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Cosco ED, Bogyo M. Recent advances in ratiometric fluorescence imaging of enzyme activity in vivo. Curr Opin Chem Biol 2024; 80:102441. [PMID: 38457961 PMCID: PMC11164639 DOI: 10.1016/j.cbpa.2024.102441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/08/2024] [Accepted: 02/19/2024] [Indexed: 03/10/2024]
Abstract
Among molecular imaging modalities that can monitor enzyme activity in vivo, optical imaging provides sensitive, molecular-level information at low-cost using safe and non-ionizing wavelengths of light. Yet, obtaining quantifiable optical signals in vivo poses significant challenges. Benchmarking using ratiometric signals can overcome dependence on dosing, illumination variability, and pharmacokinetics to provide quantitative in vivo optical data. This review highlights recent advances using fluorescent probes that are processed by enzymes to induce photophysical changes that can be monitored by ratiometric imaging. These diverse strategies include caged fluorophores that change photophysical properties upon enzymatic cleavage, as well as multi-fluorophore systems that are triggered by enzymatic cleavage to alter optical outputs in one or more fluorescent channels. The strategies discussed here have great potential for further development as well as potential broad applications for targeting diverse enzymes important for a wide range of human diseases.
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Affiliation(s)
- Emily D Cosco
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Matthew Bogyo
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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Carrico E, Sun T, Zhu C. Numerical investigation of depth-sensitive diffuse reflectance and fluorescence measurements on murine subcutaneous tissue with growing solid tumors. BIOMEDICAL OPTICS EXPRESS 2020; 11:6311-6323. [PMID: 33282492 PMCID: PMC7687953 DOI: 10.1364/boe.405321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/24/2020] [Accepted: 10/05/2020] [Indexed: 05/08/2023]
Abstract
In most biomedical optical spectroscopy platforms, a fiber-probe consisting of single or multiple illumination and collection fibers was commonly used for the delivery of illuminating light and the collection of emitted light. Typically, the signals from all collection fibers were combined and then sampled to characterize tissue samples. Such simple averaged optical measurements may induce significant errors for in vivo tumor characterization, especially in longitudinal studies where the tumor size and location vary with tumor stages. In this study, we utilized the Monte Carlo technique to optimize the fiber-probe geometries of a spectroscopy platform to enable tumor-sensitive diffuse reflectance and fluorescence measurements on murine subcutaneous tissues with growing solid tumors that have different sizes and depths. Our data showed that depth-sensitive techniques offer improved sensitivity in tumor detection compared to the simple averaged approach in both reflectance and fluorescence measurements. Through the numerical studies, we optimized the source-detector distances, fiber diameters, and numerical apertures for sensitive measurement of small solid tumors with varying size and depth buried in murine subcutaneous tissues. Our study will advance the design of a fiber-probe in an optical spectroscopy system that can be used for longitudinal tumor metabolism and vasculature monitoring.
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Affiliation(s)
- Evan Carrico
- Department of Electrical Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - Tengfei Sun
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - Caigang Zhu
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
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Abstract
The present chapter summarizes progress with optical methods that go beyond human vision. The focus is on two particular technologies: fluorescence molecular imaging and optoacoustic (photoacoustic) imaging. The rationale for the selection of these two methods is that in contrast to optical microscopy techniques, both fluorescence and optoacoustic imaging can achieve large fields of view, i.e., spanning several centimeters in two or three dimensions. Such fields of views relate better to human vision and can visualize large parts of tissue, a necessary premise for clinical detection. Conversely, optical microscopy methods only scan millimeter-sized dimensions or smaller. With such operational capacity, optical microscopy methods need to be guided by another visualization technique in order to scan a very specific area in tissue and typically only provide superficial measurements, i.e., information from depths that are of the order of 0.05-1 mm. This practice has generally limited their clinical applicability to some niche applications, such as optical coherence tomography of the retina. On the other hand, fluorescence molecular imaging and optoacoustic imaging emerge as more global optical imaging methods with wide applications in surgery, endoscopy, and non-invasive clinical imaging, as summarized in the following. The current progress in this field is based on a volume of recent review and other literature that highlights key advances achieved in technology and biomedical applications. Context and figures from references from the authors of this chapter have been used here, as it reflects our general view of the current status of the field.
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Affiliation(s)
- Daniel Razansky
- Faculty of Medicine and Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland
| | - Vasilis Ntziachristos
- Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.
- Institute of Biological and Medical Imaging, Helmholtz Zentrum München, Neuherberg, Germany.
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Burgess L, Chen J, Wolter NE, Wilson B, Zheng G. Topical MMP beacon enabled fluorescence-guided resection of oral carcinoma. BIOMEDICAL OPTICS EXPRESS 2016; 7:1089-99. [PMID: 27231609 PMCID: PMC4866449 DOI: 10.1364/boe.7.001089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 02/20/2016] [Accepted: 02/24/2016] [Indexed: 06/05/2023]
Abstract
Each year almost 300,000 individuals worldwide are diagnosed with oral cancer, more than 90% of these being oral carcinoma [N. Engl. J. Med.328, 1841993]. Surgical resection is the standard of care, but accurate delineation of the tumor boundaries is challenging, resulting in either under-resection with risk of local recurrence or over-resection with increased functional loss and negative impact on quality of life. This study evaluates, in two pre-clinical in vivo tumor models, the potential of fluorescence-guided resection using molecular beacons activated by metalloproteinases, which are frequently upregulated in human oral cancer. In both models there was rapid (<15 min) beacon activation upon local application, allowing clear fluoresecence imaging in vivo and confirmed by ex vivo fluorescence microscopy and HPLC, with minimal activation in normal oral tissues. Although the tissue penetration was limited using topical application, these findings support further development of this approach towards translation to first-in-human trials.
