bims-orenst Biomed News
on Organs-on-chips and engineered stem cell models
Issue of 2022–01–16
five papers selected by
Joram Mooiweer, University of Groningen



  1. Commun Biol. 2022 Jan 13. 5(1): 52
      Disorders of the eye leading to visual impairment are a major issue that affects millions of people. On the other side ocular toxicities were described for e.g. molecularly targeted therapies in oncology and may hamper their development. Current ocular model systems feature a number of limitations affecting human-relevance and availability. To find new options for pharmacological treatment and assess mechanisms of toxicity, hence, novel complex model systems that are human-relevant and readily available are urgently required. Here, we report the development of a human immunocompetent Choroid-on-Chip (CoC), a human cell-based in vitro model of the choroid layer of the eye integrating melanocytes and microvascular endothelial cells, covered by a layer of retinal pigmented epithelial cells. Immunocompetence is achieved by perfusion of peripheral immune cells. We demonstrate controlled immune cell recruitment into the stromal compartments through a vascular monolayer and in vivo-like cytokine release profiles. To investigate applicability for both efficacy testing of immunosuppressive compounds as well as safety profiling of immunoactivating antibodies, we exposed the CoCs to cyclosporine and tested CD3 bispecific antibodies.
    DOI:  https://doi.org/10.1038/s42003-021-02977-3
  2. ACS Appl Bio Mater. 2020 Oct 19. 3(10): 6697-6707
      The lymphatic system is a complex organ system that is essential in regulating the development of host immune responses. Because of the complexity of the lymphatic system and the existence of few in vitro models that replicate human lymphatic vessels, there is a need for a primary cell-based lymphatic model that can provide a better understanding of the effects of flow parameters, therapeutics, and other stimuli on lymphatic vessel behavior. In this report, a fluidic device models the cyclical lymphatic flow under normal and disease conditions. The device utilizes a pumpless design, operating with gravitational forces to simulate normal conditions with a shear of 0.092 Pa (0.92 dyn/cm2) as well as disease conditions with an increased shear of (0.67 Pa, 6.7 dyn/cm2). The cyclical pumping present in lymphatic vessels is replicated by applying shear stress for a period of 10 s multiple times per minute. Primary human lymphatic endothelial cells (HLECs) cultured in the device for 10 days produce less interleukin 8 (IL-8), and tumor necrosis factor alpha (TNF-α) per cell than cells cultured under static conditions. The results are consistent with previously published in vivo measurements, indicating that the fluidic device mimics conditions for IL-8 and TNF-α expression well. Data obtained with the devices also indicate that primary HLECs proliferate faster under high-shear than under low-shear conditions.
    Keywords:  lymph nodes; lymphatic vessels; microfluidic; organ-chip; tissue-chip
    DOI:  https://doi.org/10.1021/acsabm.0c00609
  3. Lab Chip. 2022 Jan 12.
      Three-dimensional (3D) tissue culture is a powerful tool for understanding physiological events. However, 3D tissues still have limitations in their size, culture period, and maturity, which are caused by the lack of nutrients and oxygen supply through the vasculature. Here, we propose a new method for culturing a 3D tissue-a spheroid-directly on an 'on-chip vascular bed'. The method can be applied to any 3D tissue because the vascular bed is preformed, so that angiogenic factors from the tissue are not necessary to induce vasculature. The essential component of the assay system is the removable membrane that initially separates the 3D tissue culture well and the microchannel in which a uniform vascular bed is formed, and then allows the tissue to be settled directly onto the vascular bed following its removal. This in vitro system offers a new technique for evaluating the effects of vasculature on 3D tissues.
    DOI:  https://doi.org/10.1039/d1lc00751c
  4. Elife. 2022 Jan 11. pii: e72579. [Epub ahead of print]11
      Atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow (d-flow), while regions exposed to stable flow (s-flow) are protected. The proatherogenic and atheroprotective effects of d-flow and s-flow are mediated in part by the global changes in endothelial cell gene expression, which regulates endothelial dysfunction, inflammation, and atherosclerosis. Previously, we identified Kallikrein-Related Peptidase 10 (Klk10, a secreted serine protease) as a flow-sensitive gene in mouse arterial endothelial cells, but its role in endothelial biology and atherosclerosis was unknown. Here, we show that KLK10 is upregulated under s-flow conditions and downregulated under d-flow conditions using in vivo& mouse models and in vitro studies with cultured endothelial cells (ECs). Single-cell RNA sequencing (scRNAseq) and scATAC sequencing (scATACseq) study using the partial carotid ligation mouse model showed flow-regulated Klk10 expression at the epigenomic and transcription levels. Functionally, KLK10 protected against d-flow-induced permeability dysfunction and inflammation in human artery ECs (HAECs), as determined by NFkB activation, expression of vascular cell adhesion molecule 1 (VCAM1) and intracellular adhesion molecule 1 (ICAM1), and monocyte adhesion. Further, treatment of mice in vivo with rKLK10 decreased arterial endothelial inflammation in d-flow regions. Additionally, rKLK10 injection or ultrasound-mediated transfection of Klk10-expressing plasmids inhibited atherosclerosis in Apoe-/- mice. Moreover, KLK10 expression was significantly reduced in human coronary arteries with advanced atherosclerotic plaques compared to those with less severe plaques. KLK10 is a flow-sensitive endothelial protein that serves as an anti-inflammatory, barrier-protective, and anti-atherogenic factor.
    Keywords:  cell biology; human; immunology; inflammation; mouse
    DOI:  https://doi.org/10.7554/eLife.72579
  5. Adv Mater. 2022 Jan 14. e2109823
      3D tissue models recapitulating human physiology are important for fundamental biomedical research, and they hold promise to become a new tool in drug development. An integrated and defined microvasculature in 3D tissue models is necessary for optimal cell functions. However, conventional bioprinting only allows the fabrication of hydrogel scaffolds containing vessel-like structures with large diameters (>100 μm) and simple geometries. Recent developments in laser photoablation enable the generation of this type of structure with higher resolution and complexity, but the photo-thermal process can compromise cell viability and hydrogel integrity. To address these limitations, the present work reports in-situ 3D patterning of collagen hydrogels by femtosecond laser irradiation to create channels and cavities with diameters ranging from 20 to 60 μm. In this process, laser irradiation of the hydrogel generates cavitation gas bubbles that rearrange the collagen fibers, thereby creating stable microchannels. Such 3D channels can be formed in cell- and organoid-laden hydrogel without affecting the viability outside the lumen and can enable the formation of artificial microvasculature by the culture of endothelial cells and cell media perfusion. Thus, this method enables organs-on-a-chip and 3D tissue models featuring complex microvasculature. This article is protected by copyright. All rights reserved.
    Keywords:  3D micromachining; direct writing; femtosecond laser; microvasculature; tissue engineering; type I collagen
    DOI:  https://doi.org/10.1002/adma.202109823