Chinese Hamster Ovary Research Articles

CXCL10 Enhances Acid-Sensing Ion Channel Currents in Rat Dorsal Root.

Both CXCL10/CXCR3 and acid-sensing ion channels (ASICs) are expressed in nociceptive sensory neurons and participate in various pain processes, but it is still unclear whether there is a link between them. Herein, we report that CXCL10 enhances the electrophysiological activity of ASICs in rat dorsal root ganglia (DRG) neurons. A brief (10min) application of CXCL10 increased acid-evoked ASIC currents in a concentration-dependent manner. CXCL10 increased the maximum response of ASICs to acidic stimuli without changing their sensitivity. CXCL10 enhanced ASIC currents in DRG cells through CXCR3, as this enhancement was completely blocked by AMG487, a selective CXCR3 antagonist. CXCL10 also increased ASIC3 currents in CHO cells coexpressing ASIC3 and CXCR3 but not in cells expressing ASIC3 alone. The CXCL10-mediated increase in ASIC currents was prevented by the application of either the G protein inhibitor GDP-β-S or the p38 mitogen-activated protein kinase (MAPK) inhibitor SB202190 but not by the ERK inhibitor U0126 or the JNK inhibitor SP600125. Moreover, CXCL10 increased the number of action potentials triggered by acidic stimuli via CXCR3. CXCL10 dose-dependently exacerbated acid-induced nociceptive behavior in rats through peripheral CXCR3. These results indicated that CXCL10/CXCR3 signaling enhanced ASIC-mediated electrophysiological activity in DRG neurons and nociception in rats via a p38 MAPK-dependent pathway, revealing a novel mechanism underlying pain. CXCL10/CXCR3 signaling may be an effective target in the treatment of pain associated with tissue acidification.

Parylene C Coating Efficacy Studies: Enhancing Biocompatibility of 3D Printed Polyurethane Parts for Biopharmaceutical and CGT Applications.

Additive manufacturing, particularly Vat photopolymerization, presents a promising technique for producing complex, tailor-made structures, making it an attractive option for generating single-use components used in biopharmaceutical manufacturing equipment or cell culture devices. However, the potential leaching of cytotoxic compounds from Vat photopolymer resins poses a significant concern, especially regarding cell growth and viability in cell culture applications. This study explores the potential of parylene C coating to enhance the inertness of a polyurethane-based photopolymer resin, aiming to prevent cytotoxicity and improve biocompatibility. The study includes an analysis of extractables from the resin and photoinitiator to evaluate the resin's composition and to define selected marker compounds for investigating the coating efficiency. The time-dependent accumulation of relevant extractable compounds over a 70-day period are assessed to address the long-term use of the coated components. The impact of irradiation on the material and the coating was evaluated, along with an accelerated aging study to address the long-term performance of the coating. Biocompatibility in terms of in vitro cell growth studies is evaluated using Chinese hamster ovary cells, a standard cell line in biopharmaceutical manufacturing. Results demonstrate that parylene C coating significantly reduces the release of cytotoxic compounds, such as the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO). Although accelerated aging indicates a reduction in the barrier properties of the coating over time, the parylene C coating still effectively slows the release of extractables and significantly improves cell compatibility of the 3D printed parts. The findings suggest that parylene C-coated components can be safely integrated into biopharmaceutical manufacturing processes, with recommendations to minimize storage times between coating application and use to ensure optimal performance.

Recombinant Antibody-Producing Stable CHOK1 Pool Stability Study.

