Name: simple continuous glucose monitoring in freely moving mice
Uploaded: 2023-02-24T13:35:00
Description: Watch this Scientific Journal Video about Simple Continuous Glucose Monitoring in Freely Moving Mice at JoVE.com

We thank Dvir Mintz DVM and the veterinary and husbandry staff in the animal facility, as well as members of our group, for fruitful discussions. This study was supported by an Israel Science Foundation grant 1541/21 awarded to D.B.Z. D.B.Z. is a Zuckerman STEM faculty.

The experiments were approved by the Hebrew University&#39;s Institutional Animal Care and Use Committee (IACUC).
NOTE: All tools must be sterilized, and handling of the cannula must be performed using a sterile technique. The protocol below is fine-tuned to a specific CGM. The protocol can be adapted to other CGMs.
1. Analgesic administration before the procedure
<ol>
	<li>Administer 5% dextrose and 0.45% saline with meloxicam at 5 mg/kg body wei...

<ol>
	<li>Polonsky, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+past+200+years+in+diabetes.">The past 200 years in diabetes.</a> New England Journal of Medicine. 367 (14), 1332-1340 (2012).</li><li>Rees, D. A., Alcolado, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+diabetes+mellitus.">Animal models of diabetes mellitus.</a> Diabetic Medicine. 22 (4), 359-370 (2005).</li><li>Pearson, J. A., Wong, F. 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R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+mice+in+diabetes+research:+The+impact+of+experimental+protocols.">The use of mice in diabetes research: The impact of experimental protocols.</a> Diabetic Medicine. 38 (12), 14705 (2021).</li><li>Klueh, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+in+normal+mice+and+mice+with+prediabetes+and+diabetes.">Continuous glucose monitoring in normal mice and mice with prediabetes and diabetes.</a> Diabetes Technology and Therapeutics. 8 (3), 402-412 (2006).</li><li>Wuyts, C., Simoens, C., Pinto, S., Philippaert, K., Vennekens, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+during+pregnancy+in+healthy+mice.">Continuous glucose monitoring during pregnancy in healthy mice.</a> Scientific Reports. 11, 4450 (2021).</li><li>Korstanje, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+in+female+NOD+mice+reveals+daily+rhythms+and+a+negative+correlation+with+body+temperature.">Continuous glucose monitoring in female NOD mice reveals daily rhythms and a negative correlation with body temperature.</a> Endocrinology. 158 (9), 2707-2712 (2017).</li><li>Han, B. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Markers+of+glycemic+control+in+the+mouse:+Comparisons+of+6-h-and+overnight-fasted+blood+glucoses+to+Hb+A1c.">Markers of glycemic control in the mouse: Comparisons of 6-h-and overnight-fasted blood glucoses to Hb A1c.</a> American Journal of Physiology - Endocrinology and Metabolism. 295 (4), 981-986 (2008).</li><li>Xie, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+measurement+noise+in+a+continuous+glucose+monitor+by+coating+the+sensor+with+a+zwitterionic+polymer.">Reduction of measurement noise in a continuous glucose monitor by coating the sensor with a zwitterionic polymer.</a> Nature Biomedical Engineering. 2 (12), 894-906 (2018).</li><li>Van Der Meulen, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urocortin3+mediates+somatostatin-dependent+negative+feedback+control+of+insulin+secretion.">Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion.</a> Nature Medicine. 21 (7), 769-776 (2015).</li><li>Peterson, Q. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+the+generation+of+human+stem+cell-derived+alpha+cells.">A method for the generation of human stem cell-derived alpha cells.</a> Nature Communications. 11, 2241 (2020).</li><li>Klueh, U., Liu, Z., Feldman, B., Kreutzer, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interstitial+fluid+physiology+as+it+relates+to+glucose+monitoring+technologies:+Importance+of+Interleukin-1+and+Interleukin-1+receptor+antagonist+in+short-term+glucose+sensor+function+in+vivo.">Interstitial fluid physiology as it relates to glucose monitoring technologies: Importance of Interleukin-1 and Interleukin-1 receptor antagonist in short-term glucose sensor function in vivo.</a> Journal of Diabetes Science and Technology. 4 (5), 1073 (2010).</li><li>Klueh, U., Antar, O., Qiao, Y., Kreutzer, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+interleukin-1/interleukin-1+receptor+antagonist+family+of+cytokines+in+long-term+continuous+glucose+monitoring+in+vivo.">Role of interleukin-1/interleukin-1 receptor antagonist family of cytokines in long-term continuous glucose monitoring in vivo.</a> Journal of Diabetes Science and Technology. 7 (6), 1538 (2013).</li><li>Klueh, U., Kaur, M., Qiao, Y., Kreutzer, D. 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This protocol offers a simple, inexpensive method to monitor glucose levels in mice that does not require challenging microsurgery and does not involve bleeding or handling the mice. The method is easy to implement in every facility and does not cause mortality, pain, or excessive discomfort to the mice. The most critical step in the protocol is inserting the cannula of the glucose sensor under the skin of the mouse. The addition of a few sutures allows the cannula to stay in place for a longer time. The sensors are smal...

