bims-orenst Biomed News
on Organs-on-chips and engineered stem cell models
Issue of 2021‒01‒24
thirteen papers selected by
Joram Mooiweer
University of Groningen

  1. Sci Rep. 2021 Jan 22. 11(1): 2080
      We report a method to generate a 3D motor neuron model with segregated and directed axonal outgrowth. iPSC-derived motor neurons are cultured in extracellular matrix gel in a microfluidic platform. Neurons extend their axons into an adjacent layer of gel, whereas dendrites and soma remain predominantly in the somal compartment, as verified by immunofluorescent staining. Axonal outgrowth could be precisely quantified and was shown to respond to the chemotherapeutic drug vincristine in a highly reproducible dose-dependent manner. The model was shown susceptible to excitotoxicity upon exposure with excess glutamate and showed formation of stress granules upon excess glutamate or sodium arsenite exposure, mimicking processes common in motor neuron diseases. Importantly, outgrowing axons could be attracted and repelled through a gradient of axonal guidance cues, such as semaphorins. The platform comprises 40 chips arranged underneath a microtiter plate providing both throughput and compatibility to standard laboratory equipment. The model will thus prove ideal for studying axonal biology and disease, drug discovery and regenerative medicine.
  2. ACS Biomater Sci Eng. 2020 Aug 10. 6(8): 4644-4652
      Intra-amniotic infection is a common cause of preterm birth that can lead to adverse neonatal outcomes. Despite the basic and clinical significance, the study in normal and diseased human amnion is highly challenging due to the limited use of human primary tissues and the distinct divergence between animal models and human. Here, we established a microengineered hiPSC-derived amnion tissue model on a chip to investigate the inflammatory responses of amnion tissues to bacterial exposure. The microdevice consisted of two parallel channels with a middle matrix channel, creating a permissive microenvironment for amnion differentiation. Dissociated hiPSCs efficiently self-organized into cell cavity and finally differentiated into a polarized squamous amniotic epithelium on the chip under perfused 3D culture. When exposed to E. coli, amnion tissue exhibited significant functional impairments compared to the control, including induced cell apoptosis, disrupted cell junction integrity, and increased inflammatory factor secretion, recapitulating a series of characteristic clinical signs of intra-amniotic infection at an early stage. Together, this amnion-on-a-chip model provides a promising platform to investigate intrauterine inflammation in early gestation, indicating its potential applications in human embryology and reproductive medicine.
    Keywords:  amnion-on-a-chip; amniotic tissue; human induced pluripotent stem cells; intrauterine inflammation; organ-on-a-chip
  3. Micromachines (Basel). 2021 Jan 16. pii: E90. [Epub ahead of print]12(1):
      We previously reported a new approach for micromanipulation and encapsulation of human stem cells using a droplet-based microfluidic device. This approach demonstrated the possibility of encapsulating and culturing difficult-to-preserve primary human hematopoietic stem cells using an engineered double-layered bead composed by an inner layer of alginate and an outer layer of Puramatrix. We also demonstrated the maintenance and expansion of Multiple Myeloma cells in this construction. Here, the presented microfluidic technique is applied to construct a 3D biomimetic model to recapitulate the human hematopoietic stem cell niche using double-layered hydrogel beads cultured in 10% FBS culture medium. In this model, the long-term maintenance of the number of cells and expansion of hHSCS encapsulated in the proposed structures was observed. Additionally, a phenotypic characterization of the human hematopoietic stem cells generated in the presented biomimetic model was performed in order to assess their long-term stemness maintenance. Results indicate that the ex vivo cultured human CD34+ cells from bone marrow were viable, maintained, and expanded over a time span of eight weeks. This novel long-term stem cell culture methodology could represent a novel breakthrough to improve Hematopoietic Progenitor cell Transplant (HPT) as well as a novel tool for further study of the biochemical and biophysical factors influencing stem cell behavior. This technology opens a myriad of new applications as a universal stem cell niche model potentially able to expand other types of cells.
