Abstract
Patient response to radiotherapy treatment varies from tumour to tumour and patient to patient
but is highly influenced by the tumour microenvironment (TME). The TME is a complex
ecosystem of biological, biophysical, biomechanical and biochemical milieus that enrich
tumour survival and influence treatment response. In vitro 3D models of cancer are emerging
to more readily recapitulate complex hallmarks of the TME, as compared to traditional 2D
cell culture and animal models. This novel field of tissue engineering is advancing as a
promising biomimetic approach for pre-clinical treatment screening and is particularly
appropriate for cancers that house a uniquely complex TME, such as pancreatic ductal
adenocarcinoma (PDAC). PDAC is a cancer of unmet clinical needs with dismal survival
statics. The PDAC TME encompasses specific hallmarks such as hypoxia that impair the
efficacy of radiotherapy treatment. The use of radiotherapy for PDAC is thought to be still
evolving, with novel treatments such as MR-guided radiotherapy emerging for more specific
tumour targeting. However, for MR-guided radiotherapy, the presence of static magnetic
fields (SMF) in combination with radiation is understudied and not fully understood. Reliable
biomimetic models of the TME to test new radiation delivery strategies and their biology
endpoints are required to more accurately predict in vivo responses of patients.
This work describes the development and validation of a hypoxic, novel polymer
(polyurethane) based highly macroporous scaffold system for long-term analysis of PDAC
radiation responses for the first time. Polyurethane (PU) scaffolds were fabricated via
thermally induced phase separation (TIPS) and surface modified with fibronectin for realistic
TME recapitulation. PDAC cell lines (PANC-1 and ASPC-1) were seed and cultured in PU
scaffolds in a hypoxic chamber (5%, 0-5%, and 1% oxygen) and were exposed to irradiation
(6 Gy). Live/dead and Caspase 3/7 analysis in line with a hypoxic biomarker (HIF-1a) post
treatment, revealed hypoxia associated radio-resistance. Furthermore, towards understanding
the biological response to MR-guided radiotherapy the presence of SMF (1.5 T) was tested in
combination with irradiation (6 Gy) to find radiation and SMF synergism. Furthermore, this
scaffold is applied to an in vitro skin biomimetic model to evaluate the versatility of such
models for not only the cancer field but for clinical and cosmetic living skin equivalent
testing. Overall, this thesis reports the use of a novel PU scaffold to investigate advanced
tissue engineering for radiation response studies and as a hybrid bi-layer model of the skin.