Diabetes mellitus (DM) is a devastating disease characterized by high blood glucose levels. Type 1 DM can be a result of an autoimmune attack on the insulin-producing beta cells in the pancreas. Type 2 DM and gestational DM, on the other hand, are characterized by a failure of the beta cells to secrete sufficient insulin in response to a rise in glucose levels1. The mouse is a common model organism used to study DM since it has similar physiology, and its normal glucose levels are close to those of humans. Furthermore, specific mouse strains may develop DM due to mutations in key signaling pathways or following exposure to specific diets, which enables disease modeling2,3,4.
Blood glucose is commonly measured in mice using glucometers designed for patients by extracting a small drop of blood (1-2 &#181;L) from the tip of the tail of the mouse. This method causes stress and requires handling of the mouse, which affects the glucose levels and prohibits the measurement of blood glucose levels in freely behaving mice or when the researcher is not close by5. Bleeding the mice may cause stress to nearby mice, particularly to mice of the same cage whose glycemia has not been measured yet, thus affecting the results. Mice respond differently depending on the handler, and the person measuring glucose may affect the glucose levels of the mice. These pitfalls call for careful experimental design and underlie some inconsistencies between experiments.
It is possible to measure glucose in freely moving mice with no bleeding by implanting glucose sensors into the aortic arch of the mice using state-of-the-art telemetry6. The resulting measurements are very good and can be sustained over a long period, but it is challenging to implant these sensors, and the telemetry system is expensive, leading to a moderate adoption of this methodology and no adoption in non-specialized labs. Subcutaneous or other glucose sensors that are tailored to the dimensions of the mice and their physiology have been developed in recent years, but these again require highly skilled experts and are in some cases costly6,7,8,9,10.
Commercial continuous glucose monitors (CGMs) that were originally developed to monitor the glucose levels of DM patients offer another option to measure glucose in freely moving mice, with lower cost and technical expertise requirements than implanted probes. Such probes have been used in basic research by a few labs5,11,12,13,14,15&#160;including our colleagues who used this protocol16. These devices typically include a sensor, a mounting device, a receiver, and a software application. The sensor has a cannula guiding the enzymatic glucosensor, adhesive tape, an energy source, short-term memory, and a wireless communication module that stores and sends the data to the receiver. The receiver can show the current glucose levels and sends the data to a server; this receiver can be a cellphone. The software application provides data for the patient and the medical care team on the glycaemia of the patient. In patients, the sensor is attached easily using the mounting device. The cannula is inserted subcutaneously by pressing the mounting device against the skin, and the sensor stays in place with the help of adhesive tape.
This is a detailed protocol for adapting a commercial CGM device to measure glucose levels in mice. This protocol describes how to surgically insert the glucose sensor and attach it to the mouse. Scripts for basic data analysis and data visualization are provided. The potential pitfalls, troubleshooting, and examples of standard results are provided. The protocol below is specific for a certain CGM but can be easily adapted to other types of commercial CGMs as they become available.

