cell culture conditions is the so-called ‘edge effect’. The edge effect refers to a pair of related problems that affect the consistency of results achieved when using cell culture plates – the differential tempera- ture distribution across the plate and differential evaporation between wells. Temperature gradients across well plates can

pose a significant problem when culturing cells. The evaporation of culture media can change the pH and osmolality, affecting cell development and reducing cell viability. Because evaporation effects tend to be greater on the outermost wells of the plate, this effect is not uniform, prompting uneven cell seeding. Traditionally, this problem is typically overcome by leaving the outer 36 wells empty, or by filling them with sterile water. However, while these approaches mitigate the edge effect, they can reduce the size of a typical 96-well plate by more than a third. To combat this problem, plates with a perimeter

moat filled with sterile water or agarose have been recently developed. These innovative culture vessel solutions reduce the evaporation and increase cell viability, while providing use of a full-size well plate so that efficiency and productivity are main- tained. Elegant solutions to cell viability problems, such as these, are benefitting the cell therapy indus- try by increasing throughput without altering workflows.

Creating realistic in vivo conditions The development of effective therapies relies upon consistent cell culture methods and the ability to recreate realistic in vivo conditions. Traditional two-dimensional (2D) monolayer cell cultures can offer highly reproducible environments that are suitable for applications, such as drug screening. However, to recreate the complex environment found in cancer tissues, more elaborate structures are typically required. Here, the additional dimen- sionality of 3D cultures can lead to more predictive cellular responses, not only influencing the spatial organisation of cell surface receptors engaged in interactions with surrounding cells, but also induc- ing physical cell constraints. Recent cultureware innovations are addressing

this challenge by making it possible to culture cells in 3D without a scaffold, allowing cells to sponta- neously aggregate and produce more physiologi- cally relevant environments. Cells cultured in this manner form spherical clusters called spheroids, which have been successfully implemented in many aspects of cell therapy. In stem cell research, for example, 3D aggregates of pluripotent stem cells, known as embryoid bodies, provide the physiolog-

Drug Discovery World Summer 2018

ical signals that prompt the differentiation to dif- ferent cell lineages. They are, therefore, highly use- ful for regenerative medicine applications as they may be used to repair damaged or diseased tissue, and could also be used for in vitro testing in the pharmaceutical industry or as a model of embryon- ic development. Spheroids and other such 3D cell cultures pro-

vide a much closer representation of an in vivo environment. However, their biological complexity means they can be difficult to culture consistently in vitro. To deliver more reproducible results, many researchers are employing round-bottomed microwell plates for spheroid production. Round- bottom plates make it possible for cells to aggre- gate to a much more uniform size and shape than is typically possible using traditional flat-bottomed culture vessels. In addition, the vessel surface can be treated

with a low binding polymer coating which encour- ages the cells to bind to each other rather than the surface, minimising variability and supporting the formation of consistent spheroids. By creating real- istic cell culture environments in this way, more reliable results can be achieved, ultimately acceler- ating the development of safe and effective cell therapies.

Maximising lab space Ongoing advances in equipment design are not only helping to improve the quality of results, they are increasing productivity too. Thanks to simple design improvements, the latest solutions are help- ing laboratories operate more efficiently by max- imising the space available for research. Take the design of orbital shakers, for example.

These important pieces of equipment are needed to aerate and agitate suspension cell cultures effec- tively, ensure that oxygen and nutrients are avail- able throughout the mixture, and avoid any cell settlement on the bottom of the flask. Traditional orbital shakers are not robust enough to be used

inside a CO2 incubator, since the heat, humidity and weak carbonic acid atmosphere are very dam- aging to the electronics. However, recent innova- tions have led to the development of orbital shak- ers with magnetic drives to dramatically reduce vibration, and sealed electronics that significantly

extend the life of the equipment used in the CO2 incubator. Remote monitoring systems that can be mounted on the incubator door serve to reduce dis- turbance to cultures, and allow at-a-glance obser- vation of settings and conditions. Capable of being used either within or outside

the CO2 incubator, CO2-resistant orbital shakers 77

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