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Eleftheriadou D, Berg M, Phillips JB, Shipley RJ. A combined experimental and computational framework to evaluate the behavior of therapeutic cells for peripheral nerve regeneration. Biotechnol Bioeng 2022; 119:1980-1996. [PMID: 35445744 PMCID: PMC9323509 DOI: 10.1002/bit.28105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 03/22/2022] [Accepted: 04/08/2022] [Indexed: 11/08/2022]
Abstract
Recent studies have explored the potential of tissue‐mimetic scaffolds in encouraging nerve regeneration. One of the major determinants of the regenerative success of cellular nerve repair constructs (NRCs) is the local microenvironment, particularly native low oxygen conditions which can affect implanted cell survival and functional performance. In vivo, cells reside in a range of environmental conditions due to the spatial gradients of nutrient concentrations that are established. Here we evaluate in vitro the differences in cellular behavior that such conditions induce, including key biological features such as oxygen metabolism, glucose consumption, cell death, and vascular endothelial growth factor secretion. Experimental measurements are used to devise and parameterize a mathematical model that describes the behavior of the cells. The proposed model effectively describes the interactions between cells and their microenvironment and could in the future be extended, allowing researchers to compare the behavior of different therapeutic cells. Such a combinatorial approach could be used to accelerate the clinical translation of NRCs by identifying which critical design features should be optimized when fabricating engineered nerve repair conduits.
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Affiliation(s)
- D Eleftheriadou
- Centre for Nerve Engineering, University College London, London, WC1E 6B.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, WC1N 1AX.,Department of Mechanical Engineering, University College London, London, WC1E 7JE
| | - M Berg
- Centre for Nerve Engineering, University College London, London, WC1E 6B.,Department of Mechanical Engineering, University College London, London, WC1E 7JE
| | - J B Phillips
- Centre for Nerve Engineering, University College London, London, WC1E 6B.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, WC1N 1AX
| | - R J Shipley
- Centre for Nerve Engineering, University College London, London, WC1E 6B.,Department of Mechanical Engineering, University College London, London, WC1E 7JE
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Scussolini M, Bauckneht M, Cossu V, Bruno S, Orengo AM, Piccioli P, Capitanio S, Yosifov N, Ravera S, Morbelli S, Piana M, Sambuceti G, Caviglia G, Marini C. G6Pase location in the endoplasmic reticulum: Implications on compartmental analysis of FDG uptake in cancer cells. Sci Rep 2019; 9:2794. [PMID: 30808900 PMCID: PMC6391477 DOI: 10.1038/s41598-019-38973-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 12/14/2018] [Indexed: 11/24/2022] Open
Abstract
The favourable kinetics of 18F-fluoro-2-deoxyglucose (FDG) permits to depict cancer glucose consumption by a single evaluation of late tracer uptake. This standard procedure relies on the slow radioactivity loss, usually attributed to the limited tumour expression of G6P-phosphatase (G6Pase). However, this classical interpretation intrinsically represents an approximation since, as in all tissues, cancer G6Pase activity is remarkable and is confined to the endoplasmic reticulum (ER), whose lumen must be reached by phosphorylated FDG to explain its hydrolysis and radioactivity release. The present study tested the impact of G6Pase sequestration on the mathematical description of FDG trafficking and handling in cultured cancer cells. Our data show that accounting for tracer access to the ER configures this compartment as the preferential site of FDG accumulation. This is confirmed by the reticular localization of fluorescent FDG analogues. Remarkably enough, reticular accumulation rate of FDG is dependent upon extracellular glucose availability, thus configuring the same ER as a significant determinant of cancer glucose metabolism.
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Affiliation(s)
- Mara Scussolini
- Department of Mathematics (DIMA), University of Genoa, Genoa, Italy.
