About

Mohammad Abbas Yaseen is an Assistant Professor in the Bioengineering department at Northeastern University College of Engineering, having joined in January 2020. His research focuses on advanced microscopy for minimally invasive, in vivo characterization of brain function. He leads the Optical Microscopy & Neuro-Imaging Lab (OMNI Lab), which develops and applies high-resolution optical technologies to investigate brain function in rodent models of human disease. His work specifically aims to investigate metabolic and immune features during healthy brain function and their alterations in disease states, with the overarching goal of understanding the etiologies of brain pathologies such as stroke and neurodegenerative diseases. His research endeavors to characterize these conditions at the cellular level within living brains to identify precise biomarkers for diagnosis and therapy.

Research topics

• Neuroscience
• Medicine
• Chemistry
• Materials science
• Biomedical engineering

Selected publications

• Chronic Aerobic Exercise Alleviates Amyloid-induced Capillary Dysfunction

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-01-16

  articleOpen accessSenior authorCorresponding

  Age-related cerebrovascular dysfunction is increasingly recognized as a critical contributor to cognitive decline and Alzheimer's disease (AD) progression. Aerobic physical activity (PA) and other modifiable lifestyle interventions can substantially reduce the likelihood of dementia; however, their ability to mitigate cerebrovascular alterations remains poorly defined. PA reportedly improves systemic vascular health and cognitive function in aging humans, but its impact on cerebrovascular function during aging and amyloid β (Aβ) pathology is unclear. Here, we longitudinally quantified microvascular oxygen tension and stimulus-evoked oxygen dynamics in awake APP/PS1dE9 mice and wild-type littermates using two-photon phosphorescence lifetime microscopy. Routine aerobic PA initiated in early adulthood preserved basal arteriolar, capillary, and venular oxygenation, prevented age-dependent increases in microvascular heterogeneity, and mitigated excessive oxygen extraction in preclinical AD mice. While amyloid pathology impaired stimulus-evoked oxygen responses across vascular compartments, PA selectively enhanced capillary dilation and accelerated hyperemic kinetics without altering vascular density or architecture. Notably, sedentary AD mice developed lower, widely-dispersed distributions in capillary oxygenation, hallmarks of malignant microvascular dysfunction, which were largely absent in physically active animals. These findings demonstrate that routine aerobic PA preserves basal capillary oxygenation and stimulus-evoked hyperemia during aging and Aβ, supporting a capillary-centric mechanism through which exercise confers neurovascular resilience in preclinical AD.

  PublisherOA PDFDOI

• Unsymmetric Heptamethine Cyanines as a General Strategy to Construct Nonaggregating Fluorophores for Biomedical Imaging

  Bioconjugate Chemistry · 2026-04-19

  article

  Heptamethine cyanine dyes are widely used as near-infrared (NIR) fluorophores in biomedical imaging. However, conventional heptamethine cyanine fluorophores are symmetric in nature, which favors fluorophore self-assembly from π–π stacking in aqueous media. This H-aggregation significantly reduces the fluorescence intensity and hampers imaging performance. Although a few nonaggregating heptamethine cyanines have been reported, no general strategy has been established for synthesizing nonaggregating heptamethine cyanine. Here, we introduce a broadly applicable approach to prevent H-aggregation by breaking the molecular symmetry of heptamethine cyanines through selective substitution along the polymethine backbone. This structural asymmetry disrupts π–π stacking interactions without adversely affecting the desirable photophysical properties of the dyes. This strategy accommodates a wide range of indolenine and polymethine substituents that enable the development of a diverse library of nonaggregating heptamethine cyanines (15 examples in total) including nonaggregating ICG analogs. One of the unsymmetrical heptamethine cyanine dyes, SAT-NIR-746, was further characterized for its aggregation behavior. SAT-NIR-746 remained monomeric in water and across a range of salt concentrations, indicating strong resistance to salt-induced H-aggregation. Furthermore, a carboxylic acid derivative of SAT-NIR-746 was converted to an NHS ester and conjugated to monoclonal antibodies (mAbs) via lysine residues. The resulting IgG-SAT-NIR-746 conjugates showed no signs of H-aggregation, further confirming the dye’s stability in both solution and protein-bound states. Finally, we show the advantages of SAT-NIR-746 for quantitative bioimaging in vitro, in vivo, and ex vivo phantom imaging.

