In vivo characterization and analysis of glioblastoma at different stages using multiscale photoacoustic molecular imaging

Utility of photoacoustic patterns in intra-operative margin assessment of breast cancer post neoadjuvant chemotherapy

Purpose

To evaluate the feasibility and accuracy of ultrasound-guided photoacoustic tomography (US-PA) for intraoperative margin assessment in breast-conserving surgery (BCS) following neoadjuvant chemotherapy (NACT).

Methods

This study, approved by the local Institutional Review Board, included 21 women with histologically confirmed breast cancer referred for BCS post-NACT. Data from 4 participants were used for training while 17 participants were analyzed. US-PA imaging was performed using the MSOT inVision 512-ECHO system, capturing chromophores like lipids, collagen, and hemoglobin up to a 5 mm depth. Imaging results were compared to histopathological findings, and diagnostic accuracy was calculated.

Results

US-PA imaging demonstrated a high diagnostic accuracy of 89.0 %, with a sensitivity and negative predictive value (NPV) of 100 %, specificity of 86.9 %, and positive predictive value (PPV) of 59.4 %. Excellent inter-observer agreement (kappa = 1) was observed. No laser-induced tissue damage was noted. The average scan time per specimen was approximately 20 minutes. False positives (n = 11) were primarily due to post-therapy fibrotic changes and extremely close tumor extensions (<2 mm).

Conclusion

US-PA provided clear visualization of tissue components, accurately correlating with histopathology. The method's high NPV minimizes the risk of re-operations and locoregional recurrence. Although the PPV was lower, it did not impact clinical management as surgeons typically excise wider margins in such cases. The study highlighted US-PA's potential as a promising tool for intraoperative margin assessment in BCS post-NACT, offering a rapid, accurate, and safe method. Further studies with larger sample sizes are needed to confirm these findings and enhance quantitative assessment methods.

Peptide-based immuno-PET/CT monitoring of dynamic PD-L1 expression during glioblastoma radiotherapy

Real-time, noninvasive programmed death-ligand 1 (PD-L1) testing using molecular imaging has enhanced our understanding of the immune environments of neoplasms and has served as a guide for immunotherapy. However, the utilization of radiotracers in the imaging of human brain tumors using positron emission tomography/computed tomography (PET/CT) remains limited. This investigation involved the synthesis of [18F]AlF-NOTA-PCP2, which is a novel peptide-based radiolabeled tracer that targets PD-L1, and evaluated its imaging capabilities in orthotopic glioblastoma (GBM) models. Using this tracer, we could noninvasively monitor radiation-induced PD-L1 changes in GBM. [18F]AlF-NOTA-PCP2 exhibited high radiochemical purity (>95%) and stability up to 4 h after synthesis. It demonstrated specific, high-affinity binding to PD-L1 in vitro and in vivo, with a dissociation constant of 0.24 nM. PET/CT imaging, integrated with contrast-enhanced magnetic resonance imaging, revealed significant accumulation of [18F]AlF-NOTA-PCP2 in orthotopic tumors, correlating with blood-brain barrier disruption. After radiotherapy (15 Gy), [18F]AlF-NOTA-PCP2 uptake in tumors increased from 9.51% ± 0.73% to 12.04% ± 1.43%, indicating enhanced PD-L1 expression consistent with immunohistochemistry findings. Fractionated radiation (5 Gy × 3) further amplified PD-L1 upregulation (13.9% ± 1.54% ID/cc) compared with a single dose (11.48% ± 1.05% ID/cc). Taken together, [18F]AlF-NOTA-PCP2 may be a valuable tool for noninvasively monitoring PD-L1 expression in brain tumors after radiotherapy.

Dichroism-sensitive photoacoustic imaging for in-depth estimation of the optic axis in fibrous tissue

Photoacoustic imaging (PAI) is a developing image modality that benefits from light-matter interaction and low acoustic attenuation to provide functional information on tissue composition at relatively large depths. Several studies have reported the potential of dichroism-sensitive photoacoustic (DS-PA) imaging to expand PAI capabilities by obtaining morphological information of tissue regarding anisotropy and predominant orientation. However, most of these studies have limited their analysis to superficial scanning of samples, where fluence effects are negligible. Herein, we present a mathematical model for the in-depth analysis of the DS-PA signal of biological samples, focusing on estimating tissue orientation. Our model is validated with a B-scan setup for DS-PA imaging in ex-vivo porcine tendon samples, for which collagen displays optical anisotropy. Results show that for in-depth DS-PA imaging, the accumulative fluence modulation due to dichroism overcomes the effect of absorption dichroism affecting the measured signals; however, this effect can be corrected based on the presented model for determining fiber orientation.

