Wednesday, January 22, 2025
1/22/2025
ABSTRACT During fetal skin development, over thirty distinct cell types emerge to form a solid barrier capable of immune surveillance and sensory detection. Due to its complexity, the skin has been challenging to reproduce in cultures. Maintenance of excised skin has only been possible for short durations. Yet, a longer-term skin culture system could greatly benefit efforts to model congenital diseases, investigate the mechanisms of cancer initiation, or mimic the site of infection, inflammation, and wounds. A critical obstacle to progress has been our inability to identify culture conditions that satisfy the metabolic needs of cells found in every skin subdomain, including skin appendages, such as hair follicles and sweat glands, and accessory structures, such as vasculature and nerves. Incorporating diverse immune cell populations has evaded previous engineering attempts. Recently, we invented a novel culture system that uses human pluripotent cells (hPSCs) to generate full-thickness skin with many of the cellular components of normal skin, including epidermis, dermis, hair follicles, and sensory nerves—collectively known as skin organoids. Although an improvement over previous skin models in terms of completeness, the resulting skin arises as a massive floating tissue that is challenging to monitor over time in culture and is devoid of immune cells. Here, we will build on preliminary data showing that skin organoids can reformat onto easily imaged microfluidic chips that we have maintained for over 100 days without apparent tissue degradation. For Goal 1, we will optimize a manufacturing process for creating hair-bearing skin organoids-on-a-chip by iteratively evaluating chip geometry, matrix composition, mechanical properties, and chemical treatments supplied to the developing tissue. We will use quantitative imaging and single-cell and spatial transcriptomics to assess the quality of our chip designs. For Goal 2, we will evaluate a novel chip design that better integrates neuro-vascular structures into the skin organoid chips. For Goal 3, we will build on exciting preliminary data to integrate myeloid and lymphoid lineage cells into developing skin organoid chips. We will define the proper timing and medium requirements for immune cell seeding and assess the fidelity of immuno-competent skin organoid chips through direct comparison to fetal histological specimens. We will test the system by simulating immune reactions due to hPSC donor incompatibility and bacterial infection. These experiments will yield chips with stereotyped neural inputs and vascular networks. Our collaborative team has strong bioengineering, material science, neuroscience, and immunology expertise and is uniquely suited to execute the project goals. Our research strategy considers how others could adopt our methodology, and we include plans for beta-testing tissue chip production in less equipped laboratories. We anticipate that our skin organoid tissue chips will provide researchers with a powerful new tool to watch and learn as human skin develops under normal and diseased conditions.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).