bims-tuchim Biomed News
on Tumor-on-chip models
Issue of 2021–07–25
twenty-one papers selected by
Philipp Albrecht, Friedrich Schiller University



  1. Front Oncol. 2021 ;11 682217
      The stroma-rich, immunosuppressive microenvironment is a hallmark of pancreatic ductal adenocarcinoma (PDA). Tumor cells and other cellular components of the tumor microenvironment, such as cancer associated fibroblasts, CD4+ T cells and myeloid cells, are linked by a web of interactions. Their crosstalk not only results in immune evasion of PDA, but also contributes to pancreatic cancer cell plasticity, invasiveness, metastasis, chemo-resistance, immunotherapy-resistance and radiotherapy-resistance. In this review, we characterize several prevalent populations of stromal cells in the PDA microenvironment and describe how the crosstalk among them drives and maintains immune suppression. We also summarize therapeutic approaches to target the stroma. With a better understanding of the complex cellular and molecular networks in PDA, strategies aimed at sensitizing PDA to chemotherapy or immunotherapy through re-programing the tumor microenvironment can be designed, and in turn lead to improved clinical treatment for pancreatic cancer patients.
    Keywords:  T cells; cancer-associated fibroblasts; immune suppression; myeloid cells; pancreatic cancer; tumor microenvironment
    DOI:  https://doi.org/10.3389/fonc.2021.682217
  2. Cancers (Basel). 2021 Jul 12. pii: 3481. [Epub ahead of print]13(14):
      Many cancer studies now recognize that disease initiation, progression, and response to treatment are strongly influenced by the microenvironmental niche. Widespread desmoplasia, or fibrosis, is fundamental to pancreatic cancer development, growth, metastasis, and treatment resistance. This fibrotic landscape is largely regulated by cancer-associated fibroblasts (CAFs), which deposit and remodel extracellular matrix (ECM) in the tumor microenvironment (TME). This review will explore the prognostic and functional value of the stromal compartment in predicting outcomes and clinical prognosis in pancreatic ductal adenocarcinoma (PDAC). We will also discuss the major dynamic stromal alterations that occur in the pancreatic TME during tumor development and progression, and how the stromal ECM can influence cancer cell phenotype, metabolism, and immune response from a biochemical and biomechanical viewpoint. Lastly, we will provide an outlook on the latest clinical advances in the field of anti-fibrotic co-targeting in combination with chemotherapy or immunotherapy in PDAC, providing insight into the current challenges in treating this highly aggressive, fibrotic malignancy.
    Keywords:  biomechanics; cancer-associated fibroblasts; extracellular matrix; pancreatic cancer; stroma; stromal targeting; tumor microenvironment
    DOI:  https://doi.org/10.3390/cancers13143481
  3. Cancers (Basel). 2021 Jul 16. pii: 3565. [Epub ahead of print]13(14):
      Therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC) can be attributed, in part, to a dense extracellular matrix containing excessive collagen deposition. Here, we describe a novel Salmonella typhimurium (ST) vector expressing the bacterial collagenase Streptomyces omiyaensis trypsin (SOT), a serine protease known to hydrolyze collagens I and IV, which are predominantly found in PDAC. Utilizing aggressive models of PDAC, we show that ST-SOT selectively degrades intratumoral collagen leading to decreases in immunosuppressive subsets, tumor proliferation and viability. Ultimately, we found that ST-SOT treatment significantly modifies the intratumoral immune landscape to generate a microenvironment that may be more conducive to immunotherapy.
    Keywords:  attenuated Salmonella typhimurium; collagen; collagenase; desmoplasia; pancreatic ductal adenocarcinoma; targeted therapies; therapeutic resistance; tumor microenvironment
    DOI:  https://doi.org/10.3390/cancers13143565
  4. Cancer Cell. 2021 Jul 14. pii: S1535-6108(21)00339-1. [Epub ahead of print]
      Fibroblasts display extensive transcriptional heterogeneity, yet functional annotation and characterization of their heterocellular relationships remains incomplete. Using mass cytometry, we chart the stromal composition of 18 murine tissues and 5 spontaneous tumor models, with an emphasis on mesenchymal phenotypes. This analysis reveals extensive stromal heterogeneity across tissues and tumors, and identifies coordinated relationships between mesenchymal and immune cell subsets in pancreatic ductal adenocarcinoma. Expression of CD105 demarks two stable and functionally distinct pancreatic fibroblast lineages, which are also identified in murine and human healthy tissues and tumors. Whereas CD105-positive pancreatic fibroblasts are permissive for tumor growth in vivo, CD105-negative fibroblasts are highly tumor suppressive. This restrictive effect is entirely dependent on functional adaptive immunity. Collectively, these results reveal two functionally distinct pancreatic fibroblast lineages and highlight the importance of mesenchymal and immune cell interactions in restricting tumor growth.