Amphiphilic hemicyanine molecular probes crossing the blood-brain barrier for intracranial optical imaging of glioblastoma

Intracranial optical imaging of glioblastoma (GBM) is challenging due to the scarcity of effective probes with blood-brain barrier (BBB) permeability and sufficient imaging depth. Herein, we describe a rational strategy for designing optical probes crossing the BBB based on an electron donor-π-acceptor system to adjust the lipid/water partition coefficient and molecular weight of probes. The amphiphilic hemicyanine dye (namely, IVTPO), which exhibits remarkable optical properties and effective BBB permeability, is chosen as an efficient fluorescence/photoacoustic probe for in vivo real-time imaging of orthotopic GBM with high resolution through the intact skull. Abnormal leakage of IVTPO adjacent to the developing tumor is unambiguously observed at an early stage of tumor development prior to impairment of BBB integrity, as assessed by commercial Evans blue (EB). Compared with EB, IVTPO demonstrates enhanced optical imaging capability and improved tumor-targeting efficacy. These results offer encouraging insights into medical diagnosis of intracranial GBM.

Quantitative evaluation of microenvironmental changes and efficacy of cupping therapy under different pressures based on photoacoustic imaging

Cupping therapy, a traditional Chinese medicinal practice, has been subjected to scientific scrutiny to validate its effects on local tissue microenvironments. This study provides a quantitative assessment of cupping therapy at different negative pressures using photoacoustic imaging. Low-pressure cupping (-20 kPa) significantly improved local blood circulation, evidenced by increased hemoglobin oxygen saturation and vessel dilation that normalized within two hours. In contrast, high-pressure cupping (-30 kPa) led to capillary rupture, bleeding, and tissue edema, similar to the clinical presentation of cupping bruises. Additionally, our research unveiled that -20 kPa cupping expedited the clearance of indocyanine green dye, suggesting enhanced lymphatic drainage, which was further supported by fluorescence imaging. This indicates a potential mechanism for cupping's pain relief effects. Moreover, cupping showed promising results in improving sepsis outcomes in mice, potentially due to its anti-inflammatory properties. This study establishes a foundation for the objective evaluation of cupping therapy, demonstrating that low-pressure cupping is effective in promoting blood and lymphatic flow while minimizing tissue damage, thereby offering a safer therapeutic approach.

Precise Identification of Glioblastoma Micro-Infiltration at Cellular Resolution by Raman Spectroscopy

Precise identification of glioblastoma (GBM) microinfiltration, which is essential for achieving complete resection, remains an enormous challenge in clinical practice. Here, the study demonstrates that Raman spectroscopy effectively identifies GBM microinfiltration with cellular resolution in clinical specimens. The spectral differences between infiltrative lesions and normal brain tissues are attributed to phospholipids, nucleic acids, amino acids, and unsaturated fatty acids. These biochemical metabolites identified by Raman spectroscopy are further confirmed by spatial metabolomics. Based on differential spectra, Raman imaging resolves important morphological information relevant to GBM lesions in a label-free manner. The area under the receiver operating characteristic curve (AUC) for Raman spectroscopy combined with machine learning in detecting infiltrative lesions exceeds 95%. Most importantly, the cancer cell threshold identified by Raman spectroscopy is as low as 3 human GBM cells per 0.01 mm2. Raman spectroscopy enables the detection of previously undetectable diffusely infiltrative cancer cells, which holds potential value in guiding complete tumor resection in GBM patients.

Dynamic characterization of vascular response and treatment in oral traumatic ulcer in mice via photoacoustic imaging

Background

Dynamic surveillance of vasculature is essential for evaluating the healing of oral ulcer. Existing techniques used in vascular imaging face limitations, such as inadequate spatial resolution, restricted diagnostic depth, and the necessity of exogenous contrast agents. Therefore, this study aimed to use robust photoacoustic imaging (PAI) for the dynamic monitoring of vascular response during healing and the associated treatment process of oral ulcer.

