A Convenient and General Expression Platform for the Production of Secreted Proteins from Human Cells

Recombinant protein expression in bacteria, typically E. coli, has been the most successful strategy for milligram quantity expression of proteins. However, prokaryotic hosts are often not as appropriate for expression of human, viral or eukaryotic proteins due to toxicity of the foreign macromolecule, differences in the protein folding machinery, or due to the lack of particular co- or post-translational modifications in bacteria. Expression systems based on yeast (P. pastoris or S. cerevisiae) ^1,2, baculovirus-infected insect (S. frugiperda or T. ni) cells ³, and cell-free in vitro translation systems ^2,4 have been successfully used to produce mammalian proteins. Intuitively, the best match is to use a mammalian host to ensure the production of recombinant proteins that contain the proper post-translational modifications. A number of mammalian cell lines (Human Embryonic Kidney (HEK) 293, CV-1 cells in Origin carrying the SV40 larget T-antigen (COS), Chinese Hamster Ovary (CHO), and others) have been successfully utilized to overexpress milligram quantities of a number of human proteins ^5-9. However, the advantages of using mammalian cells are often countered by higher costs, requirement of specialized laboratory equipment, lower protein yields, and lengthy times to develop stable expression cell lines. Increasing yield and producing proteins faster, while keeping costs low, are major factors for many academic and commercial laboratories.Here, we describe a time- and cost-efficient, two-part procedure for the expression of secreted human proteins from adherent HEK 293T cells. This system is capable of producing microgram to milligram quantities of functional protein for structural, biophysical and biochemical studies. The first part, multiple constructs of the gene of interest are produced in parallel and transiently transfected into adherent HEK 293T cells in small scale. The detection and analysis of recombinant protein secreted into the cell culture medium is performed by western blot analysis using commercially available antibodies directed against a vector-encoded protein purification tag. Subsequently, suitable constructs for large-scale protein production are transiently transfected using polyethyleneimine (PEI) in 10-layer cell factories. Proteins secreted into litre-volumes of conditioned medium are concentrated into manageable amounts using tangential flow filtration, followed by purification by anti-HA affinity chromatography. The utility of this platform is proven by its ability to express milligram quantities of cytokines, cytokine receptors, cell surface receptors, intrinsic restriction factors, and viral glycoproteins. This method was also successfully used in the structural determination of the trimeric ebolavirus glycoprotein ^5,10.In conclusion, this platform offers ease of use, speed and scalability while maximizing protein quality and functionality. Moreover, no additional equipment, other than a standard humidified CO₂ incubator, is required. This procedure may be rapidly expanded to systems of greater complexity, such as co-expression of protein complexes, antigens and antibodies, production of virus-like particles for vaccines, or production of adenoviruses or lentiviruses for transduction of difficult cell lines.     

Strain energy density as a rupture criterion for the kidney: impact tests on porcine organs, finite element simulation, and a baseline comparison between human and porcine tissues

High-velocity (up to 25 m/s) impact tests were performed on pig kidneys to characterize failure behavior at deformation rates associated with traumatic injury. Cylindrical tissue samples (n = 45) and whole perfused organs (n = 34) were impacted using both falling weights and a high-velocity pneumatic projectile impactor. Impact energy was incrementally increased until visible rupture occurred. The strain energy density failure threshold fell between 25 and 60 kJ/m3 for excised porcine tissue samples, and between 15 and 30 kJ/m3 for whole, perfused organs. The relationship between localized failure in whole organ impacts and tissue level failure thresholds observed in cylindrical tissue samples was explored using a detailed finite element model of the human kidney. The model showed good correlation between experimentally observed injury patterns and predicted strain energy density distributions within the renal parenchyma. Finally, to facilitate interpretation of the porcine renal impact results with regard to human trauma, quasi-static compression test results of freshly excised human kidney cortex samples (n = 30) were compared against similar tests on pig kidneys. Human tissues failed at Lagrange strain levels similar to porcine tissue (63+/-6.3%), but at 52% lower Lagrange stress (116+/-28 kPa), and 35% lower strain energy density (17.1+/-4.4 kJ/m3). Thus conservative interpretation of porcine test results is recommended.     

Long-term outcome of posterior spinal fusion for the correction of adolescent idiopathic scoliosis

Background

Adolescent idiopathic scoliosis (AIS) is the most common form of idiopathic scoliosis, and surgery is considered as one of the therapeutic options. However, it is associated with a variety of irreversible complications, in spite of the benefits it provides. Here, we evaluated the long-term outcome of posterior spinal fusion (PSF) of AIS to shed more light on the consequences of this surgery.

Methods

In a cross-sectional study, a total of 42 AIS patients who underwent PSF surgery were radiographically and clinically inspected for the potential post-operative complications. Radiographic assessments included the device failure, union status, and vertebral tilt below the site of fusion. Clinical outcomes were evaluated using the Oswestry disability index (ODI) and visual analogue scale (VAS).

