Biology subjects

Kaeppler, J.

Publications and source records attributed to Kaeppler, J..

5 recordsLinked to original sources

bioRxiv2025

PEG-free, Triphosphate-Stabilized LNPs Enable Potent RNA Delivery

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/695515v2_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@d919d8org.highwire.dtl.DTLVardef@12fe9aforg.highwire.dtl.DTLVardef@96e2d2org.highwire.dtl.DTLVardef@54f73_HPS_FORMAT_FIGEXP M_FIG C_FIG Polyethylene glycol (PEG)-lipids have long enabled lipid nanoparticle (LNP) formulations by providing steric stabilization and prolonged circulation. However, anti-PEG immune responses may impede repeated systemic dosing in mRNA therapeutics due to the phenomenon known as accelerated blood clearance (ABC). Here, we introduce a PEG-free, polyanionic alternative in which sodium triphosphate (3P) electrostatically associates with ionizable surface lipids, conferring long-term colloidal stability through charge repulsion rather than steric shielding. 3P-LNPs maintained size uniformity, morphology, and mRNA integrity for over nine months at 4 {degrees}C. In a proof-of-concept study involving a single intravenous injection of LNPs in mice carrying a luciferase and a GFP transgene, early expression was approximately two-fold higher compared to PEG-LNPs, while expression levels at 24 hours and hepatic tolerability remained comparable. Serum enzyme and cytokine profiles indicated no necrosis or inflammation. These findings establish 3P-LNPs as a stable, biocompatible platform free of PEG, with potential for repeat systemic mRNA administration while avoiding PEG-related effects.

biochemistry↗

bioRxiv2023

Enhanced perfusion following exposure to radiotherapy: a theoretical investigation

Tumour angiogenesis leads to the formation of blood vessels that are structurally and spatially heterogeneous. Poor blood perfusion, in conjunction with increased hypoxia and oxygen heterogeneity, impairs a tumours response to radiotherapy. The optimal strategy for enhancing tumour perfusion remains unclear, preventing its regular deployment in combination therapies. In this work, we first identify vascular architectural features that correlate with enhanced perfusion following radiotherapy, using in vivo imaging data from vascular tumours. Then, we present a novel computational model to determine the relationship between these architectural features, blood perfusion, and tumour response to radiotherapy in silico. If perfusion is defined to be the proportion of vessels that support blood flow, we find that vascular networks with small mean diameters and large numbers of angiogenic sprouts show the largest increases in perfusion post-irradiation for both biological and synthetic tumours. We also identify cases where perfusion increases due to the pruning of hypoperfused vessels, rather than blood being rerouted. These results indicate the importance of considering network composition when determining the optimal irradiation strategy. In the future, we aim to use our findings to identify tumours that are good candidates for perfusion enhancement and to improve the efficacy of combination therapies. Author summaryDysregulated tumour vasculature often contains hypoperfused blood vessels which inhibit the delivery of blood-borne anticancer therapies. Radiotherapy, used to treat more than half of all cancer patients, causes DNA damage to vascular endothelial cells, preferentially impacting smaller vessels, leading to their death and vessel pruning. At the same time, experiments measuring changes in tumour perfusion post-irradiation produce varying outcomes and, therefore, the impact of irradiation-induced vessel pruning on network-scale perfusion remains unclear. In this study, we use recent (in vivo) imaging data to identify features of tumour vascular architectures that impact perfusion change post-irradiation. We then use a newly-developed computational framework, directly informed by the experimental observations, to elucidate the relationship between the vascular geometry and topology prior to radiotherapy and the irradiation-induced changes to network perfusion. We find that perfusion increases most significantly for networks of blood vessels with small mean diameters and large numbers of angiogenic sprouts. Our results also distinguish different mechanisms of perfusion increase and we identify cases where rerouting of blood flow causes previously hypoperfused vessels to become perfused. Our study sheds more light on the impact of radiotherapy on tumour blood flow; these insights could be useful for improving anti-cancer treatments.

