bims-tuchim 2021-03-28 papers

bims-tuchim

Biomed News

on Tumor-on-chip models

Issue of 2021–03–28
fiveteen papers selected by
Philipp Albrecht, Friedrich Schiller University

Interfacial Curvature in Confined Coculture Directs Stromal Cell Activity with Spatial Corralling of Pancreatic Cancer Cells.
Chronic adrenergic stress contributes to metabolic dysfunction and an exhausted phenotype in T cells in the tumor microenvironment.
Generation, functional analysis and applications of isogenic three-dimensional self-aggregating cardiac microtissues from human pluripotent stem cells.
A cross-talk between CAR T cell subsets and the tumor microenvironment is essential for sustained cytotoxic activity.
Tumor-penetrating therapy for β5 integrin-rich pancreas cancer.
A 3D physio-mimetic interpenetrating network-based platform to decode the pro and anti-tumorigenic properties of cancer-associated fibroblasts.
Anchor-IMPACT: A Standardized Microfluidic Platform for High-throughput Anti-angiogenic Drug Screening.
A Natural Xenogeneic Endometrial Extracellular Matrix Hydrogel Toward Improving Current Human in vitro Models and Future in vivo Applications.
Hydrogels for Large-Scale Expansion of Stem Cells.
Genetically engineered myeloid cells rebalance the core immune suppression program in metastasis.
A tumor-specific mechanism of Treg enrichment mediated by the integrin αvβ8.
Antigen presentation in cancer: insights into tumour immunogenicity and immune evasion.
Artificial intelligence velocimetry and microaneurysm-on-a-chip for three-dimensional analysis of blood flow in physiology and disease.
Engineering Vascularized Organoid-on-a-Chip Models.
Direct and Label-Free Cell Status Monitoring of Spheroids and Microcarriers Using Microfluidic Impedance Cytometry.

Adv Biol (Weinh). 2021 Mar 22. e2000525

Interfacial Curvature in Confined Coculture Directs Stromal Cell Activity with Spatial Corralling of Pancreatic Cancer Cells.

Stephanie Nemec, Joey Lam, Jingxiao Zhong, Celine Heu, Paul Timpson, Qing Li, Janet Youkhana, George Sharbeen, Phoebe A Phillips, Kristopher A Kilian.

  Interfacial cues in the tumor microenvironment direct the activity and assembly of multiple cell types. Pancreatic cancer, along with breast and prostate cancers, is enriched with cancer-associated fibroblasts (CAFs) that activate to coordinate the deposition of the extracellular matrix, which can comprise over 90% of the tumor mass. While it is clear that matrix underlies the severity of the disease, the relationship between stromal-tumor cell assembly and cell-matrix dynamics remains elusive. Micropatterned hydrogels deconstruct the interplay between matrix stiffness and geometric confinement, guiding heterotypic cell populations and matrix assembly in pancreatic cancer. Interfacial cues at the perimeter of microislands guide CAF migration and direct cancer cell assembly. Computational modeling shows curvature-stress dependent cellular localization for cancer and CAFs in coculture. Regions of convex curvature enhance edge stress that activates a myofibroblast phenotype in the CAFs with migration and increased collagen I deposition, ultimately leading to a central "corralling" of cancer cells. Inhibiting mechanotransduction pathways decreases CAF activation and the associated corralling phenotype. Together, this work reveals how interfacial biophysical cues underpin aspects of stromal desmoplasia, a hallmark of disease severity and chemoresistance in the pancreatic, breast, and prostate cancers, thereby providing a tool to expand stroma-targeting therapeutic strategies.

Keywords:  cancer-associated fibroblasts; heterotypic cocultures; micropatterning; pancreatic ductal adenocarcinoma

DOI:  https://doi.org/10.1002/adbi.202000525
Cancer Immunol Res. 2021 Mar 24. pii: canimm.0445.2020. [Epub ahead of print]

Chronic adrenergic stress contributes to metabolic dysfunction and an exhausted phenotype in T cells in the tumor microenvironment.

Guanxi Qiao, Minhui Chen, Hemn Mohammadpour, Cameron R MacDonald, Mark J Bucsek, Bonnie L Hylander, Joseph J Barbi, Elizabeth A Repasky.

