Intrinsic Signals Research Articles

Low-Intensity Pulsed Ultrasound Stimulation Inhibits Cortical Spreading Depression.

Cortical spreading depression (CSD), which is closely correlated with migraine aura, cerebral ischemia, seizure, and brain injury, is a spreading wave of neuronal and glial depolarization. The purpose of this study is to investigate whether low-intensity pulsed ultrasound stimulation (PUS) inhibits CSD by modulating neural activity and hemodynamics. Behavioral test, intrinsic signal optical imaging and western blot analysis were used for evaluating the inhibition effect of PUS on CSD in rat. We found that: 1) 30min of PUS can significantly improve motor activity of rat with CSD. 2) Both 30s and 30min of PUS can significantly reduce count and propagation speed of CSD in rat and the inhibitory effect was enhanced with increase of ultrasound intensity. 3) 30min of PUS significantly enhanced levels of brain-derived neurotrophic factor protein in brain tissue with CSD. These results suggest that PUS has the potential to treat brain disorders associated with CSD.

Functional optoretinography: concurrent OCT monitoring of intrinsic signal amplitude and phase dynamics in human photoreceptors.

Intrinsic optical signal (IOS) imaging promises a noninvasive method for objective assessment of retinal function. This study demonstrates concurrent optical coherence tomography (OCT) of amplitude-IOS and phase-IOS changes in human photoreceptors. A new procedure for differential-phase-mapping (DPM) is validated to enable depth-resolved phase-IOS imaging. Dynamic OCT revealed rapid amplitude-IOS and phase-IOS changes, which occur almost right away after the stimulus onset. These IOS changes were predominantly observed within the photoreceptor outer segment (OS), particularly two boundaries connecting to the inner segment and retinal pigment epithelium. The comparative analysis supports that both amplitude-IOS and phase-IOS attribute to transient OS morphological change associated with phototransduction activation in retinal photoreceptors. A simulation modeling is proposed to discuss the relationship between the photoreceptor OS length and phase-IOS changes.

Advantages of imaging photoplethysmography for migraine modeling: new optical markers of trigemino\u2010vascular activation in rats

BackgroundExistent animal models of migraine are not without drawbacks and limitations. The aim of our study was to evaluate imaging photoplethysmography (PPG) as a method of assessing intracranial blood flow in rats and its changes in response to electrical stimulation of dural trigeminal afferents.MethodsExperiments were carried out with 32 anesthetized adult male Wistar rats. Trigeminovascular system (TVS) was activated by means of electrical stimulation of dural afferents through a closed cranial window (CCW). Parameters of meningeal blood flow were monitored using a PPG imaging system under green illumination with synchronous recording of an electrocardiogram (ECG) and systemic arterial blood pressure (ABP). Two indicators related to blood-flow parameters were assessed: intrinsic optical signals (OIS) and the amplitude of pulsatile component (APC) of the PPG waveform. Moreover, we carried out pharmacological validation of these indicators by determining their sensitivity to anti-migraine drugs: valproic acid and sumatriptan. For statistical analysis the non-parametric tests with post-hoc Bonferroni correction was used.ResultsSignificant increase of both APC and OIS was observed due to CCW electrical stimulation. Compared to saline (n = 11), intravenous administration of both the sumatriptan (n = 11) and valproate (n = 10) by using a cumulative infusion regimen (three steps performed 30 min apart) lead to significant inhibitory effect on the APC response to the stimulation. In contrast, intravenous infusion of any substance or saline did not affect the OIS response to the stimulation. It was found that infusion of either sumatriptan or valproate did not affect the response of ABP or heart rate to the stimulation.ConclusionsImaging PPG can be used in an animal migraine model as a method for contactless assessment of intracranial blood flow. We have identified two new markers of TVS activation, one of which (APC) was pharmacologically confirmed to be associated with migraine. Monitoring of changes in APC caused by CCW electrical stimulation (controlling efficiency of stimulation by OIS) can be considered as a new way to assess the peripheral mechanism of action of anti-migraine interventions.

Spatiotemporal Correlation of Epileptiform Activity and Gene Expression in vitro.

