Biology subjects

Christiansen, N.

Publications and source records attributed to Christiansen, N..

10 recordsLinked to original sources

bioRxiv2026

Transforming clinical apheresis waste into a renewable source of patient-derived CD34+ hematopoietic stem cell biobank for beta-hemoglobinopathy research and therapeutic discovery

Background aimsThe development of next-generation therapies for sickle cell disease (SCD) and beta thalassemia (beta thal), including fetal globin-inducing small molecules and gene therapy approaches, depends on patient-derived CD34+ hematopoietic stem and progenitor cells (HSPCs) for discovery and preclinical validation, but commercial vendors stock only healthy donor material and disease-specific banks hold limited inventories. Recent US Food and Drug Administration and National Institutes of Health guidance favoring human cell-based methods over animal testing underscores the value of authentic patient cells. Methods: Over 14 months we recovered, purified, and biobanked CD34+ HSPCs from clinical apheresis product waste and mobilized peripheral blood (PB) otherwise discarded after clinical procedures, using immunomagnetic selection adapted for hemoglobinopathy specimens; a microfluidic technology was evaluated separately. We quantified yield and purity for bead-selected material and cell number and viability for the microfluidic pilot; engraftment was tested in NBSGW mice. Results: Immunomagnetic selection recovered a median of 4.71 x 106 CD34+ cells from just 1 to 2 mL of apheresis product waste, comparable to the 6.0 x 106 cells from a 10 to 40 fold larger volume of PB waste, with similar purity across sources and diagnoses. Because apheresis product waste is far more concentrated, it reaches equivalent yields without the density-gradient steps required for PB waste, approximately halving processing time. Recovered cells engrafted NBSGW mice, confirming preserved repopulating capacity. The microfluidic pilot (two patients, 11 specimens) recovered 2.17 x 106 CD34+ cells per specimen at greater than 90% viability and purity. Conclusions: A center with existing apheresis infrastructure can reproducibly recover, bank, and distribute research-grade patient CD34+ HSPCs, addressing a recognized gap in the hemoglobinopathy pipeline. HighlightsO_LIClinical apheresis waste is used to generate a single-center biobank of high-quality, research-grade CD34+ HSPCs from patients with sickle cell disease and beta-thalassemia. C_LIO_LIConcentrated apheresis waste matches large-volume PB waste in CD34+ yield and purity. C_LIO_LIMicrofluidic enrichment recovers CD34+ cells at >90% viability and purity across 2 patients. C_LIO_LIRecovered CD34+ HSPCs engraft mice and form erythroid cells, preserving function. C_LI

pharmacology and toxicology↗

bioRxiv2025

Intraoperative arteriovenous patient sampling to assess in situ non-small cell lung cancer metabolism

We performed intraoperative arteriovenous sampling in participants undergoing surgical resection for non-small cell lung cancer (NSCLC) to characterize in situ tumor metabolism, directly measuring metabolite consumption and secretion in tumor-bearing lung versus normal lung and the systemic circulation. Healthy lung tissue secreted lower levels of lactate, pyruvate, and tricarboxylic acid (TCA) intermediates and consumed less glucose compared to the systemic circulation. In contrast, tumor-bearing lung demonstrated elevated lactate secretion, along with increased efflux of succinate, fumarate, glycine, and aspartate, despite similar glucose uptake. Lactate secretion correlated with tumor PET avidity but not size, and overall metabolic profiles distinguished cancerous from normal lung tissue. These findings confirm enhanced glycolysis in NSCLC in vivo, while also revealing context-dependent patterns of TCA metabolite accumulation and amino acid secretion. Our results demonstrate the utility of intraoperative sampling to uncover metabolic features of human tumors.

cancer biology↗

bioRxiv2025

Microscale dysfunction and mesoscale compensation in degenerating neuronal networks