Metabolic dysfunction and exhaustion in tumor-infiltrating T cells have been linked to ineffectual anti-tumor immunity and the failure of immune checkpoint inhibitor therapy. We report here that chronic stress plays a previously unrecognized role in regulating the state of T cells in the tumor microenvironment (TME). Using two mouse tumor models, we found that blocking chronic adrenergic stress signaling using the pan β-blocker propranolol or by using mice lacking the β2-adrenergic receptor (β2-AR), results in reduced tumor growth rates with significantly fewer infiltrating T cells that express markers of exhaustion, with a concomitant increase in progenitor exhausted T cells. We also report that blocking β-AR signaling in mice increases glycolysis and oxidative phosphorylation in tumor-infiltrating lymphocytes (TILs), which associated with increased expression of the costimulatory molecule CD28 and increased anti-tumor effector functions, including increased cytokine production. Using T cells from Nur77-GFP reporter mice to monitor T-cell activation, we observed that stress-induced β-AR signaling suppresses T-cell receptor (TCR) signaling. Together, these data suggest that chronic stress-induced adrenergic receptor signaling serves as a "checkpoint" of immune responses and contributes to immunosuppression in the TME by promoting T-cell metabolic dysfunction and exhaustion. These results also support the possibility that chronic stress, which unfortunately is increased in many cancer patients following their diagnoses, could be exerting a major negative influence on the outcome of therapies that depend upon the status of TILs and support the use of strategies to reduce stress or β-AR signaling in combination with immunotherapy.

DOI: https://doi.org/10.1158/2326-6066.CIR-20-0445
Nat Protoc. 2021 Mar 26.

Generation, functional analysis and applications of isogenic three-dimensional self-aggregating cardiac microtissues from human pluripotent stem cells.

Giulia Campostrini, Viviana Meraviglia, Elisa Giacomelli, Ruben W J van Helden, Loukia Yiangou, Richard P Davis, Milena Bellin, Valeria V Orlova, Christine L Mummery.

Tissue-like structures from human pluripotent stem cells containing multiple cell types are transforming our ability to model and understand human development and disease. Here we describe a protocol to generate cardiomyocytes (CMs), cardiac fibroblasts (CFs) and cardiac endothelial cells (ECs), the three principal cell types in the heart, from human induced pluripotent stem cells (hiPSCs) and combine them in three-dimensional (3D) cardiac microtissues (MTs). We include details of how to differentiate, isolate, cryopreserve and thaw the component cells and how to construct and analyze the MTs. The protocol supports hiPSC-CM maturation and allows replacement of one or more of the three heart cell types in the MTs with isogenic variants bearing disease mutations. Differentiation of each cell type takes ~30 d, while MT formation and maturation requires another 20 d. No specialist equipment is needed and the method is inexpensive, requiring just 5,000 cells per MT.

DOI: https://doi.org/10.1038/s41596-021-00497-2
Sci Immunol. 2021 Mar 26. pii: eabd4344. [Epub ahead of print]6(57):

A cross-talk between CAR T cell subsets and the tumor microenvironment is essential for sustained cytotoxic activity.

Morgane Boulch, Marine Cazaux, Yann Loe-Mie, Ronan Thibaut, Béatrice Corre, Fabrice Lemaître, Capucine L Grandjean, Zacarias Garcia, Philippe Bousso.

Chimeric antigen receptor (CAR) T cell therapy relies on the activity of a large pool of tumor-targeting cytotoxic effectors. Whether CAR T cells act autonomously or require interactions with the tumor microenvironment (TME) remains incompletely understood. Here, we report an essential cross-talk between CAR T cell subsets and the TME for tumor control in an immunocompetent mouse B cell lymphoma model of anti-CD19 CAR T cell therapy. Using single-cell RNA sequencing, we revealed substantial modification of the TME during CAR T cell therapy. Interferon-γ (IFN-γ) produced by CAR T cells not only enhanced endogenous T and natural killer cell activity but was also essential for sustaining CAR T cell cytotoxicity, as revealed by intravital imaging. CAR T cell-derived IFN-γ facilitated host interleukin-12 production that supported host immune and CAR T cell responses. Compared with CD8+ CAR T cells, CD4+ CAR T cells were more efficient at host immune activation but less capable of direct tumor killing. In summary, CAR T cells do not act independently in vivo but rely instead on cytokine-mediated cross-talk with the TME for optimal activity. Invigorating CAR T cell interplay with the host represents an attractive strategy to prevent relapses after therapy.

