Biology subjects

Dixon, J. B.

Publications and source records attributed to Dixon, J. B..

5 recordsLinked to original sources

bioRxiv2026

Lymph Node Dissection and Radiation in the Rat Popliteal Region Leads to Progressive Lymphatic Pump Failure and Lymphedema

BackgroundLymphedema, a chronic and incurable condition with limited therapeutic options, has limited options to quantitatively assess functional changes during its development; as a result, a deeper understanding of its pathophysiology remains hindered. To characterize lymphatic alterations and their association with disease pathology in a clinically relevant model in the rat, we developed a longitudinal iPhone-based volumetry method combined with non-invasive NIR analysis of lymphatic function. Material and methodsSecondary lymphedema was induced by surgery and single-dose irradiation. iPhone volumetry provided longitudinal measurements of hindlimb volume, while NIR imaging quantified the pumping function of major lymphatic vessels in the popliteal area. ResultsAmong 30 rats, lymphedema developed in 80%, defined as interlimb volume differences exceeding 5% and persisting through 14 days. In all rats with lymphedema, disease persisted until the end of the study at postoperative day 42 (P = 0.0015). NIR imaging revealed lymphatic dilation, dye extravasation, and lymphangiogenesis in affected limbs. Lymphatics in limbs with lymphedema exhibited increased contraction frequency, reduced amplitude, and diminished transport compared to baseline and contralateral controls (all P < 0.05). In contrast, rats that did no develop lymphedema showed no postoperative functional changes, although at baseline they displayed higher frequency and lower amplitude and transport compared with LE rats (all P < 0.001). Baseline transport values correlated negatively with swelling (r = -0.44, P = 0.002), as determined by ROC analysis, which yielded an AUC of 0.83, a sensitivity of 83.3%, and a specificity of 82.6%. Histopathology at day 42 confirmed significant dermal thickening and fat deposition in LE limbs (P < 0.001 and P = 0.002, respectively). ConclusionLongitudinal volumetry and NIR imaging applied to a clinically relevant animal model suggest a strong association between swelling and lymphatic function, which could provide deeper insight into lymphedema pathophysiology and represent valuable tools for future research and therapeutic development.

bioinformatics↗

bioRxiv2025

Metabolically driven differentiation of human pluripotent stem cells to generate robust and functional lymphatic endothelial cells

The lymphatic system plays various crucial but underappreciated roles in fluid transport and immune response in numerous organs and tissue types. Consequently, generation of lymphatic vessels has been postulated as an innovative therapeutic strategy for various diseases. However, there is a lack of efficient and reliable method to differentiate human pluripotent stem cells into lymphatic endothelial cells (LEC) for lymphatic regeneration. Current differentiation methods suffer from poor yield and low lymphatic marker expression, while also having limited clinical applicability due to its reliance on either the embryoid body intermediates or xenogenic supporting cells. Given that LECs exclusively rely on anaerobic and fatty acid metabolism due to the hypoxic environment of the lymph, here we report that the unique lymphatic-specific metabolic pathways can be exploited to promote lymphatic identity in differentiated LECs (dLECs). We show that dLECs express elevated levels of lymphatic markers compared to native endothelial cells, which is up to 15 times higher than the current leading standard of dLECs. Moreover, dLECs can form lymphatic vascular networks in both 2D and 3D, as well as secrete important lymphangiocrine for organ maturation. Upon implantation into double-ligation tail lymphedema and mammary fat pad models, dLECs were able to integrate with the host lymphatic vessels, restore fluid flow, and reduce swelling. Collectively, we show that metabolite supplementation can drive stem cell differentiation into dLECs, which can be incorporated into new alternative methods for personalized therapies and disease modeling, as well as provide a direct therapeutic option for lymphedema and lymphatic disorders. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/686405v2_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1c4caa5org.highwire.dtl.DTLVardef@d42b08org.highwire.dtl.DTLVardef@1554ffcorg.highwire.dtl.DTLVardef@1f64ae6_HPS_FORMAT_FIGEXP M_FIG C_FIG A xeno-free and stepwise differentiation protocol with VEGF-C and sodium acetate induces lymphatic identity in iPSC-derived endothelial cells. Differentiated LECs (dLECs) express key lymphatic markers as verified using bulk RNA-sequencing, qPCR, FACS, and immunostaining. These dLECs secrete important cytokines for lympangiocrine signaling, able to form robust 2D and 3D lymphatic networks, as well as demonstrate in vivo functionality and host integration in murine models.

bioengineering↗

bioRxiv2024

Lymphatic endothelial cell-targeting lipid nanoparticles delivering VEGFC mRNA improve lymphatic function after injury

