Glioblastoma multiforme (GBM) is the most common and malignant of all human primary brain cancers, in which drug treatment is still one of the most effective treatments. However, existing drug discovery and development methods rely on the use of conventional two-dimensional (2D) cell cultures, which have been proven to be poor representatives of native physiology. Here, we developed a novel three-dimensional (3D) brain cancer chip composed of photo-polymerizable poly(ethylene) glycol diacrylate (PEGDA) hydrogel for drug screening. This chip can be produced after a few seconds of photolithography and requires no silicon wafer, replica molding, and plasma bonding like microfluidic devices made of poly(dimethylsiloxane) (PDMS). We then cultured glioblastoma cells (U87), which formed 3D brain cancer tissues on the chip, and used the GBM chip to perform combinatorial treatment of Pitavastatin and Irinotecan. The results indicate that this chip is capable of high-throughput GBM cancer spheroids formation, multiple-simultaneous drug administration, and a massive parallel testing of drug response. Our approach is easily reproducible, and this chip has the potential to be a powerful platform in cases such as high-throughput drug screening and prolonged drug release. The chip is also commercially promising for other clinical applications, including 3D cell culture and micro-scale tissue engineering.

SummaryFimbrial filaments assembled by distinct chaperone pathways share a common mechanism of intersubunit interaction, as elucidated for colonization factor antigen I (CFA/I), archetype of enterotoxigenic Escherichia coli (ETEC) Class 5 fimbriae. We postulated that a highly conserved b-strand at the major subunit N-terminus represents the donor strand, analogous to interactions within Class I pili. We show here that CFA/I fimbriae utilize donor strand complementation to promote proper folding of and interactions between CFA/I subunits. We constructed a series of genetic variants of CfaE, the CFA/I adhesin, incorporating a C-terminal extension comprising a flexible linker and 10-19 of the N-terminal residues of CfaB, the major subunit. Variants with a donor strand complement (dsc) of Ն12 residues were recoverable from periplasmic fractions. Genetic disruption of the donor b-strand reduced CfaE recovery. A hexahistidine-tagged variant of dsc 19CfaE formed soluble monomers, folded into b-sheet conformation, displayed adhesion characteristic of CFA/I, and elicited antibodies that inhibited mannose-resistant haemagglutination by ETEC expressing CFA/I, CS4 and CS14 fimbriae. Immunoelectron microscopy indicated that CfaE was confined to the distal fimbrial tip. Our findings provide the basis to elucidate structure and function of this class of fimbrial adhesins and assess the feasibility of an adhesin-based vaccine.

Glioblastoma multiforme (GBM), an extremely invasive and high-grade (grade IV) glioma, is the most common and aggressive form of brain cancer. It has a poor prognosis, with a median overall survival of only 11 months in the general GBM population and 14.6 to 21 months in clinical trial participants with standard GBM therapies, including maximum safe craniotomy, adjuvant radiation, and chemotherapies. Therefore, new approaches for developing effective treatments, such as a tool for assessing tumor cell drug response before drug treatments are administered, are urgently needed to improve patient survival. To address this issue, we developed an improved brain cancer chip with a diffusion prevention mechanism that blocks drugs crossing from one channel to another. In the current study, we demonstrate that the chip has the ability to culture 3D spheroids from patient tumor specimen-derived GBM cells obtained from three GBM patients. Two clinical drugs used to treat GBM, temozolomide (TMZ) and bevacizumab (Avastin, BEV), were applied and a range of relative concentrations was generated by the microfluidic channels in the brain cancer chip. The results showed that TMZ works more effectively when used in combination with BEV compared to TMZ alone. We believe that this low-cost brain cancer chip could be further developed to generate optimal combination of chemotherapy drugs tailored to individual GBM patients.

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