Epileptiform activity alters gene expression in the central nervous system, a phenomenon that has been studied extensively in animal models. Here, we asked whether also in vitro models of seizures are in principle suitable to investigate changes in gene expression due to epileptiform activity and tested this hypothesis mainly in rodent and additionally in some human brain slices. We focused on three genes relevant for seizures and epilepsy: FOS proto-oncogene (c-Fos), inducible cAMP early repressor (Icer) and mammalian target of rapamycin (mTor). Seizure-like events (SLEs) were induced by 4-aminopyridine (4-AP) in rat entorhinal-hippocampal slices and by 4-AP/8 mM potassium in human temporal lobe slices obtained from surgical treatment of epilepsy. SLEs were monitored simultaneously by extracellular field potentials and intrinsic optical signals (IOS) for 1–4 h, mRNA expression was quantified by real time PCR. In rat slices, both duration of SLE exposure and SLE onset region were associated with increased expression of c-Fos and Icer while no such association was shown for mTor expression. Similar to rat slices, c-FOS induction in human tissue was increased in slices with epileptiform activity. Our results indicate that irrespective of limitations imposed by ex vivo conditions, in vitro models represent a suitable tool to investigate gene expression. Our finding is of relevance for the investigation of human tissue that can only be performed ex vivo. Specifically, it presents an important prerequisite for future studies on transcriptome-wide and cell-specific changes in human tissue with the goal to reveal novel candidates involved in the pathophysiology of epilepsy and possibly other CNS pathologies.

The role of RNA processing and regulation in metastatic dormancy.

Tumor dormancy is a major contributor to the lethality of metastatic disease, especially for cancer patients who develop metastases years-to-decades after initial diagnosis. Indeed, tumor cells can disseminate during early disease stages and persist in new microenvironments at distal sites for months, years, or even decades before initiating metastatic outgrowth. This delay between primary tumor remission and metastatic relapse is known as "dormancy," during which disseminated tumor cells (DTCs) acquire quiescent states in response to intrinsic (i.e., cellular) and extrinsic (i.e., microenvironmental) signals. Maintaining dormancy-associated phenotypes requires DTCs to activate transcriptional, translational, and post-translational mechanisms that engender cellular plasticity. RNA processing is emerging as an essential facet of cellular plasticity, particularly with respect to the initiation, maintenance, and reversal of dormancy-associated phenotypes. Moreover, dysregulated RNA processing, particularly that associated with alternative RNA splicing and expression of noncoding RNAs (ncRNAs), can occur in DTCs to mediate intrinsic and extrinsic metastatic dormancy. Here we review the pathophysiological impact of alternative RNA splicing and ncRNAs in promoting metastatic dormancy and disease recurrence in human cancers.

Subcellular coordination of plant cell wall synthesis.

Organelles of the plant cell cooperate to synthesize and secrete a strong yet flexible polysaccharide-based extracellular matrix: the cell wall. Cell wall composition varies among plant species, across cell types within a plant, within different regions of a single cell wall, and in response to intrinsic or extrinsic signals. This diversity in cell wall makeup is underpinned by common cellular mechanisms for cell wall production. Cellulose synthase complexes function at the plasma membrane and deposit their product into the cell wall. Matrix polysaccharides are synthesized by a multitude of glycosyltransferases in hundreds of mobile Golgi stacks, and an extensive set of vesicle trafficking proteins govern secretion to the cell wall. In this review, we discuss the different subcellular locations at which cell wall synthesis occurs, review the molecular mechanisms that control cell wall biosynthesis, and examine how these are regulated in response to different perturbations to maintain cell wall homeostasis.

Ultrashort echo time Cones double echo steady state (UTE-Cones-DESS) for rapid morphological imaging of short T2 tissues.

In this study, we aimed to develop a new technique, ultrashort echo time Cones double echo steady state (UTE-Cones-DESS), for highly efficient morphological imaging of musculoskeletal tissues with short T2 s. We also proposed a novel, single-point Dixon (spDixon)-based approach for fat suppression. The UTE-Cones-DESS sequence was implemented on a 3T MR system. It uses a short radiofrequency (RF) pulse followed by a pair of balanced spiral-out and spiral-in readout gradients separated by an unbalanced spoiling gradient in-between. The readout gradients are applied immediately before or after the RF pulses to achieve a UTE image (S+ ) and a spin/stimulated echo image (S- ). Weighted echo subtraction between S+ and S- was performed to achieve high contrast specific to short T2 tissues, and spDixon was applied to suppress fat by using the intrinsic complex signal of S+ and S- . Six healthy volunteers and five patients with osteoarthritis were recruited for whole-knee imaging. Additionally, two healthy volunteers were recruited for lower leg imaging. The UTE-Cones-DESS sequence allows fast volumetric imaging of musculoskeletal tissues with excellent image contrast for the osteochondral junction, tendons, menisci, and ligaments in the knee joint as well as cortical bone and aponeurosis in the lower leg within 5 min. spDixon yields efficient fat suppression in both S+ and S- images without requiring any additional acquisitions or preparation pulses. The rapid UTE-Cones-DESS sequence can be used for high contrast morphological imaging of short T2 tissues, providing a new tool to assess their association with musculoskeletal disorders.

