HTS/HCS to screen molecules able to maintain embryonic stem cell self-renewal or to induce differentiation: overview of protocols

Droplet microarray: miniaturized platform for rapid formation and high-throughput screening of embryoid bodies

Stem cells are influenced by various factors present in their in vivo microenvironment, such as interactions with neighboring cells, the extracellular matrix or soluble molecules. This demonstrates the high complexity of the in vivo microenvironment. Hence, many advances have been made in developing 3D screening models mimicking this complexity and the in vivo-like state in order to ensure more biomedically relevant investigations in drug discovery. In the field of stem cell research embryoid bodies are often used as relevant 3D systems. Embryoid bodies are embryonic stem cell aggregates that recapitulate the early embryonic development and that can differentiate into derivatives of the three germ layers. Embryoid bodies enable the investigation of processes underlying embryonic development, tissue generation and identification of drugs with developmental toxicity. The ability to perform high-throughput screenings using embryoid bodies could be extremely important to accelerate the progress in the field of stem cell research and embryonic development. To date, there are no simple methods to create high-density microarrays of embryoid bodies that further enable their high-throughput screening important for biomedical research. Here we demonstrate a new method that enables formation and high-throughput screening of embryoid bodies in arrays of defined, separated microdroplets. Using the superhydrophobic-hydrophilic micropattern of the droplet microarray, we demonstrate rapid and facile one-step formation of a dense array of multiple droplets containing homogeneous, single embryoid bodies. Thorough characterization of the influence of the initial cell number on embryoid body size, roundness and distribution was performed. We applied the embryoid body microarray to screen 774 FDA-approved compounds, identifying compounds with developmental toxicity such as mycophenolate mofetil or embryonic lethality such as eptifibatide. This work demonstrates the potential of the droplet microarray for the rapid formation of high-density microarrays of single embryoid bodies and their high-throughput drug screenings.

A Chemical Biology Study of Human Pluripotent Stem Cells Unveils HSPA8 as a Key Regulator of Pluripotency

Chemical biology methods such as high-throughput screening (HTS) and affinity-based target identification can be used to probe biological systems on a biomacromolecule level, providing valuable insights into the molecular mechanisms of those systems. Here, by establishing a human embryonal carcinoma cell-based HTS platform, we screened 171,077 small molecules for regulators of pluripotency and identified a small molecule, Displurigen, that potently disrupts hESC pluripotency by targeting heat shock 70-kDa protein 8 (HSPA8), the constitutively expressed member of the 70-kDa heat shock protein family, as elucidated using affinity-based target identification techniques and confirmed by loss-of-function and gain-of-function assays. We demonstrated that HSPA8 maintains pluripotency by binding to the master pluripotency regulator OCT4 and facilitating its DNA-binding activity.

Designing drugs that overcome antibacterial resistance: where do we stand and what should we do?

INTRODUCTION

In recent years, infections caused by multidrug-resistant bacterial pathogens have become a huge issue to public healthcare systems. Indeed, the misuse of antibiotics has led to, over the past 30 years, the emergence of a number of resistant bacterial strains including Staphylococcus aureus, Neisseria gonorrhoeae, Escherichia coli and Mycobacterium tuberculosis. Unfortunately, efforts to produce new antibiotics have not been sufficient to cope with the emergence of these new antibiotic-resistant (AR) strains.

AREAS COVERED

There is an urgent need to invent and employ unconventional strategies for antimicrobial drug development to tackle the rising global threats imposed by the spread of antimicrobial resistance. Herein, the authors discuss these novel design strategies and provide their expert perspective on the subject.

EXPERT OPINION

To deal with the growing threat of AR, it is important to cut down the use of antibiotics to the very minimum to diminish the risk of unknown drug-resistant bacteria and increase antibacterial vaccination programs. Furthermore, it is important to develop new classes of antibiotics that can deal with multidrug-resistant bacterial pathogens.