Methods

Kunming mice (male, 8 weeks old, 31-41 g) were treated with 50% acetic acid for 90 s on the tongue mucosa for induction of oral traumatic ulcer. Mice were randomly divided into three groups (n=12): the control, compound chamomile and lidocaine hydrochloride gel (CCLH), and phycocyanin (PC) groups. PAI was then conducted on days 0, 2, 3, 5, and 7 to obtain vessel parameters of the ulcer area, including vessel intensity, density, mean diameter, maximum diameter, and curvature. Immunohistochemical and hematoxylin and eosin (HE) staining were performed on days 3 and 7 to assess microvessel density and inflammation score. The ulcer healing rate and body weight changes were evaluated for clinical observation.

Results

Beginning on the second day after ulcer induction, there was a progressive increase over time in blood intensity and vessel parameters, including vascular density and diameter. On day 7, the CCLH and PC groups demonstrated significantly higher measures than did the control group in terms of blood intensity (P<0.05 and P<0.01), vascular density (both P values <0.05), mean diameter (both P values <0.01), and maximum diameter (P<0.01 and P<0.05). Vessel curvature in the two treatment groups exhibited no significant differences compared to that in the control group (both P values >0.05). The effects of vascular morphological changes were further supported by the histological and clinical outcomes. On day 7, compared to that of the control group, the level of microvessel density was significantly higher in both the CCLH (P<0.01) and PC (P<0.05) groups. The histopathological score in PC group was significantly lower than that of the control group on day 7 (P<0.05). Additionally, compared to that of the control group, the healing rates of the CCLH (P<0.01) and PC groups (P<0.05) were superior on day 7. On day 3, the control group showed more weight loss than did the CCLH (P<0.05) and PC (P<0.01) groups.

Conclusions

These findings indicate that PAI is a valuable strategy for the dynamic and quantitative analysis of vascular alterations in oral traumatic ulcers and support its prospective application in improving clinical treatment.

Mesenchymal Stem Cells-Involved Strategies for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints and bone destruction. Because of systemic administration and poor targeting, traditional anti-rheumatic drugs have unsatisfactory treatment efficacy and strong side effects, including myelosuppression, liver or kidney function damage, and malignant tumors. Consequently, mesenchymal stem cells (MSCs)-involved therapy is proposed for RA therapy as a benefit of their immunosuppressive and tissue-repairing effects. This review summarizes the progress of MSCs-involved RA therapy through suppressing inflammation and promoting tissue regeneration and predicts their potential clinical application.

Fully dense generative adversarial network for removing artifacts caused by microwave dielectric effect in thermoacoustic imaging

Microwave-induced thermoacoustic (TA) imaging (MTAI) combines pulsed microwave excitation and ultrasound detection to provide high contrast and spatial resolution images through dielectric contrast, which holds great promise for clinical applications. However, artifacts caused by microwave dielectric effect will seriously affect the accuracy of MTAI images that will hinder the clinical translation of MTAI. In this work, we propose a deep learning-based method fully dense generative adversarial network (FD-GAN) for removing artifacts caused by microwave dielectric effect in MTAI. FD-GAN adds the fully dense block to the generative adversarial network (GAN) based on the mutual confrontation between generator and discriminator, which enables it to learn both local and global features related to the removal of artifacts and generate high-quality images. The practical feasibility was tested in simulated, experimental data. The results demonstrate that FD-GAN can effectively remove the artifacts caused by the microwave dielectric effect, and shows superiority in denoising, background suppression, and improvement of image distortion. Our approach is expected to significantly improve the accuracy and quality of MTAI images, thereby enhancing the diagnostic accuracy of this innovative imaging technique.

