Biology subjects

Tirrell, M. V.

Publications and source records attributed to Tirrell, M. V..

6 recordsLinked to original sources

bioRxiv2025

Composite biomaterials of polyelectrolyte complex micelle nanoparticles in hyaluronic acid gels enable local, targeted miR-92a inhibition and enhanced angiogenesis in diabetic wound repair

Diabetic wounds are characterized by various cellular deficiencies, particularly insufficient angiogenesis. MicroRNA 92a (miR-92a) is a known factor in diabetic wounds that perpetuates non-healing wound phenotypes by inhibiting angiogenesis. Therefore, its local inhibition at wound sites has therapeutic potential. To achieve this, we combine a nanoparticle formulation of polyelectrolyte complex micelles (PCMs) delivering miR-92a inhibitors with a hyaluronic acid (HA) gel formulation suitable for topical application to wound sites. The nanoparticles, formed by polyelectrolyte complexation of poly(ethylene glycol)-block-poly(L-lysine) with RNA cargo, are functionalized with targeting peptides against vascular cell adhesion molecule 1 (VCAM-1) to improve affinity for inflamed endothelial cells. We demonstrate effective PCM encapsulation and controlled release from gel formulations in vitro and in vivo. These PCMs are taken up in vivo by endothelial cells and exert functional transcriptional effects on miR-92a and its downstream targets. Furthermore, our composite PCM-gel formulation significantly accelerates wound closure in diabetic mouse models and improves angiogenesis, consistent with the known role of miR-92a inhibition in vascular regeneration. This work demonstrates a highly translatable formulation for improved wound healing, and lays the framework for modular nanoparticle-gel systems that can achieve local, cell-targeted RNA delivery. HighlightsPolyelectrolyte complex micelles (PCMs) can be combined with hyaluronic acid gels. VCAM-1 targeted PCMs released from gels are taken up by endothelial cells. PCM-gels deliver miR-92a inhibitors to modulate downstream gene expression in vivo. PCM-gels accelerate wound healing and enhance angiogenesis in diabetic mice.

bioengineering↗

bioRxiv2025

Zwitterionic hydrogel designs for conducting polymers enable bioelectronics with suppressed foreign body response

For long-term, continuous operation of implantable biosensors and electrophysiological devices, the foreign body response (FBR) is a major obstacle that needs to be overcome. As the FBR progresses, any implanted device will become damaged and isolated from its physiological environment, due to encapsulation by fibrotic tissue and inflammatory immune cells. To achieve more compatible and low-impedance biointerfaces, conducting polymers, such as PEDOT:PSS, have been extensively explored as ideal materials. However, FBR on such conducting polymers remains an unmet challenge. We report a zwitteronic-hydrogel-based double-network design for PEDOT:PSS that can significantly suppress the FBR by 64%, in addition to improving conductivity by more than one order of magnitude. Surprisingly, the FBR level of this design is even lower than that of the parent zwitteronic hydrogel by 53%. Our further immunological investigations at the histological, cellular, and transcriptomic levels give deeper insights into the unique effects that come from the chemical heterogeneity. Furthermore, chronic electrocardiographic recording in mice demonstrate the benefit of this material design to long-term, implanted electrophysiology, which provides indications for the future development of immunocompatible electronic polymers.

bioengineering↗

bioRxiv2025

Mechanosensitive Endothelial METTL7A Regulates Internal m7G mRNA Methylation and Protects Against Atherosclerosis