Results

The mean age of the surgery was 14.4?±?5.1 years. The mean follow-up of the patients was 5.6?±?3.2 years. Complete union was observed in all patients, and no device failure was noticed. Pre- and post-operative vertebral tilt below the site of fusion were 11.12°?±?7.92° and 6.21°?±?5.73°, respectively (p?<?0.001). The mean post-operative ODI was 16.7?±?9.8. The mean post-operative VAS was 2.1?±?0.7. ODI value was positively correlated with follow-up periods (p?=?0.04, r?=?0.471). New degenerative disc disease (DDD) was observed in 6 out of 37 (16%) patients.

Conclusion

In spite of the efficacy and safety of PSF surgery of AIS, it might result in irreversible complications such as DDD. Moreover, the amount of post-operative disability might increase over the time and should be discussed with the patients.

     

Safety testing for neurovirulence of novel live, attenuated flavivirus vaccines: infant mice provide an accurate surrogate for the test in monkeys.

Current requirements for control of live viral vaccines, including yellow fever 17D, produced from potentially neurotropic wild-type viruses include tests for neurovirulence in nonhuman primates. We have used yellow fever 17D virus as a live vector for novel flavivirus vaccines (designated ChimeriVax) against dengue, Japanese encephalitis (JE), and West Nile (WN) viruses. For control of these vaccines, it would be preferable to substitute a test in mice for the test in a higher species (monkeys). In this study, we compare the neurovirulence of ChimeriVax vaccine candidates in suckling mice inoculated by the intracerebral (IC) route with graded doses of the test article or yellow fever 17D vaccine as a reference control. Mortality ratio and survival distribution are the outcome measures. The monkey safety test is performed as described for control of yellow fever vaccines. In both mice and monkeys, all chimeric vaccines were significantly less neurovirulent than yellow fever 17D vaccine. The test in suckling mice discriminated between strains of two different vaccines (ChimeriVax-JE and ChimeriVax-DEN1) differing by a single amino acid change, and was more sensitive for detecting virulence differences than the test in monkeys. The results indicate that the suckling mouse test is simple to perform, highly sensitive and, with appropriate validation, could complement or possibly even replace the neurovirulence component of the monkey safety test. The test in infant mice is particularly useful as a means of demonstrating biological consistency across seed virus and vaccine lots.     

Expression and Characterization of Glucose Oxidase from <Emphasis Type="Italic">Aspergillus niger</Emphasis> in <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

Glucose oxidase (GOX) is currently used in clinical, pharmaceutical, food and chemical industries. The aim of this study was expression and characterization of Aspergillus niger glucose oxidase gene in the yeast Yarrowia lipolytica. For the first time, the GOX gene of A. niger was successfully expressed in Y. lipolytica using a mono-integrative vector containing strong hybrid promoter and secretion signal. The highest total glucose oxidase activity was 370 U/L after 7 days of cultivation. An innovative method was used to cell wall disruption in current study, and it could be recommended to use for efficiently cell wall disruption of Y. lipolytica. Optimum pH and temperature for recombinant GOX activity were 5.5 and 37 °C, respectively. A single band with a molecular weight of 80 kDa similar to the native and pure form of A. niger GOX was observed for the recombinant GOX in SDS-PAGE analysis. Y. lipolytica is a suitable and efficient eukaryotic expression system to production of recombinant GOX in compered with other yeast expression systems and could be used to production of pure form of GOX for industrial applications.     

Durvalumab and taxane family combination therapy enhances the antitumoral effects for NSCLC: An in vitro study

Immunotherapy has lately become the most preferred cancer treatment method, and for non-small cell lung cancer (NSCLC) first-line treatment, there are many immunotherapy options. This study aimed to assess the effectiveness and toxicity of paclitaxel (PTX), docetaxel (DTX) chemotherapy, immune checkpoint inhibitor treatment (durvalumab; DVL), and their combination in NSCLC. A-549 cells were treated with DVL in combination with PTX and DTX (a quarter of the IC₅₀) to investigate their anticancer effects on these cells. The MTT assay, wound healing tests, and double-staining with Annexin V/PI were used to assess the cell viability, apoptosis, and migration. The results showed that a combination of 0.35 mg/mL DVL with 6.5 μg/mL PTX and 1.75 μg/mL DTX produced a synergistic effect with CI values of 0.88, 0.37, and 0.81, respectively. Moreover, the PTX + DTX + DVL combination led to a significantly increased apoptotic rate up to 88.70 ± 3.39% in the A549 cell line compared to monotherapy (p < .001). In addition, we found that the combination therapy with these agents increased the expression level of Bax, Cas-3, p53, and Bax/Bcl-2 ratio in all experimental groups. In conclusion, the results suggest that combining anti-PD-L1 antibody therapy with chemotherapy may provide a promising approach to enhance treatment outcomes and be a potentially efficacious strategy for treating NSCLC patients. Further research and clinical investigations are needed to elucidate the underlying molecular mechanisms and validate the therapeutic potential of these compounds in vivo.     