  PublisherDOI

• A multimodal monitoring platform for animal physiology and behavior during intravital brain imaging

  2025-03-20

  articleSenior author

  Optical imaging in awake rodents offers powerful, nondisruptive methods to characterize brain function and energy metabolism with high spatial and temporal resolution. However, detailed investigations are often confounded by variations in the animals’ alertness and stress levels, as well as spontaneous motion artifacts. To facilitate 2-photon microscopy and widefield optical imaging experiments in awake mice, we developed a centralized integrated device for real-time monitoring of physiology and detection of spontaneous motion artifacts. Our compact and low-cost device provides wellsynchronized, complementary measurements of the mouse’s pupil diameter and animal behavior during imaging experiments. The device is comprised of a centralized, portable data acquisition system and a customized animal positioning frame. The data acquisition system, based on a powerful microcomputer, monitors movement through one camera and a custom-designed accelerometer and records pupil diameter through another custom camera. To validate performance, our device was utilized during wide-field optical imaging experiments exploring functional brain activation. The results demonstrated that the device substantially reduces experimental setup time while effectively screening motionaffected trials. We also observed a robust correlation between brain activity and pupillary change in response to functional somatosensory activation. The results indicate that our device is a promising tool to monitor auxiliary readouts of brain activity while also streamlining optical imaging studies.

  PublisherDOI

• Unsymmetrical Heptamethine Cyanines Prevent Aggregation

  ChemRxiv · 2025-10-28

  articleOpen access

  Heptamethine cyanine dyes are widely used as near-infrared (NIR) fluorophores in biomedical imaging. However, conventional heptamethine cyanine fluorophores are symmetric in nature which favors fluorophore self-assembly from π–π stacking in aqueous media. This aggregation significantly reduces fluorescence intensity and hampers imaging performance. Although a few non-aggregating heptamethine cyanines have been reported, no general strategy has been established for synthesizing non-aggregating heptamethine cyanine. Here, we introduce a broadly applicable approach to prevent aggregation by breaking the molecular symmetry of heptamethine cyanines through selective substitution along the polymethine backbone. This structural asymmetry disrupts π–π stacking interactions without adversely affecting the desirable photophysical properties of the dyes. The strategy accommodates a wide range of indolenine and polymethine substituents that enable development of a diverse library of non-aggregating heptamethine cyanines. One of the unsymmetrical heptamethine cyanine dyes, SAT-IR-746, was further characterized for its aggregation behavior. SAT-IR-746 remained monomeric in water and across a range of salt concentrations, indicating strong resistance to salt-induced aggregation. Furthermore, a carboxylic acid derivative of SAT-IR-746 was converted to an NHS ester and conjugated to monoclonal antibodies (mAbs) via lysine residues. The resulting IgG–SAT-IR-746 conjugates showed no signs of aggregation, further confirming the dye’s stability in both solution and protein-bound states. Finally, we show the advantages of SAT-IR-746 in live-cell imaging and ex vivo phantom imaging.

  PublisherDOI

• Towards Inclusive Medical Education in Egypt: A Cross-Sectional Study of Socio-Cultural Adaptation Among International Students

  Research Square · 2025-06-12

  preprintOpen access
  PublisherOA PDFDOI

• Low-cost physiology and behavioral monitor for intravital imaging in small mammals

