Exploring metabolic effects of dipeptide feed media on CHO cell cultures by in silico model-guided flux analysis.

There is a growing interest in perfusion or continuous processes to achieve higher productivity of biopharmaceuticals in mammalian cell culture, specifically Chinese hamster ovary (CHO) cells, towards advanced biomanufacturing. These intensified bioprocesses highly require concentrated feed media in order to counteract their dilution effects. However, designing such condensed media formulation poses several challenges, particularly regarding the stability and solubility of specific amino acids. To address the difficulty and complexity in relevant media development, the biopharmaceutical industry has recently suggested forming dipeptides by combining one from problematic amino acids with selected pairs to compensate for limitations. In this study, we combined one of the lead amino acids, L-tyrosine, which is known for its poor solubility in water due to its aromatic ring and hydroxyl group, with glycine as the partner, thus forming glycyl-L-tyrosine (GY) dipeptide. Subsequently, we investigated the utilization of GY dipeptide during fed-batch cultures of IgG-producing CHO cells, by changing its concentrations (0.125 × , 0.25 × , 0.5 × , 1.0 × , and 2.0 ×). Multivariate statistical analysis of culture profiles was then conducted to identify and correlate the most significant nutrients with the production, followed by in silico model-guided analysis to systematically evaluate their effects on the culture performance, and elucidate metabolic states and cellular behaviors. As such, it allowed us to explain how the cells can more efficiently utilize GY dipeptide with respect to the balance of cofactor regeneration and energy distribution for the required biomass and protein synthesis. For example, our analysis results uncovered specific amino acids (Asn and Gln) and the 0.5 × GY dipeptide in the feed medium synergistically alleviated the metabolic bottleneck, resulting in enhanced IgG titer and productivity. In the validation experiments, we tested and observed that lower levels of Asn and Gln led to decreased secretion of toxic metabolites, enhanced longevity, and elevated specific cell growth and titer. KEY POINTS: • Explored the optimal Tyr dipeptide for the enhanced CHO cell culture performance • Systematically analyzed effects of dipeptide media by model-guided approach • Uncovered synergistic metabolic utilization of amino acids with dipeptide.

Whole exome sequencing of placental chorangioma.

INTRODUCTION: Placental chorangioma is a benign non-trophoblastic vascular proliferation of the placental chorion favored to represent hamartoma-like or hyperplastic capillary lesions. As the exact pathophysiology has not been established, we investigated the molecular characteristics of placental chorangiomas using exploratory whole exome sequencing. METHODS: Three cases were retrospectively selected and whole exome sequencing was performed on macrodissected lesions. DNA extraction, DNA quantification, library preparation and sequencing were performed with IDT xGen™ Exome Hybridization Panel v2 for library capture. Sequencing data was analyzed with an in-house bioinformatics pipeline for single-nucleotide variants and insertions/deletions. RESULTS: All neonates were delivered at term and had birth weights ranging from 11th-35th percentile for gestational age. All mothers presented with hypertensive disorder during pregnancy. Chorangiomas ranged from 0.7 cm to 5.1 cm and were well-circumscribed near the fetal surface. Case 1 showed a background of chorangiosis and acute subchorionitis, while case 2 had foci of chronic lymphocytic villitis. Whole exome sequencing did not reveal any significant pathologic variants. DISCUSSIONS: The absence of molecular alteration in placental chorangioma is likely indicative of the reactive/non-neoplastic nature of this lesion. The presence of compromised blood flow in the form of hypertensive disorders in our cases may be one of its underlying pathophysiologic mechanisms.

Driving towards digital biomanufacturing by CHO genome-scale models.

Genome-scale metabolic models (GEMs) of Chinese hamster ovary (CHO) cells are valuable for gaining mechanistic understanding of mammalian cell metabolism and cultures. We provide a comprehensive overview of past and present developments of CHO-GEMs and in silico methods within the flux balance analysis (FBA) framework, focusing on their practical utility in rational cell line development and bioprocess improvements. There are many opportunities for further augmenting the model coverage and establishing integrative models that account for different cellular processes and data for future applications. With supportive collaborative efforts by the research community, we envisage that CHO-GEMs will be crucial for the increasingly digitized and dynamically controlled bioprocessing pipelines, especially because they can be successfully deployed in conjunction with artificial intelligence (AI) and systems engineering algorithms.