Katharina Maisel

Age-related changes in the immune system result in pronounced vulnerability to acute infections and cancers, and in dysregulated inflammation and wound healing that fuel many chronic diseases. Although we understand much about some of these changes, gaps in mechanistic knowledge remain, in part hindered by a lack of well-validated in vitro models of immune aging. We propose that multidisciplinary approaches, nucleated at the interface of immunology, gerontology and engineering, have the potential to both bring substantial new knowledge, and to usher a new era of precision diagnostics and therapeutics to reprogram and rejuvenate immunity, potentially improving the length and quality of life in older adults. We outline areas to be addressed by this multidisciplinary approach, focusing on the initiation of immune responses. We discuss the potential for new approaches in drug delivery, extracellular matrix and related biomaterials, and in microphysiological and organoid systems, to advance the science of immune aging.

The extracellular matrix (ECM) plays a pivotal role in lymphatic vasculature physiology, yet the specific contribution of individual ECM components to lymphatic endothelial permeability remains poorly understood, limiting the development of physiologically relevant in vitro models for lymphatic disease research and therapeutic development. Here, we used an in vitro transwell platform to systematically investigate how four clinically relevant ECM proteins, collagen I, fibronectin, fibrin, and laminin, regulate human lymphatic endothelial cell (LEC) barrier function and junctional integrity. Fibrin and collagen I substrates enhanced barrier integrity, demonstrating 80% and 67% increases in transendothelial electrical resistance (TEER), respectively, compared to uncoated controls. FITC-dextran transport assays confirmed these findings, with fibrin and collagen I reducing permeability by 20% and 10%, respectively. Immunofluorescence analysis revealed elevated ZO-1 expression on fibrin, fibronectin, and laminin matrices, while VE-cadherin levels remained unchanged across conditions. Quantitative junctional analysis demonstrated that fibrin increased ZO-1 junction continuity by ∼35%, while collagen I and fibronectin enhanced continuity by ∼22%, with all ECM coatings reducing discontinuous junctions by 60–80%. Mechanistically, RhoA expression was reduced in LECs cultured on fibrin, suggesting decreased stress fiber formation contributes to enhanced barrier function, though overall actin cytoskeletal anisotropy remained unchanged. These findings demonstrate that ECM composition modulates LEC junctional organization and barrier integrity, with fibrin and collagen I exerting the most pronounced barrier-enhancing effects. This engineered platform provides a foundation for developing next-generation in vitro models of lymphatic vasculature that more accurately recapitulate physiological conditions, with applications in lymphedema research, cancer metastasis studies, and immune cell trafficking investigations.

Cervical cancer is a leading cause of death in women in low‐ and middle‐income countries (LMICs) and disproportionately affects women of minority populations in the United States, primarily due to a lack of infrastructural support for specialized care. A promising treatment that meets accessibility requirements is ethyl cellulose (EC)‐ethanol ablation—inducing necrotic cell death through application of ethanol to kill precancerous cells. While previous work focused on injecting EC‐ethanol to ablate high‐grade dysplasia (which can reach depths up to 5 mm below the tissue surface), low‐grade dysplasia requires a different delivery method as it is much more superficial (reaching depths of only 1–3 mm). Here, we have developed a topical gel for local ethanol ablation of low‐grade dysplasia with minimal damage to healthy cervical tissue. We investigated several gellants, including methyl cellulose (MC), EC, and Pluronic® F‐127, to develop an ethanol gel that meets parameters for low cost and topical ease of use. Formulations with F‐127 did not form gels with ethanol. Formulations with EC and MC were gel‐forming. The MC‐based formulations formed more uniform and stable gels that hold their own weight while still being spreadable at both room and body temperatures, key criteria for local cervical application. The optimal formulation contained 70% ethanol, 20% water, and 10% MC. One gram of this formulation represents approximately 5¢ material cost, and formulated gels were stable for at least 1 week when stored at 4, 22, 30, and 37°C. Additionally, the MC gel achieved localized ablation within 5 min after application to cervical cancer cells in vitro. Taken together, we have developed a low‐cost, efficacious, MC‐based ethanol gel fit for translational testing to treat low‐grade cervical dysplasia. This gel may provide a novel treatment option for women in LMICs, without causing major side effects or loss of healthy cervical tissue.

Inflammatory bowel disease (IBD) is a chronic condition characterized by recurrent gastrointestinal inflammation that requires long-term therapeutic intervention. While anti-TNF-α monoclonal antibodies (mAbs) are effective in maintaining remission in IBD, systemic delivery is associated with immunosuppression, poor targeting efficiency, and high cost. To address these limitations, we developed a synthetic mucin-based hydrogel for localized delivery of TNF-α-targeting mAbs. Mucins are heavily glycosylated biopolymers that naturally bind antimicrobial and anti-inflammatory proteins, making them well-suited for local biologic drug delivery at mucosal sites. Synthetic mucin-based hydrogels were formed by cross-linking mucin harvested from porcine small intestine with a 4-arm PEG-thiol and loaded with mAbs to evaluate biocompatibility, antibody release kinetics, and therapeutic efficacy. In vitro studies confirmed cytocompatibility of mucin-based hydrogels and demonstrated diffusion-dependent release of full-length IgG antibodies, with enhanced release under proteolytic conditions simulating the gastrointestinal environment. Moreover, mucin-based hydrogels alone were found to modulate macrophage activation in a stiffness dependent manner and dampen inflammation in lipopolysaccharide (LPS)-stimulated macrophages. Treatment of LPS-stimulated macrophages with mAb-loaded hydrogels reduced pro-inflammatory cytokine production and macrophage activation, confirming retention of mAb bioactivity. Compared to antibodies administered in solution, in vivo biodistribution studies revealed greater absorption of antibodies when loaded in mucin-based hydrogels and administered via enema in trinitrobenzene sulfonic acid-induced colitis mice, likely due to enhanced adhesion to mucosal epithelium and slowed intestinal clearance. This study demonstrates the potential of mucin-based hydrogels as a platform for local mAb delivery in IBD, enabling targeted immunosuppression while minimizing systemic exposure.