DOI: https://doi.org/10.1126/sciimmunol.abd4344
Nat Commun. 2021 03 09. 12(1): 1541

Tumor-penetrating therapy for β5 integrin-rich pancreas cancer.

Tatiana Hurtado de Mendoza, Evangeline S Mose, Gregory P Botta, Gary B Braun, Venkata R Kotamraju, Randall P French, Kodai Suzuki, Norio Miyamura, Tambet Teesalu, Erkki Ruoslahti, Andrew M Lowy, Kazuki N Sugahara.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by marked desmoplasia and drug resistance due, in part, to poor drug delivery to extravascular tumor tissue. Here, we report that carcinoma-associated fibroblasts (CAFs) induce β5 integrin expression in tumor cells in a TGF-β dependent manner, making them an efficient drug delivery target for the tumor-penetrating peptide iRGD. The capacity of iRGD to deliver conjugated and co-injected payloads is markedly suppressed when β5 integrins are knocked out in the tumor cells. Of note, β5 integrin knock-out in tumor cells leads to reduced disease burden and prolonged survival of the mice, demonstrating its contribution to PDAC progression. iRGD significantly potentiates co-injected chemotherapy in KPC mice with high β5 integrin expression and may be a powerful strategy to target an aggressive PDAC subpopulation.

DOI: https://doi.org/10.1038/s41467-021-21858-1
Acta Biomater. 2021 Mar 22. pii: S1742-7061(21)00187-2. [Epub ahead of print]

A 3D physio-mimetic interpenetrating network-based platform to decode the pro and anti-tumorigenic properties of cancer-associated fibroblasts.

Huan Cao, Hong Sheng Cheng, Jun Kit Wang, Nguan Soon Tan, Chor Yong Tay.

  Three-dimensional (3D) biomaterials with physiologically relevant and experimentally tractable biomechanical features are important platforms to advance our understanding of the influence of tissue mechanics in disease progression. Herein, an interpenetrating network (IPN) of collagen and alginate 3D culture system with tunable extracellular microstructure and mechanics is exploited as a tumor stroma proxy to study phenotypic plasticity of colorectal cancer-associated fibroblasts (CAF). In combination with Next Generation Sequencing (NGS) data analysis, we demonstrated that tuning the storage modulus of the IPN hydrogel between 49 and 419 Pa can trigger a reversible switch between an inflammatory (i-state, α-SMAlowIL-6high) and myofibroblastic (m-state, α-SMAhighIL-6low) state in CAF that is dependent on the polymer network confinement effect and ROS-HIF1-α mechanotransduction signaling axis. Secretome from m-state CAF upregulated several epithelial-mesenchymal-transition (EMT) transcripts and induced robust scattering in DLD-1, HCT116, and SW480 human colorectal adenocarcinoma, while the EMT-inducing capacity is muted in i-state CAF, suggestive of an anti-tumorigenic role. Our findings were further validated through Gene Expression Profiling Interactive Analysis (GEPIA), which showed that cytokines secreted at higher levels by i-state CAF are correlated (p<0.05) with good overall colorectal cancer patient survival. Therefore, 3D network density and spatial cellular confinements are critical biophysical determinants that can profoundly influence CAF states, paracrine signaling, and EMT-inducing potential. STATEMENT OF SIGNIFICANCE: The communication between cancer cells and cancer-associated fibroblasts (CAF) contributes to tumor metastasis. CAF represent a diverse population of cellular subsets that can either promote or restrain tumor progression. However, the origin and cause of CAF heterogeneity remain elusive, limiting CAF-directed therapies for clinical use. We studied the dynamic phenotypes of CAF using a 3D physio-mimetic culture platform consisting of an interpenetrating collagen-alginate network. Combined with transcriptomic stratification and correlative analysis using cancer patient dataset, we showed phenotypic interconversion between inflammatory and myofibroblastic states, with pro- and anti-tumorigenic functions, in human colorectal CAF. This multidisciplinary study reveals the functional diversity of colorectal CAF caused by biophysical cues. The finding will influence the development of new CAF biomarkers and cancer therapies.

