This Funding Opportunity Announcement (FOA) will support the development of in vitro platforms that recapitulate components of the human immune system. Applications that qualify for this funding will focus on engineering 3-D in vitro microphysiological immune system tissues, adding immune system responsiveness to existing in vitro platforms, and/or in vitro modelling of autoimmune diseases and inflammation. This FOA is part of a broader effort by NIH to encourage the development of validated alternatives to the use of human fetal tissue in biomedical research, as indicated in NOT-OD-19-042.
Understanding the human immune system is key to diagnosing and managing a number of physiological conditions, from wound healing and the natural response to a pathogen (virus or bacterium) to cancer and autoimmune diseases. For example, in recent years researchers and clinicians have worked to engineer a stronger immune response in certain patients, by applying an Adaptive Cell Transfer therapy via CAR T-cells. Further, the immune system, and specifically the wound healing and repair processes, can be negatively affected by certain diseases, such as diabetes, which ails over 30 million people in the United States alone. Thus, a better understanding of the immune system and its interactions with other physiological systems is key in addressing diseases. This in-depth understanding can be provided by developing animal and in vitro research models of the human immune system, with well-controlled experimental parameters.
These models do have some limitations, however. For example, the use of animal models or human-fetal-tissue-based in vitro models in biomedical research raises ethical issues and frequently these models do not completely recapitulate human physiology and pathology. On the other end of the complexity spectrum, in vitro cultures of cells grown as flat monolayers also poorly emulate in vivo tissue responses due to the lack of organizational and cellular intricacy and architecture of normal tissues. An alternative that could overcome these deficiencies is the use of tissue chip platforms, which are novel in vitro 3D tissue models. These platforms leverage micro-fabrication and microfluidic technologies to create continuously perfused, prefabricated, micrometer-sized environments for co-culturing living cells. They can incorporate different mature cell types, as well as stem and progenitor cells that comprise a given organ in combination with other complex factors found in vivo, including extracellular scaffolding, cellular interactions (including between different cell types), perfusion, hormone responses etc. Technical features of the tissue chips permit precise application of physiologically relevant fluids (such as growth media), physical forces, including biomechanical stresses (stretch and shear forces from fluid flow), electrical stimulation of excitable tissue, mechanical compression etc. – in order to simulate changing local physiologic conditions. While unlikely to completely replace animals, this technology could transform many areas of basic and translational research as a paradigm-shifting alternative to conventional tissue culture and animal models. Additionally, tissue chips could be particularly powerful when multiple tissue platforms are joined to produce rudimentary models of human physiological systems, such as circulatory, musculoskeletal, endocrine, immune etc.
A limitation of current in vitro platforms is that they do not reflect the full complexity of human physiology, such as immune responsiveness – although several unique in vitro platforms (heart, kidney, liver, lung, and others) have demonstrated human organotypic physiological functions and response to drug exposure. Additionally, models of tissues that are an integral part of the human immune system (e.g. spleen, lymph node, thymus) and in vitro models of wound healing and inflammation processes as well as autoimmune diseases are still lacking. Therefore, this funding opportunity seeks to stimulate a currently underdeveloped technology – 3D in vitro models of parts of the human immune system as well as models that expand the functionality of existing tissue chips.
We expect that the use of these tissue chips will result in unprecedented opportunities for addressing mechanistic questions of health and disease, as well as assessing biomedical interventions, especially when combined with in vitro models of other human tissues toward a comprehensive “body-on-a-chip” approach. These platforms will also aid the screening of signaling molecules, drug targets etc. and will help to develop Precision Medicine-based approaches focused on specific patient populations.
Specific Research Objectives
The goal of this initiative is to develop tools and technologies to allow robust, precise and predictable in vitro assembly and functional morphogenesis of 3D micro-tissues that play an important role in the human immune system: 1) as primary immune system organs and tissues (lymph node, lymphatic vessels, spleen, thymus, tonsils, leukocyte-producing bone marrow) and 2) as secondary tissues affected by inflammatory/wound healing processes and autoimmune diseases (e.g. gut, skin, muscle, or granuloma). These tissue chips should mimic architecture, organization, multi-tissue interfaces, physiology and disease pathology of native human tissues.
The team-based project between bioengineers and immunologists will balance the engineering aspects of tissue chip development with proven immunology expertise in the service of efficacy and validation of the in vitro models. Further, the intent of the project must be on building an in vitro platform with broad applicability to physiological conditions of the immune system, such as wound healing, inflammation, and autoimmune diseases.