Astrocyte-Derived Extracellular Vesicular miR-143-3p Dampens Autophagic Degradation of Endothelial Adhesion Molecules and Promotes Neutrophil Transendothelial Migration after Acute Brain Injury

Pivotal roles of extracellular vesicles (EVs) in the pathogenesis of central nervous system (CNS) disorders including acute brain injury are increasingly acknowledged. Through the analysis of EVs packaged miRNAs in plasma samples from patients with intracerebral hemorrhage (ICH), it is discovered that the level of EVs packaged miR-143-3p (EVs-miR-143-3p) correlates closely with perihematomal edema and neurological outcomes. Further study reveals that, upon ICH, EVs-miR-143-3p is robustly secreted by astrocytes and can shuttle into brain microvascular endothelial cells (BMECs). Heightened levels of miR-143-3p in BMECs induce the up-regulated expression of cell adhesion molecules (CAMs) that bind to circulating neutrophils and facilitate their transendothelial cell migration (TEM) into brain. Mechanism-wise, miR-143-3p directly targets ATP6V1A, resulting in impaired lysosomal hydrolysis ability and reduced autophagic degradation of CAMs. Importantly, a VCAM-1-targeting EVs system to selectively deliver miR-143-3p inhibitor to pathological BMECs is created, which shows satisfactory therapeutic effects in both ICH and traumatic brain injury (TBI) mouse models. In conclusion, the study highlights the causal role of EVs-miR-143-3p in BMECs' dysfunction in acute brain injury and demonstrates a proof of concept that engineered EVs can be devised as a potentially applicable nucleotide drug delivery system for the treatment of CNS disorders.

Photoacoustic micro-viscoelastography for mapping mechanocellular properties

Cellular biomechanical properties provide essential insights into biological functions regarding health and disease. Current measurements of the biomechanical properties of cells require physical contact with cells or pre-loading on the cells. Here, we have developed photoacoustic micro-viscoelastography (PAMVE), which utilizes the phase characteristics of photoacoustic (PA) response, for mapping mechanocellular properties in a load-free manner. PAMVE realizes the local viscoelasticity measurement on the macrophages and red blood cells with micrometer scale. Furthermore, PAMVE can successfully identify the adipose cell and skeletal muscle cell due to the difference in their composition-related biomechanical properties. PAMVE represents an irreplaceable option for interrogating characteristic mechanocellular properties, opening the possibility of studying cellular mechanobiology and pathophysiology.

Advances in photoacoustic imaging aided by nano contrast agents: special focus on role of lymphatic system imaging for cancer theranostics

Photoacoustic imaging (PAI) is a successful clinical imaging platform for management of cancer and other health conditions that has seen significant progress in the past decade. However, clinical translation of PAI based methods are still under scrutiny as the imaging quality and clinical information derived from PA images are not on par with other imaging methods. Hence, to improve PAI, exogenous contrast agents, in the form of nanomaterials, are being used to achieve better image with less side effects, lower accumulation, and improved target specificity. Nanomedicine has become inevitable in cancer management, as it contributes at every stage from diagnosis to therapy, surgery, and even in the postoperative care and surveillance for recurrence. Nanocontrast agents for PAI have been developed and are being explored for early and improved cancer diagnosis. The systemic stability and target specificity of the nanomaterials to render its theranostic property depends on various influencing factors such as the administration route and physico-chemical responsiveness. The recent focus in PAI is on targeting the lymphatic system and nodes for cancer diagnosis, as they play a vital role in cancer progression and metastasis. This review aims to discuss the clinical advancements of PAI using nanoparticles as exogenous contrast agents for cancer theranostics with emphasis on PAI of lymphatic system for diagnosis, cancer progression, metastasis, PAI guided tumor resection, and finally PAI guided drug delivery.

Programming Cell-Derived Vesicles with Enhanced Immunomodulatory Properties

Tumor-associated macrophages are the predominant immune cells present in the tumor microenvironment and mostly exhibit a pro-tumoral M2-like phenotype. However, macrophage biology is reversible allowing them to acquire an anti-tumoral M1-like phenotype in response to external stimuli. A potential therapeutic strategy for treating cancer may be achieved by modulating macrophages from an M2 to an M1-like phenotype with the tumor microenvironment. Here, programmed nanovesicles are generated as an immunomodulatory therapeutic platform with the capability to re-polarize M2 macrophages toward a proinflammatory phenotype. Programmed nanovesicles are engineered from cellular membranes to have specific immunomodulatory properties including the capability to bidirectionally modulate immune cell polarization. These programmed nanovesicles decorated with specific membrane-bound ligands can be targeted toward specific cell types including immune cells. Macrophage-derived vesicles are engineered to enhance immune cell reprogramming toward a proinflammatory phenotype.