Developing human organotypic perfused bioreactors for physiologically reproducible therapeutic compound screening of a tumour microenvironment

Lead Research Organisation: University of Oxford
Department Name: Oncology


'Developing human organotypic perfused bioreactors for physiologically reproducible therapeutic compound screening of a tumour microenvironment'

Pre-clinical testing of new therapeutics relies on the use of in-vitro and in-vivo models. These, however, have intrinsic weaknesses, one major one being the inadequate recapitulation of physiological conditions in-vivo. In cancer, for example, pre-clinical testing systems do not recapitulate the tumour microenvironment. This is a considerable drawback since the interplay of tumour and stroma cells, the extracellular matrix and the consistent supply of nutrients and oxygen via the perfusion of the microcirculation adds to the spectrum of selective pressure that leads to the heterogeneity and ultimately fate of tumour cells. This inability to reflect crucial in-vivo conditions, together with their associated costs and time constraints, and the ethical controversy of animal testing of in-vivo models, makes the search of better ways for pre-clinical therapeutic testing a matter of paramount urgency.

Tissues and organs artificially grown using bioreactors, engineered devices that support a biologically active environment, are seen as a promising type of advanced in-vitro models to initially reduce and eventually replace current conventional in-vitro and in-vivo models. Biomedical engineers, including myself, have developed bioreactors to grow these artificial tissues in order to test therapeutics, including anti-cancer compounds. Nevertheless, most of these prototypes have so far lacked perfusion, without which these advanced in-vitro models cannot recapitulate key aspects of the tumour microenvironment such as the interstitial fluid, the microcirculation of blood vessels and immune system.

Building on the work I carried out during my DPhil, here I propose to develop a culture platform (bioreactor) capable of recapitulating perfusion in the tumour microenvironment, and fit for screening of anti-cancer compounds. The developed culture platform will be tested using brain and pancreatic cancer tissue, and will focus on following up the process of angiogenesis and immune response during tumour development and responses to therapy. Therapeutic compounds known to regulate these processes will then be tested in order to validate the developed in-vitro model.

Our perfused culture platform has the potential to tackle the disadvantages inherit of conventional in-vitro and in-vivo models, relieving the ethical pressures of animal testing, and being more cost and time effective. Additionally, the small amount of cancer tissue required by this platform would make it particularly suitable for cancer types such as brain and pancreatic cancer which suffer from a lack of clinical samples.

Technical Summary

1. Different scales of bioreactors will be developed to mimic the flow of the interstitial environment of tumours, and bioreactor parameters will be optimised to improve the maintenance of homeostasis. This will allow long-term observation (> 21 days) in a physiologically relevant microenvironment [1]. 2. To realise the spatial control for the development of microtissues, micropatterning engineering tools such as soft lithography and three-dimensional bioprinting will be applied to define the distributions of a range of supporting cell types (such as networks of blood vessels) and tumour cells [2]. 3. Cellular and molecular biology techniques and immunofluorescence microscopy will allow us to elucidate the relation between some biophysical and biochemical parameters which are hard to measure or quantify in traditional in-vivo models, but with prognosis significance [3]. More importantly, parameters such as interstitial fluid dynamics, can determine the differentiation of the cells via creating chemokine gradients or shear stress, which will contribute to the heterogeneity of the tumour tissue [4]. Bioreactors with a fluidic culture environment will allow the observation of interstitial flow, which will then make it possible for testing drugs in a physiomimetic avatar. 4. To develop in-vivo pathomimetic avatars for different differentiated stages of tumour remains a bottleneck, while using tissue engineering techniques differentiation can be induced via well-controlled bioreactor parameters (as explained in #3). The differentiated advanced in-vitro models will then mimic the specific stages of tumour development, and the drug screening results obtained from these models will be more predictable of their clinical behaviours. [1] Gantenbein B et al, Curr Stem Cell Res Ther. 2015;10(4): 339-352; [2] Qian X et al, Cell. 2016; 165(5):1238-1254; [3] Morgan J et al, Nat Protoc. 2013; 8(9):1820-1836; [4] Huang Y et al, Integr Biol (Camb). 2015;7(11): 1402-1411


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