Mammalian cell line stability is an important consideration when establishing a biologics manufacturing process in the biopharmaceutical and in vitro diagnostics (IVD) industries. Traditional Chinese hamster ovary (CHO) cell line development methods use a random integration approach that requires transfection, selection, optional amplification, screenings, and single-cell cloning to select clones with acceptable productivity, product quality, and genetic stability. Site-specific integration reduces these disadvantages, and new technologies have been developed to mitigate risks associated with genetic instability. In this study, we applied the Leap-In® transposase-mediated expression system from ATUM to generate stable CHOK1 pools for the production of four recombinant antibody reagents for IVD immunoassays. CHO cell line stability is defined by consistent antibody production over time. Three of the CHOK1 pools maintained productivity suitable for manufacturing, with high antibody yields. The productivity of the remaining CHOK1 pool decreased over time; however, derivative clones showed acceptable stability. l-glutamine had variable effects on CHOK1 cell line or stable pool stability and significantly affected antibody product titer. Compared with traditional random integration methods, the ATUM Leap-In system can reduce the time needed to develop new immunoassays by using semi site-specific integration to generate high-yield stable pools that meet manufacturing stability requirements.

Ala-Cys-Cys-Ala dipeptide dimer alleviates problematic cysteine and cystine levels in media formulations and enhances CHO cell growth and metabolism

Cysteine and cystine are essential amino acids present in mammalian cell cultures. While contributing to biomass synthesis, recombinant protein production, and antioxidant defense mechanisms, cysteine poses a major challenge in media formulations owing to its poor stability and oxidation to cystine, a cysteine dimer. Due to its poor solubility, cystine can cause precipitation of feed media, formation of undesired products, and consequently, reduce cysteine bioavailability. In this study, a highly soluble cysteine containing dipeptide dimer, Ala-Cys-Cys-Ala (ACCA), was evaluated as a suitable alternative to cysteine and cystine in CHO cell cultures. Replacing cysteine and cystine in basal medium with ACCA did not sustain cell growth. However, addition of ACCA at 4 mM and 8 mM to basal medium containing cysteine and cystine boosted cell growth up to 15% and 27% in CHO-GS and CHO–K1 batch cell cultures respectively and led to a proportionate increase in IgG titer. 13C-Metabolic flux analysis revealed that supplementation of ACCA reduced glycolytic fluxes by 20% leading to more efficient glucose metabolism in CHO–K1 cells. In fed-batch cultures, ACCA was able to replace cysteine and cystine in feed medium. Furthermore, supplementation of ACCA at high concentrations in basal medium eliminated the need for any cysteine equivalents in feed medium and increased cell densities and viabilities in fed-batch cultures without any significant impact on IgG charge variants. Taken together, this study demonstrates the potential of ACCA to improve CHO cell growth, productivity, and metabolism while also facilitating the formulation of cysteine- and cystine-free feed media. Such alternatives to cysteine and cystine will pave the way for enhanced biomanufacturing by increasing cell densities in culture and extending the storage of highly concentrated feed media as part of achieving intensified bioproduction processes.

Multi-omic characterization of antibody-producing CHO cell lines elucidates metabolic reprogramming and nutrient uptake bottlenecks

Characterizing the phenotypic diversity and metabolic capabilities of industrially relevant manufacturing cell lines is critical to bioprocess optimization and cell line development. Metabolic capabilities of production hosts limit nutrient and resource channeling into desired cellular processes and can have a profound impact on productivity. These limitations cannot be directly inferred from measured data such as spent media concentrations or transcriptomics. Here, we present an integrated multi-omic analysis pipeline combining exo-metabolomics, transcriptomics, and genome-scale metabolic network analysis and apply it to three antibody-producing Chinese Hamster Ovary cell lines to identify reprogramming features associated with high-producing clones and metabolic bottlenecks limiting product formation in an industrial bioprocess. Analysis of individual datatypes revealed a decreased nitrogenous byproduct secretion in high-producing clones and the topological changes in peripheral metabolic pathway expression associated with phase shifts. An integrated omics analysis in the context of the genome-scale metabolic model elucidated the differences in central metabolism and identified amino acid utilization bottlenecks limiting cell growth and antibody production that were not evident from exo-metabolomics or transcriptomics alone. Thus, we demonstrate the utility of a multi-omics characterization in providing an in-depth understanding of cellular metabolism, which is critical to efforts in cell engineering and bioprocess optimization.

Impact of fluazuron on oocyte maturation: May the antiparasitic affect bovine reproduction?

