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Hydrogels with dynamically tunable crosslinking are invaluable for directing stem cell fate and mimicking a stiffening matrix during fibrosis or tumor development. The increases in matrix stiffness during tissue development are often accompanied by the accumulation of extracellular matrices (e.g., collagen, hyaluronic acid (HA)), a phenomenon that has received little attention in the development of dynamic hydrogels. In this contribution, we present a gelatin-based cell-laden hydrogel system capable of being dynamically stiffened while accumulating HA, a key glycosaminoglycans (GAG) increasingly deposited by stromal cells during tumor progression. Central to this strategy is the synthesis of a dually-modified gelatin macromer – gelatin-norbornene-carbohydrazide (GelNB-CH), which is susceptible to both thiol-norbornene photopolymerization and hydrazone click chemistry. We demonstrate that the crosslinking density of cell-laden thiol-norbornene hydrogels can be dynamically tuned via simple incubation with aldehyde-bearing macromers (e.g., oxidized dextran (oDex) or oHA). The GelNB-CH hydrogel system is highly cytocompatible, as demonstrated by in situ encapsulation of pancreatic cancer cells (PCC) and cancer-associated fibroblasts (CAF). This unique dynamic stiffening scheme provides a platform to study tandem accumulation of HA and elevation in matrix stiffness in the pancreatic tumor microenvironment. Hydrogels permitting on-demand and secondary crosslinking are ideal for mimicking a stiffening tumor microenvironment (TME). However, none of the current dynamic hydrogels account for both stiffening and accumulation of hyaluronic acid (HA), a major extracellular matrix component increasingly deposited in tumor stromal tissues, including pancreatic ductal adenocarcinoma (PDAC). The current work addresses this gap by developing a dynamic hydrogel system capable of simultaneously increasing stiffness and HA accumulation. This is achieved by a new gelatin macromer permitting sequential thiol-norbornene (for primary network crosslinking) and hydrazone click chemistry (for bioinert or biomimetic stiffening with oxidized dextran (oDex) or oHA, respectively). The results of this study provide new insights into how dynamically changing physicochemical matrix properties guide cancer cell fate processes. [Display omitted] [ABSTRACT FROM AUTHOR]

TMPRSS2-ERG is the most common gene fusion in conventional prostatic adenocarcinoma (PCa), identified in about 40% to 70% of cases. Mucinous PCa and PCa with mucinous features are rare subtypes of prostate cancer, and ERG expression in these subtypes has not been well characterized in a large series. A search was made through the surgical pathology and expert consultation files of 2 major academic institutions for cases of mucinous PCa and PCa with mucinous features. The former were obtained from radical prostatectomy cases and the latter from radical prostatectomy cases, transurethral resection of the prostate, and prostate needle core biopsies. A tissue microarray composed of additional cases of mucinous PCa was also included in the study. Immunohistochemical stains for ERG were performed on all the cases. A total of 51 cases of mucinous PCa and PCa with mucinous features were identified. Twenty-five of 51 (47%) cases were positive for ERG expression, including 10/24 (42%) radical prostatectomy specimens, 7/14 (50%) biopsies, 2/4 (50%) transurethral resection of the prostate specimens, 6/9 (67%) from a tissue microarray. This is the largest study to date specifically characterizing ERG expression in mucinous PCa and PCa with mucinous features, with emphasis on comparison with adjacent conventional PCa. ERG is expressed in almost 50% of cases of mucinous PCa and PCa with mucinous features, similar to rates of expression in conventional PCa. This study strongly suggests that these rare subtypes of PCa are clonally related to conventional PCa. [ABSTRACT FROM AUTHOR]

Spatially and temporally varying patterns of morphogen signals during development drive cell fate specification at the proper location and time. However, current in vitro methods typically do not allow for precise, dynamic spatiotemporal control of morphogen signaling and are thus insufficient to readily study how morphogen dynamics affect cell behavior. Here, we show that optogenetic Wnt/β-catenin pathway activation can be controlled at user-defined intensities, temporal sequences, and spatial patterns using engineered illumination devices for optogenetic photostimulation and light activation at variable amplitudes (LAVA). By patterning human embryonic stem cell (hESC) cultures with varying light intensities, LAVA devices enabled dose-responsive control of optoWnt activation and Brachyury expression. Furthermore, time-varying and spatially localized patterns of light revealed tissue patterning that models the embryonic presentation of Wnt signals in vitro. LAVA devices thus provide a low-cost, user-friendly method for high-throughput and spatiotemporal optogenetic control of cell signaling for applications in developmental and cell biology. • Design of illumination devices for optogenetic photostimulation of multiwell plates • Spatiotemporal control of canonical Wnt signaling in human embryonic stem cells • Dose-dependent optogenetic Wnt activation • Spatial light patterns model embryonic presentation of Wnt signals in vitro With optogenetics, protein-protein interactions and cell signaling can be controlled with light. To allow user-defined illumination patterns to be projected onto cell cultures, Repina et al. designed programmable photostimulation devices called LAVA devices and use them to optogenetically induce patterns of Wnt signaling in human embryonic stem cells. [ABSTRACT FROM AUTHOR]

Translation of human pluripotent stem cell (hPSC)-derived therapies to the clinic demands scalable, cost-effective methods for cell expansion. Culture media currently used for hPSC expansion rely on high concentrations and frequent supplementation of recombinant growth factors due to their short half-life at physiological temperatures. Here, we developed a biomaterial strategy using mineral-coated microparticles (MCMs) to sustain delivery of basic fibroblast growth factor (bFGF), a thermolabile protein critical for hPSC pluripotency and proliferation. We show that the MCMs stabilize bFGF against thermally induced activity loss and provide more efficient sustained release of active growth factor compared to polymeric carriers commonly used for growth factor delivery. Using a statistically driven optimization approach called Design of Experiments, we generated a bFGF-loaded MCM formulation that supported hPSC expansion over 25 passages without the need for additional bFGF supplementation to the media, resulting in greater than 80% reduction in bFGF usage compared to standard approaches. This materials-based strategy to stabilize and sustain delivery of a thermolabile growth factor has broad potential to reduce costs associated with recombinant protein supplements in scalable biomanufacturing of emerging cell therapies. [ABSTRACT FROM AUTHOR]

[Display omitted] A microwave mediated synthesis of 2-aminooxazoles at 150 °C was developed, providing products with a variety of functional groups. The reaction takes 5 min and provides product with a simple precipitation at moderate to good yields without the need for recrystallization or flash chromatography. [ABSTRACT FROM AUTHOR]