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			<td>2%&#160; Chlorhexidine Gluconate and 70%&#160; Isopropyl Alcohol</td>
			<td>3M</td>
			<td>ID&#160;7000136290</td>
			<td></td>
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		<tr>
			<td>5% Dextrose and 0.45% Sodium Chloride Injection, USP</td>
			<td>Braun</td>
			<td>L6120</td>
			<td></td>
		</tr>
		<tr>
			<td>Castroviejo needle holder</td>
			<td>FST</td>
			<td>12061-02</td>
			<td></td>
		</tr>
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			<td>Extra Fine Bonn scissors</td>
			<td>FST</td>
			<td>14084-08</td>
			<td></td>
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			<td>FreeStyle Libre 1 reader</td>
			<td>Abbott</td>
			<td>ART27543&#160;</td>
			<td></td>
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		<tr>
			<td>FreeStyle Libre sensor</td>
			<td>Abbott</td>
			<td>ART36687</td>
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			<td>FreeStyle Libre sensor applicator</td>
			<td>Abbott</td>
			<td>ART36787</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze pads</td>
			<td>Sion medical</td>
			<td>PC912017</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps</td>
			<td>FST</td>
			<td>11052-10</td>
			<td></td>
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			<td>Hair Removal Cream</td>
			<td>Veet</td>
			<td>3116523</td>
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			<td>High-fat high-sucrose diet</td>
			<td>Envigo Teklad diets</td>
			<td>TD.08811</td>
			<td></td>
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		<tr>
			<td>Isoflurane, USP Terrell</td>
			<td>Piramal</td>
			<td>26675-46-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Meloxicam 5 mg/mL</td>
			<td>Chanelle Pharma</td>
			<td>08749/5024</td>
			<td></td>
		</tr>
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			<td>MiniARCO Clipper kit</td>
			<td>Moser</td>
			<td>CL8787-KIT</td>
			<td></td>
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			<td>PROLENE Polypropylene Suture 5-0</td>
			<td>Ethicon</td>
			<td>8725H</td>
			<td></td>
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			<td>Puralube Opthalmic Ointment</td>
			<td>Perrigo</td>
			<td>574402511</td>
			<td></td>
		</tr>
		<tr>
			<td>Q-tips&#160;</td>
			<td>B.H.W</td>
			<td>271676</td>
			<td></td>
		</tr>
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			<td>SomnoSuite Low-Flow Anesthesia System</td>
			<td>Kent Scientific</td>
			<td>SOMNO</td>
			<td></td>
		</tr>
	</tbody>
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simple continuous glucose monitoring in freely moving mice

Mice are a common model organism used to study metabolic diseases such as diabetes mellitus. Glucose levels are typically measured by tail-bleeding, which requires handling the mice, causes stress, and does not provide data on freely behaving mice during the dark cycle. State-of-the-art continuous glucose measurement in mice requires inserting a probe into the aortic arch of the mouse, as well as a specialized telemetry system. This challenging and expensive method has not been adopted by most labs. Here, we present a simple protocol involving the utilization of commercially available continuous glucose monitors used by millions of patients to measure glucose continuously in mice as a part of basic research. The glucose-sensing probe is inserted into the subcutaneous space in the back of the mouse through a small incision to the skin and is held in place tightly using a couple of sutures. The device is sutured to the mouse skin to ensure it remains in place. The device can measure glucose levels for up to 2 weeks and sends the data to a nearby receiver without any need to handle the mice. Scripts for the basic data analysis of glucose levels recorded are provided. This method, from surgery to computational analysis, is cost-effective and potentially very useful in metabolic research.

Surgical outcome 
Results from eight HSD:ICR mice (aged 8 weeks) fed a high-fat high-sucrose diet (HFHS) for 18 weeks and five lean HSD:ICR mice (aged 12 weeks) are shown. The device we used stores data for up to 8 h. Access to the local animal facility was restricted to 07:00-19:00, thus prohibiting data collection during the late P.M. hours, when the mice are active. The mice were, therefore, placed in a room with reverse lighting for 7 days before the surgical procedure, with dark hours between 8...