Keywords:  Cancer-associated fibroblasts; Interpenetrating network hydrogel; Mechanotransduction; Tumor microenvironment

DOI:  https://doi.org/10.1016/j.actbio.2021.03.037
Biotechnol Bioeng. 2021 Mar 25.

Anchor-IMPACT: A Standardized Microfluidic Platform for High-throughput Anti-angiogenic Drug Screening.

Suryong Kim, Jihoon Ko, Seung-Ryeol Lee, Dohyun Park, Seunghyuk Park, Noo Li Jeon.

  In vitro models are becoming more advanced to truly present physiological systems while enabling high-throughput screening and analysis. Organ-on-a-chip devices provide remarkable results through the reconstruction of a three-dimensional (3D) cellular microenvironment although they need to be further developed in terms of multiple liquid patterning principle, material properties and scalability. Here we present a 3D anchor-based microfluidic injection-molded plastic array culture platform (Anchor-IMPACT) that enables selective, space-intensive patterning of hydrogels using anchor-island for high-throughput angiogenesis evaluation model. Anchor-IMPACT consists of a central channel and an anchor-island, integrating the array into an abbreviated 96-well plate format with a standard microscope slide size. The anchor-island enables selective 3D cell patterning without channel-to-channel contact or any hydrogel injection port using an anchor structure unlike conventional culture compartment. The hydrogel was patterned into defined regions by spontaneous capillary flow under hydrophilic conditions. We configured multiple cell patterning structures to investigate the angiogenic potency of colorectal cancer (CRC) cells in Anchor-IMPACT and the morphological properties of the angiogenesis induced by the paracrine effect were evaluated. In addition, the efficacy of anticancer drugs against angiogenic sprouts was verified by following dose-dependent responses. Our results indicate that Anchor-IMPACT offers not only a model of high-throughput experimentation but also an advanced 3D cell culture platform and can significantly improve current in vitro models while providing the basis for developing predictive preclinical models for biopharmaceutical applications. This article is protected by copyright. All rights reserved.

Keywords:  Angiogenesis; Colorectal Cancer; High-throughput Screening; Microfluidics; Organ-on-a-Chip

DOI:  https://doi.org/10.1002/bit.27765
Front Bioeng Biotechnol. 2021 ;9 639688

A Natural Xenogeneic Endometrial Extracellular Matrix Hydrogel Toward Improving Current Human in vitro Models and Future in vivo Applications.

Sara López-Martínez, Hannes Campo, Lucía de Miguel-Gómez, Amparo Faus, Alfredo T Navarro, Ana Díaz, Antonio Pellicer, Hortensia Ferrero, Irene Cervelló.

  Decellularization techniques support the creation of biocompatible extracellular matrix hydrogels, providing tissue-specific environments for both in vitro cell culture and in vivo tissue regeneration. We obtained endometrium derived from porcine decellularized uteri to create endometrial extracellular matrix (EndoECM) hydrogels. After decellularization and detergent removal, we investigated the physicochemical features of the EndoECM, including gelation kinetics, ultrastructure, and proteomic profile. The matrisome showed conservation of structural and tissue-specific components with low amounts of immunoreactive molecules. EndoECM supported in vitro culture of human endometrial cells in two- and three-dimensional conditions and improved proliferation of endometrial stem cells with respect to collagen and Matrigel. Further, we developed a three-dimensional endometrium-like co-culture system of epithelial and stromal cells from different origins. Endometrial co-cultures remained viable and showed significant remodeling. Finally, EndoECM was injected subcutaneously in immunocompetent mice in a preliminary study to test a possible hypoimmunogenic reaction. Biomimetic endometrial milieus offer new strategies in reproductive techniques and endometrial repair and our findings demonstrate that EndoECM has potential for in vitro endometrial culture and as treatment for endometrial pathologies.