| | - Matteo Bauckneht
- Nuclear Medicine Unit, Department of Health Science, University of Genova, Genoa, Italy
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Vanessa Cossu
- Nuclear Medicine Unit, Department of Health Science, University of Genova, Genoa, Italy
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Silvia Bruno
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Anna Maria Orengo
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Patrizia Piccioli
- Unit of Cellular Biology, Policlinico San Martino Hospital, Genova, Italy
| | - Selene Capitanio
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Nikola Yosifov
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Silvia Ravera
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
- Department of Pharmacy, Biochemistry Laboratory, University of Genova, Genova, Italy
| | - Silvia Morbelli
- Nuclear Medicine Unit, Department of Health Science, University of Genova, Genoa, Italy
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Michele Piana
- Department of Mathematics (DIMA), University of Genoa, Genoa, Italy
- CNR Institute SPIN, Genoa, Italy
| | - Gianmario Sambuceti
- Nuclear Medicine Unit, Department of Health Science, University of Genova, Genoa, Italy
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
| | - Giacomo Caviglia
- Department of Mathematics (DIMA), University of Genoa, Genoa, Italy
| | - Cecilia Marini
- Nuclear Medicine Unit, Policlinico San Martino Hospital, Genoa, Italy
- CNR Institute of Bioimages and Molecular Physiology, Milan, Italy
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Dexamethasone-induced insulin resistance: kinetic modeling using novel PET radiopharmaceutical 6-deoxy-6-[(18)F]fluoro-D-glucose. Mol Imaging Biol 2015; 16:710-20. [PMID: 24819311 DOI: 10.1007/s11307-014-0737-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE An insulin-resistant rat model, induced by dexamethasone, was used to evaluate a Michaelis-Menten-based kinetic model using 6-deoxy-6-[(18)F]fluoro-D-glucose (6-[(18)F]FDG) to quantify glucose transport with PET. PROCEDURES Seventeen, male, Sprague-Dawley rats were studied in three groups: control (Ctrl), control + insulin (Ctrl + I), and dexamethasone + insulin (Dex + I). PET scans were acquired for 2 h under euglycemic conditions in the Ctrl group and under hyperinsulinemic-euglycemic conditions in the Ctrl + I and Dex + I groups. RESULTS Glucose transport, assessed according to the 6-[(18)F]FDG concentration, was highest in skeletal muscle in the Ctrl + I, intermediate in the Dex + I, and lowest in the Ctrl group, while that in the brain was similar among the groups. Modeling analysis applied to the skeletal muscle uptake curves yielded values of parameters related to glucose transport that were greatest in the Ctrl + I group and increased to a lesser degree in the Dex + I group, compared to the Ctrl group. CONCLUSION 6-[(18)F]FDG and the Michaelis-Menten-based model can be used to measure insulin-stimulated glucose transport under basal and an insulin resistant state in vivo.
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Kadlecek S, Shaghaghi H, Siddiqi S, Profka H, Pourfathi M, Rizi R. The effect of exogenous substrate concentrations on true and apparent metabolism of hyperpolarized pyruvate in the isolated perfused lung. NMR IN BIOMEDICINE 2014; 27:1557-1570. [PMID: 25330438 PMCID: PMC4342041 DOI: 10.1002/nbm.3219] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 08/12/2014] [Accepted: 08/26/2014] [Indexed: 06/04/2023]
Abstract
Although relatively metabolically inactive, the lung has an important role in maintaining systemic glycolytic intermediate and cytosolic redox balance. Failure to perform this function appropriately may lead to lung disease progression, including systemic aspects of these disorders. In this study, we experimentally probe the response of the isolated, perfused organ to varying glycolytic intermediate (pyruvate and lactate) concentrations, and the effect on the apparent metabolism of hyperpolarized 1-(13)C pyruvate. Twenty-four separate conditions were studied, from sub-physiological to super-physiological concentrations of each metabolite. A three-compartment model is developed, which accurately matches the full range of experiments and includes a full account of evolution of agent concentration and polarization. The model is then refined using a series of approximations which are shown to be applicable to cases of physiological relevance, and which facilitate an intuitive understanding of the saturation and scaling behavior. Perturbations of the model assumptions are used to determine the sensitivity to input parameter estimates, and finally the model is used to examine the relationship between measurements accessible by NMR and the underlying physiological parameters of interest. Based on the observed scaling of lactate labeling with lactate and pyruvate concentrations, we conclude that the level of hyperpolarized lactate signal in the lung is primarily determined by the rate at which NAD(+) is reduced to NADH. Further, although weak dependences on other factors are predicted, the modeled NAD(+) reduction rate is largely governed by the intracellular lactate pool size. Conditions affecting the lactate pool can therefore be expected to display the highest contrast in hyperpolarized (13)C-pyruvate imaging. The work is intended to serve as a basis both to interpret the signal dynamics of hyperpolarized measurements in the normal lung and to understand the cause of alterations seen in a variety of disease and exposure models.
