Directed biomechanical compressive forces enhance fusion efficiency in model placental trophoblast cultures.

The syncytiotrophoblast is a multinucleated structure that arises from fusion of mononucleated cytotrophoblasts, to sheath the placental villi and regulate transport across the maternal-fetal interface. Here, we ask whether the dynamic mechanical forces that must arise during villous development might influence fusion, and explore this question using in vitro choriocarcinoma trophoblast models. We demonstrate that mechanical stress patterns arise around sites of localized fusion in cell monolayers, in patterns that match computational predictions of villous morphogenesis. We then externally apply these mechanical stress patterns to cell monolayers and demonstrate that equibiaxial compressive stresses (but not uniaxial or equibiaxial tensile stresses) enhance expression of the syndecan-1 and loss of E-cadherin as markers of fusion. These findings suggest that the mechanical stresses that contribute towards sculpting the placental villi may also impact fusion in the developing tissue. We then extend this concept towards 3D cultures and demonstrate that fusion can be enhanced by applying low isometric compressive stresses to spheroid models, even in the absence of an inducing agent. These results indicate that mechanical stimulation is a potent activator of cellular fusion, suggesting novel avenues to improve experimental reproductive modelling, placental tissue engineering, and understanding disorders of pregnancy development.

Biomimetic sharkskin surfaces with antibacterial, cytocompatible, and drug delivery properties.

Fighting with the infection is one of the most challenging and costly burdens of the healthcare system. Several types of antibiotics and antibacterial agents have been designed and used in combating this dilemma. Nevertheless, the overuse of drugs and the difficulties of proper delivery have led to the development of drug-resistance in many species of bacteria which has reduced the efficacy of antibiotics. Furthermore, localized delivery of these drugs can be more effective in eliminating biomaterial surface-associated infection compared to systemic administration. This type of infection occurs mostly by the formation of a bacterial biofilm layer on the surface of the implantable biomaterial which is the interface between the biomaterial and the tissue. Sharkskin topography is known for its antibacterial properties due to its unique pattern. Herein, antibacterial properties and drug release potentials of sharkskin mimicked chitosan membranes are investigated with the aim of studying the impact of this topography in reducing bacterial biofilm formation on drug-loaded polymeric membranes. Ampicillin sodium salt and caffeic acid phenethyl ester (CAPE) loaded chitosan (CH) membranes were fabricated. Gram-positive Staphylococcus aureus bacteria strain is used in antibacterial experiments, and human dermal fibroblast (HDFa) and keratinocyte (HaCaT) cells were used as model cell lines in cytocompatibility tests. Drug release, bacterial biofilm growth, and swelling ratio test results show the superiority of sharkskin topography in controlling the rate of drug release as well as considerably reducing bacterial biofilm formation. Furthermore, it was established that 2.5 mg mL-1 Amp content along with 500 µM CAPE yield in maximum antibacterial effect while not having cytotoxic effects on mammalian cells. Fabricated sharkskin mimicked drug-loaded membrane, which utilizes the combination of antibacterial compounds and antibacterial surface topography, also acts as an effective carrier for high concentrations of drugs.