replacement with cardiac arrest: short-term results in a porcine survival model.

OBJECTIVES: Favourable outcomes with mitral annuloplasty have been achieved with transapical cardioscopic (TAC) surgery in a survival animal model. In addition, experimental TAC on a non-survival animal model also showed adequate access to remove the native mitral valve and implant a prosthetic valve, but the surgical procedure took a long time and lacked follow-up data. The goal of this study was to develop a clinically translatable TAC mitral valve replacement (MVR) procedure using technical and instrumental refinements to reduce the surgical time and to evaluate functional recovery and short-term durability using a survival porcine model. We hypothesized that MVR could be achieved with subannular implantation of the bioprosthesis via the TAC approach. METHODS: TAC MVR using the Hancock II™ (Medtronic)® mitral prosthesis was performed in 6 pigs via an incision over the xiphoid process, under cardiopulmonary bypass and cardiac arrest. COR-KNOT® and minimally invasive cardiac surgery instruments were used. Haemodynamics, echocardiography, cardiac computed tomography, ventriculography and electrocardiography were used to evaluate the function of the mitral prosthesis and left ventricle, coronary system and conduction system in the perioperative period and 4 weeks later. RESULTS: A postimplant examination showed that the mitral prosthesis was competent, without a paravalvular leak. The left ventricular ejection fraction was comparable to preoperative values (65.2 ± 4.1 vs 67.2 ± 7.9). The bypass, cross-clamp and implant times were 177.2 ± 44.2 min, 135.3 ± 47.6 min and 94.0 ± 41.2 min, respectively. The prosthesis was in a good position. The apical scar was intact and not aneurysmal 4 weeks after the implant. The valve was properly sutured to the annulus, without a postimplant paravalvular leak. All animals recovered after 1 month of follow-up with preserved ventricular function and normal wall motion. CONCLUSIONS: We successfully managed to replace the mitral valve with a biological prosthesis via the apex with encouraging bypass and cross-clamp times. This technique may provide an alternative for a selected group of patients with diseased mitral valves who have indications for MVR and still in a high-risk redo setting with conventional sternotomy or minimally invasive cardiac surgery-MVR.

Transapical cardioscopic mitral annuloplasty: a short-term survival study in a porcine model.

OBJECTIVES: The transapical approach provides concurrent surgical access to the mitral and the aortic valves, the root of the aorta and the left atrium. We previously showed the feasibility of transapical cardioscopic (TAC) surgery in a non-survival porcine model. However, reproducibility and feasibility of ring implantation using TAC have not been reported. Therefore, in this study, we hypothesized that implantation of a mitral annuloplasty ring can be feasibly and safely carried out endoscopically via the apex of the heart. METHODS: Using a porcine model in a short-term survival study, TAC mitral annuloplasty was performed in 6 pigs via an incision over the xyphoid, under cardiopulmonary bypass and cardiac arrest. A mitral annuloplasty ring was implanted via the apex to a normal mitral annulus, using a customized set of instruments and techniques. Haemodynamics, echocardiography, cardiac computed tomography, ventriculography, electrocardiography and histopathology studies were used to evaluate the function of the mitral valve and the left ventricle, coronary system and conduction system in the perioperative period and 4 weeks later. RESULTS: All 6 animals survived and recovered from the TAC annuloplasty procedure. Postimplantation examination showed that the mitral valve was competent, left ventricular ejection fraction was 63 ± 4%, left ventricular length was 6.2 ± 0.5 cm and left ventricular end-diastolic volume was 80 ± 10 ml, which were comparable to preoperative values. Apart from a dense scar at the apex, no significant injury was noticed on the ventricle, the chordae and the mitral leaflets. The bypass, cross-clamp and implantation times were 181 ± 55 min, 130 ± 37 min and 47 ± 6 min, respectively. CONCLUSIONS: Despite long surgical times due to the initial learning curve, successful execution of mitral ring annuloplasty could be safely achieved using the TAC approach, via a small incision without the involvement of sternum or the right pleural cavity, thereby potentially expanding the indication to patients with high-risk full sternotomy or right thoracotomy.

Angiogenic peptide nanofibers repair cardiac tissue defect after myocardial infarction.

Myocardial infarction remains one of the top leading causes of death in the world and the damage sustained in the heart eventually develops into heart failure. Limited conventional treatment options due to the inability of the myocardium to regenerate after injury and shortage of organ donors require the development of alternative therapies to repair the damaged myocardium. Current efforts in repairing damage after myocardial infarction concentrates on using biologically derived molecules such as growth factors or stem cells, which carry risks of serious side effects including the formation of teratomas. Here, we demonstrate that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization in cardiovascular tissue after myocardial infarction, without the addition of any biologically derived factors or stem cells. When the GAG mimetic nanofiber gels were injected in the infarct site of rodent myocardial infarct model, increased VEGF-A expression and recruitment of vascular cells was observed. This was accompanied with significant degree of neovascularization and better cardiac performance when compared to the control saline group. The results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair. STATEMENT OF SIGNIFICANCE: We present a synthetic bioactive peptide nanofiber system can enhance cardiac function and enhance cardiovascular regeneration after myocardial infarction (MI) without the addition of growth factors, stem cells or other biologically derived molecules. Current state of the art in cardiac repair after MI utilize at least one of the above mentioned biologically derived molecules, thus our approach is ground-breaking for cardiovascular therapy after MI. In this work, we showed that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization and cardiomyocyte differentiation for the regeneration of cardiovascular tissue after myocardial infarction in a rat infarct model. When the peptide nanofiber gels were injected in infarct site at rodent myocardial infarct model, recruitment of vascular cells was observed, neovascularization was significantly induced and cardiac performance was improved. These results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair.