Biology subjects

Saad, M. A.

Publications and source records attributed to Saad, M. A..

6 recordsLinked to original sources

bioRxiv2024

Temporal dynamics of fluorescence and photoacoustic signals of a Cetuximab-IRDye800 conjugate in EGFR-overexpressing tumors

Molecular fluorescence-guided surgery has shown promise for tumor margin delineation but is limited by its depth profiling capability. Interestingly, most fluorophores, either clinically approved or in clinical trials, can also be used as photoacoustic contrast agents, yet their use is limited due to the low light fluence permitted for clinical use and the limited sensitivity of current photoacoustic imaging systems. There is therefore an urgent unmet need to establish methods for enhancing contrast in molecular targeted PA imaging which could potentially complement and overcome limitations in molecular fluorescence guided therapies. In this study, we compare the photoacoustic (PA) and fluorescence imaging capabilities of a cetuximab-IRDye800 conjugate in a subcutaneous tumor xenograft model. We demonstrate that while the fluorescence signal increases steadily over time after administration of cetuximab-IRDye800, PA signal peaks early ([~]2 fold higher at 6-hour as compared to pre-injection controls) and then decreases ([~]1.3 fold higher at 24-hour as compared to pre-injection controls). This pattern aligns with previous findings using other antibody-conjugated PA contrast agents. Mechanistically, we demonstrate that the formation of H-aggregates upon antibody conjugation enhances PA contrast of the IRDye800. The disruption of these H-aggregates, as the antibody-dye conjugate is degraded post receptor-mediated endocytosis, decreases PA signal intensity. The timeframe of maximum PA signal and decrease thereafter is consistent with the time frame of receptor-mediated endocytosis of cetuximab-IRDye800. Our data suggests that tumor cell surface binding results in peak PA signal while lysosomal localization and degradation results in a significant drop in PA signal. Our study sheds light on the distinct temporal dynamics of PA and fluorescence signals of Cetuximab-IRDye800 conjugate and we propose that optimizing IRDye800 conjugation to antibodies can further enhance PA signal intensity when timed to precisely to capture IRDye800 in an H-aggregate form.

cancer biology↗

bioRxiv2023

A Dual Function Antibody Conjugate Enabled Photoimmunotherapy Complements Fluorescence and Photoacoustic Imaging of Head and Neck Cancer Spheroids

Several molecular-targeted imaging and therapeutic agents are in clinical trials for image-guided surgery and photoimmunotherapy (PIT) of head and neck cancers. In this context, we have previously reported the development, characterization, and specificity of a dual function antibody conjugate (DFAC) for multi-modal imaging and photoimmunotherapy (PIT) of EGFR over-expressing cancer cells. The DFAC reported previously and used in the present study, comprises of an EGFR targeted antibody - Cetuximab conjugated to Benzoporphyrin derivative (BPD) for fluorescence imaging and PIT, and a Si-centered naphthalocyanine dye for photoacoustic imaging. We report here the evaluation and performance of DFAC in detecting microscopic cancer spheroids by fluorescence and photoacoustic imaging along with their treatment by PIT. We demonstrate that while fluorescence imaging can detect spheroids with volumes greater than 0.049 mm3, photoacoustic imaging-based detection was possible even for the smallest spheroids (0.01 mm3), developed in the study. When subjected to PIT, the spheroids showed a dose-dependent response with smaller spheroids (0.01 and 0.018 mm3) showing a complete response with no recurrence when treated with 100 J/cm2. Together our results demonstrate the complementary imaging and treatment capacity of DFAC. This potentially enables fluorescence imaging to assess tumor presence on a macroscopic scale followed by photoacoustic imaging for delineating tumor margins guiding surgical resection and elimination of any residual microscopic disease by PIT, in a single intra-operative setting.

cancer biology↗

bioRxiv2022

Sparse-spectral microendoscopy for real-time visualization of tumor cell phenotype and microenvironment spatial heterogeneity in vivo