Induction of apoptosis in SSN-1cells by Snakehead Fish Vesiculovirus (SHVV) via Matrix protein dependent intrinsic pathway

An increasing important area in immunology is the process cell death mechanism, enabling the immune system triggered thru extrinsic or intrinsic signals to effectively remove unwanted or virus infected cells called apoptosis. A recently isolated infectious Snakehead fish vesiculovirus (SHVV), comprising negative strand RNA and encoded viral matrix (M) proteins, is responsible for causing cytopathic effects in infected fish cells. However, the mechanism by which viral M protein mediates apoptosis has not been elucidated. Therefore, in the present experiments, it was investigated the regulatory potential of apoptosis signals during SHVV infection. By employing the model of SHVV infection in SSN-1 cells, the accelerated apoptosis pathway involves an intrinsic pathway requiring the activation of caspase-9 but not caspase-3 or -8. In the groups of infection (SHVV) or treatment (hydrogen peroxide) were induced apoptotic morphological changes and indicated the activation of the main caspases, i.e.; executioner caspase-3, initiators caspase-8 and caspase-9 using colorimetric assays. Turning to the role of viral M protein when it was overexpressed in SSN-1 cells, it was indicated that the viral M gene alone has the ability to induce apoptosis. To elucidate the mechanism of apoptosis in SSN-1 cells, the activation inhibitors of main caspases were used showing that inhibiting of caspase-3 or caspase-8 activation did not seize induction of apoptosis in virus-infected SSN-1 cells. However, the inhibiting of caspase-9 activation reduced significantly the apoptosis initiation process and sharply the expression of viral M gene, suggesting that SHVV plays a major role in the early induction of apoptosis by caspase-9. Interestingly, there were also differences in the mitochondrial membrane potential after the apoptotic induction of caspases, which confirm that caspase-9 is primarily responsible for the cleavage of caspases during apoptosis. Taken together, these findings can therefore be assumed that viral M protein induces apoptosis via the intrinsic apoptotic pathway in SHVV infecting SSN-1 cells.

Wavelength censoring for spectroscopy in optical functional neuroimaging

Optical neuromonitoring provides insight into neurovascular physiology and brain structure and function. These methods rely on spectroscopy to relate light absorption changes to variation of concentrations of physiologic chromophores such as oxy- and deoxyhemoglobin. In clinical or preclinical practice, data quality can vary significantly across wavelengths. In such situations, standard spectroscopic methods may perform poorly, resulting in data loss and limiting field-of-view. To address this issue, and thereby improve the robustness of optical neuromonitoring, we develop, in this manuscript, novel methods to perform spectroscopy even when data quality exhibits wavelength-dependent spatial variation. We sought to understand the impact of spatial, wavelength-based censoring on the physiologic accuracy and utility of hemoglobin spectroscopy. The principles of our analysis are quite general, but to make the methodology tangible we focused on optical intrinsic signal imaging of resting-state functional connectivity in mice. Starting with spectroscopy using four sources, all possible subset spectroscopy matrices were assessed theoretically, using simulated data, and using experimental data. These results were compared against the use of the full spectroscopy matrix to determine which subsets yielded robust results. Our results demonstrated that accurate calculation of changes in hemoglobin concentrations and the resulting functional connectivity network maps was possible even with censoring of some wavelengths. Additionally, we found that the use of changes in total hemoglobin (rather than oxy- or deoxyhemoglobin) yielded results more robust to experimental noise and allowed for the preservation of more data. This new and rigorous image processing method should improve the fidelity of clinical and preclinical functional neuroimaging studies.