Essential characteristics of the tissue models should include all or some of the following features: 1) multicellular architecture that represents characteristics of the tissues or organs of pathology; 2) functional representation of normal and / or diseased human biology; 3) reproducible and viable operation under physiological conditions in culture; and 4) accurate representation of normal and / or disease phenotypes. To demonstrate a functional representation of normal or diseased human immune tissue models, the model characteristics should be cross-validated with clinical measures in humans. Ideally the platform should utilize human primary tissue or iPSC-derived patient cell sources and be compatible with high content screening platforms that include multiple molecular read-outs, such as gene expression, proteomic, metabolomic, or epigenomic analyses. The bioengineered platform should also provide spatial and temporal control of the cellular microenvironment, while enabling continuous monitoring (sensing), probing (direct in-cell measurements), and sampling (testing and continuous data collection and analysis) of the system.
Quantitative milestones and benchmarks should be described in the Research Strategy as a tool to monitor periodic progress.
Examples of research supported by this FOA include, but are not limited to, the following areas:
- A microphysiological lymphoid organ (e.g. lymph node, spleen, thymus, lymphopoietic bone marrow-on-a-chip
- Integration of immune effector and/or regulatory cells into an existing in vitro tissue model
- Wound healing in fibrous tissue
- Models of pathological immune processes (e.g. chronic inflammatory processes, non-healing wounds, ulcerated, progressive skin ulcers etc.)
- Models of granuloma and their interactions with other tissues
Desired model characteristics may include, but are not limited to the following:
- Innovative and creative approaches using tissue-on-chips technology towards 3-D models that include relevant anatomical and cellular elements
- Integration of proposed disease models with other organ systems to understand how tissue interactions influence disease pathogenesis, comorbidities, and treatment
- Inclusion of immune elements (e.g., lymphocytes, macrophages, neutrophils, or mucosa-associated lymphoid tissue)
- Inclusion of site-specific microbiota, where appropriate
- Accurate reflection of human host – pathogen interactions, where appropriate
- Capacity to test biomarkers or candidate therapeutics
- Applying genome manipulation strategies, such as CRISPR/Cas9, Talen and Zinc-finger to introduce relevant variants
To be considered for funding for this initiative, applications should NOT focus on the following:
- The use of animal tissues
- Genetic / epigenetic manipulation of specific immune cells that do not entail interaction with non-lymphoid tissues
- Cancer models
Cells: The use of transformed or immortalized cell lines as well as animal tissue is discouraged, except for preliminary, proof of concept studies. The use of primary cells, organ explants, or pluripotent stem cells, e.g., iPSC, is encouraged. Multipotent or unipotent stem cells also may be utilized where appropriate. The current NIH guidance on stem cell usage can be found at http://stemcells.nih.gov/policy/pages/2009guidelines.aspx.
Biomaterials: Native extracellular matrices (ECM) are dynamic, complex microenvironments that can drive functional and biomechanical development. Applicants should consider the biological properties and potential downstream effects when choosing ECM materials. Biomaterials should be chosen to avoid confounding characteristics, e.g., the plastic polydimethylsiloxane (PDMS) binds hydrophobic drugs or reagents, which decreases the intended concentration, and can leach the endocrine disruptor cyclosilane into the medium.
Leveraging Existing Research Resources
NIH utilizes expertise (organ physiology, regulatory science, stem cells, bioengineering etc.) from many Institutes, Centers, and Offices at the NIH and the Food and Drug Administration, as well as the private sector. The Tissue Chip (TC) Consortium, which comprises all these partnerships, and the funded investigators, holds an in-person meeting every 6 months and plays a pivotal role in advancing the MPS technology. Awardees from this FOA will be members of the TC Consortium. Awardees should budget travel for two annual visits to the TC Consortium at NIH, Bethesda, MD.
NIAMS: NIAMS is interested in applications developing in vitro human tissue platforms that recapitulate the human immune system or components of the system in the NIAMS mission relevant diseases, conditions, organs, and tissue systems, such as engineering 3D in vitro microphysiological human immune system tissues, adding immune system responsiveness to existing in vitro human musculoskeletal and/or skin tissue platforms, and/or modelling autoimmune diseases and inflammation of NIAMS mission areas.
Deadlines: February 27, 2019 for non-AIDS proposals; March 26, 2019 for AIDS proposals. Letters of intent are due 30 days prior to the deadline.
Filed Under: Funding Opportunities