BACKGROUNDInternal N7-methylguanosine (m7G) is a recently identified chemical modification of mammalian mRNA and a component of the epitranscriptome. While the epitranscriptome plays a key role in regulating RNA metabolism and cellular function, the specific contribution of internal m7G to cardiovascular health and disease remains unknown. Atherosclerosis preferentially develops at sites where disturbed blood flow activates endothelial cells, but whether internal m7G and its regulatory machinery influence endothelial mechanotransduction and atherogenesis is unclear. METHODSWe integrated epitranscriptomic profiling, human tissue analysis, genetically modified mouse models, and targeted nanomedicine approaches to investigate the role of Methyltransferase-like protein 7A (METTL7A), a putative internal m7G methyltransferase, in regulating the flow-sensitive endothelial transcriptome and atherosclerosis. Vascular endothelial cells were subjected to well-defined athero-protective and athero-prone flow waveforms in vitro and in vivo. METTL7A function was assessed using RNA sequencing (RNA-seq), liquid chromatography-tandem mass spectrometry (LC-MS/MS), crosslinking immunoprecipitation sequencing (CLIP-seq), RNA stability assays, and a CRISPR-Cas-inspired RNA targeting system (CIRTS). METTL7A expression in human coronary arteries with and without atherosclerosis was evaluated by RNA-seq and immunostaining. In vivo atherosclerosis studies were conducted in both global and endothelial-specific Mettl7a1 knockout mice. Endothelial METTL7A expression was restored using cationic polymer-based nanoparticles delivering CDH5 promoter-driven METTL7A plasmids or VCAM1-targeted lipid nanoparticles delivering N1-methylpseudouridine (m{superscript 1}{Psi})-modified METTL7A mRNA. RESULTSAthero-protective unidirectional flow significantly induced METTL7A expression, which promoted internal m7G methylation of endothelial transcripts, while other major epitranscriptomic marks and cap-associated m7G were not affected by METTL7A. METTL7A preferentially binds to AG-enriched motifs in protein-coding mRNAs and plays a key role in regulating KLF4 and NFKBIA transcripts, enhancing their internal m7G and stability and supporting vascular homeostasis. In contrast, endothelial METTL7A expression was significantly reduced by disturbed blood flow and in human atherosclerotic lesions. Global or endothelial-specific loss of METTL7A exacerbated disturbed flow-induced atherosclerosis in mice, independent of serum lipid levels. Restoration of endothelial METTL7A, via nanoparticle-mediated plasmid or m1{Psi} mRNA delivery, markedly reduced lesion formation in Mettl7a1-/- and ApoE-/- mice. CONCLUSIONSThese findings establish METTL7A as a previously unrecognized mechanosensitive methyltransferase that maintains endothelial homeostasis by stabilizing key anti-inflammatory transcripts, KLF4 and NFKBIA, through internal m7G methylation. Loss of METTL7A disrupts endothelial function and accelerates atherogenesis in response to disturbed flow. Therapeutic restoration of endothelial METTL7A, via targeted nanoparticle-mediated gene or m1{Psi} mRNA delivery, significantly lessens atherosclerosis. Collectively, these results uncover a novel epitranscriptomic mechanism governing vascular health and position METTL7A as a promising target for precision nanomedicine in atherosclerotic cardiovascular disease.

molecular biology↗

bioRxiv2025

Precision mRNA Nanomedicine for Targeted Vascular Therapies in ARDS and Atherosclerosis

Vascular diseases, including acute respiratory distress syndrome (ARDS) and atherosclerosis, are leading causes of global morbidity and mortality, underscoring the critical need for innovative therapies. While human genetics has uncovered specific molecular mechanisms in endothelial cells that drive acute and chronic vascular inflammation central to these conditions, effective in vivo strategies to spatiotemporally target these disease-causing pathways using therapeutic mRNAs remain limited. Here, we present a modular and tunable nanoparticle platform (PROGRAMMED nanoparticles) engineered to selectively deliver therapeutic mRNAs to target cells with distinct molecular signatures, such as inflamed endothelial cells expressing vascular cell adhesion molecule 1 (VCAM1). This approach restores key genetics-informed endothelial pathways implicated in disease, including the loss of Kruppel-like factor 2 (KLF2) in acute inflammation underlying ARDS and the suppression of phospholipid phosphatase 3 (PLPP3) in chronic inflammation driving atherosclerosis. In multiple preclinical models, these precision mRNA nanomedicine strategies demonstrated compelling therapeutic efficacy. VCAM1-targeting PROGRAMMED nanoparticles delivering KLF2 mRNA to inflamed lung microvascular endothelial cells significantly improved microvascular health and alleviated virus-induced ARDS. Similarly, PLPP3 mRNA delivery by VCAM1-targeting PROGRAMMED nanoparticles attenuated arterial inflammation, slowed atherosclerosis progression, and promoted regression of advanced plaques. This innovative platform offers a transformative approach for spatiotemporal mRNA therapies targeting inflamed endothelial cells, providing a minimally invasive and highly specific strategy to address acute and chronic vascular diseases. Moreover, the modularity of PROGRAMMED nanoparticles, particularly their ability to display diverse targeting motifs, holds substantial potential for addressing a broad spectrum of vascular complications and other diseases that require precise spatiotemporal correction of dysregulated genes.