Fluazuron is a novel veterinary pour-on antitick formulation which can be applied simultaneously with bovine reproduction management strategies. Considering the economic importance of the livestock industry in many countries, it is important to know whether antiparasitics such as fluazuron may cause embryonic loss. The aim of this study was to evaluate the toxicological effect of fluazuron on bovine oocytes during in vitro maturation. The best fluazuron concentrations were determined in a preliminary experiment on Chinese hamster ovary (CHO)-K1 cells and further used to compare fluazuron toxicity in both study models. Results of the annexin V and alkaline single cell gel electrophoresis assays demonstrated that fluazuron caused cytotoxicity and genotoxicity in bovine cumulus cells at all the concentrations tested (50, 75 and 100 μg fluazuron/mL). The evaluation of cortical granules and mitochondria distribution showed that cytoplasmic maturation was not affected by fluazuron treatment. However, a decrease in metaphase II + polar body, degenerate oocytes as well as disorganized chromatin in polar body were observed at all concentrations tested. Whereas the fertilization process was not altered by 50 μg/mL fluazuron, the embryo development rate decreased significantly. No significant differences were observed in any of the oxidative stress parameters assessed. This study contributes to a better understanding of fluazuron in bovines, suggesting that the antiparasitic may affect bovine reproduction and might cause embryo loss.

Sialyllactose supplementation enhances sialylation of Fc-fusion glycoprotein in recombinant Chinese hamster ovary cell culture

Sialylation during N-glycosylation plays an important role in the half-life of therapeutic glycoproteins in vivo and has sparked interest in the production of therapeutic proteins using recombinant Chinese hamster ovary (rCHO) cells. To improve the sialylation of therapeutic proteins, we examined the effect of sialyllactose supplementation on sialylation of Fc-fusion glycoproteins produced in rCHO cells. Two enzymatically-synthesized sialyllactoses, 3′-sialyllactose (3′-SL) and 6′-sialyllactose (6′-SL), were administered separately to two rCHO cell lines producing the same Fc-fusion glycoprotein derived from DUKX-B11 and DG44, respectively. Two sialyllactoses successfully increased sialylation of Fc-fusion glycoprotein in both cell lines, as evidenced by isoform distribution, sialylated N-glycan formation, and sialic acid content. Increased sialylation by adding sialyllactose was likely the result of increased amount of intracellular CMP-sialic acid (CMP-SA), the direct nucleotide sugar for sialylation. Furthermore, the degree of sialylation enhanced by sialyllactoses was slightly effective or nearly similar compared with the addition of N-acetylmannosamine (ManNAc), a representative nucleotide sugar precursor, to increase sialylation of glycoproteins. The effectiveness of sialyllactose was also confirmed using three commercially available CHO cell culture media. Taken together, these results suggest that enzymatically-synthesized sialyllactose represents a promising candidate for culture media supplementation to increase sialylation of glycoproteins in rCHO cell culture.

Novel Piperazine Derivatives of Vindoline as Anticancer Agents.

A series of novel vindoline-piperazine conjugates were synthesized by coupling 6 N-substituted piperazine pharmacophores at positions 10 and 17 of Vinca alkaloid monomer vindoline through different types of linkers. The in vitro antiproliferative activity of the 17 new conjugates was investigated on 60 human tumor cell lines (NCI60). Nine compounds presented significant antiproliferative effects. The most potent derivatives showed low micromolar growth inhibition (GI50) values against most of the cell lines. Among them, conjugates containing [4-(trifluoromethyl)benzyl]piperazine (23) and 1-bis(4-fluorophenyl)methyl piperazine (25) in position 17 of vindoline were outstanding. The first one was the most effective on the breast cancer MDA-MB-468 cell line (GI50 = 1.00 μM), while the second one was the most effective on the non-small cell lung cancer cell line HOP-92 (GI50 = 1.35 μM). The CellTiter-Glo Luminescent Cell Viability Assay was performed with conjugates 20, 23, and 25 on non-tumor Chinese hamster ovary (CHO) cells to determine the selectivity of the conjugates for cancer cells. These compounds exhibited promising selectivity with estimated half-maximal inhibitory concentration (IC50) values of 2.54 μM, 10.8 μM, and 6.64 μM, respectively. The obtained results may have an impact on the design of novel vindoline-based anticancer compounds.