Diagnosis of Infectious Diseases: Tuberculosis, Malaria and HIV and Aids – A Review

Achieving and sustaining global healthcare is one of the challenges of our time. Healthcare entails sensitive and competent diagnosis of pathogens, treatment and prevention. Infectious diseases have claimed millions of lives and escalated poverty conditions especially in developing regions. Hence, the United Nations Millennium Development Goals (MDGs) between the years 2000 and 2015 included healthcare: the eradication of infectious diseases and rehabilitating societal damages triggered by the diseases. Great efforts have been taken towards this goal; evident by the decline in the statistics of global malaria, human immune deficiency virus (HIV) infections and mortality cases recorded at the end of the MDGs era. However, current infectious diseases statistics from resource-constrained regions are still a sore point. Africa and South East Asia recorded the highest number of both new infections and death cases worldwide. Science and technology face the challenge of producing Point of Care Testing (POCT) devices suitable for such regions to achieve efficient detection of diseases across the global spectrum. This paper reviews traditional and new techniques used for the detection of some infectious diseases: malaria, tuberculosis and HIV. The drawbacks of these techniques are discussed and solutions such as Plasmonic metal-based immuno chemical biosensors are considered. For example, vibrational spectroscopy (Raman), which has a potential for the detection and identification of infectious diseases using traditionally weaker intrinsic Raman signals can be improved by the inclusion of the Plasmonic metals, a phenomenon called Surface Enhanced Raman spectroscopy (SERS). Hence, with innumerable references, this paper also reviews SERS application in biosensing and synergising with new technologies such as microfluidics.

Electrochemical sensor for the assessment of carbohydrate deficient transferrin: Application to diagnosis of congenital disorders of glycosilation

Carbohydrate deficient transferrin (CDT) is used as biomarker of different health problems as, for example, congenital disorders of glycosylation (CDG). We propose a screen-printed-based electrochemical sensor for the determination of carbohydrate deficient transferrin using an Os (VI) tag-based electrochemistry. When transferrin is labeled with Os (VI) complex, it generates two voltammetric signals: one from carbohydrates (electrochemical signal of osmium (VI) complex at -0.9 V/Ag) and one from the amino acids present in glycoprotein (intrinsic electrochemical signal of glycoprotein at +0.8 V/Ag). The relationship between the two analytical signals (carbohydrate signal/protein signal) is an indicator of the degree of glycosylation (electrochemical index of glycosylation), which has shown an excellent correlation (r = 0.990) with the official parameter %CDT obtained by CE-UV. The suitability of this approach was demonstrated by analyzing serum samples from CDG patients.

In vivo optoretinography of phototransduction activation and energy metabolism in retinal photoreceptors.

The objective of this study is to verify the anatomic correlate of the second (2nd) outer retina band in optical coherence tomography (OCT), and to demonstrate the potential of using intrinsic optical signal (IOS) imaging for concurrent optoretinography (ORG) of phototransduction activation and energy metabolism in stimulus activated retinal photoreceptors. A custom-designed OCT was employed for depth-resolved IOS imaging in mouse retina activated by a visible light flicker stimulation. The spatiotemporal properties of the IOS changes at the photoreceptor outer segment (OS) and inner segment (IS) were quantitatively evaluated. Rapid IOS change was observed at the OS almost right away, and the IOS at the IS was relatively slow. Comparative analysis indicates that the OS-IOS reflects transient OS deformation caused by the phototransduction activation, and IS-IOS might reflect the energy metabolism caused by mitochondria activation in retinal photoreceptors. The consistency of the distribution of the IS-IOS and the 2nd OCT band supports the IS ellipsoid (ISe), which has abundant mitochondria, as the signal source of the 2nd OCT band of the outer retina.

Abstract PS19-08: Intratumoral heterogeneity of second-harmonic generation scattering from tumor collagen and its effects on metastatic risk prediction