    Keywords:  Hematopoietic stem cell; Microdroplets; Microfluidics; Stem cell culture
  4. Small. 2021 Jan 22. e2006091
      Formation of 3D networks is a crucial process for endothelial cells during development of primary blood vessels under both normal and pathological conditions. In order to investigate effects of oxygen microenvironment and matrix composition on the 3D network formation, an upside-down microfluidic cell culture device capable of generating oxygen gradients is developed in this paper. In cell experiments, network formation of human umbilical vein endothelial cells (HUVECs) within fibrinogen-based hydrogels with different concentrations of hyaluronic acid (HA) is systematically studied. In addition, five different oxygen microenvironments (uniform normoxia, 5%, and 1% O2 ; oxygen gradients under normoxia and 5% O2 ) are also applied for the cell culture. The generated oxygen gradients are characterized based on fluorescence lifetime measurements. The experimental results show increased 3D cell network length when the cells are cultured under the oxygen gradients within the hydrogels with the HA addition suggesting their roles in promoting network formation. Furthermore, the formed networks tend to align along the direction of the oxygen gradients indicating the presence of gradient-driven cellular response. The results demonstrate that the developed upside-down microfluidic device can provide an advanced platform to investigate 3D cell culture under the controlled oxygen microenvironments for various biomedical studies in vitro.
    Keywords:  endothelial cells; hydrogels; microfluidics; oxygen gradients; oxygen microenvironments
  5. Crit Rev Food Sci Nutr. 2021 Jan 22. 1-17
      Microfluidic intestine-on-a-chip enables novel means of emulating human intestinal pathophysiology in vitro, which can potentially reduce animal testing and substitute simple 2D culture system. Though a great deal of work has been done in the development of microfluidic platforms for intestinal disease modeling and drug screening, potential investigation of the effect of bioactive food compounds on intestinal inflammation remains largely unexplored. In this review, different biomaterials and chip designs have been explored in the fabrication of intestine-on-a-chip. Other key parameters must be carefully controlled and selected, including shear stress, cell type and cell co-culture spatial configuration, etc. Appropriate techniques to quantify the barrier integrity including trans-epithelial electric resistance, specific tight junction markers and permeability measurements should be standardized and compared with in vivo data. Integration of the gut microbiome and the provision of intestinal-specific environment are the key parameters to realize the in vivo intestinal model simulation and accelerate the screening efficiency of bioactive food compounds.
    Keywords:  Microfluidics; anti-inflammation; barrier integrity; foodborne nanoparticles; intestinal models; tissue engineering
  6. Biomaterials. 2021 Jan 08. pii: S0142-9612(21)00019-3. [Epub ahead of print]269 120668
      Generating microliver tissues to recapitulate hepatic function is of increasing importance in tissue engineering and drug screening. But the limited availability of primary hepatocytes and the marked loss of phenotype hinders their application. Human induced hepatocytes (hiHeps) generated by direct reprogramming can address the shortage of primary hepatocytes to make personalized drug prediction possible. Here, we simplify preparation of reprogramming reagents by expressing six transcriptional factors (HNF4A, FOXA2, FOXA3, ATF5, PROX1, and HNF1) from two lentiviral vectors, each expressing three factors. Transducing human fetal and adult fibroblasts with low vector dosage generated human induced hepatocyte-like cells (hiHeps) displaying characteristics of mature hepatocytes and capable of drug metabolism. To mimic the physiologic liver microenvironment and improve hepatocyte function, we prepared 3D scaffold-free microliver spheroids using hiHeps and human liver nonparenchymal cells through self-assembly without exogenous scaffolds. We then introduced the microliver spheroids into a two-organ microfluidic system to examine interactions between hepatocytes and tumor cells. The hiHeps-derived spheroids metabolized the prodrug capecitabine into the active metabolite 5-fluorouracil and induced toxicity in downstream tumor spheroids. Our results demonstrate that hiHeps can be used to make microliver spheroids and combined with a microfluidic system for drug evaluation. Our work could make it possible to use patient-specific hepatocyte-like cells to predict drug efficacy and side effects in various organs from the same patient.
    Keywords:  Direct reprogramming; Drug metabolism; Drug testing; Induced hepatocytes; Liver spheroid; Microfluidics; Organ-on-a-chip
  7. ACS Biomater Sci Eng. 2020 Jun 08. 6(6): 3649-3663
      Recent studies have suggested that microenvironmental stimuli play a significant role in regulating cellular proliferation and migration, as well as in modulating self-renewal and differentiation processes of mammary cells with stem cell (SCs) properties. Recent advances in micro/nanotechnology and biomaterial synthesis/engineering currently enable the fabrication of innovative tissue culture platforms suitable for maintenance and differentiation of SCs in vitro. Here, we report the design and fabrication of an open microfluidic device (OMD) integrating removable poly(ε-caprolactone) (PCL) based electrospun scaffolds, and we demonstrate that the OMD allows investigation of the behavior of human cells during in vitro culture in real time. Electrospun scaffolds with modified surface topography and chemistry can influence attachment, proliferation, and differentiation of mammary SCs and epigenetic mechanisms that maintain luminal cell identity as a function of specific morphological or biochemical cues imparted by tailor-made fiber post-treatments. Meanwhile, the OMD architecture allows control of cell seeding and culture conditions to collect more accurate and informative in vitro assays. In perspective, integrated systems could be tailor-made to mimic specific physiological conditions of the local microenvironment and then analyze the response from screening specific drugs for more effective diagnostics, long-term prognostics, and disease intervention in personalized medicine.
