Collective cell motion in an epithelial sheet can be quantitatively described by a stochastic interacting particle model.

Modelling the displacement of thousands of cells that move in a collective way is required for the simulation and the theoretical analysis of various biological processes. Here, we tackle this question in the controlled setting where the motion of Madin-Darby Canine Kidney (MDCK) cells in a confluent epithelium is triggered by the unmasking of free surface. We develop a simple model in which cells are described as point particles with a dynamic based on the two premises that, first, cells move in a stochastic manner and, second, tend to adapt their motion to that of their neighbors. Detailed comparison to experimental data show that the model provides a quantitatively accurate description of cell motion in the epithelium bulk at early times. In addition, inclusion of model "leader" cells with modified characteristics, accounts for the digitated shape of the interface which develops over the subsequent hours, providing that leader cells invade free surface more easily than other cells and coordinate their motion with their followers. The previously-described progression of the epithelium border is reproduced by the model and quantitatively explained.

GlycoFi's technology to control the glycosylation of recombinant therapeutic proteins.

IMPORTANCE OF THE FIELD: Therapeutic properties of many glycoproteins strongly depend on the composition of their glycans. Most of the current approved glycoproteins are produced in mammalian cell lines, which yield mixture of different glycoforms close to the human one but not fully identical. Glyco-engineering is being developed as a method to control the composition of carbohydrates. Many alternative glycoprotein productions systems are actively investigated including new-engineered yeast strains, as developed by GlycoFi, a biotech company fully owned by Merck & Co. since 2006. AREAS COVERED IN THIS REVIEW: The objectives of this opinion paper is to present a comprehensive overview of the technological breakthrough developed by GlycoFi to produce recombinant human proteins with controlled glycosylation patterns in yeast, in comparison to other glyco-engineering technologies and to discuss the application to large-scale manufacturing of biologicals. WHAT THE READER WILL GAIN: Research papers and recent review articles on protein glycosylation and glyco-engineering, and in-depth search of the bibliography by the GlycoFi's research team, summary of recent meetings discussing the biosimilar topic were analyzed by the authors and will help the reader to gain insight in the field. TAKE HOME MESSAGE: The glyco-engineering technology of the Pichia pastoris N-glycosylation pathway developed by GlycoFi allows producing human proteins with complex N-glycosylation modifications, which are similar to the ones performed in human. Moreover, more homogeneous glycosylation patterns are observed, as opposed to the large heterogeneity of glycan moieties that are found naturally in mammals or in other production systems such as Chinese hamster ovary and NS0 cell lines. These properties associated with the perspective to industrialize the manufacturing process of Pichia makes it a very promising expression system to produce large-scale batches of therapeutics at a lower cost.

[Producing several hundred of kilograms of monoclonal antibodies for therapy: a constant challenge]. / Du milligramme à la tonne d'anticorps monoclonaux : outils et perspectives de production.

Discovering and designing novel therapeutic monoclonal antibodies (mAb) is just the beginning. In order to support clinical evaluations and to reach the market place, rapid and cost effective production platforms are needed. Process development and production efficiency play a crucial role in this space since they influence the cost of good and ultimately wide access to these life-saving medications. Due to their therapeutic dosages and repeated uses, the yearly need for certain mAb, especially those used in the treatments of cancer and inflammation, amounts to several hundred of kilograms. Consequently, significant technological investments are needed to support these extraordinary large needs for such complex proteins, and the industry is constantly aiming at reducing production costs while maintaining product quality to high levels. This review discusses some of the critical scientific and engineering decisions, which span from the selection of cell-line expression platforms to choices of technologies, which influence mAbs cost of goods that need to be made along the development path of a therapeutic mAb.

Methods and platforms for the quantification of splice variants' expression.

The relatively limited number of human protein encoding genes highlights the importance of the diversity generated at the level of the mRNA transcripts. As alternative RNA splicing plays a key role in mediating this diversity, it becomes critical to develop the tools and platforms that will deliver quantitative information on the specific expression levels associated with splice isoforms. This chapter describes the constraints generated by this global transcriptome analysis and the state-of-the-art techniques and products available to the scientific community.

A microarray configuration to quantify expression levels and relative abundance of splice variants.

Over the past decade, alternative RNA splicing has raised a great interest appearing to be of high importance in the generation of expression diversity. This regulatory process plays a critical role in the normal development and its impact on the initiation and development of human disorders as well as on the pharmacological properties of drugs is increasingly being recognized. Only few studies describe specific alternative splicing expression profiling. Microarray strategies have been conceived to address alternative splicing events but with very few experimental data related to their abilities to provide true quantification values. We have developed a specific microarray configuration relying on a few, well optimized probes per splice event. Basically, five probes of 24mer are used to fully characterize a splice event. These probes are of two types, exon probes and junction probes, and are either specific to a splice event or not. The performances of such a 'splice array' were validated on synthetic model systems and on complex biological materials. The results indicate that DNA chips based on this design combining exon and junction derived probes enable the detection and, absolute and relative quantification of splice variants. In addition, this strategy is compatible with all the microarrays that use oligonucleotide probes.