Panagiotis Symvoulidis

Massachusetts Institute of Technology | MIT · McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences

Serial sectioning combined with microscopy provides high resolution volumetric data to complement in-vivo imaging modalities and aid ex-vivo diagnostics. We describe the design of a fully-automated cryomicrotome combined with a multispectral reflection and fluorescence imaging system that enables high-throughput analyses of biological specimens wit...

Reconstructing a three-dimensional scene from multiple simultaneously acquired perspectives (the light field) is an elegant scanless imaging concept that can exceed the temporal resolution of currently available scanning-based imaging methods for capturing fast cellular processes. We tested the performance of commercially available light field came...

A long-standing objective in neuroscience has been to image distributed neuronal activity in freely behaving animals. Here we introduce NeuBtracker, a tracking microscope for simultaneous imaging of neuronal activity and behavior of freely swimming fluorescent reporter fish. We showcase the value of NeuBtracker for screening neurostimulants with re...

Genetic risk for autism spectrum disorder (ASD) is associated with hundreds of genes spanning a wide range of biological functions1–6. The alterations in the human brain resulting from mutations in these genes remain unclear. Furthermore, their phenotypic manifestation varies across individuals7,8. Here we used organoid models of the human cerebral...

The emerging clinical use of targeted fluorescent agents heralds a shift in intraoperative imaging practices that overcome the limitations of human vision. However, in contrast to established radiological methods, no appropriate performance specifications and standards have been established in fluorescence molecular imaging. Moreover, the dependenc...

Lipid membranes are key to the nanoscale compartmentalization of biological systems, but fluorescent visualization of them in intact tissues, with nanoscale precision, is challenging to do with high labeling density. Here, we report ultrastructural membrane expansion microscopy (umExM), which combines a novel membrane label and optimized expansion...

Real-time 3D fluorescence microscopy is crucial for the spatiotemporal analysis of live organisms, such as neural activity monitoring. The eXtended field-of-view light field microscope (XLFM), also known as Fourier light field microscope, is a straightforward, single snapshot solution to achieve this. The XLFM acquires spatial-angular information i...

Neurons interact in networks distributed throughout the brain. Although much effort has focused on whole-brain calcium imaging, recent advances in genetically encoded voltage indicators (GEVIs) raise the possibility of imaging voltage of neurons distributed across brains. To achieve this, a microscope must image at high volumetric rate and signal-t...

De novo heterozygous loss-of-function mutations in PTEN are strongly associated with Autism spectrum disorders (ASD); however, it is unclear how heterozygous mutations in this gene affects different cell types during human brain development, and how these effects vary across individuals. Here, we used human cortical organoids from different donors...

Real-time 3D fluorescence microscopy is crucial for the spatiotemporal analysis of live organisms, such as neural activity monitoring. The eXtended field-of-view light field microscope (XLFM), also known as Fourier light field microscope, is a straightforward, single snapshot solution to achieve this. The XLFM acquires spatial-angular information i...

Real-time 3D fluorescence microscopy is crucial for the spatiotemporal analysis of live organisms, such as neural activity monitoring. The eXtended field-of-view light field microscope (XLFM), also known as Fourier light field microscope, is a straightforward, single snapshot solution to achieve this. The XLFM acquires spatial-angular information i...

Zebrafish are common model organisms in developmental biology, but have recently emerged as imaging targets of research in cancer, tissue regeneration, metabolic disorders, functional genomics, and phenotype‐based drug discovery. Conventionally, zebrafish are studied during the first few days of development using optical microscopy methods. However...

De novo heterozygous loss-of-function mutations in PTEN are strongly associated with Autism spectrum disorders (ASD); however, it is unclear how heterozygous mutations in this gene affects different cell types during human brain development, and how these effects vary across individuals. Here, we used human cortical organoids from different donors...

One of the major challenges in large scale optical imaging of neuronal activity is to simultaneously achieve sufficient temporal and spatial resolution across a large volume. Here, we introduce sparse decomposition light-field microscopy (SDLFM), a computational imaging technique based on light-field microscopy (LFM) that takes algorithmic advantag...

Most imaging studies of immunotherapy have focused on tracking labeled T cell biodistribution in vivo for understanding trafficking and homing parameters and predicting therapeutic efficacy by the presence of transferred T cells at or in the tumour mass. Conversely, we investigate here a novel concept for longitudinally elucidating anatomical and p...

The sampling patterns of the light field microscope (LFM) are highly depth-dependent, which implies non-uniform recoverable lateral resolution across depth. Moreover, reconstructions using state-of-the-art approaches suffer from strong artifacts at axial ranges, where the LFM samples the light field at a coarse rate. In this work, we analyze the sa...

Zebrafish animal models have traditionally been used in developmental biology studies but have recently become promising models of cancer, tissue regeneration and metabolic disorders, as well as efficient platforms for functional genomics and phenotype-based drug discovery. Most studies of zebrafish have examined only the embryonic or larval stages...

Video S4. Demonstration of 3D Reconstructed Ex Vivo Mouse Brain at 0.2-mm Increment in Rostro-caudal Axis, Related to Figure 4

Video S6. Demonstration of 3D Reconstructed In Vivo Mouse Brain at 0.2-mm Increment in Rostro-Caudal Axis, Related to Figure 6

Video S1. Testing of the Custom-Made Device for Mechanical Stimulation (Deflection) of Whiskers Using Magnetic Force, Related to Figures 1 and 2 An “in-house” designed electromagnetic unit was used to generate sufficient magnetic force for whisker deflections at varying frequencies.

