PDCOs are derived directly from clinical tissue biospecimens and therefore reflect the native tumor environment and provide valuable insight into both clonality and heterogeneity. However, primary prostate PDCO protocol development has been halted by low efficiency and logistic limitations. Prostate tissue is difficult to obtain and is largely regarded as a scarce clinical specimen. Additionally, low PDCO yields are often only enough for single analyte investigations of few parameters that limit comprehensive interrogation of individual patient specimens and do not allow high-throughput assessment. Furthermore, traditional tissue processing protocols including washing steps, material transfers between tubes, pipetting, and sectioning also associate with the loss of precious PDCO material.
Prostate PDCO workflow in the Stacks microfluidic platform
Our approach to adapt organoid analysis to an integrated microfluidic platform (known as Stacks) enables more efficient utilization of limited PDCO samples while simultaneously improving experimental throughput at the microscale. Furthermore, the integrated in-chip analytic features allow for enhanced assay sensitivity of PC-relevant biomarkers, which would otherwise be highly challenging to detect in more traditional methods like formalin fixation and paraffin embedding (FFPE). The technology in Stacks is based on open microfluidic principles that allow simple fluid exchanges and in-chip immunofluorescent labeling without the need for sample transfer. The thin layer of 3D hydrogel in Stacks wells (holding a total volume of 4.5 ul) permits direct mounting and fluorescent imaging without the need for preprocessing, FFPE or sectioning, which can result in sample loss of limited clinical material. Live cells can be easily recovered from the microwells and subjected to multi-analyte interrogation including transcriptomic, genomic, epigenomic, proteomic profiles, and in parallel, conditioned media can be harvested for multiplexed secreted factor analysis.
The data from our study provides foundational evidence to support the integrated analysis of PDCOs in Stacks. These data will pave the way for further studies investigating tumor biology and therapeutic strategies using PDCOs in Stacks. We see great potential for this approach and believe that it has the capacity to improve the efficiency and translation of PC research as well as directly impact the clinical care of patients. In particular, the incorporation of primary, multi-cellular biology and tumor heterogeneity (both inter-patient and intra-tumor) into these in vitro systems may lead to a more comprehensive understanding of tumor biology and support more translational advances in PC treatment over shorter time periods and at less expense. In addition, the high-throughput, in-chip capabilities of the system open the door for real-time analysis of patient tumors for selection of the most effective treatment, rapid drug cultures or evaluation of disease state, analogous to “n of 1 clinical trials”. We are therefore continuing to optimize this system for broad utilization amongst the research community and are exploring the opportunities for expanded contexts of use.
Written by: Erika Heninger, PhD, David Kosoff, MD, Nan Sethakorn MD, PhD and Joshua M. Lang, MD, University of Wisconsin Carbone Cancer Center, Department of Medicine, University of Wisonsin, Madison
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