Abstract Second harmonic generation (SHG) is an intrinsic optical signal that can be generated from fibrillar collagen. The directionality of SHG emission is influenced by the diameter and spacing of collagen fibrils, and the disorder in their packing within collagen fibers. One measure of SHG directionality is the ratio of forward- to backward-scattered SHG, or “F/B”. F/B has been used to assess healthy vs diseased tissue in breast, ovarian, and lung cancer, and is an independent prognostic indicator of metastasis free survival time in ER+, lymph node-negative (N0), invasive ductal carcinoma (IDC). Here we assess the heterogeneity in F/B within tumor sections from ER+ N0 IDC, and its effect on the use of F/B for metastatic risk prediction. We find that F/B of tumor collagen varies between the tumor/host interface and the more cellular tumor bulk (p<0.0001, Student’s t-test), and that F/B from the tumor/host interface, but not tumor bulk, is prognostic of metastasis free survival in 95 IDC ER+ N0 patients (p=0.0020 and 0.10, respectively, log rank test for trend). This result was repeated with two additional image analysis procedures to generate F/B with reduced user input and hence reduced possibility of bias. Using Random Survival Forests to generate a data-driven predictive model, we find that F/B from the tumor/host interface, but not bulk, as well as a 21-gene prognostic score inferred from Affymetrix data, both contribute to predicting metastasis-free survival in this cohort. Any tool to help predict metastasis and assist with treatment decisions is likely to be applied in combination with the now well-established genomic scores. To understand how F/B can support genomic methods for guiding treatment decisions we divided our patient samples into two cohorts based upon the value of their 21-gene score relative to the TAILORx cutoff of 26 (separating low-intermediate and high-risk groups). The F/B value from tumor-host interface identifies a subgroup of patients in the low-intermediate risk group with poor clinical outcome (p=0.045, log rank test for trend). Overall, this data reveals that intratumor heterogeneity can impact the ability of F/B to predict patient outcome, and that F/B specifically from the tumor-host interface may provide a tool to better identify patients in need of adjuvant treatment or enrollment in clinical trials. Citation Format: Edward Brown, Danielle Desa, Wencheng Wu, Robert Hill, John Martens, Robert Strawderman, Bradley Turner. Intratumoral heterogeneity of second-harmonic generation scattering from tumor collagen and its effects on metastatic risk prediction [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-08.

A rapid-onset diffusion functional MRI signal reflects neuromorphological coupling dynamics

Functional Magnetic Resonance Imaging (fMRI) has transformed our understanding of brain function in-vivo. However, the neurovascular coupling mechanisms underlying fMRI are somewhat “distant” from neural activity. Interestingly, evidence from Intrinsic Optical Signals (IOSs) indicates that neural activity is also coupled to (sub)cellular morphological modulations. Diffusion-weighted functional MRI (dfMRI) experiments have been previously proposed to probe such neuromorphological couplings, but the underlying mechanisms have remained highly contested. Here, we provide the first direct link between in vivo ultrafast dfMRI signals upon rat forepaw stimulation and IOSs in acute slices stimulated optogenetically. We reveal a hitherto unreported rapid onset (<100 ms) dfMRI signal component which (i) agrees with fast-rising IOSs dynamics; (ii) evidences a punctate quantitative correspondence to the stimulation period; and (iii) is rather insensitive to a vascular challenge. Our findings suggest that neuromorphological coupling can be detected via dfMRI signals, auguring well for future mapping of neural activity more directly compared with blood-oxygenation-level-dependent mechanisms.

Variability in atlas registration of optical intrinsic signal imaging and its effect on functional connectivity analysis.

To compare neuroimaging data between subjects, images from individual sessions need to be aligned to a common reference or "atlas." Atlas registration of optical intrinsic signal imaging of mice, for example, is commonly performed using affine transforms with parameters determined by manual selection of canonical skull landmarks. Errors introduced by such procedures have not previously been investigated. We quantify the variability that arises from this process and consequent errors from misalignment that affect interpretation of functional neuroimaging data. We propose an improved method, using separately acquired high-resolution images and demonstrate improvements in variability and alignment using this method.

Denoising Seismic Signal via Resampling Local Applicability Functions

We propose a novel seismic signal processing approach to efficiently and effectively attenuate seismic random noises. The proposed approach is a generalized seismic noise attenuation solution that can be applied to typical denoising operators. Our work has two main contributions. First, conventional filtering operators “regularize” the denoised results through the operator design. However, as seismic data have strong nonstationarity, it is inevitable to remove certain signal components. The resampling mechanism alleviates the signal loss. Second, the resampling operation does not require a lot of parameter tuning, which improves the denoising efficiency. Using the proposed approach, compared with existing denoising operators, the intrinsic seismic signal components are better recovered since random noise has been suppressed. Synthetic example and field data applications quantitatively and qualitatively demonstrate excellent performances of the proposed approach.

Spermatogonial stem cells: A story of self-renewal and differentiation.