  Neurophotonics · 2025-01-25 · 1 citations

  articleOpen accessSenior authorCorresponding

  Significance: Functional brain imaging experiments in awake animals require meticulous monitoring of animal behavior to screen for spontaneous behavioral events. Although these events occur naturally, they can alter cell signaling and hemodynamic activity in the brain and confound functional brain imaging measurements. Aim: We developed a centralized, user-friendly, and stand-alone platform that includes an animal fixation frame, compact peripheral sensors, and a portable data acquisition system. The affordable, integrated platform can benefit imaging experiments by monitoring animal behavior for motion detection and alertness levels as complementary readouts for brain activity measurements. Approach: A custom acquisition system was designed using a powerful, inexpensive microcomputer. We customized an accelerometer and miniature camera modules for efficient, real-time monitoring of animal motion detection and pupil diameter. We then tested and validated the platform's performance with optical intrinsic signal imaging and GCaMP fluorescence calcium imaging in functional activation experiments in awake mice. Results: The integrated platform shows promise for detecting spontaneous motion and pupil dilation while imaging. Stimulus-induced pupil dilation was found to initiate earlier than cortical hemodynamics with a slower rise time. Compared with neuronal calcium response, stimulus-induced pupil dilation initiated later with a slower rise time. Conclusions: We developed an integrated platform to monitor animal motion and pupil dynamics. The device can be easily coupled and synchronized with optical brain imaging systems to monitor behavior, alertness, and spontaneous motion for awake animal studies.

  PublisherDOI

• Prolonged systemic inflammation worsens impairments to astrocyte Ca ²⁺ and functional hyperemia in Alzheimer’s disease

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-09-04 · 1 citations

  preprintOpen accessSenior authorCorresponding

  SUMMARY Chronic neuroinflammation in Alzheimer’s disease (AD) activates astrocytes—key regulators of both brain immunity and neurovascular coupling. The primed immune environment in AD brain also renders it highly susceptible to secondary systemic inflammatory challenges. Inflammatory activation drives phenotypic shifts in astrocytes that may compromise their ability to regulate cerebral blood flow. The capacity for inflammation-activated astrocytes to retain this regulatory function, however, remains unknown. To investigate astrocyte regulation of cerebral blood flow in AD brain and under systemic inflammation, we investigated astrocytic Ca 2+ dynamics and functional hyperemia at rest and during brief and prolonged sensory stimulation in 12-month-old female APP/PS1dE9 mice. We further examined how a secondary systemic inflammatory challenge induced by low-dose, repeated injection of LPS modulates astrocytic signaling and neurovascular function. AD mice exhibited elevated spontaneous but diminished stimulation-evoked astrocytic Ca 2+ activity, accompanied by impaired sustained functional hyperemia, particularly within the capillary network. LPS-induced systemic inflammation further suppressed both spontaneous and evoked astrocytic Ca 2+ responses and attenuated functional hyperemia. Together, these findings reveal that inflammation disrupts astrocyte-dependent regulation of sustained neurovascular responses in the AD brain. HIGHLIGHTS Astrocytes in AD mice exhibit increased spontaneous Ca 2+ signaling but cannot sustain stimulus-evoked Ca 2+ release. Reduced astrocyte Ca 2+ release during 30s functional brain activation correlates with impaired neurovascular coupling in both penetrating arterioles and capillaries of AD mice A secondary, 14-day systemic inflammatory challenge further suppressed functional hyperemia of 30 s stimulus–evoked astrocytic Ca 2+ release in AD mice. A secondary inflammatory insult lasting 14 days reduced amyloid deposition in the AD brain.

  PublisherOA PDFDOI

• LPS-induced systemic inflammation reduced sensory stimulation-evoked astrocyte Ca2+ without altering the vascular response in the APP/PS1dE9 mouse model

  2025-03-19

  articleSenior author

  Neuroinflammation and neurovascular dysfunction are two major pathologies in Alzheimer’s disease (AD), yet their interplay remains poorly understood. Astrocytes are central players in both brain immunity and neurovascular coupling. In this study, we induced neuroinflammation through systemic administration of lipopolysaccharide (LPS) in 12-month-old APP/PS1dE9 mice and simultaneously monitored the astrocyte Ca²⁺ signaling and the brain hemodynamics with two-photon microscopy. We showed that the spontaneous release of Ca²⁺ in astrocytes was elevated in AD mice and decreased by 14 days of LPS administration. Interestingly, LPS-induced inflammation did not alter astrocytic Ca²⁺ signaling or vascular responses during brief sensory stimulation but significantly suppressed astrocytic Ca²⁺ signaling during sustained sensory stimulation without affecting vascular responses. These findings highlight the nuanced impact of neuroinflammation on astrocytic Ca²⁺ dynamics and brain hemodynamics in AD, shedding light on mechanisms that link these pathologies.

