Monitoring cell endocytosis of liposomes by real-time electrical impedance spectroscopy

HER2-targeted, enzyme-activated liposomes show superior in vivo efficacy in an ovarian cancer model

Liposomes carrying chemotherapeutic drugs can accumulate passively in solid tumors at high levels. However, additional targeting of the liposomes towards e.g. receptors expressed on cancer cells may improve their interaction and therapeutic properties. In this study, we designed a liposomal delivery system, which utilizes the intrinsic characteristics of HER2-positive tumors to ensure efficient delivery of oxaliplatin to the cancer cells. On the liposome surface, trastuzumab, an antibody specific to the HER2 receptor, was shown to facilitate internalization by the cancer cells. A polyethylene glycol (PEG) layer on the liposome surface provides protection from mononuclear phagocyte system uptake. To optimize the interaction between liposomes and cancer cells, a protease-sensitive cleavable peptide linker was inserted at the base of each PEG. The PEG layer is then cleaved off by intra- and extracellular matrix metalloproteinases (MMPs) upon accumulation in the tumor. Our data demonstrate that the removal of PEG significantly destabilizes the liposomes and leads to substantial oxaliplatin release. The proposed beneficial effect of combining antibody-mediated internalization with MMP sensitivity was confirmed in a series of in vivo studies using ovarian cancer xenograft models. The results demonstrated that HER2-targeted MMP-sensitive liposomes have superior anticancer activity compared to non-targeted and non-cleavable liposomes.

APELLA: Open-Source, miniaturized All-in-One powered Lab-on-a-Disc platform

We present an unconventional approach to a common Lab-on-a-Disc (LoD) that combines a quadcopter propulsion system, a miniaturized 2.4 GHz Wi-Fi spy camera, 9.74 Watt Qi wireless power, and an Arduino into an open-source, miniaturized All-in-one powered lab-on-disc platform (APELLA). The quadcopter propulsion generates thrust to rotate (from 0.1 to 24.5 Hz) or shake the LoD device, while the spy camera enables a real-time (30 frames per second) and high definition (1280 × 720 pixels) visualization of microfluidic channels without requiring a bulky and heavy stroboscopic imaging setup. A mobile device can communicate with an Arduino microcontroller inside the APELLA through a Bluetooth interface for closed loop and sequential frequency control. In a proof-of-concept study, the APELLA achieved comparable mixing efficiency to a traditional spin stand and can capture rapid microfluidic events at low rotational frequencies (<5Hz). The APELLA is low-cost (c.a. 100 Euro), compact (15.6 × 15.6 × 10 cm³), lightweight (0.59 kg), portable (powered by a 5 V USB power bank), and energy efficient (uses < 6% power of the conventional system), making it ideal for field deployment, education, resource-limited labs.

Moving perfusion culture and live-cell imaging from lab to disc: proof of concept toxicity assay with AI-based image analysis

In vitro, cell-based assays are essential in diagnostics and drug development. There are ongoing efforts to establish new technologies that enable real-time detection of cell-drug interaction during culture under flow conditions. Our compact (10 × 10 × 8.5 cm) cell culture and microscope on disc (CMoD) platform aims to decrease the application barriers of existing lab-on-a-chip (LoC) approaches. For the first time in a centrifugal device, (i) cells were cultured for up to six days while a spindle motor facilitated culture medium perfusion, and (ii) an onboard microscope enabled live bright-field imaging of cells while the data wirelessly transmitted to a computer. The quantification of cells from the acquired images was done using artificial intelligence (AI) software. After optimization, the obtained cell viability data from the AI-based image analysis proved to correlate well with data collected from commonly used image analysis software. The CMoD was also suitable for conducting a proof-of-concept toxicity assay with HeLa cells under continuous flow. The half-maximal inhibitory time (IT50) for various concentrations of doxorubicin (DOX) in the case of HeLa cells in flow, was shown to be lower than the IT50 obtained from a static cytotoxicity assay, indicating a faster onset of cell death in flow. The CMoD proved to be easy to handle, enabled cell culture and monitoring without assistance, and is a promising tool for examining the dynamic processes of cells in real-time assays.

Modification of taxifolin particles with an enteric coating material promotes repair of acute liver injury in mice through modulation of inflammation and autophagy signaling pathway

PURPOSE

Taxifolin (TAX) is a flavanol compound with hepatoprotective effect, but its application is severely limited by its poor water solubility and low oral bioavailability. Therefore, it is important to urgently find a method to improve the oral bioavailability of TAX.

METHODS

In this study, hydroxypropyl methylcellulose acetate succinate modified taxifolin liposomes (HPMCAS-TAX-Lips) were prepared by a thin-film dispersion method, and a series of physicochemical properties of the liposomes were studied. The cumulative in vitro release rates of free TAX, taxifolin liposomes (TAX-Lips), and HPMCAS-TAX-Lips in the simulated gastrointestinal fluid were measured by in vitro release experiments, and the effect of HPMCAS-TAX-Lips on the human hepatoellular carcinomas (HepG2) cells was detected by MTT assay. Finally, the hepatoprotective mechanism of HPMCAS-TAX-Lips was explored through in vivo experiments.

RESULTS

The results showed that the particle size of HPMCAS-TAX-Lips was 100.44 ± 2.85 nm, the zeta potential was - 51.13 ± 0.57 mV, the PDI was 0.170 ± 0.088, and the EE was 87.9 ± 3.73%. The in vitro release results showed that the cumulative release rates of TAX-Lips and HPMCAS-TAX-Lips in simulated gastric fluid for 24 h were 92.60 ± 5.31% and 66.91 ± 1.20%, respectively. The cumulative release rates in simulated intestinal fluid for 24 h were 72.61 ± 4.38% and 53.94 ± 3.2%, respectively. The results of cytotoxicity experiments proved that HPMCAS-TAX-Lips had a significant inhibitory effect on HepG2 cells. In vivo experiments further showed that HPMCAS-TAX-Lips significantly improved the survival rate of lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver injury mice and exerted hepatoprotective effects by regulating the expression of autophagy proteins and inhibiting the activation of toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling pathway.

CONCLUSION

This study proved the significant hepatoprotective effect of HMPCAS-TAX-Lips and provided a new idea for the application of TAX.

Impedance-based Real-time Monitoring of Neural Stem Cell Differentiation

We present here the first impedance-based characterization of the differentiation process of two human mesencephalic fetal neural stem lines. The two dopaminergic neural stem cell lines used in this study, Lund human mesencephalic (LUHMES) and human ventral mesencephalic (hVM1 Bcl-X_L), have been developed for the study of Parkinsonian pathogenesis and its treatment using cell replacement therapy. We show that if only relying on impedance magnitude analysis, which is by far the most usual approach in, e.g., cytotoxicity evaluation and drug screening applications, one may not be able to distinguish whether the neural stem cells in a population are proliferating or differentiating. However, the presented results highlight that equivalent circuit analysis can provide detailed information on cellular behavior, e.g. simultaneous changes in cell morphology, cell-cell contacts, and cell adhesion during formation of neural projections, which are the fundamental behavioral differences between proliferating and differentiating neural stem cells. Moreover, our work also demonstrates the sensitivity of impedance-based monitoring with capability to provide information on changes in cellular behavior in relation to proliferation and differentiation. For both of the studied cell lines, in already two days (one day after induction of differentiation) equivalent circuit analysis was able to show distinction between proliferation and differentiation conditions, which is significantly earlier than by microscopic imaging. This study demonstrates the potential of impedance-based monitoring as a technique of choice in the study of stem cell behavior, laying the foundation for screening assays to characterize stem cell lines and testing the efficacy epigenetic control.