On-Chip Construction of Liver Lobules with Self-Assembled Perfusable Hepatic Sinusoid Networks.

Although various liver chips have been developed using emerging organ-on-a-chip techniques, it remains an enormous challenge to replicate the liver lobules with self-assembled perfusable hepatic sinusoid networks. Herein we develop a lifelike bionic liver lobule chip (LLC), on which the perfusable hepatic sinusoid networks are achieved using a microflow-guided angiogenesis methodology; additionally, during and after self-assembly, oxygen concentration is regulated to mimic physiologically dissolved levels supplied by actual hepatic arterioles and venules. This liver lobule design thereby produces more bionic liver microstructures, higher metabolic abilities, and longer lasting hepatocyte function than other liver-on-a-chip techniques that are able to deliver. We found that the flow through the unique micropillar design in the cell coculture zone guides the radiating assembly of the hepatic sinusoid, the oxygen concentration affects the morphology of the sinusoid by proliferation, and the oxygen gradient plays a key role in prolonging hepatocyte function. The expected breadth of applications our LLC is suited to is demonstrated by means of preliminarily testing chronic and acute hepatotoxicity of drugs and replicating growth of tumors in situ. This work provides new insights into designing more extensive bionic vascularized liver chips, while achieving longer lasting ex-vivo hepatocyte function.

An iron oxide nanoparticle-based transdermal nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors.

Transdermal delivery is an attractive strategy for treating superficial tumors. However, the applications of existing transdermal systems have been limited by low transdermal efficiency and poor therapeutic outcomes. Here, we develop a transdermal nanoplatform (+)T-SiDs, based on superparamagnetic iron oxide core, surface-modified with cationic lipids, transdermal enhanced peptide TD, and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR), and loaded with doxorubicin. The (+)T-SiDs compositions enable MR/NIR dual-modal imaging guided synergistic chemo-photothermal therapy to superficial tumors treatment via transdermal delivery. The (+)T-SiDs exhibit good stability, efficient cellular uptake, pH/photothermal responsive drug release, and high photothermal conversion efficiency (47.45%). Importantly, the transdermal delivery of (+)T-SiDs is significantly enhanced by TD functionalization. In vivo MR/NIR imaging shows that the (+)T-SiDs exhibit high transdermal efficiency and specificity in localization to the tumor site. Moreover, in comparison with individual chemo- or photothermal therapies, the combination of chemo-photothermal therapy exhibits more efficient tumor inhibition effects. This work presents a new transdermal treatment nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors, with efficient tumor eradication and low systemic toxicity thus offering strong potential for clinical adoption. STATEMENT OF SIGNIFICANCE: Transdermal delivery is an attractive strategy for treating superficial tumors. However, a highly efficient transdermal nanoplatform remains to be developed. Herein, we designed a multifunctional transdermal nanoplatform for dual-modal imaging-guided chemo-photothermal therapy of superficial tumors, comprised of a super-paramagnetic iron oxide (SPIO) nanoparticle, which can act as an MRI contrast agent and photothermal agent; a transdermal enhanced peptide (TD) and cationic lipids, which can accelerate skin penetration; and a NIR dye (DiR) and doxorubicin (DOX), which can achieve a synergistic enhanced chemo-photothermal therapy with NIR imaging ability. The transdermal nanoplatform achieved efficient tumor eradication and low systemic toxicity, thus offering strong potential for clinical adoption.

On-chip analysis of magnetically labeled cells with integrated cell sorting and counting techniques.

In studies on cell therapies, cells often need to be magnetically labeled and then tracked using magnetic resonance imaging (MRI) techniques. To achieve good imaging performance on infused cells, the analysis of the sorted, labeled cells before infusion is necessary. Herein, we developed a microfluidic chip to quantitatively analyze magnetically labeled cells. The chip was equipped with a magnetophoresis-based cell sorting function and an impedance-based cell counting function. Using RAW264.7 macrophages, we confirmed the two functions of the chip, obtained the number and the magnetic loading distribution of the sorted, labeled cells, and ultimately demonstrated the broad applications of the chip in rapidly selecting a proper flow rate for the buffer solution in the cell sorting process, determining the total average magnetic loading of the labeled cells for the cell labeling process, and offering a necessary reference for the processing of the sorted cells for high performance in vivo imaging. This work provides an integrated lab-on-a-chip design for quantitatively analyzing magnetically labeled cells and thus can promote MRI-based cell-tracking studies.

On-Chip Sonoporation-Based Flow Cytometric Magnetic Labeling.

Tracing magnetically labeled cells with magnetic resonance imaging (MRI) is an emerging and promising approach to uncover in vivo behaviors of cells in cell therapy. Today, existing methods for the magnetic labeling of cells are cumbersome and time-consuming, which has greatly limited the progress of such studies on cell therapy. Thus, in this study, using the flow cytometric loading technology, we develop a sonoporation-based microfluidic chip (i.e., a microfluidic chip integrated with ultrasound; MCU), to achieve the safe, instant, convenient, and continuous magnetic labeling of cells. For the MCU we designed, a suitable group of operating conditions for safely and efficiently loading superparamagnetic iron oxide (SPIO) nanoparticles into DC2.4 cells was identified experimentally. Under the identified operating conditions, the DC2.4 cells could be labeled in approximately 2 min with high viability (94%) and a high labeling quantity of SPIO nanoparticles (19 pg of iron per cell). In addition, the proliferative functions of the cells were also well maintained after labeling. Furthermore, the in vivo imaging ability of the DC2.4 cells labeled using the MCU was verified by injecting the labeled cells into the leg muscle of the C57BL/6 mice. The results show that the excellent imaging outcome can be continuously achieved for 7 days at a density of 106 cells/mL. This work can provide insight for the design of magnetic cell labeling devices and promote the MRI-based study of cell therapies.

Large-scale high-density culture of hepatocytes in a liver microsystem with mimicked sinusoid blood flow.

In vitro engineering of liver tissue is a rapidly developing field for various biomedical applications. However, liver tissue culture is currently performed on only a small scale with a low density of hepatocytes. In this study, a simple design was introduced in a liver microsystem to enhance the transport of nutrients (e.g., oxygen and glucose) for the three-dimensional large-scale, high-density culture of hepatocytes. In this design, convection across the cell culture zone was generated to mimic sinusoid blood flow (SBF) based on the pressure difference between two fluids flowing in a countercurrent manner on either side of the cell culture zone. First, the distributions of living and dead cells in different culture subzones under various perfusion flow rates were observed, analysed, and compared. Then, the enhanced transport of nutrients was experimentally validated in relation to the viability of cells and theoretically explained by comparing the fluid velocity and oxygen concentration distribution in the cell culture zone in counterflow and coflow modes. Finally, the functions of the SBF-mimicked liver microsystem were assessed on the basis of specific metabolites, synthesized proteins, and bilirubin detoxification of hepatocytes, with collagen and alginate as extracellular matrices. Under this design, the density of hepatocytes cultured at the 3-mm-thickness scale reached ~7 × 107  cells/ml on Day 7, and the metabolism and detoxification functions of the cells worked well. In addition, a liver rope-like structure and sphere-like clusters of cells were observed. This work provides insight for the design of a bionic liver microsystem.