“Conservation cloning” of vulnerable Esfahan mouflon (Ovis orientalis isphahanica): in vitro and in vivo studies

Among the wide range of bio-conservational strategies envisaged, recent accomplishments in the field of interspecies somatic cell nuclear transfer (iSCNT) hold considerable promise due to its unique potential to decelerate or prevent rapid loss of animal genetic resources, and even to revive extinct species. Accordingly, this study was carried out to investigate if in vitro matured and enucleated oocytes of domestic sheep could be used for interspecies conservation cloning of Esfahan mouflon (Ovis orientalis isphahanica), a vulnerable species classified by the International Union for Conservation of Nature. Cryo-banked fibroblasts of a mouflon (derived from a genome resource bank) and a domestic sheep (prepared during a recent study) were cultured in vitro and used for karyotyping. Prior to SCNT, fibroblast donor cells were serum starved for 5 days. Using the zona-free SCNT technique, in vitro matured and enucleated domestic sheep oocytes were reconstituted with nuclei donor cells of mouflon and domestic sheep, and their competencies for in vitro development to the blastocyst stage were compared. The cloned mouflon blastocysts were then surgically transferred into the uterus of the synchronized domestic sheep. Karyotype analysis confirmed that fibroblasts of the Esfahan mouflon had the correct number of diploid chromosomes (2n = 54). Evaluation of 907 activated reconstructs [Esfahan mouflon (n = 667), domestic sheep (n = 240)] revealed no significant difference in the term of blastocyst development (7.6 ± 0.5% vs. 9.3 ± 0.5%, respectively). After the transfer of 12 cloned Esfahan mouflon blastocysts to five domestic sheep recipients, two (40.0%) pregnancies were established in which both (100%) were sustained until caesarean section (days 147 and 150 of pregnancy, respectively) and culminated in the live births of cloned Esfahan mouflon lambs. However, the newborns did not survive and died soon after birth. Karyotype and genetic analyses confirmed that both clones had correct diploid chromosome number (2n = 54), and were genetically identical to each other in addition to their original cell donor. This study highlighted the importance of “conservation cloning” using closely related abundant alternate species.

     

Unmet need for hypercholesterolemia care in 35 low- and middle-income countries: A cross-sectional study of nationally representative surveys

BackgroundAs the prevalence of hypercholesterolemia is increasing in low- and middle-income countries (LMICs), detailed evidence is urgently needed to guide the response of health systems to this epidemic. This study sought to quantify unmet need for hypercholesterolemia care among adults in 35 LMICs.Methods and findingsWe pooled individual-level data from 129,040 respondents aged 15 years and older from 35 nationally representative surveys conducted between 2009 and 2018. Hypercholesterolemia care was quantified using cascade of care analyses in the pooled sample and by region, country income group, and country. Hypercholesterolemia was defined as (i) total cholesterol (TC) ≥240 mg/dL or self-reported lipid-lowering medication use and, alternatively, as (ii) low-density lipoprotein cholesterol (LDL-C) ≥160 mg/dL or self-reported lipid-lowering medication use. Stages of the care cascade for hypercholesterolemia were defined as follows: screened (prior to the survey), aware of diagnosis, treated (lifestyle advice and/or medication), and controlled (TC <200 mg/dL or LDL-C <130 mg/dL). We further estimated how age, sex, education, body mass index (BMI), current smoking, having diabetes, and having hypertension are associated with cascade progression using modified Poisson regression models with survey fixed effects.High TC prevalence was 7.1% (95% CI: 6.8% to 7.4%), and high LDL-C prevalence was 7.5% (95% CI: 7.1% to 7.9%). The cascade analysis showed that 43% (95% CI: 40% to 45%) of study participants with high TC and 47% (95% CI: 44% to 50%) with high LDL-C ever had their cholesterol measured prior to the survey. About 31% (95% CI: 29% to 33%) and 36% (95% CI: 33% to 38%) were aware of their diagnosis; 29% (95% CI: 28% to 31%) and 33% (95% CI: 31% to 36%) were treated; 7% (95% CI: 6% to 9%) and 19% (95% CI: 18% to 21%) were controlled. We found substantial heterogeneity in cascade performance across countries and higher performances in upper-middle-income countries and the Eastern Mediterranean, Europe, and Americas. Lipid screening was significantly associated with older age, female sex, higher education, higher BMI, comorbid diagnosis of diabetes, and comorbid diagnosis of hypertension. Awareness of diagnosis was significantly associated with older age, higher BMI, comorbid diagnosis of diabetes, and comorbid diagnosis of hypertension. Lastly, treatment of hypercholesterolemia was significantly associated with comorbid hypertension and diabetes, and control of lipid measures with comorbid diabetes. The main limitations of this study are a potential recall bias in self-reported information on received health services as well as diminished comparability due to varying survey years and varying lipid guideline application across country and clinical settings.ConclusionsCascade performance was poor across all stages, indicating large unmet need for hypercholesterolemia care in this sample of LMICs—calling for greater policy and research attention toward this cardiovascular disease (CVD) risk factor and highlighting opportunities for improved prevention of CVD.

Maja Marcus and colleagues use nationally-representative surveys conducted between 2009 and 2018 to investigate the unmet need for hypercholesterolemia care in 35 low- and middle-income countries.