Dysfunction of the lymphatic system following injury, disease, or cancer treatment can lead to lymphedema, a debilitating condition with no cure. Advances in targeted therapy have shown promise for treating diseases where conventional therapies have been ineffective and lymphatic vessels have recently emerged as a new therapeutic target. Lipid nanoparticles (LNPs) have emerged as a promising strategy for tissue specific delivery of nucleic acids. Currently, there are no approaches to target LNPs to lymphatic endothelial cells, although it is well established that intradermal (ID) injection of nanoparticles will drain to lymphatics with remarkable efficiency. To design an LNP that would effectively deliver mRNA to LEC after ID delivery, we screened a library of 150 LNPs loaded with a reporter mRNA, for both self-assembly and delivery in vivo to lymphatic endothelial cells (LECs). We identified and validated several LNP formulations optimized for high LEC uptake when administered ID and compared their efficacy for delivery of functional mRNA with that of free mRNA and mRNA delivered with a commercially available MC3-based LNP (Onpattro). The lead LEC-specific LNP was then loaded with VEGFC mRNA to test the therapeutic advantage of the LEC-specific LNP (namely, LNP7) for treating a mouse tail lymphatic injury model. A single dose of VEGFC mRNA delivered via LNP7 resulted in enhanced LEC proliferation at the site of injury, and an increase in lymphatic function up to 14-days post-surgery. Our results suggest a therapeutic potential of VEGFC mRNA lymphatic-specific targeted delivery in alleviating lymphatic dysfunction observed during lymphatic injury and could provide a promising approach for targeted, transient lymphangiogenic therapy. One Sentence SummaryDevelopment of a novel lymphatic endothelial cell-targeting lipid nanoparticle via in vivo screening for mRNA delivery improves lymphatic regeneration and function after injury.

bioengineering↗

bioRxiv2021

Multichromatic Near-Infrared Imaging to Assess Interstitial Lymphatic and Venous Uptake In Vivo

SignificanceChanges in interstitial fluid clearance are implicated in many diseases. Using NIR imaging with properly sized tracers could enhance our understanding of how venous and lymphatic drainage are involved in disease progression or enhance drug delivery strategies. AimWe investigated multichromatic NIR imaging with multiple tracers to assess in vivo microvascular clearance kinetics and pathways in different tissue spaces. ApproachWe used a chemically inert IR Dye 800CW (free dye) to target venous capillaries and a purified conjugate of IR Dye 680RD with a 40 kDa PEG (PEG) to target lymphatic capillaries in vivo. Optical imaging settings were validated and tuned in vitro using tissue phantoms. We investigated multichromatic NIR imagings utility in two in vivo tissue beds - the mouse tail and rat knee joint. We then tested the ability of the approach to detect interstitial fluid perturbations due to exercise. ResultsIn an in vitro simulated tissue environment, free dye and PEG mixture allowed for simultaneous detection without interference. Co-injected NIR tracers cleared from the interstitial space via distinct routes allowed assessment lymphatic and venous uptake in the mouse tail. We determined that exercise after injection transiently increased lymphatic drainage as measured by lower normalized intensity immediately after exercise, while exercise pre-injection exhibited a transient delay in clearance from the joint ConclusionsNIR imaging enables of simultaneous imaging of lymphatic and venous-mediated fluid clearance with great sensitivity and can be used to measure transient changes in clearance rates and pathways.

bioengineering↗

bioRxiv2020

Effect of human synovial fluid from osteoarthritis patients and healthy individuals on lymphatic contractility

The lymphatic system has been proposed to play a crucial role in the development and progression of osteoarthritis (OA). The synovial fluid (SF) of arthritic joints contains mediators of the inflammatory response and products of the injury to articular tissues, while lymphatic system plays a critical role in resolving inflammation and overall joint homeostasis. Despite the importance of both the lymphatic system and SF in OA disease, their relationship is still poorly understood. Here, we utilized SF derived from osteoarthritis patients (OASF) and healthy individuals (HSF) to investigate potential effects of SF on migration of lymphatic endothelial cells (LECs) in vitro, and lymphatic contractility of femoral lymphatic vessels (LVs) ex vivo. Both OASF and HSF treatments led to an increased migratory response in vitro compared to LECs treatment with media without serum. Ex vivo, both OASF and HSF treatments to the lumen of isolated LVs led to significant differences in the tonic and phasic contractions and these observations were dependent on the SF treatment time. Specifically, OASF treatment transiently enhanced the RFLVs tonic contractions. Regarding the phasic contractions, OASF generated either an abrupt reduction after 1 hr of treatment or a complete cease of contractions after an overnight treatment, while HSF treatment displayed a gradual decrease in lymphatic contractility. The observed variations after SF treatments suggest that the pump function of lymphatic vessel draining the joint could be directly compromised in OA and thus might present a new therapeutic target.

bioengineering↗