Evaluation of two transposases for improving expression of recombinant proteins in Chinese hamster ovary cell stable pools by co-transfection and supertransfection approaches.

Transposons are genetic elements capable of cutting and pasting genes of interest via the action of a transposase and offer many advantages over random or targeted integration of DNA in the creation of Chinese hamster ovary (CHO) cell lines for recombinant protein expression. Unique transposases have different recognition sites, allowing multiple transposases to be co-transfected together. They also allow for supertransfection (transfection on a previously transfected pool or cell line) with a second transposase to integrate additional copies of the same gene or an additional gene without disruption of the previously integrated DNA which to our knowledge has not been previously described in literature. Two fluorescent proteins, EGFP and tagRFP657, were either co-transfected or supertransfected into CHO cells using two unique transposases and showed high expression efficiency with similar expression levels (measured as mean fluorescence intensity), regardless of whether the genes were co-transfected or supertransfected onto an existing stable pool. Additionally, dual selection of the genes, both in the absence of L-glutamine and the presence of puromycin, led to higher expression levels than single selection alone. These results demonstrate that supertransfection using unique transposases could be a useful strategy for increasing titers of existing cell lines or for overexpressing helper (non-therapeutic) genes to improve expression and/or product quality of existing pools and cell lines, potentially saving significant time and resources.

MRAP2a Binds and Modulates Activity and Localisation of Prokineticin Receptor 1 in Zebrafish.

The prokineticin system plays a role in hypothalamic neurons in the control of energy homeostasis. Prokineticin receptors (PKR1 and PKR2), like other G-protein-coupled receptors (GPCRs) are involved in the regulation of energy intake and expenditure and are modulated by the accessory membrane protein 2 of the melanocortin receptor (MRAP2). The aim of this work is to characterise the interaction and regulation of the non-melanocortin receptor PKR1 by MRAP2a in zebrafish (zMRAP2a) in order to use zebrafish as a model for the development of drugs targeting accessory proteins that can alter the localisation and activity of GPCRs. To this end, we first showed that zebrafish PKR1 (zPKR1) is able to interact with both zMRAP2a and human MRAP2 (hMRAP2). This interaction occurs between the N-terminal region of zPKR1 and the C-terminal domain of zMRAP2a, which shows high sequence identity with hMRAP2 and a similar propensity for dimer formation. Moreover, we demonstrated that in Chinese hamster ovary (CHO) cells, zMRAP2a or hMRAP2 are able to modulate zPKR1 activation induced by zebrafish PK2 (zPK2) resulting in an impaired ERK and STAT3 activation.

Enhanced efficacy of glycoengineered rice cell-produced trastuzumab.

For several decades, a plant-based expression system has been proposed as an alternative platform for the production of biopharmaceuticals including therapeutic monoclonal antibodies (mAbs), but the immunogenicity concerns associated with plant-specific N-glycans attached in plant-based biopharmaceuticals has not been completely solved. To eliminate all plant-specific N-glycan structure, eight genes involved in plant-specific N-glycosylation were mutated in rice (Oryza sativa) using the CRISPR/Cas9 system. The glycoengineered cell lines, PhytoRice®, contained a predominant GnGn (G0) glycoform. The gene for codon-optimized trastuzumab (TMab) was then introduced into PhytoRice® through Agrobacterium co-cultivation. Selected cell lines were suspension cultured, and TMab secreted from cells was purified from the cultured media. The amino acid sequence of the TMab produced by PhytoRice® (P-TMab) was identical to that of TMab. The inhibitory effect of P-TMab on the proliferation of the BT-474 cancer cell line was significantly enhanced at concentrations above 1 μg/mL (****P < 0.0001). P-TMab bound to a FcγRIIIa variant, FcγRIIIa-F158, more than 2.7 times more effectively than TMab. The ADCC efficacy of P-TMab against Jurkat cells was 2.6 times higher than that of TMab in an in vitro ADCC assay. Furthermore, P-TMab demonstrated efficient tumour uptake with less liver uptake compared to TMab in a xenograft assay using the BT-474 mouse model. These results suggest that the glycoengineered PhytoRice® could be an alternative platform for mAb production compared to current CHO cells, and P-TMab has a novel and enhanced efficacy compared to TMab.