Cancer heterogeneity and its transformation with time propels treatment resistance and confounds patient outcomes. The inability to monitor in vivo the low abundance, heterocellular phenotypes that resist treatment and ultimately lead to patient death limits the ability to design precision therapies. Here we overcome limitations in multiplexed fluorescence phenotyping to introduce real-time, cellular resolution visualization of tumor heterogeneity in vivo. This method was performed to simultaneously map for the first time 5 individual biomarkers of stemness, proliferation, metabolism, leukocytes and angiogenesis deep within the peritoneal cavities of micrometastatic cancer mouse models at 17 frames per second (fps). The newly developed imaging system revealed distinct cancer cell phenotype-immune cell spatial correlations and clearly visualized the dynamic spatial response of resistant cancer cell niches following treatment. Furthermore, wide-field datasets were generated to facilitate derivation of a mathematical framework for quantifying biomarker spatial variation and thereby overcoming the area restrictions of conventional tumor biopsy. These results pave the way for real-time identification of cancer cell phenotypes in a clinical setting, on which optimized treatment regimens can be based for personalized treatment and precision therapy e.g., tumor margin determination during surgical resection. Additionally, this modality can be used to obtain more fundamental insights into tumor heterogeneity and how treatments affect the molecular and cellular responses of patient-specific disease.

bioengineering↗

bioRxiv2021

Photoimmunotherapy retains its anti-tumor efficacy with increasing stromal content in heterotypic pancreatic cancer spheroids

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease characterized by increased levels of desmoplasia that contributes to reduced drug delivery and poor treatment outcomes. In PDAC, the stromal content can account for up to 90% of the total tumor volume. The complex interplay between stromal components, including pancreatic cancer associated fibroblasts (PCAFs), and PDAC cells in the tumor microenvironment (TME) have a significant impact on prognoses and thus needs to be recapitulated in vitro when evaluating various treatment strategies. This study is a systematic evaluation of photodynamic therapy (PDT) in 3D heterotypic coculture models of PDAC with varying ratios of patient derived PCAFs that simulate heterogenous PDAC tumors with increasing stromal content. The efficacy of antibody-targeted PDT (photoimmunotherapy; PIT) using cetuximab photoimmunoconjugates (PICs) of benzoporphyrin derivative (BPD) is contrasted with that of liposomal BPD (Visudyne(R)), which is currently in PDT clinical trials for PDAC. We demonstrate that both Visudyne(R)-PDT and PIT were effective in heterotypic PDAC 3D spheroids with a low stromal content. However, as the stromal content increases above 50% in the 3D spheroids, the efficacy of Visudyne(R)-PDT is reduced by up to 10-fold, while PIT retains its efficacy. PIT was found to be 10-fold, 19-fold and 14-fold more phototoxic in spheroids with 50%, 75% and 90% PCAFs, respectively, as compared to Visudyne(R)-PDT. This marked difference in efficacy is attributed to the ability of PICs to penetrate and distribute within spheroids with a higher stromal content, whereas Visudyne(R) is restricted to the spheroid periphery. This study thus demonstrates how the stromal content in PDAC spheroids directly impacts their responsiveness to PDT and proposes PIT to be a highly suited treatment option for desmoplastic tumors with particularly high degrees of stromal content.

cancer biology↗

bioRxiv2021

Safety and Immunogenicity Evaluation of Inactivated whole-virus-SARS-COV-2 In Mice As Emerging Vaccine Development In Egypt