    Keywords:  CAF; CD105; CyTOF; Eng; cancer-associated fibroblast lineages; mass cytometry; pancreatic cancer; tumor microenvironment; tumor-restrictive fibroblasts
    DOI:  https://doi.org/10.1016/j.ccell.2021.06.017
  5. Cancers (Basel). 2021 Jul 02. pii: 3331. [Epub ahead of print]13(13):
      During the metastatic process, breast cancer cells must come into contact with the extra-cellular matrix (ECM) at every step. The ECM provides both structural support and biochemical cues, and cell-ECM interactions can lead to changes in drug response. Here, we used fibroblast-derived ECM (FDM) to perform high throughput drug screening of 4T1 breast cancer cells on metastatic organ ECM (lung), and we see that drug response differs from treatment on plastic. The FDMs that we can produce from different organs are abundant in and contains a complex mixture of ECM proteins. We also show differences in ECM composition between the primary site and secondary organ sites. Furthermore, we show that global kinase signalling of 4T1 cells on the ECM is relatively unchanged between organs, while changes in signalling compared to plastic are significant. Our study highlights the importance of context when testing drug response in vitro, showing that consideration of the ECM is critically important.
    Keywords:  cancer; drug screening; fibroblast-derived matrix
    DOI:  https://doi.org/10.3390/cancers13133331
  6. Nat Cancer. 2020 Nov;1(11): 1097-1112
      Pancreatic ductal adenocarcinoma (PDA) is characterized by an immune-suppressive tumor microenvironment that renders it largely refractory to immunotherapy. We implemented a multimodal analysis approach to elucidate the immune landscape in PDA. Using a combination of CyTOF, single-cell RNA sequencing, and multiplex immunohistochemistry on patient tumors, matched blood, and non-malignant samples, we uncovered a complex network of immune-suppressive cellular interactions. These experiments revealed heterogeneous expression of immune checkpoint receptors in individual patient's T cells and increased markers of CD8+ T cell dysfunction in advanced disease stage. Tumor-infiltrating CD8+ T cells had an increased proportion of cells expressing an exhausted expression profile that included upregulation of the immune checkpoint TIGIT, a finding that we validated at the protein level. Our findings point to a profound alteration of the immune landscape of tumors, and to patient-specific immune changes that should be taken into account as combination immunotherapy becomes available for pancreatic cancer.
    Keywords:  CD8+ T cells; Single-cell RNA sequencing; TIGIT; immune checkpoints; pancreatic cancer; tumor immunology
    DOI:  https://doi.org/10.1038/s43018-020-00121-4
  7. Cancers (Basel). 2021 Jul 01. pii: 3321. [Epub ahead of print]13(13):
      Pancreatic ductal adenocarcinoma (PDAC) has the worst survival rate of all cancers. This poor prognosis results from the lack of efficient systemic treatment regimens, demanding high-dose chemotherapy that causes severe side effects. To overcome dose-dependent toxicities, we explored the efficacy of targeted drug delivery using a protease-dependent drug-release system. To this end, we developed a PDAC-specific drug delivery system based on mesoporous silica nanoparticles (MSN) functionalized with an avidin-biotin gatekeeper system containing a protease linker that is specifically cleaved by tumor cells. Bioinformatic analysis identified ADAM9 as a PDAC-enriched protease, and PDAC cell-derived conditioned medium efficiently cleaved protease linkers containing ADAM9 substrates. Cleavage was PDAC specific as conditioned medium from leukocytes was unable to cleave the ADAM9 substrate. Protease linker-functionalized MSNs were efficiently capped with avidin, and cap removal was confirmed to occur in the presence of PDAC cell-derived ADAM9. Subsequent treatment of PDAC cells in vitro with paclitaxel-loaded MSNs indeed showed high cytotoxicity, whereas no cell death was observed in white blood cell-derived cell lines, confirming efficacy of the nanoparticle-mediated drug delivery system. Taken together, this research introduces a novel ADAM9-responsive, protease-dependent, drug delivery system for PDAC as a promising tool to reduce the cytotoxicity of systemic chemotherapy.
