Rapid scan EPR: Automated digital resonator control for low-latency data acquisition

O’Connell, Ryan; Tseytlin, Oxana; Bobko, Andrey A.; Eubank, Timothy; Tseytlin, Mark

doi:10.1016/j.jmr.2022.107308

Cited by 2 publications

(4 citation statements)

References 54 publications

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“…A previously described [ 25 , 26 , 52 , 54 , 55 ] lab-built rapid scan (RS) EPR instrument operating at ~ 800 MHz was used for imaging. This instrument was originally designed for pre-clinical imaging.…”

Section: Methodsmentioning

confidence: 99%

“…This instrument was originally designed for pre-clinical imaging. A recently developed digital automatic control RS EPR upgrade was utilized for data acquisition [ 25 ]. The upgraded imaging system permits uninterrupted data acquisition without the need for manual resonator tuning and coupling.…”

Section: Methodsmentioning

confidence: 99%

“…It would be practically impossible to make algae cells generate O-17 by means of photosynthesis. Functional electron paramagnetic resonance imaging (EPRI) is proposed as a tool that serves the 4D bioprinting needs [ 25 – 35 ]. EPRI is analogous to MRI but detects signals generated by the electron rather than nuclear spins.…”

Section: Introductionmentioning

confidence: 99%

“…This instrument is based on the pulsed EPR method that permits imaging of oxygen-sensitive probes with relatively long relaxation times. In this study, we used a different EPR method called rapid scan (RS) [ 25 , 51 – 57 ]. RS is a relatively novel technique that is less restrictive with respect to probe relaxation times as compared to pulse EPR.…”

Section: Introductionmentioning

confidence: 99%

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Electron Spin Resonance Probe Incorporation into Bioinks Permits Longitudinal Oxygen Imaging of Bioprinted Constructs

Sarvari,

McGee,

O’Connell

et al. 2023

Mol Imaging Biol

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Purpose Bioprinting is an additive manufacturing technology analogous to 3D printing. Instead of plastic or resin, cell-laden hydrogels are used to produce a construct of the intended biological structure. Over time, cells transform this construct into a functioning tissue or organ. The process of printing followed by tissue maturation is referred to as 4D bioprinting. The fourth dimension is temporal. Failure to provide living cells with sufficient amounts of oxygen at any point along the developmental timeline may jeopardize the bioprinting goals. Even transient hypoxia may alter cells' differentiation and proliferation or trigger apoptosis. Electron paramagnetic resonance (EPR) imaging modality is proposed to permit 4D monitoring of oxygen within bioprinted structures. Procedures Lithium octa-n-butoxy-phthalocyanine (LiNc-BuO) probes have been introduced into gelatin methacrylate (GelMA) bioink. GelMA is a cross-linkable hydrogel, and LiNc-BuO is an oxygen-sensitive compound that permits longitudinal oximetric measurements. The effects of the oxygen probe on printability have been evaluated. A digital light processing (DLP) bioprinter was built in the laboratory. Bioprinting protocols have been developed that consider the optical properties of the GelMA/LiNc-BuO composites. Acellular and cell-laden constructs have been printed and imaged. The post-printing effect of residual photoinitiator on oxygen depletion has been investigated. Results Models have been successfully printed using a lab-built bioprinter. Rapid scan EPR images reflective of the expected oxygen concentration levels have been acquired. An unreported problem of oxygen depletion in bioprinted constructs by the residual photoinitiator has been documented. EPR imaging is proposed as a control method for its removal. The oxygen consumption rates by HEK293T cells within a bioprinted cylinder have been imaged and quantified. Conclusions The feasibility of the cointegration of 4D EPR imaging and 4D bioprinting has been demonstrated. The proof-of-concept experiments, which were conducted using oxygen probes loaded into GelMA, lay the foundation for a broad range of applications, such as bioprinting with many types of bioinks loaded with diverse varieties of molecular spin probes.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron Spin Resonance Probe Incorporation into Bioinks Permits Longitudinal Oxygen Imaging of Bioprinted Constructs

Sarvari,

McGee,

O’Connell

et al. 2023

Mol Imaging Biol

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Dose-Specific Intratumoral GM-CSF Modulates Breast Tumor Oxygenation and Antitumor Immunity

Mihalik,

Steinberger,

Stevens

et al. 2023

The Journal of Immunology

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GM-CSF has been employed as an adjuvant to cancer immunotherapy with mixed results based on dosage. We previously showed that GM-CSF regulated tumor angiogenesis by stimulating soluble vascular endothelial growth factor (VEGF) receptor-1 from monocytes/macrophages in a dose-dependent manner that neutralized free VEGF, and intratumoral injections of high-dose GM-CSF ablated blood vessels and worsened hypoxia in orthotopic polyoma middle T Ag (PyMT) triple-negative breast cancer (TNBC). In this study, we assessed both immunoregulatory and oxygen-regulatory components of low-dose versus high-dose GM-CSF to compare effects on tumor oxygen, vasculature, and antitumor immunity. We performed intratumoral injections of low-dose GM-CSF or saline controls for 3 wk in FVB/N PyMT TNBC. Low-dose GM-CSF uniquely reduced tumor hypoxia and normalized tumor vasculature by increasing NG2+ pericyte coverage on CD31+ endothelial cells. Priming of “cold,” anti-PD1–resistant PyMT tumors with low-dose GM-CSF (hypoxia reduced) sensitized tumors to anti-PD1, whereas high-dose GM-CSF (hypoxia exacerbated) did not. Low-dose GM-CSF reduced hypoxic and inflammatory tumor-associated macrophage (TAM) transcriptional profiles; however, no phenotypic modulation of TAMs or tumor-infiltrating lymphocytes were observed by flow cytometry. In contrast, high-dose GM-CSF priming increased infiltration of TAMs lacking the MHC class IIhi phenotype or immunostimulatory marker expression, indicating an immunosuppressive phenotype under hypoxia. However, in anti-PD1 (programmed cell death 1)–susceptible BALB/c 4T1 tumors (considered hot versus PyMT), high-dose GM-CSF increased MHC class IIhi TAMs and immunostimulatory molecules, suggesting disparate effects of high-dose GM-CSF across PyMT versus 4T1 TNBC models. Our data demonstrate a (to our knowledge) novel role for low-dose GM-CSF in reducing tumor hypoxia for synergy with anti-PD1 and highlight why dosage and setting of GM-CSF in cancer immunotherapy regimens require careful consideration.

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Rapid scan EPR: Automated digital resonator control for low-latency data acquisition

Cited by 2 publications

References 54 publications

Electron Spin Resonance Probe Incorporation into Bioinks Permits Longitudinal Oxygen Imaging of Bioprinted Constructs

Electron Spin Resonance Probe Incorporation into Bioinks Permits Longitudinal Oxygen Imaging of Bioprinted Constructs

Dose-Specific Intratumoral GM-CSF Modulates Breast Tumor Oxygenation and Antitumor Immunity

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