Keywords:  3D culture; decellularization; endometrium; extracellular matrix hydrogels; tissue engineering

DOI:  https://doi.org/10.3389/fbioe.2021.639688
Acta Biomater. 2021 Mar 18. pii: S1742-7061(21)00167-7. [Epub ahead of print]

Hydrogels for Large-Scale Expansion of Stem Cells.

Sheng Yin, Yi Cao.

  Stem cells demonstrate considerable promise for various preclinical and clinical applications, including drug screening, disease treatments, and regenerative medicine. Producing high-quality and large amounts of stem cells is in demand for these applications. Despite challenges, as hydrogel-based cell culture technology has developed, tremendous progress has been made in stem cell expansion and directed differentiation. Hydrogels are soft materials with abundant water. Many hydrogel properties, including biodegradability, mechanical strength, and porosity, have been shown to play essential roles in regulating stem cell proliferation and differentiation. The biochemical and physical properties of hydrogels can be specifically tailored to mimic the native microenvironment that various stem cells reside in vivo. A few hydrogel-based systems have been developed for successful stem cell cultures and expansion in vitro. In this review, we summarize various types of hydrogels that have been designed to effectively enhance the proliferation of hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs), respectively. According to each stem cell type's preference, we also discuss strategies for fabricating hydrogels with biochemical and mechanical cues and other characteristics representing microenvironments of stem cells in vivo. STATEMENT OF SIGNIFICANCE: In this review article we summary current progress on the construction of hydrogel systems for the culture and expansion of various stem cells, including hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs). The Significance includes: (1) Provide detailed discussion on the stem cell niches that should be considered for stem cell in vitro expansion. (2) Summarize various strategies to construct hydrogels that can largely recapture the microenvironment of native stem cells. (3) Suggest a few future directions that can be implemented to improve current in vitro stem cell expansion systems.

Keywords:  Hydrogel; hematopoietic stem cell; mechanical properties; mesenchymal stem cell; pluripotent stem cell; stem cell; stem cell expansion

DOI:  https://doi.org/10.1016/j.actbio.2021.03.026
Cell. 2021 Mar 19. pii: S0092-8674(21)00237-3. [Epub ahead of print]

Genetically engineered myeloid cells rebalance the core immune suppression program in metastasis.

Sabina Kaczanowska, Daniel W Beury, Vishaka Gopalan, Arielle K Tycko, Haiying Qin, Miranda E Clements, Justin Drake, Chiadika Nwanze, Meera Murgai, Zachary Rae, Wei Ju, Katherine A Alexander, Jessica Kline, Cristina F Contreras, Kristin M Wessel, Shil Patel, Sridhar Hannenhalli, Michael C Kelly, Rosandra N Kaplan.

  Metastasis is the leading cause of cancer-related deaths, and greater knowledge of the metastatic microenvironment is necessary to effectively target this process. Microenvironmental changes occur at distant sites prior to clinically detectable metastatic disease; however, the key niche regulatory signals during metastatic progression remain poorly characterized. Here, we identify a core immune suppression gene signature in pre-metastatic niche formation that is expressed predominantly by myeloid cells. We target this immune suppression program by utilizing genetically engineered myeloid cells (GEMys) to deliver IL-12 to modulate the metastatic microenvironment. Our data demonstrate that IL12-GEMy treatment reverses immune suppression in the pre-metastatic niche by activating antigen presentation and T cell activation, resulting in reduced metastatic and primary tumor burden and improved survival of tumor-bearing mice. We demonstrate that IL12-GEMys can functionally modulate the core program of immune suppression in the pre-metastatic niche to successfully rebalance the dysregulated metastatic microenvironment in cancer.

Keywords:  T cells; cancer immunology; genetically engineered myeloid cells; immune suppression; immunotherapy; interleukin 12; metastasis tumor microenvironment; pre-metastatic niche; stem cell niche

DOI:  https://doi.org/10.1016/j.cell.2021.02.048
Sci Immunol. 2021 Mar 26. pii: eabf0558. [Epub ahead of print]6(57):

A tumor-specific mechanism of Treg enrichment mediated by the integrin αvβ8.