The current worldwide pandemic COVID-19 is causing severe human health problems, with high numbers of mortality rates and huge economic burdens that require an urgent demand for safe, and effective and vaccine development. Our study was the first trail to development and evaluation of safety and immune response to inactivated whole SARS-COV-2 virus vaccine adjuvanted with aluminium hydroxide. We used characterized SARS-COV-2 strain, severe acute respiratory syndrome coronavirus 2 isolates (SARS-CoV-2/human/EGY/Egy-SERVAC/2020) with accession numbers; MT981440; MT981439; MT981441; MT974071; MT974069 and MW250352 at GenBank that isolated from Egyptian patients SARS-CoV-2-positive. Development of the vaccine was carried out in a BSL - 3 facilities and the immunogenicity was determined in mice at two doses (55{micro}g and 100{micro}g per dose). All vaccinated mice were received a booster dose 14 days post first immunization. Our results demonstrated distinct cytopathic effect on the vero cell monolayers induced through SARS-COV-2 propagation and the viral particles were identified as Coronaviridae by transmission electron microscopy. SARS-CoV-2 was identified by RT-PCR performed on the cell culture. Immunogenicity of the developed vaccine indicated the high antigen-binding and neutralizing antibody titers, regardless the dose concentration, with excellent safety profiles.However, no deaths or clinical symptoms in mice groups. The efficacy of the inactivated vaccine formulation was tested by wild virus challenge the vaccinated mice and detection of viral replication in lung tissues. Vaccinated mice recorded complete protection from challenge infection three weeks post second dose. SARS-COV-2 replication was not observed in the lungs of mice following SARS-CoV-2 challenge, regardless of the level of serum neutralizing antibodies. This finding will support the future trials for evaluation an applicable SARS-CoV-2 vaccine candidate.

immunology↗

bioRxiv2018

Computational Screening of Potential Inhibitors of Desulfobacter postgatei for Pyrite Scale Prevention in Oil and Gas Wells

Sulfate-reducing bacteria (SRB) such as Desulfobacter postgatei are often found in oil and gas wells. However, they lead to the release of hydrogen sulfide which in turn leads to the formation of iron sulfide scale such as pyrite. ATP sulfurylase is an enzyme present in SRB, which catalyzes the formation of adenylyl sulfate (APS) and inorganic pyrophosphatase (PPi) from ATP and sulfate which is one of the first steps in hydrogen sulfide production by D. postgatei. Virtual screening using molecular docking and machine learning tools was used to identify three potential inhibitors of ATP sulfurylase from a database of about 40 million compounds. These selected hits ((S,E)-1-(4-methoxyphenyl)-3-(9-((m-tolylimino)methyl)-9,10-dihydroanthracen-9-yl)pyrrolidine-2,5-dione;,methyl 2-[[(1S)-5-cyano-2-imino-1-(4-phenylthiazol-2-yl)-3-azaspiro[5.5]undec-4-en-4-yl]sulfanyl]acetate and (4S)-4-(3-chloro-4-hydroxy-phenyl)-1-(6-hydroxypyridazin-3-yl)-3-methyl-4,5-dihydropyrazolo[3,4-b]pyridin-6-ol), which are known as A, B and C respectively) all had good binding affinities with ATP sulfurylase and were further analyzed for their toxicological properties. The molecular docking results showed that all the compounds have negative binding energy with compound A having the highest docking score. However, based on the physicochemical and toxicological properties, compound C is the best choice as it does not violate any of the recommended properties that relate to absorption and distribution. Only compound C was predicted to be both safe and effective as a potential inhibitor of ATP sulfurylase. The binding mode of compound C revealed favorable interactions with the amino residues LEU 213, ASP 308, ARG 307, TRP 347, LEU 224, GLN 212, MET211 and HIS 309.\n\nImportanceScale formation formed by hydrogen sulfide, which is produced by sulfate reducing bacteria such as Desulfobacter postgatei has been a persistent problem in the oil and gas industry leading to loss of money, time and even lives. The three selected hits from the virtual screenings of about 40 million compounds would possibly inhibit the enzyme, ATP sulfurylase, which is involved in the first reaction in hydrogen sulfide formation in Desulfobacter postgatei. The selected inhibitors are expected to significantly reduce the formation of hydrogen sulfide and consequently prevent the development of pyrite scale in oil and gas wells.

biochemistry↗