    Keywords:  ADAM9; MSN; PDAC; drug delivery; mesoporous silica nanoparticles; pancreatic cancer
    DOI:  https://doi.org/10.3390/cancers13133321
  8. Cancers (Basel). 2021 Jul 14. pii: 3519. [Epub ahead of print]13(14):
      Pancreatic ductal adenocarcinoma is an aggressive tumor characterized by the presence of an abundant stromal compartment contributing significantly to the malignant phenotype. Pancreatic stellate cells are peculiar fibroblasts present in the stroma and represent the predominant source of extracellular matrix proteins, pro-inflammatory cytokines, and growth factors, including hepatocyte growth factor (HGF). Exploiting a co-culture system of human pancreatic stellate cells and cancer cells, we demonstrated that fibroblast activation was reduced upon HGF/MET axis inhibition. To unveil the signaling pathways sustaining stroma modulation orchestrated by MET activation in the tumor, we analyzed the gene expression profile in pancreatic cancer cells stimulated with HGF and treated with HGF/MET inhibitors. Transcriptome analysis showed that, among all the genes modulated by HGF, a subset of 125 genes was restored to the basal level following treatment with the inhibitors. By examining these genes via ingenuity pathway analysis, tenascin C emerged as a promising candidate linking MET signaling and tumor microenvironment. MET-dependent tenascin C modulation in pancreatic cancer cells was validated at RNA and protein levels both in vitro and in vivo. In conclusion, this work identifies tenascin C as a gene modulated by MET activation, suggesting a role in MET-mediated tumor-stroma interplay occurring during pancreatic tumor progression.
    Keywords:  MET oncogene; hepatocyte growth factor; metastasis; pancreatic ductal adenocarcinoma; tenascin C; tumor microenvironment
    DOI:  https://doi.org/10.3390/cancers13143519
  9. ACS Biomater Sci Eng. 2021 Jul 12. 7(7): 2964-2972
      Vasculature is a key component of many biological tissues and helps to regulate a wide range of biological processes. Modeling vascular networks or the vascular interface in organ-on-a-chip systems is an essential aspect of this technology. In many organ-on-a-chip devices, however, the engineered vasculatures are usually designed to be encapsulated inside closed microfluidic channels, making it difficult to physically access or extract the tissues for downstream applications and analysis. One unexploited benefit of tissue extraction is the potential of vascularizing, perfusing, and maturing the tissue in well-controlled, organ-on-a-chip microenvironments and then subsequently extracting that product for in vivo therapeutic implantation. Moreover, for both modeling and therapeutic applications, the scalability of the tissue production process is important. Here we demonstrate the scalable production of perfusable and extractable vascularized tissues in an "open-top" 384-well plate (referred to as IFlowPlate), showing that this system could be used to examine nanoparticle delivery to targeted tissues through the microvascular network and to model vascular angiogenesis. Furthermore, tissue spheroids, such as hepatic spheroids, can be vascularized in a scalable manner and then subsequently extracted for in vivo implantation. This simple multiple-well plate platform could not only improve the experimental throughputs of organ-on-a-chip systems but could potentially help expand the application of model systems to regenerative therapy.
    Keywords:  angiogenesis; hydrogel; liver; organ-on-a-chip; tissue spheroids; vasculature
    DOI:  https://doi.org/10.1021/acsbiomaterials.0c00236
  10. Cancers (Basel). 2021 Jul 14. pii: 3526. [Epub ahead of print]13(14):
      Tumour cells do not exist as an isolated entity. Instead, they are surrounded by and closely interact with cells of the environment they are emerged in. The tumour microenvironment (TME) is not static and several factors, including cancer cells and therapies, have been described to modulate several of its components. Fibroblasts are key elements of the TME with the capacity to influence tumour progression, invasion and response to therapy, which makes them attractive targets in cancer treatment. In this review, we focus on fibroblasts and their numerous roles in the TME with a special attention to recent findings describing their heterogeneity and role in therapy response. Furthermore, we explore how different therapies can impact these cells and their communication with cancer cells. Finally, we highlight potential strategies targeting this cell type that can be employed for improving patient outcome.