Impact of PEG Content on Doxorubicin Release from PLGA-co-PEG Nanoparticles.

Nanoparticles (NPs) have become attractive vehicles for drug delivery in cancer therapy due to their ability to accumulate in tumours and mitigate side effects. This study focuses on the production of doxorubicin (DOX)-loaded NPs comprising Poly (lactic-co-glycolic acid)-Polyethylene glycol with varying PEG proportions and the examination of their impact on drug release kinetics. DOX-loaded NPs, composed of PLGA-co-PEG with PEG contents of 0%, 5%, 10%, and 15%, were synthesized by the solvent evaporation technique, exhibited spherical morphology, and had sizes ranging from 420 nm to 690 nm. In vitro drug release studies revealed biphasic profiles, with higher PEG contents leading to faster and more extensive drug release. The Baker-Lonsdale model demonstrated the best fit to the drug release data, indicating that the release process is diffusion-controlled. The diffusion coefficients for DOX determined ranged from 6.3 × 10-18 to 7.55 × 10-17 cm2s-1 and exhibited an upward trend with increasing PEG content in the polymer. In vitro cytotoxicity tests with CHO cells showed that unloaded NPs are non-toxic, while DOX-loaded PLGA-PEG 15% NPs induced a greater decrease in cellular viability compared to their PLGA counterparts. A mathematical relationship between the diffusion coefficient and PEG percentage was derived, providing a practical tool for optimizing DOX release profiles.

Comparison of the Immunogenicity of the LZ901 Vaccine and HZ/su Vaccine in a Mouse Model.

Herpes zoster (HZ) is an infectious disease caused by the reactivation of varicella zoster virus (VZV), with 68% of cases occurring in adults over 50 years of age. HZ/su (Shingrix®) was approved by the Food and Drug Administration in 2017 for the prevention of HZ in individuals ≥ 50 years of age and showed very good protection from HZ. However, due to the use of the adjuvant AS01B, adverse reactions caused by Shingrix are a concern. Aluminum hydroxide is the most commonly used adjuvant and is widely used in a variety of vaccines. We developed a recombinant zoster vaccine (code: LZ901) consisting of a tetramer of VZV glycoprotein E (gE) and a human Fc fusion protein expressed in CHO cells, an immune complex-like molecule that can be adsorbed with an aluminum hydroxide adjuvant. We compared the immunogenicity of LZ901 with that of HZ/su in BALB/c mice. The results showed that LZ901 induced levels of gE-specific IgG antibodies comparable to those induced by HZ/su, and the results of FAMA titers further demonstrated their similar neutralizing antibody abilities. Most importantly, LZ901 induced higher levels of cell-mediated immunity (CMI) (which plays a decisive role in the efficacy of zoster vaccines) than HZ/su in BALB/c mice. The numbers of cytokine-producing T cells in LZ901-vaccinated mice were significantly greater than those in v-vaccinated mice, and the proportions of CD4+ and CD8+ T cells producing at least two types of cytokines in LZ901-vaccinated mice were significantly greater than those in HZ/su-vaccinated mice.

Optimization of the Process of Chinese Hamster Ovary (CHO) Cell Fed-Batch Culture to Stabilize Monoclonal Antibody Production and Overall Quality: Effect of pH Control Strategies

Optimization of the Process of Chinese Hamster Ovary (CHO) Cell Fed-Batch Culture to Stabilize Monoclonal Antibody Production and Overall Quality: Effect of pH Control Strategies

Revisiting the impact of genomic hot spots: C12orf35 locus as a hot spot and engineering target.

