The Balance Between Shear Flow and Extracellular Matrix in Ovarian Cancer-on-Chip.

Ovarian cancer is the most lethal gynecologic cancer in developed countries. In the tumor microenvironment, the extracellular matrix (ECM) and flow shear stress are key players in directing ovarian cancer cells invasion. Artificial ECM models based only on ECM proteins are used to build an ovarian tumor-on-chip to decipher the crosstalk between ECM and shear stress on the migratory behavior and cellular heterogeneity of ovarian tumor cells. This work shows that in the shear stress regime of the peritoneal cavity, the ECM plays a major role in driving individual or collective ovarian tumor cells migration. In the presence of basement membrane proteins, migration is more collective than on type I collagen regardless of shear stress. With increasing shear stress, individual cell migration is enhanced; while, no significant impact on collective migration is measured. This highlights the central position that ECM and flow shear stress should hold in in vitro ovarian cancer models to deepen understanding of cellular responses and improve development of ovarian cancer therapeutic platforms. In this frame, adding flow provides significant improvement in biological relevance over the authors' previous work. Further steps for enhanced clinical relevance require not only multiple cell lines but also patient-derived cells and sera.

In Vitro Models of Ovarian Cancer: Bridging the Gap between Pathophysiology and Mechanistic Models.

Ovarian cancer (OC) is a disease of major concern with a survival rate of about 40% at five years. This is attributed to the lack of visible and reliable symptoms during the onset of the disease, which leads over 80% of patients to be diagnosed at advanced stages. This implies that metastatic activity has advanced to the peritoneal cavity. It is associated with both genetic and phenotypic heterogeneity, which considerably increase the risks of relapse and reduce the survival rate. To understand ovarian cancer pathophysiology and strengthen the ability for drug screening, further development of relevant in vitro models that recapitulate the complexity of OC microenvironment and dynamics of OC cell population is required. In this line, the recent advances of tridimensional (3D) cell culture and microfluidics have allowed the development of highly innovative models that could bridge the gap between pathophysiology and mechanistic models for clinical research. This review first describes the pathophysiology of OC before detailing the engineering strategies developed to recapitulate those main biological features.

Three-Dimensional Collagen Topology Shapes Cell Morphology, beyond Stiffness.

Cellular heterogeneity is associated with many physiological processes, including pathological ones, such as morphogenesis and tumorigenesis. The extracellular matrix (ECM) is a key player in the generation of cellular heterogeneity. Advances in our understanding rely on our ability to provide relevant in vitro models. This requires obtainment of the characteristics of the tissues that are essential for controlling cell fate. To do this, we must consider the diversity of tissues, the diversity of physiological contexts, and the constant remodeling of the ECM along these processes. To this aim, we have fabricated a library of ECM models for reproducing the scaffold of connective tissues and the basement membrane by using different biofabrication routes based on the electrospinning and drop casting of biopolymers from the ECM. Using a combination of electron microscopy, multiphoton imaging, and AFM nanoindentation, we show that we can vary independently protein composition, topology, and stiffness of ECM models. This in turns allows one to generate the in vivo complexity of the phenotypic landscape of ovarian cancer cells. We show that, while this phenotypic shift cannot be directly correlated with a unique ECM feature, the three-dimensional collagen fibril topology patterns cell shape, beyond protein composition and stiffness of the ECM. On this line, this work is a further step toward the development of ECM models recapitulating the constantly remodeled environment that cells face and thus provides new insights for cancer model engineering and drug testing.

Fabrication of aptamer modified TiO2 nanofibers for specific capture of circulating tumor cells.

Herein, we developed an inexpensive titanium dioxide (TiO2) nanofiber substrate for efficient and selective capture of circulating tumor cells (CTCs) from mimic patients' samples. The TiO2 nanofiber substrates were fabricated by electrospinning in combination with the calcination process. The surface of nanofiber substrates was modified with the anti-adhesion molecule, bovine serum albumin (BSA) and the nucleolin aptamer AS1411, wherein, aptamer AS1411 specifically binds to the nucleolin protein overexpressed on the membrane surface of cancer cells. The formed TiO2 nanofiber substrates exhibited high efficacy and specificity to capture nucleolin positive cells through synergistic topographic interactions. Using the rare number of cell capture experiments, the capture efficiency of up to 75 % was achieved on the surface of the nanofiber substrate for rare number target cells spiked in the white blood cells (WBCs) from 1 mL whole blood samples. In conclusion, this study highlighted the potential of the TiO2-BSA-biotin-AS1411 nanofiber substrate as a highly efficient platform to realize the selective and specific capture of rare CTCs in the clinical settings.