Robert I Seed, Kenji Kobayashi, Saburo Ito, Naoki Takasaka, Anthony Cormier, Jillian M Jespersen, Jean Publicover, Suprita Trilok, Alexis J Combes, Nayvin W Chew, Jocelyne Chapman, Matthew F Krummel, Jianlong Lou, James Marks, Yifan Cheng, Jody L Baron, Stephen L Nishimura.

Regulatory T cells (Tregs) that promote tumor immune evasion are enriched in certain tumors and correlate with poor prognosis. However, mechanisms for Treg enrichment remain incompletely understood. We described a mechanism for Treg enrichment in mouse and human tumors mediated by the αvβ8 integrin. Tumor cell αvβ8 bound to latent transforming growth factor-β (L-TGF-β) presented on the surface of T cells, resulting in TGF-β activation and immunosuppressive Treg differentiation in vitro. In vivo, tumor cell αvβ8 expression correlated with Treg enrichment, immunosuppressive Treg gene expression, and increased tumor growth, which was reduced in mice by αvβ8 inhibition or Treg depletion. Structural modeling and cell-based studies suggested a highly geometrically constrained complex forming between αvβ8-expressing tumor cells and L-TGF-β-expressing T cells, facilitating TGF-β activation, independent of release and diffusion, and providing limited access to TGF-β inhibitors. These findings suggest a highly localized tumor-specific mechanism for Treg enrichment.

DOI: https://doi.org/10.1126/sciimmunol.abf0558
Nat Rev Cancer. 2021 Mar 09.

Antigen presentation in cancer: insights into tumour immunogenicity and immune evasion.

Suchit Jhunjhunwala, Christian Hammer, Lélia Delamarre.

Immune checkpoint blockade, which blocks inhibitory signals of T cell activation, has shown tremendous success in treating cancer, although success still remains limited to a fraction of patients. To date, clinically effective CD8+ T cell responses appear to target predominantly antigens derived from tumour-specific mutations that accumulate in cancer, also called neoantigens. Tumour antigens are displayed on the surface of cells by class I human leukocyte antigens (HLA-I). To elicit an effective antitumour response, antigen presentation has to be successful at two distinct events: first, cancer antigens have to be taken up by dendritic cells (DCs) and cross-presented for CD8+ T cell priming. Second, the antigens have to be directly presented by the tumour for recognition by primed CD8+ T cells and killing. Tumours exploit multiple escape mechanisms to evade immune recognition at both of these steps. Here, we review the tumour-derived factors modulating DC function, and we summarize evidence of immune evasion by means of quantitative modulation or qualitative alteration of the antigen repertoire presented on tumours. These mechanisms include modulation of antigen expression, HLA-I surface levels, alterations in the antigen processing and presentation machinery in tumour cells. Lastly, as complete abrogation of antigen presentation can lead to natural killer (NK) cell-mediated tumour killing, we also discuss how tumours can harbour antigen presentation defects and still evade NK cell recognition.

DOI: https://doi.org/10.1038/s41568-021-00339-z
Proc Natl Acad Sci U S A. 2021 Mar 30. pii: e2100697118. [Epub ahead of print]118(13):

Artificial intelligence velocimetry and microaneurysm-on-a-chip for three-dimensional analysis of blood flow in physiology and disease.

Shengze Cai, He Li, Fuyin Zheng, Fang Kong, Ming Dao, George Em Karniadakis, Subra Suresh.