Cell penetrating peptides have emerged as a prime tool for enhancing nanocarrier barrier penetration and targeted drug delivery outcomes. Illustration made using BioRender. The graphical abstract was created in BioRender. Maisel, K. (2025) https://BioRender.com/iouxsm2.

Lymph nodes are highly specialized immune organs that orchestrate the adaptive immune response. In the lymph nodes, naïve B and T lymphocytes encounter cognate antigens, sparking their activation and response to foreign substances. Lymph nodes grow in response to an immune challenge, at least in part to accommodate increased numbers of infiltrating and proliferating B and T lymphocytes. This behavior is supported by a robust three-dimensional network of extracellular matrix (ECM) fibers and fibroblastic reticular cells (FRCs). ECM fibers and FRCs work synergistically to alternate stretching and contractile forces between them allowing the lymph node to maintain structural integrity during rapid tissue reconstruction. These changes ultimately alter the material properties of the lymph node, which can impact cell migration, proliferation, and differentiation. Recent work has investigated the physiological implications of the changing lymph node microenvironment; however, the biophysical properties of the lymph nodes during these changes remain largely unexplored. Here, we use multiple particle tracking microrheology (MPT), a minimally invasive nanoparticle-based technique to investigate the biophysical properties (elastic/loss moduli, microviscosity, pore size) of lymph nodes post inflammatory stimulus. Our results highlight mechanical changes both during the initial phases of the acute inflammatory response and upon resolution of inflammation, a topic that is relatively understudied. We show that B and T cell rich areas exhibit comparable changes in biomechanical properties over time, suggesting that they restructure in a similar fashion during acute inflammation. Additionally, for the first time, we show that biological sex modulates lymph node biomechanics in acute inflammation: Lymph nodes from female mice showed a ∼20-fold increase in elastic and loss moduli at peak inflammation, while lymph nodes from male mice had a ∼5-fold decrease in both moduli. Additionally, lymph nodes from female mice appeared to permanently remodel during the resolution of acute inflammation resulting in the maintenance of an overall higher elastic and loss modulus, while lymph nodes from male mice returned to the biomechanics of untreated lymph nodes. We also found that at least some of the changes in biomechanical properties were correlated with changes in ECM materials in the lymph nodes, suggesting a structure-function relationship. Overall, our studies provide key insights into how biomechanical properties in lymph nodes are altered during inflammation, a previously unstudied area, and lay the foundation for structure-function relationships involved in immune response. Additionally, we demonstrate a robust technique for the analysis of the lymph node interstitial tissue properties and how they vary with inflammatory stimuli.

Lymphangioleiomyomatosis (LAM) is a devastating disease primarily found in women of reproductive age that leads to cystic destruction of the lungs. Recent work has shown that LAM causes immunosuppression and that checkpoint inhibitors can be used as LAM treatment. Toll-like receptor (TLR) agonists can also reactivate immunity, and the TLR9 agonist CpG oligodeoxynucleotide (CpG-ODN) has been effective in treating lung cancer in animal models. In this study, we investigated the use of TLR9 agonist CpG-ODN as LAM immunotherapy in combination with checkpoint inhibitor anti-PD1 and standard of care rapamycin, and determined the immune mechanisms underlying therapeutic efficacy. We used survival studies, flow cytometry, ELISA, and histology to assess immune response and survival after intranasal treatment with CpG-ODN in combination with rapamycin or anti-PD1 therapy in a mouse model of metastatic LAM. We found that local administration of CpG-ODN enhances survival in a mouse model of LAM. We found that a lower dose led to longer survival, likely because of fewer local side effects, but increased LAM nodule count and size compared with the higher dose. CpG-ODN treatment also reduced regulatory T cells and increased the number of T-helper type 17 cells as well as cytotoxic T cells. These effects appear to be mediated in part by plasmacytoid dendritic cells because depletion of plasmacytoid dendritic cells reduces survival and abrogates T-helper type 17 cell response. Finally, we found that CpG-ODN treatment is effective in early-stage and progressive disease and is additive with anti-PD1 therapy and rapamycin. In summary, we have found that TLR9 agonist CpG-ODN can be used as LAM immunotherapy and effectively synergizes with rapamycin and anti-PD1 therapy in LAM.

Being able to isolate and prepare single cells for the analysis of tissue samples has rapidly become crucial for new biomedical discoveries and research. Manual protocols for single-cell isolations are highly time-consuming and prone to user variability. Automated mechanical protocols are able to reduce processing time and sample variability but aren't easily accessible or cost-effective in lower-resourced research settings. The device described here was designed for semi-automated tissue dissociation using commercially available materials as a low-cost alternative for academic laboratories. Instructions to fabricate, assemble, and operate the device design have been provided. The dissociation protocol reliably produces single-cell suspensions with comparable cell yields and sample viability to manual preparations across multiple mouse tissues. The protocol provides the ability to process up to 12 tissue samples simultaneously per device, making studies requiring large sample sizes more manageable. The accompanying software also allows for customization of the device protocol to accommodate varying tissues and experimental constraints.