Progressive neurodegenerative diseases involve neuronal dysfunction from cellular to circuit to whole-brain levels, but complexity and variability, both between and within diseases, pose significant research challenges. However, although they are differentiated by anatomical origins, vulnerable neuronal subtypes, and specific misfolded proteins, neurodegenerative diseases also share many important features. During presymptomatic disease phases, neural networks initiate multiple compensatory processes to maintain network function, including increased network centralisation and reliance on a rich-club of hub nodes, which have been proposed as common reconfigurations to neural network damage. Currently, while supporting evidence for such mechanisms has been found in some neurodegenerative diseases, it is limited in others, like ALS. This knowledge gap makes it challenging to ascertain if there are indeed common pre-symptomatic mechanisms within and across different neurodegenerative diseases. To address this, we investigated the structural and functional properties of ALS patient derived motor neuron networks and counterpart networks from a healthy donor using longitudinal multielectrode array recordings and graph theory-based network analysis. We demonstrate microscale-level motor neuron dysfunction, including TDP-43 proteinopathy, hyperactivity and reduced spike amplitude. Structurally, we observed neurite hypertrophy, indicating that degenerating networks attempt to establish new connections. We furthermore document mesoscale-level functional reconfigurations, including increased rich-club connectivity and network assortativity, indicating functional compensation in ALS where networks become more centralised to maintain computational capacity. We thus provide novel evidence that ALS networks become increasingly centralised, which places progressively mounting demands on a rich-club, predisposing networks to further damage, consistent with existing models of common reconfigurations in neurodegenerative disease. Significance statementThis study makes significant contributions to preclinical modelling of neurodegenerative disease, with specific relevance for ALS research. By utilising human cellular models, longitudinal extracellular electrophysiology, and advanced network analysis, we show that known features of ALS can be recapitulated in in vitro engineered neural networks, and that these networks allow for novel hypothesis testing and identification of pre-symptomatic pathological processes including increased centralisation. This has previously been observed in other neurodegenerative diseases, but evidence has been limited in ALS. Our results advance our understanding of motor neuron network dynamics in ALS and contribute to a shared understanding of how neurodegenerative diseases affect neural networks which go beyond specific disease diagnosis, elucidating fundamental processes in neural network function and disease response.

neuroscience↗

bioRxiv2025

Induced long-term potentiation improves synaptic stability and restores network function in ALS motor neurons

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease causing progressive dysfunction and degeneration of upper and lower motor neurons. An increasing body of evidence has identified synaptic alterations in patients and experimental models of ALS. Importantly, these have been associated with functional impairments in motor neuron networks, suggesting that synaptic impairments are early events in the disease cascade resulting in functional compensatory reconfigurations. The synapse may therefore represent a disease-modifying target to delay disease progression. In this study, we aimed to stabilize synapses and modify structural connectivity to restore network balance in ALS patient-derived motor neuron networks. To this end, we blocked the potassium channels using tetraethylammonium (TEA) which has been shown to induce chemical long-term potentiation (cLTP). The unperturbed ALS patient-derived motor neuron networks developed clear signs of subtle network dysfunction, including increased firing rate and bursting, and accompanying structural abnormalities. These features were partially restored by temporarily blocking the potassium channels. Specifically, the TEA-treated ALS networks were characterized by a reduction in aberrant branching and stabilization of dendritic spines, alongside a temporary reduction in firing rate and bursting. Furthermore, protein expression assays revealed restoration of dysregulated molecular pathways, including protein synthesis and metabolic pathways, and upregulation of pathways involved in synapse organization in the TEA-treated ALS networks. Collectively, these findings improve our understanding of the association between synaptic impairments and functional alterations in ALS, and demonstrate the relevance of modulating synaptic plasticity to promote network balance.

neuroscience↗

bioRxiv2024

Inducible, but not constitutive, pancreatic REG/Reg isoforms are regulated by intestinal microbiota and pancreatic diseases

The REG/Reg gene locus encodes for a conserved family of potent antimicrobial but also pancreatitis-associated proteins. Here we investigated whether REG/Reg family members differ in their baseline expression levels and abilities to be regulated in the pancreas and gut upon perturbations. We found, in human and mouse, pancreas and gut differed in REG/Reg isoform levels and preferences, with duodenum most resembling the pancreas. Pancreatic acinar cells and intestinal enterocytes were the dominant REG producers. Intestinal symbiotic microbes regulated the expression of the same, select Reg members in gut and pancreas. These Reg members had the most STAT3-binding sites close to the transcription start sites and were partially IL-22 dependent. We thus categorized them as "inducible" and others as "constitutive". Indeed, also in models of pancreatic-ductal adenocarcinoma and pancreatitis, only inducible Reg members were upregulated in pancreas. While intestinal Reg expression remained unchanged upon pancreatic perturbation, pancreatitis altered the microbial composition of the duodenum and feces shortly after disease onset. Our study reveals differential usage and regulation of REG/Reg isoforms as a mechanism for tissue-specific innate immunity, highlights the intimate connection of pancreas and duodenum, and implies a gut-to-pancreas communication axis resulting in a coordinated Reg response.

