Biology subjects

Hess, D. A.

Publications and source records attributed to Hess, D. A..

6 recordsLinked to original sources

bioRxiv2026

Inositol phosphates, pyrophosphates and the genes involved in their turnover in the streptophyte green alga Chara braunii

Inositol phosphates (InsPs) and inositol pyrophosphates (PP-InsPs) are conserved signalling molecules, but their evolutionary origin and diversification in the green lineage remain poorly understood. Here we investigated the InsP network in the streptophyte alga Chara braunii, a key lineage lose to the origin of land plants. Using capillary electrophoresis-electrospray ionization mass spectrometry, we detected a broad spectrum of InsP and PP-InsP species from InsP3 to InsP8, including multiple positional isomers. Developmental profiling across dormant oospores, young thalli and mature thalli revealed extensive metabolic remodeling, with InsP6 as the dominant metabolite and distinct stage-dependent changes in lower InsPs and pyrophosphorylated species. Multiple PP-InsP5 and (PP)2-InsP4 isomers were identified, together with an unassigned additional InsP8-like signal, indicating further pathway complexity. Bioinformatic analyses identified candidate homologs of major InsP metabolic enzymes, supporting the presence of an enzymatic framework for InsP synthesis and turnover similar to land plants. Environmental perturbation revealed isomer-selective effects: prolonged light and dark phases strongly affected the accumulation of specific InsP5 and PP-InsP5 isomers, with 1-PP-InsP5 emerging as the most stimulus-responsive pyrophosphate species, whereas heat stress preferentially reduced 4-PP-InsP5. Together, these findings show that a structurally complex and environmentally responsive InsP network was already established in streptophyte algae before the emergence of land plants.

plant biology↗

bioRxiv2025

Co delivery of human adipose derived stromal cells and endothelial colony forming cells in cell-assembled decellularized adipose tissue scaffolds for applications in soft tissue regeneration

Cellular therapies involving the co-delivery of cells with complementary pro-regenerative functionality hold promise as a strategy to promote soft tissue regeneration. In particular, the co-delivery of adipose-derived stromal cells (ASCs) and endothelial colony-forming cells (ECFCs) has shown promise for regenerating stable blood vessels in vivo. The current study developed novel "cell-assembled" scaffolds for co-delivering human ASCs and ECFCs within a supportive decellularized adipose tissue (DAT) matrix, with the objective of enhancing their localized retention and augmenting their capacity to stimulate adipose tissue regeneration. Human ASCs and ECFCs were seeded separately onto human-derived DAT microcarriers under cell-type specific conditions. The cell-seeded microcarriers were then combined and cultured for 8 days under conditions that promoted matrix remodeling to fuse the microcarriers into 3D engineered tissues containing ASCs+ECFCs, ASCs alone, or ECFCs alone. Co-culture with ECFCs within the scaffolds was shown to modulate ASC pro-angiogenic gene expression, with some ECFCs forming tubule-like structures in vitro in both the ASC+ECFC and ECFC alone groups. In vivo bioluminescence imaging using a dual luciferase reporter system showed that co-delivery with ASCs enhanced ECFC retention following subcutaneous implantation in athymic nu/nu mice, but co-delivery did not alter the localized retention of viable ASCs. Interestingly, while immunofluorescence staining for CD31 and microcomputed tomography angiography indicated that vascular regeneration was similar in the cell-assembled scaffolds containing ASC+ECFCs, ASCs alone, and ECFCs alone, histological staining revealed that extensive regions of the ECFC alone scaffolds had remodelled into adipose tissue at 29 days post-implantation.

bioengineering↗

bioRxiv2024

Probing the effects of polysaccharide hydrogel composition on the viability and pro-angiogenic function of human adipose-derived stromal cells