Traditional Chinese hamster ovary (CHO) cell line development is based on random integration (RI) of transgene that causes clonal variation and subsequent large-scale clone screening. Therefore, site-specific integration (SSI) of transgenes into genomic hot spots has recently emerged as an alternative method for cell line development. However, the specific mechanisms underlying hot spot site formation remain unclear. In this study, we aimed to generate landing pad (LP) cell lines via the RI of transgenes encoding fluorescent reporter proteins flanked by recombination sites to facilitate recombinase-mediated cassette exchange. The RI-based LP cell line expressing high reporter levels with spontaneous C12orf35 locus deletion exhibited similar reporter fluorescent protein levels compared to targeted integrants with an identical reporter LP construct at the CHO genome hot spot, the C12orf35 locus. Additionally, Resf1, a C12orf35 locus gene, knockout (KO) in the RI-based LP cell line with conserved C12orf35 increased reporter expression levels, comparable to those in cell lines with C12orf35 locus disruption. These results indicate that the effect of SSI into the C12orf35 locus, a genomic hot spot, on high-level transgene expression was caused by C12orf35 disruption. In contrast to C12orf35 KO, KO at other well-known hot spot sites at specific loci of genes, including Fer1L4, Hprt1, Adgrl4, Clcc1, Dop1b, and Ddc, did not increase transgene expression. Overall, our findings suggest that C12orf35 is a promising engineering target and a hot spot for SSI-based cell line development.

Development of technology for culturing a cell line producing a single-domain antibody fused with the Fc fragment of human IgG1

Objectives. To develop an effective technology for the cultivation of Chinese hamster ovary (CHO) cells stably producing GamP2C5 antibody which is a component I of the GamCoviMab candidate drug for emergency prevention and therapy of infection caused by SARS-CoV-2 virus; to select optimal cultivation parameters and to scale this technology in production.Methods. The study was performed on CHO GamP2C5 (clone 78) cell culture, producing a single-domain antibody fused to the Fc fragment of human IgG1 GamP2C5. Different culture media and supplements were used. Cells were cultured in Erlenmeyer flasks, Biostat® RM 20 wave-mixed bioreactor, Ambr® 250 mini bioreactors, STR 200 stirred-tank bioreactor.Results. Using molecular-genetic and biotechnological methods, a stable clone producer of CHO GamP2C5 antibody, clone 78, was obtained. Then a technique was worked out for the cultivation of the obtained clone producer on different culture media. The most suitable cultivation regimes, culture media, and optimal supplements were selected. This technology was tested in laboratory conditions in a 10-L reactor, and then successfully scaled up for production at the MedGamal Branch of the Gamaleya National Research Center for Epidemiology and Microbiology.Conclusions. This study demonstrates the fundamental feasibility of developing and scaling up a culture technology, in order to produce a drug based on a modified single-domain antibody with virus neutralizing activity against different strains of SARS-CoV-2 virus.

Overcoming the inconsistent cell culture performance caused by single-use bioreactors during scaling-up the manufacturing process for a therapeutic bispecific antibody

Single use technology has been widely used in modern biopharmaceutical process development and manufacturing. However, there are concerns about the adverse effects of disposable materials on bioprocess, product quality and patient safety. Recently, we observed slow cell growth, increased lactate accumulation, and decreased production titer during scaling up a bispecific antibody (BsAb) upstream process from 3 L to 500 L bioreactor. To investigate the phenomenon, we conducted medium incubation and leachable spike-in experiments. We found that cell culture medium incubated in CX5–14 bag caused poor cell culture performance, which was correlated with the concentration of bis(2,4-di-tert-butylphenyl)-phosphate (bDtBPP), a breakdown product of the antioxidant Irgafos®168 in polyethylene film. In addition, when the media were spiked with 0.15 μg/ml or a greater concentration of bDtBPP, slow cell growth and reduced BsAb expression level were observed. In contrast, Aegis5–14 film produced bDtBPP at a level of below detection during medium incubation. Thus, the bispecific-expressing CHO cell line restores normal cell culture performance and production titer when Aegis5–14 single-use bioreactor was employed in large-scale manufacturing. Our results reveal the importance of evaluating leachable profiles from disposable materials during process development of bispecifics and other novel therapeutic modalities.

