High throughput physiological micro-models for in vitro pre-clinical drug testing: a review of engineering systems approaches

Abstract

To address the low success rate of new drug discovery, there has been significant growth of in vitro physiological micro-models based on human cells. These may be in the form of cell spheroids, organs-on-a-chip, or multi-cellular tissue cultures, and it is expected that the more biomimetic environment they create will be more accurate than standard cell culture in drug screening prior to clinical testing. However, commercial use of complex co-cultures is still limited. This is due to a lack of validation, low throughput rates, and a lack of compatibility with standard assessment techniques. This review paper focusses specifically on the different engineering approaches used to create, mature and analyse these micro-models, with the aim of exploring which approaches have the potential for high throughput. Active and passive pumping and nozzle based dispensing techniques are considered for fluid handling, with transwells, cell patterning, spheroid cultures and microfluidics considered for establishing and maintaining co-cultures, together with conventional analysis techniques (proteomic and genomic approaches, and immunohistochemistry) and novel sensor systems for downstream analysis are considered. It is concluded that (i) throughput is essential for validation as well as exploitation of the models, and (ii) an integrated approach to model re-design for high throughput is key, with the limitations on throughput at each stage considered in order to develop a system which can deliver and analyse at high throughput rates at all stages of the process.

NGN2 mmRNA-Based Transcriptional Programming in Microfluidic Guides hiPSCs Toward Neural Fate With Multiple Identities

“…The use of microfluidics allows for a better delivery of mmRNA to target cells, including hiPSCs which have epithelial morphology and could be refractory to transfection. On the other hand, direct programming on a chip could have technological advantages because it provides an easily scalable system for disease modeling or drug screening applications ( Zhang et al, 2020 ). In fact, the entire process from seeding hiPSC to neural induction is seamless, does not require intermediate cell sorting and low amount of media and mmRNA at microliter scale are needed, thus converting a quite expensive protocol in a cost-effective procedure.…”

The Application and Working Principles of Passive Pumping Mechanism

“…However, the system does suffer from its limited flow rate which is a disadvantage when performing long term perfusion experiences. [12] Figure 2. PPM function by using different surface tension [1]…”

“…In this types of PPM, the device is capable of producing a very slow(could potentially last for days and weeks) and near constant flow. Because of the advantage, the device is very capable when performing long term cell cultures [12].…”

Microvalve Bioprinting of MSC-Chondrocyte Co-Cultures

“…Such models have applications for both pathophysiological disease research and therapeutic screening by providing a methodology to increase the throughput of early-stage research whilst simultaneously reducing the costs associated with therapeutic development. Despite this, 3D cell culture techniques increase the time, cost, and complexity of setting up and analysing models, thus limiting adoption within commercial environments that require high-throughput screening [ 17 , 18 , 19 , 20 , 21 ].…”