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Affiliation(s)
- Laura Burgess
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto ON M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto ON M5G 1L7, Canada
| | - Juan Chen
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto ON M5G 1L7, Canada
| | - Nikolaus E. Wolter
- Department of Otolaryngology – Head & Neck Surgery, University of Toronto, 190 Elizabeth St, Rm 3S438, RFE Building Toronto, ON, M5G 2N2, Canada
| | - Brian Wilson
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto ON M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto ON M5G 1L7, Canada
| | - Gang Zheng
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto ON M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto ON M5G 1L7, Canada
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Sunar U. Monitoring photodynamic therapy of head and neck malignancies with optical spectroscopies. World J Clin Cases 2013; 1:96-105. [PMID: 24303476 PMCID: PMC3845916 DOI: 10.12998/wjcc.v1.i3.96] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/02/2013] [Accepted: 05/08/2013] [Indexed: 02/05/2023] Open
Abstract
In recent years there has been significant developments in photosensitizers (PSs), light sources and light delivery systems that have allowed decreasing the treatment time and skin phototoxicity resulting in more frequent use of photodynamic therapy (PDT) in the clinical settings. Compared to standard treatment approaches such as chemo-radiation and surgery, PDT has much reduced morbidity for head and neck malignancies and is becoming an alternative treatment option. It can be used as an adjunct therapy to other treatment modalities without any additive cumulative side effects. Surface illumination can be an option for pre-malignant and early-stage malignancies while interstitial treatment is for debulking of thick tumors in the head and neck region. PDT can achieve equivalent or greater efficacy in treating head and neck malignancies, suggesting that it may be considered as a first line therapy in the future. Despite progressive development, clinical PDT needs improvement in several topics for wider acceptance including standardization of protocols that involve the same administrated light and PS doses and establishing quantitative tools for PDT dosimetry planning and response monitoring. Quantitative measures such as optical parameters, PS concentration, tissue oxygenation and blood flow are essential for accurate PDT dosimetry as well as PDT response monitoring and assessing therapy outcome. Unlike conventional imaging modalities like magnetic resonance imaging, novel optical imaging techniques can quantify PDT-related parameters without any contrast agent administration and enable real-time assessment during PDT for providing fast feedback to clinicians. Ongoing developments in optical imaging offer the promise of optimization of PDT protocols with improved outcomes.
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Sunar U, Rohrbach DJ, Morgan J, Zeitouni N, Henderson BW. Quantification of PpIX concentration in basal cell carcinoma and squamous cell carcinoma models using spatial frequency domain imaging. BIOMEDICAL OPTICS EXPRESS 2013; 4:531-7. [PMID: 23577288 PMCID: PMC3617715 DOI: 10.1364/boe.4.000531] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/05/2013] [Accepted: 03/05/2013] [Indexed: 05/17/2023]
Abstract
5-aminolaevulinic acid photodynamic therapy (ALA-PDT) is an attractive treatment option for nonmelanoma skin tumors, especially for multiple lesions and large areas. The efficacy of ALA-PDT is highly dependent on the photosensitizer (PS) concentration present in the tumor. Thus it is desirable to quantify PS concentration and distribution, preferably noninvasively to determine potential outcome. Here we quantified protoporphyrin IX (PpIX) distribution induced by topical and intra-tumoral (it) administration of the prodrug ALA in basal and squamous cell carcinoma murine models by using spatial frequency domain imaging (SFDI). The in vivo measurements were validated by analysis of the ex vivo extraction of PpIX. The study demonstrates the feasibility of non-invasive quantification of PpIX distributions in skin tumors.
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Affiliation(s)
- Ulas Sunar
- Department of Cell Stress Biology & PDT Center, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - Daniel J. Rohrbach
- Department of Cell Stress Biology & PDT Center, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - Janet Morgan
- Department of Dermatology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - Natalie Zeitouni
- Department of Dermatology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
| | - Barbara W. Henderson
- Department of Cell Stress Biology & PDT Center, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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Bioimpedance for pain monitoring during cutaneous photodynamic therapy: Preliminary study. Photodiagnosis Photodyn Ther 2011; 8:307-13. [DOI: 10.1016/j.pdpdt.2011.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 06/01/2011] [Accepted: 06/03/2011] [Indexed: 12/29/2022]
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Microneedle Pre-treatment of Human Skin Improves 5-Aminolevulininc Acid (ALA)- and 5-Aminolevulinic Acid Methyl Ester (MAL)-Induced PpIX Production for Topical Photodynamic Therapy Without Increase in Pain or Erythema. Pharm Res 2010; 27:2213-20. [DOI: 10.1007/s11095-010-0227-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/21/2010] [Indexed: 10/19/2022]
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