Pre-clinical Xenograft Tumor models coupled with immunohistochemistry (IHC) and quantitative image analysis is an established approach within many Oncology focused Pharmaceutical R&D programs to investigate factors involved in malignant transformation, invasion and metastasis, as well as to examine response to therapy. However, achieving robust, detailed and consistent results from study to study depends on a number of factors including standardising the tissue collection and histology/IHC procedures through to the choice of image analysis software utilised.
Most drug evaluation studies will evaluate a biomarker parameter associated with a particular target mechanism such as proliferation, angiogenesis, apoptosis or changes in expression of a specific intercellular protein. Key to the evaluation of such parameters, highlighted for example using an IHC approach, is first defining the appropriate tissue region of interest (ROI) within a section for analysis. The cellular content and distribution within Xenografts is, by nature, highly heterogeneous. ROI selection therefore usually involves separating necrotic regions from the viable regions, which can be difficult to perform manually, leading to a dilution in quality of the ROI chosen for quantitative image analysis.
This problem has led certain image analysis software design companies, such as Definiens (www.definiens.com), to develop specific algorithms that are capable of carrying out automated detection of viable tissue within Xenograft samples (see images below). Furthermore, Definiens Tissue Studio software can not only detect viable areas but also analyse whole tissue sections which increases the robustness of the analysis compared to analysis carried out on smaller focussed ROI’s within a section.
The next step involves defining the cellular analysis to be performed, be it cytoplasmic, nuclear or membrane associated staining. Popular Xenograft read outs include Ki67 positive stained nuclear cell count, CD31/34 stained micro vessel density, area of specific biomarker cellular staining or the mean intensity of staining across the ROI. Again, utilising software such as Tissue Studio that delivers true cell by cell analysis will increase the robustness of the final data interpretation and build confidence in the Go/No Go decisions made on the study outcome. For more information see our Xenograft Image Analysis page
If you are interested in outsourcing such work, OracleBio offers a full tissue processing, histology/IHC, digital slide scanning and quantitative digital image analysis services utilising Definiens Tissue Studio software. Please contact us at info@oraclebio.com for more details.