N-Glycosylation Deficiency in Transgene α7 nAChR and RIC3 Expressing CHO Cells Without NACHO.

The human neuronal nicotinic acetylcholine receptor α7 (nAChR) is an important target implicated in diseases like Alzheimer's or Parkinson's, as well as a validated target for drug discovery. For α7 nAChR model systems, correct folding and ion influx functions are essential. Two chaperones, resistance to inhibitors of cholinesterase 3 (RIC3) and novel nAChR regulator (NACHO), enhance the assembly and function of α7 nAChR. This study investigates the consequence of NACHO absence on α7 nAChR expression and function. Therefore, the sequences of human α7 nAChR and human RIC3 were transduced in Chinese hamster ovary (CHO) cells. Protein expression and function of α7 nAChR were confirmed by Western blot and voltage clamp, respectively. Cellular viability was assessed by cell proliferation and lactate dehydrogenase assays. Intracellular and extracellular expression were determined by in/on-cell Western, compared with another nAChR subtype by novel cluster fluorescence-linked immunosorbent assay, and N-glycosylation efficiency was assessed by glycosylation digest. The transgene CHO cell line showed expected protein expression and function for α7 nAChR and cell viability was barely influenced by overexpression. While intracellular levels of α7 nAChR were as anticipated, plasma membrane insertion was low. The glycosylation digest revealed no appreciable N-glycosylation product. This study demonstrates a stable and functional cell line expressing α7 nAChR, whose protein expression, function, and viability are not affected by the absence of NACHO. The reduced plasma membrane insertion of α7 nAChR, combined with incorrect matured N-glycosylation at the Golgi apparatus, suggests a loss of recognition signal for lectin sorting.

P-594 Retrospective comparative study of follitropin delta vs follitropin alfa in progestin-primed ovarian stimulation (PPOS) protocol in IVF

Abstract Study question Could the individualized fixed-dose algorithm with follitropin delta show a similar pregnancy rate to conventional dosing with follitropin alfa in PPOS protocol? Summary answer Individualized fixed-dose algorithm with follitropin delta showed a similar pregnancy rate to follitropin alfa In PPOS protocol. What is known already Follitropin delta (REKOVELLE, Ferring Pharmaceuticals, Switzerland) is the first human cell line driven recombinant follicle-stimulating hormone (FSH) with an individualized fixed-dose algorithm based on serum AMH level and body weight. Follitropin alfa is a Chinese hamster ovarian cell driven recombinant FSH and its dosing is adjusted according to follicular response during the stimulation period. There was no significant difference between follitropin delta and follitropin alfa in terms of pregnancy rate under GnRH antagonist protocol. Study design, size, duration A retrospective analysis of 355 patients aged under 40 years who underwent ovarian stimulation in PPOS protocol using follitropin delta or follitropin alfa and on whom frozen-thawed single blastocyst transfer was conducted between August 2021 and November 2023 was performed. Participants/materials, setting, methods 193 cycles of women who used follitropin delta were compared to 162 cycles of women who used follitropin alfa. The following clinical outcomes on each treatment group were analyzed: chemical pregnancy rate (serum β hCG), clinical pregnancy rate (gestational sac), ongoing pregnancy rate(gestational sac and fetal heartbeat), serum E2 level at trigger day, cycle proportion of ≥ 10 oocytes retrieval, blastocyst formation rate, cycle proportion of ≥ 5 blastocysts and cycle proportion of ≥ 2 good quality blastocysts. Main results and the role of chance Baseline demographics in the follitropin delta group and the follitropin alfa group were not significantly different: age, 33.9 ± 3.5 years vs 34.5 ± 3.2 years; body weight, 53.5 ± 8.3 kg vs 53.8 ± 5.9 kg; number of previous IVF cycles, 0.2 ± 0.6 vs 0.3 ± 0.7; serum AMH level, 5.5 ± 2.9 ng/mL vs 5.3 ± 3.8 ng/mL, respectively. The chemical pregnancy rate (69.9% vs. 64.8%, P = 0.308), clinical pregnancy rate (58.0% vs. 56.2%, P = 0.748) and ongoing pregnancy rate (51.8% vs. 46.3%, P = 0.338) were comparable between the follitropin delta group and the follitropin alfa group. The individualized follitropin delta treatment resulted in a smaller cycle proportion of ≥ 10 oocytes retrieval (77.7% vs. 90.8%, P &amp;lt; 0.001) with lower serum E2 level at trigger day (3273 ± 1577 pg/mL vs. 3927 ± 1732 pg/mL, p &amp;lt; 0.001). However, the blastocyst formation rate was significantly higher in the follitropin delta group (75.5% vs. 68.7%, p &amp;lt; 0.001). Moreover, the cycle proportion of ≥ 5 blastocysts (71.0% vs. 76.4%, P = 0.286) and the cycle proportion of ≥ 2 good quality blastocysts (51.8% vs. 60.3%, P = 0.115) were comparable between the groups. Limitations, reasons for caution This is a non-controlled, retrospective study. Wider implications of the findings Follitropin delta in its individualized fixed-dose regimen could have the potential to decrease the risk of OHSS by minimizing excessive ovarian response, whereas a similar pregnancy rate to conventional dosing regimen could be expected due to the number of good quality blastocysts secured. Trial registration number not applicable