Video S5. Demonstration of 3D Reconstructed Ex Vivo Mouse Brain at 0.2-mm Increment in Dorsal-Ventral Axis, Related to Figure 4

Video S2. Testing of the Custom-Made Device for Mechanical Stimulation (Deflection) of Whiskers Using Magnetic Force, Related to Figures 1 and 2

Video S3. Testing of the Custom-Made Device for Mechanical Stimulation (Deflection) of Whiskers Using Magnetic Force, Related to Figures 1 and 2

In traditional optical imaging, limited light penetration constrains high-resolution interrogation to tissue surfaces. Optoacoustic imaging combines the superb contrast of optical imaging with deep penetration of ultrasound, enabling a range of new applications. We used multispectral optoacoustic tomography (MSOT) for functional and structural neur...

Deep tissue penetration with calcium sensor for photoacoustics (CaSPA): the metallochromic compound changes its color upon binding of calcium thereby modulating the amount of laser energy that is converted into local heat, in turn generating mechanical waves that can be detected by ultrasound transducers to map the patterns of calcium dynamics in l...

We introduce a selective and cell-permeable Calcium (Ca²⁺) Sensor for Photoacoustics (CaSPA) which is a versatile imaging technique that allows for fast volumetric mapping of photoabsorbing molecules with deep tissue penetration. To optimize for Ca²⁺-dependent photoacoustic signal changes, we synthesized a selective metallochromic sensor with high...

In-vivo fluorescently labelled drug (bevacizumab) breast cancer specimen where obtained from patients. We propose a new structured method to determine the optimal classification threshold in targeted fluorescence intra-operative imaging.

In vivo tumor labeling with fluorescent agents may assist endoscopic and surgical guidance for cancer therapy as well as create opportunities to directly observe cancer biology in patients. However, malignant and non-malignant tissues are usually distinguished on fluorescence images by applying empirically determined fluorescence intensity threshol...

Supplemental material summarizing the Materials and Methods for the Validation procedure.

The diversity of the design and geometrical alignments of ultrasonic transducers with recordings over a wide range of frequency bandwidths empower the exquisite scalability and versatility of optoacoustic imaging. In this study, we implement a high-resolution optoacoustic mesoscopy system for imaging the vasculature and oxygen saturation within sub...

Multispectral tissue imaging based on optical cameras and continuous-wave tissue illumination is commonly used in medicine and biology. Surprisingly, there is a characteristic absence of a critical look at the quantities that can be uniquely characterized from optically diffuse matter by multispectral imaging. Here, we investigate the fundamental q...

Supplementary Figures 1-8, Supplementary Tables 1 & 2, Supplementary Notes 1-6 and Supplementary References.

We used raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz, and at 100 MHz, to monitor tumor growth, and tumor angiogenesis, which is a central hallmark of cancer, in-vivo. In this study we compared the performance, and the effect of the 50 MHz, and the 100 MHz frequencies on the quality of the final image. The system is based on a reflection-mode...

Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation by tissue optical properties, an effect that causes spectral corruption. Predictions of the spectral variations of light fluence in tissue are challenging since the spatial distribution of optical properties in tissue cannot be r...

Optical mesoscopy extends the capabilities of biological visualization beyond the limited penetration depth achieved by microscopy. However, imaging of opaque organisms or tissues larger than a few hundred micrometers requires invasive tissue sectioning or chemical treatment of the specimen for clearing photon scattering, an invasive process that i...

Wide-field targeted fluorescence evolves as a promising approach for interventional guidance. We present an overview of the key developments from our laboratory and discuss their potential to shift the surgical and endoscopic imaging paradigm.

Angiogenesis is a central cancer hallmark, necessary for supporting tumor growth and metastasis. In vivo imaging of angiogenesis is commonly applied, to understand dynamic processes in cancer development and treatment strategies. However, most radiological modalities today assess angiogenesis based on indirect mechanisms, such as the rate of contra...

Administration of drugs via inhalation is an attractive route for pulmonary and systemic drug delivery. The therapeutic outcome of inhalation therapy depends not only on the dose of the lung-delivered drug, but also on its bioactivity and regional distribution. Fluorescence imaging has the potential to monitor these aspects already during preclinic...

The increasing preclinical and clinical utilization of digital cameras for photographic measurements of tissue conditions motivates the study of reflectance measurements obtained with planar illumination. We examine herein a formula that models the total diffuse reflectance measured from a semi-infinite medium using an exponentially decaying source...

Molecular fluorescence imaging is a commonly used method in various biomedical fields and is undergoing rapid translation toward clinical applications. Color images are commonly superimposed with fluorescence measurements to provide orientation, anatomical information, and molecular tissue properties in a single image. New adaptive methods that pro...

White-light surveillance colonoscopy is the standard of care for the detection and removal of premalignant lesions to prevent colorectal cancer, and the main screening recommendation following treatment for recurrence detection. However, it lacks sufficient diagnostic yield, exhibits unacceptable adenoma miss-rates and is not capable of revealing f...

In this study, we compare two evolving techniques for obtaining high-resolution 3D anatomical data of a mouse specimen. On the one hand, we investigate cryotome-based planar epi-illumination imaging (cryo-imaging). On the other hand, we examine X-ray phase-contrast micro-computed tomography (micro-CT) using synchrotron radiation. Cryo-imaging is a...

We reported earlier the delivery of antiangiogenic single chain antibodies by using oncolytic vaccinia virus strains to enhance their therapeutic efficacy. Here, we provide evidence that gene-evoked production of melanin can be used as a therapeutic and diagnostic mediator, as exemplified by insertion of only one or two genes into the genome of an...