Mammalian spermatogenesis is a complex but well-coordinated process in which spermatogonial stem cells (SSC) of the testis develop to form spermatozoa. During testicular homeostasis, the spermatogonial stem cells self-renew to maintain the stem cell pool or differentiate to form a progeny of germ cells which sequentially transform to spermatozoa. Accumulating evidence from clinical data and diverse model organisms suggest that the fate of spermatogonial stem cells towards self-renewal or differentiation is governed by intrinsic signals within the cells and by extracellular signals from the SSC niche. Here, we review the past and the most recent developments in understanding the nature of spermatogonial stem cells and the regulation of their homeostasis in mice. We also review the potential clinical applications of spermatogonial stem cells in male infertility as well as in germline modification, by virtue of gene correction and conversion of somatic cells to biologically competent male germline cells.

Measurement of Metabolites from Migrating Cells.

Metastasis is a multistep process that involves responses to extrinsic and intrinsic signals at every step. It is thus only truly appreciated in the context of a whole organism. Nevertheless, in vitro studies can be used to facilitate understanding of the possible factors contributing to any phenotype that is associated with metastatic competence. The use of migration assays-where monolayers of cells migrate to cover gaps or "wounds"-has been described for decades to identify signaling pathways that regulate motile competence and to screen for ways of interfering with this ability. Here we depict the combination of such an assay with assessment of indicators of carbon metabolism using commercially available assays. This enables identification of changes in cellular metabolism associated with actively migrating cells.

Capturing and Detection of Amyloid-Β Aggregation with Affinity Peptide-Incorporated AU Electrode

In solution, the Aβ peptides fold into α-helical or random extended chain structures, as well as soluble β-sheet structure that eventually precipitate as amyloid and the complicated aggregation mechanism study needed new detection techniques. In this study, we demonstrate a novel affinity peptide-incorporated (with amino acid sequence of GNNPLHVHHDKRGGGC) Au electrochemical biosensor for the detection of tyrosine residues on Aβ monomers. Cyclic Voltammetry (CV) and Atomic Force Microscopy (AFM) were used to validate biosensor assembly and functionality. CV was employed for biosensor interrogation in the presence of Aβ oligomers or monomers. The attachment of Aβ peptides to Au was confirmed by CV and AFM imaging. The intrinsic oxidation signal of the captured Aβ peptides, containing a single tyrosine (Tyr) residues, was monitored at a peak potential of 0.6 V (vs Ag/AgCl within this sensor). The affinity polypeptide composite electrode was obtained by optimizing the modification process, which can respond to the concentration from 1 pM to 1 µM of Aβ 1-42 polypeptide monomer molecule. The peak current intensities were concentration dependent. And with the exposure decreasing with the Aβ aggregation, the peak current also decreased and compared with AFM images to reveal the Aβ aggregation pattern. The proposed process provides new routes for analysis of Aβ aggregation interactions and electrochemical biosensor development.

Revealing the Distribution of Aggregation-Induced Emission Nanoparticles via Dual-Modality Imaging with Fluorescence and Mass Spectrometry.

Aggregation-induced emission nanoparticles (AIE NPs) are widely used in the biomedical field. However, understanding the biological process of AIE NPs via fluorescence imaging is challenging because of the strong background and poor penetration depth. Herein, we present a novel dual-modality imaging strategy that combines fluorescence imaging and label-free laser desorption/ionization mass spectrometry imaging (LDI MSI) to map and quantify the biodistribution of AIE NPs (TPAFN-F127 NPs) by monitoring the intrinsic photoluminescence and mass spectrometry signal of the AIE molecule. We discovered that TPAFN-F127 NPs were predominantly distributed in the liver and spleen, and most gradually excreted from the body after 5 days. The accumulation and retention of TPAFN-F127 NPs in tumor sites were also confirmed in a tumor-bearing mouse model. As a proof of concept, the suborgan distribution of TPAFN-F127 NPs in the spleen was visualized by LDI MSI, and the results revealed that TPAFN-F127 NPs were mainly distributed in the red pulp of the spleen with extremely high concentrations within the marginal zone. The in vivo toxicity test demonstrated that TPAFN-F127 NPs are nontoxic for a long-term exposure. This dual-modality imaging strategy provides some insights into the fine distribution of AIE NPs and might also be extended to other polymeric NPs to evaluate their distribution and drug release behaviors in vivo.