Search for: All records

Model systems play a crucial role in biological and biomedical research, especially in the search for new treatments for challenging diseases such as glioblastoma multiforme (GBM). Organoids are 3D in vitro multicellular “middle-ground” model systems that recapitulate highly organized and heterogeneous in vivo organ-like systems, often through stem cell differentiation. Incorporating Matrigel™ or other exogenous extracellular matrices (ECMs) that do not naturally occur in the human body is common practice for organoid generation, ignoring the role of dynamic reciprocity between the cells and the ECM in tissue development. In this study, we describe a method to develop GBM organoids (GBOs) from cells without the need for exogenous ECM encapsulation and without cell culture media changes to produce stable tissue-like organoids that reach a 4 mm diameter in as little as 6 weeks. We observed a transition from homogenous cell populations to tissue-like structures when GBOs were larger than 1 mm in diameter. Transcriptomic analysis revealed that the greatest gene expression changes occurred when GBOs were 2 mm in diameter, with collagen VI as the most upregulated ECM-related gene. Quantitative and histochemical assessments further supported native ECM synthesis with significantly higher levels of glycosaminoglycans and collagen in GBOs compared with spheroids. To our knowledge, this study presents the first reproducibly large GBOs with natively produced ECMs. Organoids with natively synthesized ECMs promise to eliminate artifacts and variability from aged, homogeneic, or xenogeneic scaffolds and to provide insights for ECM-targeted drug development. 

Circulating tumor cells (CTCs) are some of the key culprits that cause cancer metastasis and metastasis-related deaths. These cells exist in a dynamic microenvironment where they experience fluid shear stress (FSS), and the CTCs that survive FSS are considered to be highly metastatic and stem cell-like. Biophysical stresses such as FSS are also known to cause the production of extracellular vesicles (EVs) that can facilitate cell-cell communication by carrying biomolecular cargos such as microRNAs. Here, we hypothesized that physiological FSS will impact the yield of EV production, and that these EVs will have biomolecules that transform the recipient cells. The EVs were isolated using direct flow filtration with and without FSS from the MDA-MB-231 cancer cell line, and the expression of key stemness-related genes and microRNAs was characterized. There was a significantly increased yield of EVs under FSS. These EVs also contained significantly increased levels of miR-21, which was previously implicated to promote metastatic progression and chemotherapeutic resistance. When these EVs from FSS were introduced to MCF-7 cancer cells, the recipient cells had a significant increase in their stem-like gene expression and CD44+/CD24− cancer stem cell-like subpopulation. There was also a correlated increased proliferation along with an increased ATP production. Together, these findings indicate that the presence of physiological FSS can directly influence the EVs’ production and their contents, and that the EV-mediated transfer of miR-21 can have an important role in FSS-existing contexts, such as in cancer metastasis. 

Gallium-based liquid metals are unique in their deformably, conductive nature and the oxide that grows natively on their surface. The oxide of galinstan, gallium–indium–tin, is composed of Ga/In/Sn oxides known for their semiconducting properties. The native galinstan oxide, however, is amorphous and improving electrical properties is understudied. In this work, annealing, a method for improving conductivity and hardness in metals and ceramics, is studied to control galinstan oxide crystallinity, modulus, and resistivity. It was found that while annealing increases crystallinity and grain size, local composition and thickness must also be considered when analyzing galinstan oxide electrical and mechanical properties.