Effect of RGD content in poly(ethylene glycol)-crosslinked poly(methyl vinyl ether-alt-maleic acid) hydrogels on the expansion of ovarian cancer stem-like cells.

The extracellular matrix (ECM) affects cell behaviors, such as survival, proliferation, motility, invasion, and differentiation. The arginine-glycine-aspartic acid (RGD) sequence is present in several ECM proteins, such as fibronectin, collagen type I, fibrinogen, laminin, vitronectin, and osteopontin. It is very critical to develop ECM-like substrates with well-controlled features for the investigation of influence of RGD on the behavior of tumor cells. In this study, poly(ethylene glycol) (PEG)-crosslinked poly(methyl vinyl ether-alt-maleic acid) (P(MVE-alt-MA)) hydrogels (PEMM) with different RGD contents were synthesized, fully characterized, and established as in vitro culture platforms to investigate the effects of RGD content on cancer stem cell (CSC) enrichment. The morphology, proliferation, and viability of SK-OV-3 ovarian cancer cells cultured on hydrogels with different RGD contents, the expression of CSC markers and malignant signaling pathway-related genes, and drug resistance were systematically evaluated. The cell aggregates formed on the hydrogel surface with a lower RGD content acquired certain CSC-like properties, thus drug resistance was enhanced. In contrast, the drug sensitivity of cells on the higher RGD content surface increased because of less CSC-like properties. However, the presence of RGD in the stiff hydrogels (PEMM2) had less effect on the stemness expression than did its presence in the soft hydrogels (PEMM1). The results suggest that RGD content and matrix stiffness can lead to synergetic effects on the expression of cancer cell stemness and the epithelial-mesenchymal transition (EMT), interleukin-6 (IL-6), and Wnt pathways.

Expansion of Ovarian Cancer Stem-like Cells in Poly(ethylene glycol)-Cross-Linked Poly(methyl vinyl ether-alt-maleic acid) and Alginate Double-Network Hydrogels.

A better understanding of cancer stem cells (CSCs) is essential for research on cancer therapy and drug resistance. Currently, increasingly more investigations are focused on obtaining CSCs to study the mechanism of their enhanced malignancy. In this work, three kinds of double-network hydrogels (PEMM/alginate), consisting of poly(ethylene glycol) (PEG) covalently cross-linked poly(methyl vinyl ether-alt-maleic acid) (P(MVE-alt-MA)) (network 1, denoted as PEMM) and Sr2+ (or Ca2+, Fe3+) ionically cross-linked alginates (network 2, denoted as SrAlg, CaAlg, or FeAlg), were prepared. The stiffness, morphology, and components of the PEMM/alginate hydrogels were systematically investigated to understand their effects on CSC enrichment. Only the PEMM/FeAlg hydrogels could support the long-term growth, proliferation, and spheroid formation of SK-OV-3 cells. The expression of CSC-related markers was evaluated with the levels of protein and gene at different stages. The cell spheroids cultured in the PEMM/FeAlg hydrogels acquired certain CSC-like properties, thus drug resistance was enhanced, especially in the PEMM-1/FeAlg hydrogel. In vivo tumorigenicity experiments also confirmed the presence of more CSCs in the PEMM-1/FeAlg hydrogel. The results suggest that matrix stiffness, morphology, and cations act synergistically on the regulation of the epithelial-mesenchymal transition (EMT), interleukin-6 (IL-6), and Wnt pathways, affecting the invasiveness of ovarian cancer and the conversion of the non-CSCs into CSCs. The PEMM-1/FeAlg hydrogel with lower elastic modulus, a more macroporous morphology, and higher swelling rate can significantly enhance the stemness, malignancy, and tumorigenicity of SK-OV-3 cells.

Crosslinked Dextran Gel Microspheres with Computed Tomography Angiography and Drug Release Function.