systems biology↗

bioRxiv2020

A lineage-tracing tool to map the fate of post-hypoxic H1299 NSCLC tumour cells

Intratumoural hypoxia is a common characteristic of malignant treatment-resistant cancers. However, hypoxia-modification strategies for the clinic remain elusive. To date little is known on the behaviour of individual hypoxic tumour cells in their microenvironment. To explore this issue in a spatial and temporally-controlled manner we developed a genetically encoded sensor by fusing the O2-labile Hypoxia-Inducible Factor 1 to eGFP and a tamoxifen-regulated Cre recombinase. Under normoxic conditions HIF-1 is degraded but under hypoxia, the HIF-1-GFP-Cre-ERT2 fusion protein is stabilised and in the presence of tamoxifen activates a tdTomato reporter gene that is constitutively expressed in hypoxic progeny. We visualise the random distribution of hypoxic tumour cells from hypoxic or necrotic regions and vascularised areas using immunofluorescence and intravital microscopy. Once tdTomato expression is induced, it is stable for at least 4 weeks. Using this system, we could show that the post-hypoxic cells were more proliferative in vivo than non-labelled cells. Our results demonstrate that single-cell lineage tracing of hypoxic tumour cells can allow visualisation of their behaviour in living tumours using intravital microscopy. This tool should prove valuable for the study of dissemination and treatment response of post-hypoxic tumour cells in vivo at single-cell resolution. Summary StatementHere we developed and characterised a novel HIF-1-Cre fusion gene to trace the progeny of hypoxic tumour cells in a temporal and spatially resolved manner using intravital microscopy.

cancer biology↗

bioRxiv2019

Abnormal morphology biases haematocrit distribution in tumour vasculature and contributes to heterogeneity in tissue oxygenation

Oxygen heterogeneity in solid tumours is recognised as a limiting factor for therapeutic efficacy. This heterogeneity arises from the abnormal vascular structure of the tumour, but the precise mechanisms linking abnormal structure and compromised oxygen transport are only partially understood. In this paper, we investigate the role that RBC transport plays in establishing oxygen heterogeneity in tumour tissue. We focus on heterogeneity driven by network effects, which are challenging to observe experimentally due to the reduced fields of view typically considered. Motivated by our findings of abnormal vascular patterns linked to deviations from current RBC transport theory, we calculate average vessel lengths [Formula] and diameters [Formula] from tumour allografts of three cancer cell lines and observe a substantial reduction in the ratio [Formula] compared to physiological conditions. Mathematical modelling reveals that small values of the ratio{lambda} (i.e. {lambda} < 6) can bias haematocrit distribution in tumour vascular networks and drive heterogeneous oxygenation of tumour tissue. Finally, we show an increase in the value of{lambda} in tumour vascular networks following treatment with the anti-angiogenic cancer agent DC101. Based on our findings, we propose{lambda} as an effective way of monitoring the efficacy of antiangiogenic agents and as a proxy measure of perfusion and oxygenation in tumour tissue undergoing anti-angiogenic treatment. Significance statementOxygen heterogeneity in solid tumours is recognised as a limiting factor for therapeutic efficacy. This heterogeneity arises from the abnormal tumour vascular structure. We investigate the role that anomalies in RBC transport play in establishing oxygen heterogeneity in tumour tissue. We introduce a metric to characterise tumour vasculature (mean vessel length-to-diameter ratio,{lambda} ) and demonstrate how it predicts tissue oxygen heterogeneity. We also report an increase in{lambda} following treatment with the antiangiogenic agent DC101. Together, we propose{lambda} as an effective way of monitoring the action of anti-angiogenic agents and a proxy measure of oxygen heterogeneity in tumour tissue. Unravelling the causal relationship between tumour vascular structure and tissue oxygenation will pave the way for new personalised therapeutic approaches.

cancer biology↗

bioRxiv2019

Radiation resistant cancer cells enhance the survival and resistance of sensitive cells in prostate spheroids

Intratumoural heterogeneity contributes to local tumour recurrence and variable responses to radiotherapy in prostate cancer. Despite the multiclonal nature of the disease, tumour control probability for conventional treatment plans is modelled on the assumption that tumour cells in the target region respond identically and independently. Here, using tumour cell subpopulations with different radiation sensitivities from prostate tumour cell lines, we show that radiation resistant cells enhance the survival and radiation resistance of radio-sensitive cells in spheroids but not in monolayer culture. Mathematical modelling indicates that these phenotypic changes result from both competitive and antagonistic cellular interactions in spheroids. Interactions mediated by oxygen constraints define the spatial localisation of the cell populations in spheroids and in xenografts, while those mediated by paracrine signals further modify the microenvironment. Our results show new mechanisms of radiotherapy resistance mediated by cellular interactions and by the microenvironment.

cancer biology↗