Watch this Scientific Journal Video about Simple Continuous Glucose Monitoring in Freely Moving Mice at JoVE.com

Simple Continuous Glucose Monitoring in Freely Moving Mice

Here, we describe a simple method to implant a commercial continuous glucose monitor designed for patients onto mice and provide the scripts to analyze the results.

Mice are a common model organism used to study metabolic diseases such as diabetes mellitus. Glucose levels are typically measured by tail-bleeding, which ...

Our protocol offers a simple inexpensive method to monitor glucose levels in mice. The main advantage of this technique is that it does not require challenging microsurgery, and does not involve bleeding, or handling the mice. This method can be used to identify elusive glucose management phenotypes in mouse models of obesity and diabetes.While attempting this protocol, the most critical step is the insertion of the cannula under the skin, and tightening of the inner sutures in order to keep the cannula in place. To begin shave the midline of the back of the anesthetized mouse, and use a depilatory cream to ensure complete hair removal. Open and load the sensor.Then mount the sensor onto the sensor mounting device to expose the sensor's tape and cannula side. The cannula is void from the needle. Suture two 5-0 taper point sutures to the tape on both sides of the cannula.For the dorsal skin preparation, make a two millimeter incision in the center of the shaved area above the spine using sharp scissors. Briefly insert small forceps with a blunt edge under the skin to form a small subcutaneous pocket, so that the cannula can be inserted easily into the pocket. Pass a suture through the skin on each side of the incision.For the sensor insertion, remove the sensor completely from the sensor mounting device and hold the sensor with forceps to keep the surrounding tape from sticking to itself. Carefully insert the cannula into the subcutaneous pocket. Pull the sutures on each side, and tighten and tie them to attach the sensor firmly in place.This will prevent the cannula from slipping out of the subcutaneous pocket once the adhesive tape loosens over time, Cut the ends of the sutures and discard them. Attach adhesive tape surrounding the sensor, and make eight discontinuous sutures around the sensor attaching the border of the sensors taped to the skin. Activate the sensor.Once the cannula is inserted, and the CGM is successfully activated, collect the data using the receiver. The raw output data of three days from a single mouse using the code provided is shown here. The axis parameters, and all the other parameters can be modulated in the code.Here, the data for three days are shown for clarity. Making a subcutaneous pocket and the addition of a few sutures allows the sensor's cannula to stay in place for a longer time. The continuous data acquired using this technique allowed us to uncover an elusive metabolic phenotype in a specific mouse strain.

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A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other important biological functions. The islets primarily consist of five types of hormone-secreting cells: &#945; cells secrete glucagon, &#946; cells secrete insulin, &#948; cells secrete somatostatin, &#949; cells secrete ghrelin, and PP cells secrete pancreatic polypeptide. Sixty to 80% of the cells in the islets are &#946; cells, which are the most important cell population to study insulin secretion. Pancreatic islets are a crucial model system to study ex vivo insulin secretion. Acquiring high quality islets is of great importance for diabetes research. Most islet isolation procedures require technically difficult to access site of collagenase injection, harsh and complex digestion procedures, and multiple density gradient purification steps. This paper features a simple high yield mouse islet isolation method with detailed descriptions and realistic demonstrations, showing the following specific steps: 1) injection of collagenase P at the ampulla of Vater, a small area joining the pancreatic duct and the common bile duct, 2) enzymatic digestion and mechanical separation of the exocrine pancreas, and 3) a single gradient purification step. The advantages of this method are the injection of digestive enzyme using the more accessible ampulla of Vater, more complete digestion using combination of enzymatic and mechanical approaches, and a simpler single gradient purification step. This protocol produces approximately 250&#8212;350 islets per mouse; and islets are suitable for various ex vivo studies. Possible caveats of this procedure are potentially damaged islets due to enzymatic digestion and/or prolonged gradient incubation, all of which can be largely avoided by careful ad justification of incubation time.