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Muzic RF, Chandramouli V, Huang HM, Wu C, Hatami A, Ismail-Beigi F. Human radiation dosimetry of 6-[18F]FDG predicted from preclinical studies. Med Phys 2014; 41:031910. [PMID: 24593728 DOI: 10.1118/1.4866217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors are developing 6-[(18)F]fluoro-6-deoxy-D-glucose (6-[(18)F]FDG) as an in vivo tracer of glucose transport. While 6-[(18)F]FDG has the same radionuclide half-life as 2-[(18)F]fluoro-2-deoxy-D-glucose (2-[(18)F]FDG) which is ubiquitously used for PET imaging, 6-[(18)F]FDG has special biologic properties and different biodistributions that make it preferable to 2-[(18)F]FDG for assessing glucose transport. In preparation for 6-[(18)F]FDG use in human PET scanning, the authors would like to determine the amount of 6-[(18)F]FDG to inject while maintaining radiation doses in a safe range. METHODS Rats were injected with 6-[(18)F]FDG, euthanized at specified times, and tissues were collected and assayed for activity content. For each tissue sample, the percent of injected dose per gram was calculated and extrapolated to that for humans in order to construct predicted time-courses. Residence times were calculated as areas under the curves and were used as inputs to OLINDA/EXM in order to calculate the radiation doses. RESULTS Unlike with 2-[(18)F]FDG for which the urinary bladder wall receives the highest absorbed dose due to urinary excretion, with 6-[(18)F]FDG there is little urinary excretion and osteogenic cells and the liver are predicted to receive the highest absorbed doses: 0.027 mGy/MBq (0.100 rad/mCi) and 0.018 mGy/MBq (0.066 rad/mCi), respectively. Also, the effective dose from 6-[(18)F]FDG, i.e., 0.013 mSv/MBq (0.046 rem/mCi), is predicted to be approximately 30% lower than that from 2-[(18)F]FDG. CONCLUSIONS 6-[(18)F]FDG will be safe for use in the PET scanning of humans.
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Affiliation(s)
- Raymond F Muzic
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106; and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Visvanathan Chandramouli
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Hsuan-Ming Huang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Chunying Wu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Ahmad Hatami
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Faramarz Ismail-Beigi
- Department of Medicine, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
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Huang HM, Chandramouli V, Ismail-Beigi F, Muzic RF. Hyperglycemia-induced stimulation of glucose transport in skeletal muscle measured by PET-[18F]6FDG and [18F]2FDG. Physiol Meas 2012; 33:1661-73. [PMID: 22986442 DOI: 10.1088/0967-3334/33/10/1661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A physiologically based model proposed by our group has been developed to assess glucose transport and phosphorylation in skeletal muscle. In this study, we investigated whether our model has the ability to detect a glucose-induced increase in glucose transport in skeletal muscle. In particular, we used small-animal positron emission tomography (PET) data obtained from [18F]6-fluoro-6-deoxy-D-glucose ([18F]6FDG). A 2 h PET scan was acquired following a bolus injection of [18F]6FDG in rats currently under euglycemic or hyperglycemic conditions, while somatostatin was infused during both conditions in order to prevent a rise in the endogenous plasma insulin concentration. We were thus able to assess the effect of hyperglycemia per se. For a comparison of radiopharmaceuticals, additional rats were studied under the same conditions, using [18F]2-fluoro-2-deoxy-D-glucose ([18F]2FDG). When [18F]6FDG was used, the time-activity curves (TACs) for skeletal muscle had distinctly different shapes during euglycemic and hyperglycemic conditions. This was not the case with [18F]2FDG. For both [18F]6FDG and [18F]2FDG, the model detects increases in both interstitial and intracellular glucose concentrations, increases in the maximal velocity of glucose transport and increases in the rate of glucose transport, all in response to hyperglycemia. In contrast, there was no increase in the maximum velocity of glucose phosphorylation or in the glucose phosphorylation rate. Our model-based analyses of the PET data, obtained with either [18F]6FDG or [18F]2FDG, detect physiological changes consistent with established behavior. Moreover, based on differences in the TAC shapes, [18F]6FDG appears to be superior to [18F]2FDG for evaluating the effect of hyperglycemia on glucose metabolism in skeletal muscle.
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Affiliation(s)
- Hsuan-Ming Huang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
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