High-Efficiency Isolation and Rapid Identification of Heterogeneous Circulating Tumor Cells (CTCs) Using Dual-Antibody-Modified Fluorescent-Magnetic Nanoparticles.

Extreme rarity and inherent heterogeneity of circulating tumor cells (CTCs) result in a tremendous challenge for the CTC isolation from patient blood samples with high efficiency and purity. Current CTC isolation approaches mainly rely on the epithelial cell adhesion molecule (EpCAM), which may significantly reduce the ability to capture CTCs when the expression of EpCAM is lost or down-regulated in epithelial-mesenchymal transition. Here, a rapid and highly efficient method is developed to isolate and identify heterogeneous CTCs with high efficiency from patient blood samples using the fluorescent-magnetic nanoparticles (F-MNPs). A dual-antibody interface targeting EpCAM and N-cadherin is fabricated onto the F-MNPs to capture epithelial CTCs as well as mesenchymal CTCs from whole blood samples. The poly(carboxybetaine methacrylate) brushes of excellent antifouling properties are employed to decrease nonspecific cell adhesion. Moreover, the F-MNPs provide a prompt identification strategy for heterogeneous CTCs (F-MNPs+, Hoechst 33342+, and CD45-) that can directly identify CTCs in a gentle one-step processing within 1 h after isolation from patient blood samples. This has been demonstrated through artificial samples as well as patient samples in details.

Porphyrin-based metal-organic frameworks: protonation induced Q band absorption.

In this work, porphyrin-based MOF nanosheets were formulated. The as-developed Gd-TCPP MOF nanosheets could be protonated significantly in an acidic solution, which greatly enhanced the UV-vis absorption at 665 nm. Also, a significant structural reorganization occurred to achieve a nanowire structure. As the center of the porphyrin had a metal coordination atom, the Q band absorption had better stability due to their inability to be protonated. These results confirm that the UV-vis absorption of the MOFs can be regulated via porphyrin protonation, and the protonation of the nanosheets in the acidic solution can be avoided by adding a metal coordination atom to the porphyrin center. We also found that zinc ions had better coordination ability with the pyrrole nitrogen of the inner porphyrin core of Gd-TCPP MOF nanosheets. Finally, the protonation of MOFs was confirmed by the yield of singlet oxygen. Also, metallic oxide nanoparticles can be formed in situ and adsorbed on the Gd-TCPP MOF nanosheets. These results are useful for the preparation of metallic oxide nanoparticle-loaded nanomaterials. This work may open novel avenues for changing the UV-vis absorption of porphyrin-based nanomaterials.

Dual-antibody Modified PLGA Nanofibers for Specific Capture of Epithelial and Mesenchymal CTCs.

CTC detection has great potential to provide crucial clinical information for early cancer diagnosis, patient prognosis, personalized therapy, and cancer progress monitoring etc. It has been proved that the disease progress is associated with an increase in mesenchymal CTCs, while most mature techniques have been developed based on epithelial CTC detection. In present work, a dual-antibody nanointerface against EpCAM and N-Cadherin was developed to capture epithelial CTCs as well as mesenchymal CTCs from blood samples. A uniform poly-(lactic-co-glycolic acid) (PLGA) nanofiber substrate was fabricated by electrospinning to provide a platform for cell capture (i.e., MCF-7 and GIST882 cells), modified with BSA and dual antibodies. Our results showed the dual-antibody substrates exhibited an improved capture efficiency of target cells compared to the mono-antibody ones, revealing potential application of the dual-antibody PLGA nanofibers for efficient capture of epithelial and mesenchymal CTCs in clinic.