This islet isolation protocol described a novel route of collagenase injection to digest the exocrine tissue and a simplified gradient procedure to purify the islets from mice. It involves enzymatic digestion, gradient separation/purification, and islet hand-picking. Successful isolation can yield 250&#8211;350 high quality and fully functional islets per mouse.

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other ...

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. In vivo cardiac-specific gene delivery is commonly achieved by either systemic or local delivery. Systemic injection via tail vein is easy and efficient in manipulating cardiac gene expression by using recombinant adeno-associated virus 9 (AAV9). However, this method requires a relatively high amount of vector for efficient transduction, and may result in nontarget organ gene transduction. Here, we describe a simple, efficient, and time-saving method of intramyocardial injection for in vivo cardiac-specific gene manipulation in mice. Under anesthesia (without ventilation), the pectoral major and minor muscles were bluntly dissected, and the mouse heart was quickly exposed by manual externalization through a small incision at the fourth intercostal space. Subsequently, adenovirus encoding luciferase (Luc) and vitamin D receptor (VDR), or short hairpin RNA (shRNA) targeting VDR, was injected with a Hamilton syringe into the myocardium. Subsequent in vivo imaging demonstrated that luciferase was successfully overexpressed specifically in the heart. Moreover, Western blot analysis confirmed the successful overexpression or silencing of VDR in the mouse heart. Once mastered, this technique can be used for gene manipulation, as well as injection of cells or other materials such as nanogels in the mouse heart.

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Here we present a protocol for cardiac-specific gene manipulation in mice. Under anesthesia, the mouse hearts were externalized through the fourth intercostal space. Subsequently, adenoviruses encoding specific genes were injected with a syringe into the myocardium, followed by protein expression measurement via in vivo imaging and Western blot analysis.

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. ...

Detecting Establishment of Shared Blood Supply in Parabiotic Mice by Caudal Vein Glucose Injection

Parabiosis is an experimental method for surgically combining two parallel animals along the longitudinal axis of the body. We present a protocol for detecting the successful establishment of blood chimerism in parabionts by a caudal vein injection of glucose. Parabiotic mice were constructed. Glucose was injected into the donor mouse through the tail vein, and the fluctuation of blood glucose level was measured in both mice using a blood glucometer at different time points. Our results showed that after glucose injection, the blood glucose level in donor mice increased sharply after 1 min and decreased slowly thereafter. Meanwhile, the blood glucose level of the recipient mice peaked 15 min after injection. Similar results were obtained with Evans blue, used as a positive control for glucose. The synchronous fluctuation of blood glucose levels indicates that blood flow between the two mice was established successfully.

Here we describe a new method of detecting successful establishment of shared blood circulation of two parabionts through a caudal vein injection of glucose, which causes minimal damage and is not fatal to the parabionts.

Parabiosis is an experimental method for surgically combining two parallel animals along the longitudinal axis of the body. We present a protocol for ...

Simple Detection of Primary Cilia by Immunofluorescence

Primary cilia are dynamically regulated during cell cycle progression, specifically during the G0/G1 phases of the cell cycle, being resorbed prior to mitosis. Primary cilia can be visualized with highly sophisticated methods, including transmission electron microscopy, 3D imaging, or using software for the automatic detection of primary cilia. However, immunofluorescent staining of primary cilia is needed to perform these methods. This publication describes a protocol for the easy detection of primary cilia in vitro by staining acetylated alpha tubulin (axoneme) and gamma tubulin (basal body). This immunofluorescent staining protocol is relatively simple and results in high-quality images. The present protocol describes how four cell lines (C2C12, MEF, NHLF, and skin fibroblasts) expressing primary cilia were fixed, immunostained, and imaged with a fluorescent or confocal microscope.

Primary cilia are extracellular structures associated with the centriole. Primary cilia detection by immunofluorescent staining is a relatively simple procedure that results in extremely high-quality images. In this protocol, fibroblasts expressing primary cilia were fixed, immunostained, and imaged in a fluorescent or confocal microscope.

Primary cilia are dynamically regulated during cell cycle progression, specifically during the G0/G1 phases of the cell cycle, being resorbed prior to ...