P-621 Rekovelle® vs Gonal-F®: in vitro characterization of intracellular signals induced by the two FSH preparations

Abstract Study question Do Rekovelle® and Gonal-F® modulate preparation-specific signalling? Summary answer Gonal-F® and Rekovelle® induce preparation-specific pattern of intracellular signalling. What is known already Rekovelle® and Gonal-F® are two commercial preparations of recombinant FSH used in assisted reproduction. These preparations differ in originator cells (PER.C6® cell line of human fetal retinal origin for Rekovlle®; modified Chinese Hamster Ovary cell line for Gonal-F®), likely reflecting glycosylation profiles impacting their mode of action. Study design, size, duration 3-year in vitro functional comparison of Rekovelle® and Gonal-F®, using the transfected HEK293 cell line expressing FSH receptor (FSHR). Participants/materials, setting, methods FSHR-expressing HEK293 cells were treated with increasing concentrations of GonalF® and Rekovelle® (pM-µM) to evaluate receptor-receptor interaction and trafficking, intracellular cyclic adenosine monophosphate (cAMP) and Ca2+ increase by bioimaging techniques, as well as phospho-protein by Western blotting, and genomic effects by CRE-luciferase reporter gene activity. Main results and the role of chance Both the preparations induced similar, dose-dependent increase of receptor trafficking through intracellular organelles. These data were obtained by evaluation of the interaction between FSHR and endosomal markers RAB-GTPases (Rab) 5 and 7. Rekovelle® induced more pronounced steroifogenic signals than Gonal-F®, detected as FSHR-FSHR interactions at the cell membrane, cAMP accumulation, cAMP-responsive elements binding protein (CREB) phosphorylation and CRE promoter activity. Interestingly, while cell treatment by Gonal-F® mediated complete dose-response of cAMP, consisting in the continuous increase of the second messenger together with the increase of FSH concentration, Rekovelle® had biphasic action where cAMP increased from 0 to 100 nM although decreased at 1 µM Rekovelle® dose. Moreover, Rekovelle® was 10-times more potent than Gonal-F® in activating intracellular Ca2+ activation. The two preparations induced similar pattern of extracellular signal-regulated kinases 1 and 2 (ERK1/2) phosphorylation. In conclusion, Rekovelle® has higher potency than Gonal-F® in activating cAMP- and Ca2+-dependent intracellular events, potentially resulting in preparation-specific steroidogenic pattern. Limitations, reasons for caution Experiments were performed in the transfected HEK293 cell line in vitro and should be confirmed by clinical observations. Wider implications of the findings We described different intracellular events mediated by Gonal-F® and Rekovelle® in vitro, likely originated by different glycan profiles and possibly impacting the ovarian response during assisted reproduction. Trial registration number Not Applicable