    Keywords:  electrospun scaffolds; mammary luminal cells; polydimethylsiloxane; preclinical screening; surface treatments
  8. ACS Biomater Sci Eng. 2020 Sep 14. 6(9): 5326-5336
      Fabrication of a 3D in vitro model that mimics the artery takes an important role in understanding pathological cell behaviors and mechanisms of vascular diseases by proposing an advanced model that can recapitulate a native vessel condition in a controlled manner. Because a model geometry and the structure of cells are significant for the recapitulation of the hemodynamics of arterial and cell functions, it is necessary to mimic geometries and to induce the proper morphology and orientation of the cells when fabricating a model. In this study, smooth muscle cells (SMCs) and endothelial cells (ECs), which were the main elements in the arterial wall, were cocultured in a multichannel device connected with polydimethylsiloxane (PDMS) fluidic chamber modules to parallelly fabricate a pefusable 3D in vitro human artery-mimicking multichannel system. In the coculture model, a circular PDMS channel with a wrinkled-surface guided directionality and contractile morphology to SMCs, and media perfusion induced directionality to a confluent EC layer as in vivo. Protein markers of cells and synthesized extracellular matrices were demonstrated. Because multichannels were connected to a microfluidic module in a device, it was possible to easily control the microenvironmental conditions and to fabricate coculture models in parallel with a single flow system. Coculture models that can be tuned in designs such as diameter, wall shear stress, and geometry of artery disease were constructed by 3D-printed molds to recapitulate various cellular microenvironments and to model vessels effectively. Finally, the effect of wall shear stress on cells was compared using a device with four different degrees of stenosis channels and investigated in parallel.
    Keywords:  3D in vitro coculture model; 3D-printed mold; endothelial cells; microfluidic module; smooth muscle cells; wrinkled structure
  9. ACS Biomater Sci Eng. 2020 Apr 13. 6(4): 2469-2477
      Liver fibrosis is a critical liver disease which can lead to liver cirrhosis, cancer, and liver failure. Among various etiological factors, activated stellate cells are a major factor that can induce liver fibrosis. Several studies have presented in vitro models to identify drugs for liver fibrosis; however, there are still limitations in terms of the 2D culture conditions, random co-culture of liver cells, and lack of extracellular matrix components. Therefore, a 3D liver fibrosis-on-a-chip was developed with three liver cell types (hepatocytes, activated stellate cells, and endothelial cells) using a novel cell-printing technique with gelatin bioinks, which were used to deliver each nonparenchymal liver cell type as a multilayer construct. Liver fibrosis-specific gene expression, collagen accumulation, cell apoptosis, and reduced liver functions caused by activated stellate cells were also evaluated. Furthermore, previously reported chemicals were added to the 3D liver fibrosis-on-a-chip to examine the downregulation of activated hepatic stellate cells. In conclusion, the developed 3D liver fibrosis-on-a-chip could be used as a potential in vitro model in the research field.
    Keywords:  3D liver fibrosis-on-a-chip; cell delivery; cell-printing technology; gelatin bioink; liver
  10. Microsyst Nanoeng. 2021 ;7 4
      The vascular network of the circulatory system plays a vital role in maintaining homeostasis in the human body. In this paper, a novel modular microfluidic system with a vertical two-layered configuration is developed to generate large-scale perfused microvascular networks in vitro. The two-layer polydimethylsiloxane (PDMS) configuration allows the tissue chambers and medium channels not only to be designed and fabricated independently but also to be aligned and bonded accordingly. This method can produce a modular microfluidic system that has high flexibility and scalability to design an integrated platform with multiple perfused vascularized tissues with high densities. The medium channel was designed with a rhombic shape and fabricated to be semiclosed to form a capillary burst valve in the vertical direction, serving as the interface between the medium channels and tissue chambers. Angiogenesis and anastomosis at the vertical interface were successfully achieved by using different combinations of tissue chambers and medium channels. Various large-scale microvascular networks were generated and quantified in terms of vessel length and density. Minimal leakage of the perfused 70-kDa FITC-dextran confirmed the lumenization of the microvascular networks and the formation of tight vertical interconnections between the microvascular networks and medium channels in different structural layers. This platform enables the culturing of interconnected, large-scale perfused vascularized tissue networks with high density and scalability for a wide range of multiorgan-on-a-chip applications, including basic biological studies and drug screening.