Cell therapies harnessing the pro-vascular regenerative capacities of mesenchymal stromal cell (MSC) populations, including human adipose-derived stromal cells (hASCs), have generated considerable interest as an emerging treatment strategy for peripheral arterial disease (PAD) and its progression to critical limb ischemia (CLI). There is evidence to support that polysaccharide hydrogels can enhance therapeutic efficacy when applied as minimally-invasive delivery systems to support MSC survival and retention within ischemic tissues. However, there has been limited research to date on the effects of hydrogel composition on the phenotype and function of encapsulated cell populations. Recognizing this knowledge gap, this study compared the pro-angiogenic function of hASCs encapsulated in distinct but similarly-modified natural polysaccharide hydrogels composed of methacrylated glycol chitosan (MGC) and methacrylated hyaluronic acid (MHA). Initial in vitro studies confirmed high viability (>85%) of the hASCs following encapsulation and culture in the MGC and MHA hydrogels over 14 days, with a decrease in the cell density observed over time. Moreover, higher levels of a variety of secreted pro-angiogenic and immunomodulatory factors were detected in conditioned media samples collected from the hASCs encapsulated in the MGC-based hydrogels compared to the MHA hydrogels. Subsequent testing focused on comparing hASC delivery within the MGC and MHA hydrogels to saline controls in a femoral artery ligation-induced CLI (FAL-CLI) model in athymic nu/nu mice over 28 days. For the in vivo studies, the hASCs were engineered to express tdTomato and firefly luciferase to quantitatively compare the efficacy of the two platforms in supporting the localized retention of viable ASCs through longitudinal cell tracking with bioluminescence imaging (BLI). Interestingly, hASC retention was significantly enhanced when the cells were delivered in the MHA hydrogels as compared to the MGC hydrogels or saline. However, laser Doppler perfusion imaging (LDPI) indicated that the restoration of hindlimb perfusion was similar between the treatment groups and controls. These findings were corroborated by endpoint immunofluorescence (IF) staining showing similar levels of CD31+ cells in the ligated limbs at 28 days in all groups. Overall, this study demonstrates that enhanced MSC retention may be insufficient to augment vascular regeneration, emphasizing the complexity of designing biomaterials platforms for MSC delivery for therapeutic angiogenesis. In addition, the data points to a potential challenge in approaches that seek to harness the paracrine functionality of MSCs, as strategies that increase the secretion of immunomodulatory factors that can aid in regeneration may also lead to more rapid MSC clearance in vivo.

bioengineering↗

bioRxiv2023

Delivery of human adipose-derived stromal cells within mechanically resilient hydrogels induces adverse outcomes in a femoral artery ligation model in athymic nu/nu mice

The delivery of human adipose-derived stromal cells (hASCs) to ischemic tissues represents a promising strategy to promote vascular regeneration for patients with critical limb ischemia (CLI). Building on previous work, this study focused on the in vivo characterization of a hydrogel cell delivery platform for hASCs composed of peptide-functionalized methacrylated glycol chitosan (MGC-RGD) and a terminally acrylated triblock copolymer of poly(ethylene glycol) and poly(trimethylene carbonate) (PEG(PTMC-A)2) in athymic nu/nu mice with femoral artery ligation-induced critical limb ischemia (FAL-CLI). This immunodeficient mouse strain was selected to enable human cell transplantation in a model with conserved monocyte/macrophage function, recognizing that macrophages are key regulators of the biomaterial implant response, as well as vascular repair and regeneration. The hASCs were engineered to co-express tdTomato and firefly luciferase to enable longitudinal cell tracking using bioluminescence imaging (BLI). Interestingly, the hASCs were better retained following delivery in saline compared to hydrogel delivery. However, laser Doppler perfusion imaging (LDPI) analysis indicated that the restoration of hindlimb perfusion was similar between the two cell treatment groups. Critically, delivery of the hASCs within the hydrogels was associated with adverse outcomes only observed within this treatment group, including severe swelling, discoloration, and necrosis, which necessitated early euthanasia of some mice. CD45 staining supported that the combination of the cells and the hydrogels induced an inflammatory host response. These findings contrast with previous positive results when the platform was tested for hASC delivery in more severely immunocompromised NOD/SCID mice with FAL-CLI, as well as allogeneic rat ASC delivery in a healthy immunocompetent rat model. Overall, this study emphasizes the potential importance of testing cell delivery platforms in pre-clinical disease models that have retained host immune cell function, especially for immunomodulatory cell populations such as ASCs.

