Abstract 305: Bioinspired synthetic hydrogel in pancreatic cancer organoid matrix modeling
Authors: Hossan Md Shahadat , Stram Austin , Lin Ethan Samuel , McIlwain Sean , Lebakken Connie , Richards William , Kratz Jeremy D. 
Published: March 2024

Abstract
Background: Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer mortality with a primary hallmark, including dense collagen matrix in the desmoplastic stroma. Organoid technologies often rely on commercially available EHS mouse sarcoma matrix materials, and it remains uncertain how batch-to-batch variability of this matrix impacts the consistency of cancer signaling. Here, we present a novel photo-activated hydrogel tuned to the properties of the desmoplastic stroma in PDAC organoid cultures.
Method: We designed multiple synthetic hydrogel materials with tunable mechanical properties, including SP-139 (Stem Pharm, Inc), a polyethylene glycol-based hydrogel functionalized with norbornene and formed with both degradable and non-degradable crosslinking peptides and a cell adhesion peptide (CRGDS). We used rheometry to measure the elastic modulus of the polymerized hydrogel after visible light photoactivation (395 nm) and expanded multiple cancer organoid cultures. RNAseq was performed from patient-derived xenografts to expanded organoids across matrix designs (Cultrex® v. SP-139) and analyzed by GSVA pathway analyses.
Result: We optimized the ratio of non-degradable v. degradable crosslinking peptide to support culture expansion and enzymatic digestion with dispase II (125 µg/mL) and collagenase II (1 mg/mL). Using rheometry, SP-139 at 75% v/v had increased elastic modulus versus Cultrex RGF BME matrix Type 2 at 100% v/v (4992±76.3 v. 68.4±5.6 Pa, p&lt;0.0001). Phenotypic growth was confirmed across serial passages (&gt;8) and a diversity of gastrointestinal cancer types (n=5). Baseline growth rates were identical over 48h between SP-139 (75% v/v) and Cultrex (50% v/v) (+13.4% v. +13.0, p=0.75). Growth remained consistent for SP-139 yet increased with Cultrex at interval of 48-96h (+12.9% SP-139 v +22.4% Cultrex, p&lt;0.005) and interval of 96-144h (+13.6% SP-139 v +24.0% Cultrex®, p&lt;0.0001). Therapeutic response was assessed using 3D CellTiter-Glo® using gemcitabine 100 µM (24h) with comparable inhibition of normalized cell viability in SP-139 v. Cultrex® (35.4±1.9% v. 52.3±6.5%, n.s.) and qualitatively with viability staining using calcein AM and Caspase 3/7FITC. RNAseq revealed Cultrex, when compared to SP-139, yielded down regulation of epoxygenase p450 pathways (padj&lt;0.012) and negative regulation of the p38 MAP kinase cascade (padj&lt;0.048).
Conclusions: Functionalized PEG-based synthetic hydrogel matrix materials can be tuned for physical properties to mimic cancer tissue microenvironments more accurately. SP-139, designed to mimic the desmoplastic stroma of the pancreatic cancer microenvironment, has favorable properties including controlled growth rates and compatibility with high content imaging by luminescence and fluorescence. RNAseq pathway analysis shows SP-139 maintains pathways of p450 and MAP kinase signaling of importance with therapeutic resistance.
Citation Format: Md Shahadat Hossan, Austin Stram, Ethan Samuel Lin, Sean McIlwain, Connie Lebakken, William Richards, Jeremy D. Kratz. Bioinspired synthetic hydrogel in pancreatic cancer organoid matrix modeling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 305.