    Keywords:  cancer associated fibroblast (CAF); cell communication; signalling; therapy resistance; tumour microenvironment (TME)
    DOI:  https://doi.org/10.3390/cancers13143526
  11. Biochim Biophys Acta Mol Cell Res. 2021 Jul 19. pii: S0167-4889(21)00157-9. [Epub ahead of print] 119103
      The function of biological tissues in health and disease is regulated at cellular level and is highly influenced by the physical microenvironment, through the interaction of forces between cells and ECM, which are perceived through mechanosensing pathways. In cancer, both chemical and physical signaling cascades and their interactions are involved during cell-cell and cell-ECM communications to meet requirements of tumor growth. Among stroma cells, cancer associated fibroblasts (CAFs) play key role in tumor growth and pave the way for cancer cells to initiate metastasis and invasion to other tissues, and without recruitment of CAFs, the process of cancer invasion is dysfunctional. This is through an intense chemical and physical cross talks with tumor cells, and interactive remodeling of ECM. During such interaction CAFs apply traction forces and depending on the mechanical properties, deform ECM and in return receive physical signals from the micromechanical environment. Such interaction leads to ECM remodeling by manipulating ECM structure and its mechanical properties. The results are in form of deposition of extra fibers, stiffening, rearrangement and reorganization of fibrous structure, and degradation which are due to a complex secretion and expression of different markers triggered by mechanosensing of tumor cells, specially CAFs. Such events define cancer progress and invasion of cancer cells. A systemic knowledge of chemical and physical factors provides a holistic view of how cancer process and enhances the current treatment methods to provide more diversity among targets that involves tumor cells and ECM structure.
    Keywords:  Cancer associated fibroblasts; Cancer mechanics; Cross talk; Cytoskeleton
    DOI:  https://doi.org/10.1016/j.bbamcr.2021.119103
  12. ACS Biomater Sci Eng. 2021 Jul 21.
      Three-dimensional (3D) models have led to a paradigm shift in disease modeling in vitro, particularly for cancer. The past decade has seen a phenomenal increase in the development of 3D models for various types of cancers with a focus on studying stemness, invasive behavior, angiogenesis, and chemoresistance of cancer cells, as well as contributions of its stroma, which has expanded our understanding of these processes. Cancer biology is moving into exploring the emerging hallmarks of cancer, such as inflammation, immune evasion, and reprogramming of energy metabolism. Studies into these emerging concepts have provided novel targets and treatment options such as antitumor immunotherapy. However, 3D models that can investigate the emerging hallmarks are few and underexplored. As commonly used immunocompromised mice and syngenic mice cannot accurately mimic human immunology, stromal interactions, and metabolism and require the use of prohibitively expensive humanized mice, there is tremendous scope to develop authentic 3D tumor models in these areas. Taking the specific case of breast cancer, we discuss the currently available 3D models, their applications to mimic signaling in cancer, tumor-stroma interactions, drug responses, and assessment of drug delivery systems and therapies. We discuss the lacunae in the development of 3D tumor models for the emerging hallmarks of cancer, for lesser-explored forms of breast cancer, and provide insights to develop such models. We discuss how the next generation of 3D models can provide a better mimic of human cancer modeling compared to xenograft models and the scope toward preclinical models and precision medicine.
    Keywords:  breast cancer; drug testing; emerging hallmarks; precision medicine; three-dimensional (3D) models
    DOI:  https://doi.org/10.1021/acsbiomaterials.1c00230
  13. Adv Mater. 2021 Jul 19. e2102624
      The construction of an in vitro 3D cellular model to mimic the human liver is highly desired for drug discovery and clinical applications, such as patient-specific treatment and cell-based therapy in regenerative medicine. However, current bioprinting strategies are limited in their ability to generate multiple cell-laden microtissues with biomimetic structures. This study presents a method for producing hepatic-lobule-like microtissue spheroids using a bioprinting system incorporating a precursor cartridge and microfluidic emulsification system. The multiple cell-laden microtissue spheroids can be successfully generated at a speed of approximately 45 spheroids min-1 and with a uniform diameter. Hepatic and endothelial cells are patterned in a microtissue spheroid with the biomimetic structure of a liver lobule. The spheroids allow long-term culture with high cell viability, and the structural integrity is maintained longer than that of non-structured spheroids. Furthermore, structured spheroids show high MRP2, albumin, and CD31 expression levels. In addition, the in vivo study reveals that structured microtissue spheroids are stably engrafted. These results demonstrate that the method provides a valuable 3D structured microtissue spheroid model with lobule-like constructs and liver functions.