immunology↗

bioRxiv2024

Reduced spatial spread of nodes in geometric network models improves topology associated with increased computational capabilities

Biological neural networks are characterized by short average path lengths, high clustering, and modular and hierarchical architectures. These complex network topologies strike a balance between local specialization and global synchronization via long-range connections, resulting in highly efficient communication. Efficient network organization and information processing are directly affected after network perturbation, e.g., as a result of trauma or neurodegenerative disease. Here, we used a spatial network model combining changes to spatial constraints on neuron placement with different wiring probabilities to investigate the effects of wiring cost principles on network complexity for different spatial conformations. By combining different wiring probabilities with varying levels of spatial clustering, we aimed to understand how alterations to mechanisms such as the neurons ability to group together, leading to different levels of clustering, in combination with altered axon outgrowth and branching, change network topology. Through targeted pruning of the networks we further aimed to understand how these topologies changed due to perturbations, resulting in a breakdown of function. We found that both long-range and intermediate wiring probabilities only conform to small-world architectures for neurons in dense spatial clusters due to a decrease in wiring cost within clusters. Furthermore, both small-worldness and modularity were reduced in systems with long-range connections caused by a reduction in network clustering. The presence of long-range connections were found to improve global information transmission, especially in networks with strong spatial clustering. In addition, these connections were shown to have a protective effect on the networks during targeted pruning, maintaining global connectivity even with high levels of pruning. Combining spatial clustering with wiring cost principles allows for novel insights into mechanisms underlying adaptive or maladaptive network alterations, explaining how specific interactions may lead to observed changes in networks. Our findings corroborate previous work showing that both wiring probability and spatial distributions play a key role in neural network development and response to perturbations, and increase our understanding of how maladaptive responses may lead to increased strain on local circuitry while negatively impacting global communication. Author summaryBiological neural networks organize into networks capable of performing a variety of complex tasks in a cost-efficient manner. In networks where neurons are subject to neuropathological disease or perturbations, the mechanisms leading to these networks are disrupted, resulting in changes to the computational capabilities of the networks which can be challenging to elucidate. In this study, we combine spatial network models with different wiring costs used to establish connections between nodes of the network to gain an understanding of how changes to the wiring cost and spatial distribution of nodes in a network impacts the resulting topologies. We find that irrespective of wiring cost, sufficient spatial clustering is required for the emergence of network capabilities related to onset and maintenance of activity found in biological neural networks. Furthermore, we find that a balance between local connectivity and long-range connections improve outcomes when networks are subject to targeted perturbations of these connections. To summarize, spatial models prove an efficient method for understanding how changes related to wiring cost and targeted deletion of connections may change topologies of networks, allowing us to understand how specific changes to networks may arise and manifest in in vitro and in vivo cases.

neuroscience↗

bioRxiv2024

Dysregulation of synaptic transcripts underlies network abnormalities in ALS patient-derived motor neurons

Amyotrophic lateral sclerosis (ALS) is characterized by dysfunction and loss of upper and lower motor neurons. Several studies have identified structural and functional alterations in the motor neurons before the manifestation of symptoms, yet the underlying cause of such alterations and how they contribute to the progressive degeneration of affected motor neuron networks remain unclear. Importantly, the short and long-term spatiotemporal dynamics of neuronal network activity make it challenging to discern how ALS-related network reconfigurations emerge and evolve. To address this, we systematically monitored the structural and functional dynamics of motor neuron networks with a confirmed endogenous C9orf72 mutation. We show that ALS patient-derived motor neurons display time-dependent neural network dysfunction, specifically reduced firing rate and spike amplitude, impaired bursting, but higher overall synchrony in network activity. These changes coincided with altered neurite outgrowth and branching within the networks. Moreover, transcriptional analyses revealed dysregulation of molecular pathways involved in synaptic development and maintenance, neurite outgrowth and cell adhesion, suggesting impaired synaptic stabilization. This study identifies early synaptic dysfunction as a contributing mechanism resulting in network-wide structural and functional compensation, which may over time render the networks vulnerable to neurodegeneration.