    Keywords:  Engineering; Microfluidics
  11. ACS Biomater Sci Eng. 2020 May 11. 6(5): 3081-3090
      Airborne particulate matters have posed significant risk to human health worldwide. Fine particulate matters (PM2.5, aerodynamic diameter <2.5 μm) are associated with increased morbidity and mortality attributed to pulmonary diseases. An advanced in vitro model would benefit the assessment of PM2.5 induced pulmonary injuries and drug development. In this work, we present a PM2.5 exposure model to evaluate the pulmonary risk of fine particulate matter exposure in an organotypic manner with the help of 3D human lung-on-a-chip. By compartmentalized co-culturing of human endothelial cells, epithelial cells, and extra cellular matrix, our lung-on-a-chip recapitulated the structural features of the alveolar-blood barrier, which is pivotal for exogenous hazard toxicity evaluation. PM2.5 was applied to the channel lined with lung epithelial cells to model the pulmonary exposure of fine particulate matter. The results indicated acute high dose PM2.5 exposure would lead to various malfunctions of the alveolar-capillary barrier, including adheren junction disruption, increased ROS generation, apoptosis, inflammatory biofactor expression in epithelial cells and endothelial cells, elevated permeability, and monocyte attachments. Collectively, our lung-on-a-chip model provides a simple platform to investigate the complex responses after PM2.5 exposure in a physiologically relevant level, which could be of great potential in environmental risk assessment and therapeutic treatment development.
    Keywords:  PM2.5; lung-on-a-chip; microfluidics; toxicity
  12. Cells. 2021 Jan 05. pii: E74. [Epub ahead of print]10(1):
      Human induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs) and pericytes provide a powerful tool for cardiovascular disease modelling, personalized drug testing, translational medicine, and tissue engineering. Here, we report a novel differentiation protocol that results in the fast and efficient production of ECs and pericytes from keratinocyte-derived hiPSCs. We found that the implementation of a 3D embryoid body (EB) stage significantly improves the differentiation efficiency. Compared with the monolayer-based technique, our protocol yields a distinct EC population with higher levels of EC marker expression such as CD31 and vascular endothelial cadherin (VE-cadherin). Furthermore, the EB-based protocol allows the generation of functional EC and pericyte populations that can promote blood vessel-like structure formation upon co-culturing. Moreover, we demonstrate that the EB-based ECs and pericytes can be successfully used in a microfluidic chip model, forming a stable 3D microvascular network. Overall, the described protocol can be used to efficiently differentiate both ECs and pericytes with distinct and high marker expression from keratinocyte-derived hiPSCs, providing a potent source material for future cardiovascular disease studies.
    Keywords:  hiPSC-derived endothelial cells; hiPSC-derived pericytes; human pluripotent stem cells; self-assembled microvascular network; vasculature-on-a-chip
  13. ACS Biomater Sci Eng. 2020 Sep 14. 6(9): 5040-5050
      Targeted drug delivery remains attractive but challenging for cancer therapy. Cell-mediated drug delivery has emerged as a promising strategy to improve targeted drug delivery to tumors due to the intrinsic ability of certain types of cells (e.g., macrophage) to pass through physiological barriers and specifically home to tumors. To fundamentally understand how macrophage-based drug carriers transport and interact with the tumor microenvironment, we developed a tumor-microenvironment-on-a-chip (TMOC) model that enables the coculture of tumor spheroids and macrophages in a three-dimensional (3D) gel matrix. By introducing drug-loaded macrophages, the TMOC model allows real-time observation of macrophage migration toward the tumor, infiltration into tumor spheroids, and subsequent response of tumor to drugs. Our results demonstrated the superior capability of macrophages migrating toward the tumor and infiltrate tumor spheroids. Drug loading in macrophages had minimum effect on their cell viability, and drug-carrying macrophages exhibited greater tumor cell cytotoxicity compared to their nanoparticle counterparts. Our work highlighted the great potential of macrophages as novel drug carriers for targeted drug delivery, and the TMOC model serves as a versatile platform to enable quick evaluation of such cell-mediated drug delivery systems.
    Keywords:  drug delivery; macrophage carrier; microfluidics; nanoparticle; tumor microenvironment