  Understanding the mechanics of blood flow is necessary for developing insights into mechanisms of physiology and vascular diseases in microcirculation. Given the limitations of technologies available for assessing in vivo flow fields, in vitro methods based on traditional microfluidic platforms have been developed to mimic physiological conditions. However, existing methods lack the capability to provide accurate assessment of these flow fields, particularly in vessels with complex geometries. Conventional approaches to quantify flow fields rely either on analyzing only visual images or on enforcing underlying physics without considering visualization data, which could compromise accuracy of predictions. Here, we present artificial-intelligence velocimetry (AIV) to quantify velocity and stress fields of blood flow by integrating the imaging data with underlying physics using physics-informed neural networks. We demonstrate the capability of AIV by quantifying hemodynamics in microchannels designed to mimic saccular-shaped microaneurysms (microaneurysm-on-a-chip, or MAOAC), which signify common manifestations of diabetic retinopathy, a leading cause of vision loss from blood-vessel damage in the retina in diabetic patients. We show that AIV can, without any a priori knowledge of the inlet and outlet boundary conditions, infer the two-dimensional (2D) flow fields from a sequence of 2D images of blood flow in MAOAC, but also can infer three-dimensional (3D) flow fields using only 2D images, thanks to the encoded physics laws. AIV provides a unique paradigm that seamlessly integrates images, experimental data, and underlying physics using neural networks to automatically analyze experimental data and infer key hemodynamic indicators that assess vascular injury.

Keywords:  blood flow in microaneurysm; deep learning; diabetic retinopathy; image analysis; three-dimensional flow fields

DOI:  https://doi.org/10.1073/pnas.2100697118
Annu Rev Biomed Eng. 2021 Mar 23.

Engineering Vascularized Organoid-on-a-Chip Models.

Venktesh S Shirure, Christopher C W Hughes, Steven C George.

Recreating human organ-level function in vitro is a rapidly evolving field that integrates tissue engineering, stem cell biology, and microfluidic technology to produce 3D organoids. A critical component of all organs is the vasculature. Herein, we discuss general strategies to create vascularized organoids, including common source materials, and survey previous work using vascularized organoids to recreate specific organ functions and simulate tumor progression. Vascularization is not only an essential component of individual organ function but also responsible for coupling the fate of all organs and their functions. While some success in coupling two or more organs together on a single platform has been demonstrated, we argue that the future of vascularized organoid technology lies in creating organoid systems complete with tissue-specific microvasculature and in coupling multiple organs through a dynamic vascular network to create systems that can respond to changing physiological conditions. Expected final online publication date for the Annual Review of Biomedical Engineering, Volume 23 is June 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DOI: https://doi.org/10.1146/annurev-bioeng-090120-094330
Small. 2021 Mar 24. e2007500

Direct and Label-Free Cell Status Monitoring of Spheroids and Microcarriers Using Microfluidic Impedance Cytometry.

Lingyan Gong, Chayakorn Petchakup, Pujiang Shi, Pei Leng Tan, Lay Poh Tan, Chor Yong Tay, Han Wei Hou.

  3D cellular spheroids/microcarriers (100 µm-1 mm) are widely used in biomanufacturing, and non-invasive biosensors are useful to monitor cell quality in bioprocesses. In this work, a novel microfluidic approach for label-free and continuous-flow monitoring of single spheroid/microcarrier (hydrogel and Cytodex) based on electrical impedance spectroscopy using co-planar Field's metal electrodes is reported. Through numerical simulation and experimental validation, two unique impedance signatures (|ZLF | (60 kHz), |ZHF | (1 MHz)) which are optimal for spheroid growth and viability monitoring are identified. Using a closed-loop recirculation system, it is demonstrated that |ZLF | increases with breast cancer (MCF-7) spheroid biomass, while higher opacity (impedance ratio |ZHF |/|ZLF |) indicates cell death due to compromised cell membrane. Anti-cancer drug (paclitaxel)-treated spheroids also exhibit lower |ZLF | with increased cell dissociation. Interestingly, impedance characterization of adipose-derived mesenchymal stem cell differentiation on Cytodex microcarriers reveals that adipogenic cells (higher intracellular lipid content) exhibit higher impedance than osteogenic cells (more conductive due to calcium ions) for both microcarriers and single cell level. Taken together, the developed platform offers great versatility for multi-parametric analysis of spheroids/microcarriers at high throughput (≈1 particle/s), and can be readily integrated into bioreactors for long-term and remote monitoring of biomass and cell quality.

Keywords:  biomanufacturing; impedance cytometry; label-free; microfluidics; stem cell differentiation

DOI:  https://doi.org/10.1002/smll.202007500