bioengineering↗

bioRxiv2021

Polymersomes decorated with SARS-CoV-2 spike protein receptor binding domain elicit robust humoral and cellular immunity

A diverse portfolio of SARS-CoV-2 vaccine candidates is needed to combat the evolving COVID-19 pandemic. Here, we developed a subunit nanovaccine by conjugating SARS-CoV-2 Spike protein receptor binding domain (RBD) to the surface of oxidation-sensitive polymersomes. We evaluated the humoral and cellular responses of mice immunized with these surface-decorated polymersomes (RBDsurf) compared to RBD-encapsulated polymersomes (RBDencap) and unformulated RBD (RBDfree), using monophosphoryl lipid A-encapsulated polymersomes (MPLA PS) as an adjuvant. While all three groups produced high titers of RBD-specific IgG, only RBDsurf elicited a neutralizing antibody response to SARS-CoV-2 comparable to that of human convalescent plasma. Moreover, RBDsurf was the only group to significantly increase the proportion of RBD-specific germinal center B cells in the vaccination-site draining lymph nodes. Both RBDsurf and RBDencap drove similarly robust CD4+ and CD8+ T cell responses that produced multiple Th1-type cytokines. We conclude that multivalent surface display of Spike RBD on polymersomes promotes a potent neutralizing antibody response to SARS-CoV-2, while both antigen formulations promote robust T cell immunity.

bioengineering↗

bioRxiv2017

Partitioning and Enhanced Self-Assembly of Actin in Polypeptide Coacervates

Biomolecules exist and function in cellular micro-environments that control their spatial organization, local concentration and biochemical reactivity. Due to the complexity of native cytoplasm, the development of artificial bioreactors and cellular mimics to compartmentalize, concentrate and control the local physicochemical properties is of great interest. Here, we employ self-assembling polypeptide coacervates to explore the partitioning of the ubiquitous cytoskeletal protein actin into liquid polymer-rich droplets. We find that actin spontaneously partitions into coacervate droplets and is enriched by up to {approx}30-fold. Actin polymerizes into micrometer-long filaments and, in contrast to the globular protein BSA, these filaments localize predominately to the droplet periphery. We observe up to a 50-fold enhancement in the actin filament assembly rate inside coacervate droplets, consistent with the enrichment of actin within the coacervate phase. Together these results suggest that coacervates can serve as a versatile platform in which to localize and enrich biomolecules to study their reactivity in physiological environments.\n\nSIGNIFICANCE STATEMENTLiving cells harbor many protein-rich membrane-less organelles, the biological functions of which are defined by compartment composition and properties. Significant differences between the physico-chemical properties of these crowded compartments and the dilute solutions in which biochemical reactions are traditionally studied pose a major challenge for understanding regulation of organelle composition and component activity. Here, we report the spontaneous partitioning and accelerated polymerization of the cytoskeletal protein actin inside model polypeptide coacervates as a proof-of-concept demonstration of coacervates as bioreactors for studying biomolecular reactions in cell-like environments. Our work introduces exciting avenues for the use of synthetic polymers to control the physical and biological properties of bioreactors in vitro, enabling studies of biochemical reactions in cell-like micro-environments.

biophysics↗