Long-term Culture of Human Breast Cancer Specimens and Their Analysis Using Optical Projection Tomography

Abstract

Breast cancer is a leading cause of mortality in the Western world. It is well established that the spread of breast cancer, first locally and later distally, is a major factor in patient prognosis. Experimental systems of breast cancer rely on cell lines usually derived from primary tumours or pleural effusions. Two major obstacles hinder this research: (i) some known sub-types of breast cancers (notably poor prognosis luminal B tumours) are not represented within current line collections; (ii) the influence of the tumour microenvironment is not usually taken into account.We demonstrate a technique to culture primary breast cancer specimens of all sub-types. This is achieved by using three-dimensional (3D) culture system in which small pieces of tumour are embedded in soft rat collagen I cushions. Within 2-3 weeks, the tumour cells spread into the collagen and form various structures similar to those observed in human tumours1. Viable adipocytes, epithelial cells and fibroblasts within the original core were evident on histology. Malignant epithelial cells with squamoid morphology were demonstrated invading into the surrounding collagen. Nuclear pleomorphism was evident within these cells, along with mitotic figures and apoptotic bodies.We have employed Optical Projection Tomography (OPT), a 3D imaging technology, in order to quantify the extent of tumour spread in culture. We have used OPT to measure the bulk volume of the tumour culture, a parameter routinely measured during the neo-adjuvant treatment of breast cancer patients to assess response to drug therapy.Here, we present an opportunity to culture human breast tumours without sub-type bias and quantify the spread of those ex vivo. This method could be used in the future to quantify drug sensitivity in original tumour. This may provide a more predictive model than currently used cell lines.

Targeting of Rac GTPases blocks the spread of intact human breast cancer

“…We have recently succeeded in establishing a robust system for long-term culture of human breast cancer explants, successfully growing >90% tumours of all major sub-types [ 4 , 5 ]. In these cultures, primary breast cancer biopsies from invasive breast cancers are explanted into the centre of a type I collagen matrix.…”

“…Furthermore, there are serious doubts regarding the relevance of drug testing in established cancer cell lines and transfer of results to the clinic [ 3 ]. We have developed a three-dimensional culture system that allows maintenance of complex breast cancer specimens explanted ex vivo for up to four weeks after surgical resection in a supporting matrix of exogenous stromal type I collagen [ 4 , 5 ]. These ex vivo cultures offer a relatively rapid and quantitative avenue to explore mechanisms of tumour spread and evaluate new treatments.…”

The practicalities of using tissue slices as preclinical organotypic breast cancer models

“…While this type of model has potential in drug discovery programmes, further development is required to allow more precise quantification of end point measurements and allow for high throughput analysis which is not possible in the current experimental format. A recent complementary approach has described the use of 3D explant cultures using 1 mm 3 fragments of breast tumours generated from core biopsies taken from surgical resections and then embedded collagen I 5. Potentially this is a more flexible model as the authors cite a success rate of >95%.…”

Characterising the tumour morphological response to therapeutic intervention

“…The culture system is fully described (Leeper et al, 2011). Briefly, multiple core biopsies were harvested from consenting patients at the time of curative surgical resection for invasive breast cancer.…”