    Keywords:  3D bioprinting; hepatic lobules; microtissues; preset extrusions; spheroids; tissue engineering
    DOI:  https://doi.org/10.1002/adma.202102624
  14. J Gastroenterol. 2021 Jul 19.
      Pancreatic fibrosis (PF) is an essential component of the pathobiology of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Activated pancreatic myofibroblasts (PMFs) are crucial for the deposition of the extracellular matrix, and fibrotic reaction in response to sustained signaling. Consequently, understanding of the molecular mechanisms of PMF activation is not only critical for understanding CP and PDAC biology but is also a fertile area of research for the development of novel therapeutic strategies for pancreatic pathologies. This review analyzes the key signaling events that drive PMF activation including, initiating signals from transforming growth factor-β1, platelet derived growth factor, as well as other microenvironmental cues, like hypoxia and extracellular matrix rigidity. Further, we discussed the intracellular signal events contributing to PMF activation, and crosstalk with different components of tumor microenvironment. Additionally, association of epidemiologically established risk factors for CP and PDAC, like alcohol intake, tobacco exposure, and metabolic factors with PMF activation, is discussed to comprehend the role of lifestyle factors on pancreatic pathologies. Overall, this analysis provides insight into the biology of PMF activation and highlights salient features of this process, which offer promising therapeutic targets.
    Keywords:  Cell signaling; Chronic pancreatitis; Myofibroblast; Pancreatic cancer; Pancreatic fibrosis
    DOI:  https://doi.org/10.1007/s00535-021-01800-4
  15. Commun Biol. 2021 Jul 21. 4(1): 893
      Immunotherapy has emerged as a promising approach to treating several forms of cancer. Use of immune cells, such as natural killer (NK) cells, along with small molecule drugs and antibodies through antibody dependent cell-mediated cytotoxicity (ADCC) has been investigated as a potential combination therapy for some difficult to treat solid tumors. Nevertheless, there remains a need to develop tools that support co-culture of target cancer cells and effector immune cells in a contextually relevant three-dimensional (3D) environment to provide a rapid means to screen for and optimize ADCC-drug combinations. To that end, here we have developed a high throughput 330 micropillar-microwell sandwich platform that enables 3D co-culture of NK92-CD16 cells with pancreatic (MiaPaCa-2) and breast cancer cell lines (MCF-7 and MDA-MB-231). The platform successfully mimicked hypoxic conditions found in a tumor microenvironment and was used to demonstrate NK-cell mediated cell cytotoxicity in combination with two monoclonal antibodies; Trastuzumab and Atezolizumab. The platform was also used to show dose response behavior of target cancer cells with reduced EC50 values for paclitaxel (an anti-cancer chemotherapeutic) when treated with both NK cells and antibody. Such a platform may be used to develop more personalized cancer therapies using patient-derived cancer cells.
    DOI:  https://doi.org/10.1038/s42003-021-02417-2
  16. ACS Biomater Sci Eng. 2021 Jul 12. 7(7): 2900-2925
      Tissue building does not occur exclusively during development. Even after a whole body is built from a single cell, tissue building can occur to repair and regenerate tissues of the adult body. This confers resilience and enhanced survival to multicellular organisms. However, this resiliency comes at a cost, as the potential for misdirected tissue building creates vulnerability to organ deformation and dysfunction-the hallmarks of disease. Pathological tissue morphogenesis is associated with fibrosis and cancer, which are the leading causes of morbidity and mortality worldwide. Despite being the priority of research for decades, scientific understanding of these diseases is limited and existing therapies underdeliver the desired benefits to patient outcomes. This can largely be attributed to the use of two-dimensional cell culture and animal models that insufficiently recapitulate human disease. Through the synergistic union of biological principles and engineering technology, organ-on-a-chip systems represent a powerful new approach to modeling pathological tissue morphogenesis, one with the potential to yield better insights into disease mechanisms and improved therapies that offer better patient outcomes. This Review will discuss organ-on-a-chip systems that model pathological tissue morphogenesis associated with (1) fibrosis in the context of injury-induced tissue repair and aging and (2) cancer.