bioengineering↗

bioRxiv2023

Targeting the MR1-MAIT Cell Axis Improves Vaccine Efficacy and Affords Protection against Viral Pathogens

Mucosa-associated invariant T (MAIT) cells are MR1-restricted, innate-like T lymphocytes with tremendous antibacterial and immunomodulatory functions. MAIT cells also sense and respond to viral infections in an MR1-independent fashion. However, whether they can be directly targeted in immunization strategies against viral pathogens is unknown. We addressed this question in multiple wild-type and genetically altered but clinically relevant mouse strains using several vaccine platforms against influenza viruses, poxviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We demonstrate that 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU), a riboflavin-based MR1 ligand of bacterial origin, can synergize with viral vaccines to expand MAIT cells in multiple tissues, reprogram them towards a pro-inflammatory MAIT1 phenotype, license them to bolster mainstream virus-specific CD8+ T cell responses, and potentiate heterosubtypic antiviral protection. Repeated 5-OP-RU administration did not render MAIT cells anergic, thus allowing for its inclusion in prime-boost immunization protocols. Mechanistically, tissue MAIT cell accumulation was due to their robust proliferation, as opposed to altered migratory behavior, and required viral vaccine replication competency, Toll-like receptor 3 (TLR3) and cell-autonomous type I interferon receptor signaling. Furthermore, the observed phenomenon was manifest in young and old female and male mice, and could also be recapitulated in a human cell culture system in which peripheral blood mononuclear cells were exposed to replicating virions and 5-OP-RU. In conclusion, although viruses and virus-based vaccines are devoid of the riboflavin biosynthesis machinery that supplies MR1 ligands, targeting MR1 enhances the efficacy of vaccine-elicited antiviral immunity. We propose 5-OP-RU as a non-classic but potent and versatile vaccine adjuvant against respiratory viruses.

immunology↗

bioRxiv2020

Ultrafiltration Segregates Tissue Regenerative Stimuli Harboured Within and Independent of Extracellular Vesicles

The release of extracellular vesicles (EVs) from human multipotent stromal cells (MSC) has been proposed as a mechanism by which MSC mediate regenerative functions in vivo. Our recent work has characterized MSC derived from human pancreatic tissues (Panc-MSC) that generated a tissue regenerative secretome. Despite these advancements, it remains unknown whether regenerative stimuli are released independent or within extracellular vesicles. Herein, this study demonstrates ultrafiltration is a simple method to enrich for EVs which can be injected in murine models of tissue regeneration. The enrichment of EVs from Panc-MSC conditioned media (CM) was validated using nanoscale flow cytometry and atomic force microscopy; in addition to the exclusive detection of classical EV-markers CD9, CD81, CD63 using label-free mass spectrometry. Additionally, we identified several pro-regenerative stimuli, such as WNT5A or ANGPT1, exclusive to EV-enriched CM. Endothelial cell tubule formation was enhanced in response to both Panc-MSC CM fractions in vitro yet only intramuscular injection of EV-enriched CM demonstrated vascular regenerative functions in NOD/SCID mice with unilateral hind-limb ischemia (*<p<0.05). Furthermore, both EV-depleted and EV-enriched CM reduced hyperglycemia following intrapancreatic injection in hyperglycemic mice (**p<0.01). Collectively, understanding the functional synergy between compartments of the secretome is required to advance cell-free biotherapeutics into applications of regenerative medicine.

cell biology↗