neuroscience↗

bioRxiv2024

ALS patient-derived motor neuron networks exhibit microscale dysfunction and mesoscale compensation rendering them highly vulnerable to perturbation

Amyotrophic lateral sclerosis affects upper and lower motor neurons, causing progressive neuropathology leading to structural and functional alterations of affected neural networks long prior to development of symptoms. Certain genetic mutations, such as expansions in C9orf72, predispose motor neuron populations to pathological dysfunction. However, it is not known how underlying pathological predisposition affects structural and functional dynamics within vulnerable networks. Here, we studied micro-and mesoscale dynamics of ALS patient derived motor neuron networks over time. We show, for the first time, that ALS patient derived motor neurons with endogenous genetic predisposition develop classical ALS cytopathology in the form of cytoplasmic TDP-43 inclusions and self-organise into computationally efficient networks, albeit with functional hallmarks of higher metabolic cost compared to healthy controls. These hallmarks included microscale impairments and mesoscale compensation including increased centralisation of function. Moreover, we show that these networks are highly susceptible to transient perturbation by exhibiting induced hyperactivity.

neuroscience↗

bioRxiv2022

Selective inhibition of excitatory synaptic transmission alters the emergent bursting dynamics of in vitro neural networks

Neurons in vitro connect to each other and form neural networks that display emergent electrophysiological activity. This activity begins as spontaneous uncorrelated firing in the early phase of development, and as functional excitatory and inhibitory synapses mature, the activity typically emerges as spontaneous network bursts. Network bursts are events of coordinated global activation among many neurons interspersed with periods of silencing and are important for synaptic plasticity, neural information processing, and network computation. While bursting is the consequence of balanced excitatory-inhibitory (E/I) interactions, the functional mechanisms underlying their evolution from physiological to potentially pathophysiological states, such as decreasing or increasing in synchrony, are still poorly understood. Synaptic activity, especially that related to maturity of E/I synaptic transmission, is known to strongly influence these processes. In this study, we used selective chemogenetic inhibition to target and disrupt excitatory synaptic transmission in in vitro neural networks to study functional response and recovery of spontaneous network bursts over time. We found that over time, inhibition resulted in increases in both network burstiness and synchrony. Our results indicate that the disruption in excitatory synaptic transmission during early network development likely affected inhibitory synaptic maturity which resulted in an overall decrease in network inhibition at later stages. These findings lend support to the importance of E/I balance in maintaining physiological bursting dynamics and, conceivably, information processing capacity in neural networks.

neuroscience↗

bioRxiv2019

Describing the fecal metabolome in cryogenically collected samples from healthy participants.

IntroductionThe chemical composition of feces plays an important role in human metabolism. Metabolomics and lipidomics are valuable tools for screening the metabolite composition in feces. Here we set out to describe fecal metabolite composition in healthy participants in frozen stools.\n\nMethodsFrozen stool samples were collected from 10 healthy volunteers and cryogenically drilled in four areas along the specimen. Polar metabolites were analyzed using derivatization followed by two-dimensional gas chromatography and time of flight mass spectrometry. Lipids were detected using ultra high-performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry. The technical variation threshold was set to 30% in pooled quality control samples and metabolite variation was then assessed in four areas per specimen. A data-generated network using metabolites found in all areas was computed for healthy participants.\n\nResults2326 metabolic features were detected. Out of a total of 298 metabolites that were annotated we report here 185 that showed a technical variation of x< 30%. These metabolites included amino acids, fatty acid derivatives, carboxylic acids and phenolic compounds. Lipids predominantly belonged to the groups of diacylglycerols, triacylglycerols and ceramides. Metabolites varied between sampling areas (14%-80%). A network using metabolites present in all areas showed two main clusters, DAG lipids and phenyllactic acid.\n\nConclusionsIn feces from healthy participants, the main groups detected were phenolic compounds, ceramides, diacylglycerols and triacylglycerols. Metabolite levels differed considerably depending on the sampling area.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=52 SRC=\"FIGDIR/small/708685v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (16K):\norg.highwire.dtl.DTLVardef@17db665org.highwire.dtl.DTLVardef@51e140org.highwire.dtl.DTLVardef@19b55d7org.highwire.dtl.DTLVardef@120d399_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