  PublisherDOI

• Towards inclusive medical education in Egypt: a cross-sectional study of sociocultural adaptation among international students

  BMC Medical Education · 2025-11-29

  articleOpen access

  BACKGROUND: International medical students face unique challenges in adjusting to new sociocultural environments, particularly in resource-limited settings. In Egypt, despite calls for increasing cultural diversity in medical education, limited research has explored how international students adapt and what factors influence their experience. This study aimed to assess the sociocultural adaptation of international medical students at Mansoura University to inform targeted strategies enhancing their inclusion and well-being. METHODS: A cross-sectional study was conducted among international medical students at Mansoura University between September and November 2024 using an online survey. Data were collected through convenience and snowball sampling, along with a non-probability proportionate quota based on academic year. The survey included sociodemographic items and the Sociocultural Adaptation Scale-Revised (SCAS-R), a validated tool that assesses five aspects of sociocultural adaptation on a five-point Likert scale. RESULTS: A total of 395 international students participated, with a mean SCAS-R adaptation score of 3.37 (SD = 0.69). Adaptation was highest among 1st-year students (3.52) and lower in subsequent years (2nd: 3.21; 3rd: 3.39; 4th: 3.31; 5th: 3.48). Males reported higher scores in personal interest/community involvement (3.09 vs. 2.86, p = 0.011) and language proficiency (4.25 vs. 4.00, p = 0.036). Arab students had significantly higher overall adaptation than non-Arabs (3.40 vs. 3.21, p = 0.046), primarily due to stronger language proficiency (4.42 vs. 2.76, p < 0.001). Students with sufficient income showed better adaptation in communication (3.41 vs. 3.15, p = 0.021), ecological adjustment (3.32 vs. 2.99, p = 0.008), and language (4.18 vs. 3.83, p = 0.039). CONCLUSION: The findings of this study emphasize the need for medical institutions to implement inclusive support strategies, including bilingual language training, targeted financial assistance, and sustained integration efforts beyond the first academic year. TRIAL REGISTRATION: Not applicable.

  PublisherDOI

• Advanced Techniques for Enhancing Low-Noise Amplifier Performance: A Review

  Maǧallaẗ al-handasaẗ al-rāfidayn · 2024-03-01

  reviewOpen access

  This paper reviews prior investigations into low noise amplifier (LNA) design. In this work, various modern LNA architectures will be examined, with a focus on five technologies: Cascode Distributed LNA, Coupled-Line Feedback in 0.15-m GaAs pHEMT Technology, Dual-Band CMOS LNA in 65-nm CMOS, CMOS LNA Using Post-distortion technique and 22-nm FD-SOI CMOS. In this review, Low power dissipation rate, input and output synchronization, high gain, and low noise levels are examined. In order to design a new successful LNA, each topology's performance is then examined. Future research will be conducted based on comparisons of these five topologies.

  PublisherOA PDFDOI

Recent grants

• Exploring preclinical amyloid pathology with optical microscopy

  NIH · $432k · 2019–2022

• In Vivo Imaging Alzheimers Disease Pathology with 2-Photon/Lifetime Microscopy

  NIH · $747k · 2015–2018

• NIH Grant K99AG042026

  NIH · $274k · 2015

• Relating Neuroimmune and Neurovascular Alterations During Alzheimer's Disease Progression

  NIH · $2.7M · 2018–2024

Frequent coauthors

• Sava Sakadžić

  409 shared

• David A. Boas

  291 shared

• Anna Devor

  Boston University

  227 shared

• Cenk Ayata

  117 shared

• Vivek J. Srinivasan

  106 shared

• Louis Gagnon

  Université Laval

  104 shared

• Buyin Fu

  102 shared

• Carlos A. Gómez

  91 shared

Labs

• Optical Microscopy & Neuro-Imaging LabPI