For computed tomography (CT) angiography and drug release application, a kind of novel dextran hydrogel microspheres were prepared. ß-cyclodextrin (ß-CD) grafted poly(methyl vinyl ether-altmaleic acid) (PMVE-alt-MA-g-ß-CD) and succinic acid modified dextran (Dex-SA) were first prepared, and then PMVE-alt-MA-g-ß-CD was further used as the cross-linking agent to cross link Dex-SA for the formation of dextran hydrogel microspheres by using an inverse suspension polymerization method for the potential interventional embolization. The average diameter of the dextran hydrogel microspheres was 35 µm with 90% ranging from 20 µm to 50 µm. The obtained microspheres showed a rather high swelling rate and loading capacity of drug doxorubicin hydrochloride with content of 9.2 wt%. The results of in vitro experiments showed that about 35.5% of the total amount of the encapsulated doxorubicin hydrochloride can be released after 4 h at 37 °C. The microspheres had a good mechanical stiffness with Young's modulus of about 20.0 kPa. Iodine molecules (I2) can be incorporated within the cavity of grafted cyclodextrin only through simply soaking in I2 aqueous solution, and these I2-loaded microspheres can preliminarily realize the function of CT angiography. This kind of dextran hydrogel microspheres with good biocompatibility would be a promising embolization material.

Self-healing pH-sensitive poly[(methyl vinyl ether)-alt-(maleic acid)]-based supramolecular hydrogels formed by inclusion complexation between cyclodextrin and adamantane.

Self-healing materials are of interest for drug delivery, cell and gene therapy, tissue engineering, and other biomedical applications. In this work, on the base of biocompatible polymer poly(methyl vinyl ether-alt-maleic acid) (P(MVE-alt-MA)), host polymer ß-cyclodextrin-grafted P(MVE-alt-MA) (P(MVE-alt-MA)-g-ß-CD) and guest polymer adamantane-grafted P(MVE-alt-MA) (P(MVE-alt-MA)-g-Ad) were first prepared. Then through taking advantage of the traditional host-guest interaction of ß-cyclodextrin and adamantane, a novel self-healing pH-sensitive physical P(MVE-alt-MA)-g-ß-CD/P(MVE-alt-MA)-g-Ad supramolecular hydrogels were obtained after simply mixing the aqueous solution of host polymer and guest polymer. This kind of supramolecular hydrogels not only possess pH-sensitivity, but also possess the ability to repair themselves after being damaged.

Poly(dopamine)-inspired surface functionalization of polypropylene tissue mesh for prevention of intra-peritoneal adhesion formation.

Polypropylene (PP), as one of the most common prosthetic materials, has been widely used in intra-peritoneal repair. However, its adhesion to viscera has severely limited its application. Therefore it is critical to improve the PP surface with an anti-adhesion property. In this work, based on dopamine-inspired chemistry, virgin PP (V-PP) mesh was first pretreated with O2 plasma, subsequently dipped in dopamine aqueous solution for 24 h, and then chitosan (CS) was grafted onto it. Finally the anti-adhesion mesh (O-PP/PDA/CS) was obtained. The formation procedure of a PDA/CS ad-layer was characterized by water contact angle measurements, ATR-FTIR, SEM, and XPS. The results show that a PDA/CS ad-layer could be coated on the PP surface efficiently. NIH/3T3 cells were first cultured on O-PP/PDA/CS meshes to evaluate the availability of anti-adhesion and biocompatibility in vitro, and then the efficacy of the PDA/CS-coating as a barrier for reducing postsurgical adhesions was evaluated using a rat abdominal wall defect model. Compared with the V-PP group, NIH/3T3 cells exhibited higher viability in the O-PP/PDA/CS groups as evaluated by the CCK-8 method. In addition, NIH/3T3 cells grow into round-shapes on the O-PP/PDA/CS surface. This indicates that the modification strategy can facilely lead to excellent properties of anti-adhesion. In vivo tests further indicate that O-PP/PDA/CS meshes were effective in reducing adhesion formation.