    Keywords:  3D bioengineered tissue models; aging; cancer; drug testing; fibrosis; iPSCs; in vitro disease modeling; organ-on-a-chip; tissue morphogenesis
    DOI:  https://doi.org/10.1021/acsbiomaterials.0c01089
  17. Curr Protoc. 2021 Jul;1(7): e199
      In recent years, 3D culture of tumor spheroids has managed to revolutionize cancer research and drug discovery. 2D monolayer cells grown in cell culture flasks undergo radical changes in cell behavior, structure, and function owing to varying environmental cues and are unable to provide predictive data for preclinical evaluation. 3D tumor spheroids can better recapitulate tumor architecture, cell-cell and cell-matrix connectivity, and the tissue complexity of tumors grown in animal models. However, many of the existing techniques to culture 3D spheroids are time-consuming and ineffective and produce irregular-shaped spheroids that cannot be easily incorporated in biological assays. The set of protocols described herein makes use of a commercial hair brush as a template to create concave micro-well impressions in agarose. This technique is easy, inexpensive, and adaptable and also has the ability to produce uniform, homogenous cancer spheroids, with large diameter (∼1000 μm) and thickness (∼250 μm), within 24 to 48 hr after cell seeding. The 3D spheroids produced using the agarose micro-well platform function as an excellent 3D in vitro model for understanding the extent of penetration, uptake, and distribution of targeted cargos such as a diagnostic or therapeutic agents for identification and treatment of cancer. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Fabrication of agarose micro-well scaffold for growing tumor spheroids using a commercial hair brush Basic Protocol 2: Formation of homogenous tumor spheroids in agarose micro-well platform Basic Protocol 3: Assessing viability of 3D tumor spheroids grown in agarose micro-wells using confocal microscopy Basic Protocol 4: Analyzing uptake and penetration of targeted fluorescent bioconjugate in 3D tumor spheroids using two-photon imaging.
    Keywords:  agarose hydrogel; comb template; micro-well platform; tumor spheroids
    DOI:  https://doi.org/10.1002/cpz1.199
  18. Proc Natl Acad Sci U S A. 2021 Jul 27. pii: e2025570118. [Epub ahead of print]118(30):
      Neoantigen-specific T cells are strongly implicated as being critical for effective immune checkpoint blockade treatment (ICB) (e.g., anti-PD-1 and anti-CTLA-4) and are being targeted for vaccination-based therapies. However, ICB treatments show uneven responses between patients, and neoantigen vaccination efficiency has yet to be established. Here, we characterize neoantigen-specific CD8+ T cells in a tumor that is resistant to ICB and neoantigen vaccination. Leveraging the use of mass cytometry combined with multiplex major histocompatibility complex (MHC) class I tetramer staining, we screened and identified tumor neoantigen-specific CD8+ T cells in the Lewis Lung carcinoma (LLC) tumor model (mRiok1). We observed an expansion of mRiok1-specific CD8+ tumor-infiltrating lymphocytes (TILs) after ICB targeting PD-1 or CTLA-4 with no sign of tumor regression. The expanded neoantigen-specific CD8+ TILs remained phenotypically and functionally exhausted but displayed cytotoxic characteristics. When combining both ICB treatments, mRiok1-specific CD8+ TILs showed a stem-like phenotype and a higher capacity to produce cytokines, but tumors did not show signs of regression. Furthermore, combining both ICB treatments with neoantigen vaccination did not induce tumor regression either despite neoantigen-specific CD8+ TIL expansion. Overall, this work provides a model for studying neoantigens in an immunotherapy nonresponder model. We showed that a robust neoantigen-specific T-cell response in the LLC tumor model could fail in tumor response to ICB, which will have important implications in designing future immunotherapeutic strategies.
    Keywords:  CyTOF; LLC; immunotherapies; neoantigen; vaccination
    DOI:  https://doi.org/10.1073/pnas.2025570118
  19. ACS Biomater Sci Eng. 2021 Jul 12. 7(7): 2880-2899
      Polydimethylsiloxane (PDMS) is the predominant material used for organ-on-a-chip devices and microphysiological systems (MPSs) due to its ease-of-use, elasticity, optical transparency, and inexpensive microfabrication. However, the absorption of small hydrophobic molecules by PDMS and the limited capacity for high-throughput manufacturing of PDMS-laden devices severely limit the application of these systems in personalized medicine, drug discovery, in vitro pharmacokinetic/pharmacodynamic (PK/PD) modeling, and the investigation of cellular responses to drugs. Consequently, the relatively young field of organ-on-a-chip devices and MPSs is gradually beginning to make the transition to alternative, nonabsorptive materials for these crucial applications. This review examines some of the first steps that have been made in the development of organ-on-a-chip devices and MPSs composed of such alternative materials, including elastomers, hydrogels, thermoplastic polymers, and inorganic materials. It also provides an outlook on where PDMS-alternative devices are trending and the obstacles that must be overcome in the development of versatile devices based on alternative materials to PDMS.
    Keywords:  PDMS-free; biomaterials; drug testing; elastomers; glass; hydrogels; microfabrication; microphysiological systems; organ-on-a-chip; polydimethylsiloxane; silicon; thermoplastic polymers
    DOI:  https://doi.org/10.1021/acsbiomaterials.0c00640
  20. Nat Commun. 2021 07 21. 12(1): 4445
      Immune checkpoint inhibitors demonstrate clinical activity in many tumor types, however, only a fraction of patients benefit. Combining CD137 agonists with these inhibitors increases anti-tumor activity preclinically, but attempts to translate these observations to the clinic have been hampered by systemic toxicity. Here we describe a human CD137xPD-L1 bispecific antibody, MCLA-145, identified through functional screening of agonist- and immune checkpoint inhibitor arm combinations. MCLA-145 potently activates T cells at sub-nanomolar concentrations, even under suppressive conditions, and enhances T cell priming, differentiation and memory recall responses. In vivo, MCLA-145 anti-tumor activity is superior to immune checkpoint inhibitor comparators and linked to recruitment and intra-tumor expansion of CD8 + T cells. No graft-versus-host-disease is observed in contrast to other antibodies inhibiting the PD-1 and PD-L1 pathway. Non-human primates treated with 100 mg/kg/week of MCLA-145 show no adverse effects. The conditional activation of CD137 signaling by MCLA-145, triggered by neighboring cells expressing >5000 copies of PD-L1, may provide both safety and potency advantages.
    DOI:  https://doi.org/10.1038/s41467-021-24767-5
  21. Adv Exp Med Biol. 2021 ;1302 1-14
      The C-C motif chemokine ligand 2 (CCL2) is a crucial mediator of immune cell recruitment during microbial infections and tissue damage. CCL2 is also frequently overexpressed in cancer cells and other cells in the tumor microenvironment, and a large body of evidence indicates that high CCL2 levels are associated with more aggressive malignancies, a higher probability of metastasis, and poorer outcomes in a wide range of cancers. CCL2 plays a role in recruiting tumor-associated macrophages (TAMs), which adopt a pro-tumorigenic phenotype and support cancer cell survival, facilitate tumor cell invasion, and promote angiogenesis. CCL2 also has direct, TAM-independent effects on tumor cells and the tumor microenvironment, including recruitment of other myeloid subsets and non-myeloid cells, maintaining an immunosuppressive environment, stimulating tumor cell growth and motility, and promoting angiogenesis. CCL2 also plays important roles in the metastatic cascade, such as creating a pre-metastatic niche in distant organs and promoting tumor cell extravasation across endothelia. Due to its many roles in tumorigenesis and metastatic processes, the CCL2-CCR2 signaling axis is currently being pursued as a potential therapeutic target for cancer.
    Keywords:  Angiogenesis; CCL2; CCR2; Cancer; Extravasation; Immunity; Immunosuppression; Invasion; MCP-1; Macrophage; Metastasis; Microenvironment; NFκB; TAM; Tumor
    DOI:  https://doi.org/10.1007/978-3-030-62658-7_1