Name: protocol to create chronic wounds in diabetic mice
Uploaded: 2019-09-25T13:30:00
Description: Watch this Scientific Journal Video about Protocol to Create Chronic Wounds in Diabetic Mice at JoVE.com

The authors have no acknowledgements.

All experiments were completed in accordance and compliance with federal regulations and University of California policy and procedures have been approved by the University of California, Riverside IACUC.
1. Animal
<ol>
	<li>Use diabetic and obese B6.BKS(D)-Leprdb/J mice for the chronic wound model. Purchasing options include either heterozygotes for breeding or homozygotes directly for experiments.</li>
	<li>Breed heterozygote males and females to produce offspring. Only...

Once chronic wounds are created on the mice, the model can be used to study impaired wound healing processes involved in the initiation of chronicity. The model can also be used to test the efficacy of a wide range of chemicals and drugs that can reverse chronic wound development and impaired healing and lead to wound closure and healing. Different time points after the onset of chronicity can be studied: e.g., days 1-5 after wounding for early onset of chronicity and days 20 and beyond for full strength chronic...

Wound healing involves complex cellular and molecular processes that are temporally and spatially regulated, organized in sequential and overlapping stages that involve many different cell types including but not limited to the immune response and the vascular system1. Immediately after the skin sustains an injury, factors and blood cells aggregate to the wound site and initiate the coagulation cascade to form a clot. After homeostasis is achieved, the blood vessels dilate to let into the wound site oxygen, nutrients, enzymes, antibodies and chemotactic factors that chemoattract polymorphonucleocytes to clear the wound bed of foreign debris and secrete proteolytic enzymes2. Activated platelets secrete a variety of growth factors to stimulate the keratinocytes at the wound edge to re-epithelialize the wounded area. Monocytes recruited to the wound site differentiate into macrophages which phagocytose bacteria and dead neutrophils and secrete additional factors to maintain keratinocyte proliferative and pro-migratory signals. In the proliferation phase, while re-epithelialization continues, new granulation tissue composed of fibroblasts, monocytes/macrophages, lymphocytes, and endothelial cells continue the rebuilding process2. Angiogenesis is stimulated by promoting endothelial cell proliferation and migration, resulting in new vessel development. Epithelialization and remodeling of the extracellular matrix construct a barrier against the environment. As the wound heals and granulation tissue evolves into a scar, apoptosis eliminates inflammatory cells, fibroblasts, and endothelial cells without causing additional tissue damage. The tensile strength of the tissue is enhanced by fibroblasts remodeling various components of the extracellular matrix, like collagen, so that the newly formed tissue is almost as strong and flexible as unwounded skin2.
Any deviation from this highly concerted progression towards wound closure leads to impaired and/or chronic wounds3. Chronic wounds are characterized by increased oxidative stress, chronic inflammation, damaged microvasculature, and abnormal collagen matrix in the wound4. Oxidative stress, especially in the wound, can delay wound closure2,5. When, in the first stage of wound healing, the inflammatory phase becomes unregulated, the host tissue assumes extensive damage due to a continuous influx of inflammatory cells5 that release cytotoxic enzymes, an increase in free oxygen radicals, and unregulated inflammatory mediators, resulting in cell death6,7.
In this destructive microenvironment, biofilm-forming bacteria take advantage of host nutrients and contribute to the damage of the host tissue2. These biofilms are difficult to control and remove because the hydrated extracellular polymeric substances composed of proteins, DNA, RNA, and polysaccharides allows bacteria harbored within to be tolerant to conventional antibiotic therapies and evade the host&#39;s innate and adaptive immune response2,8,9.
Studying chronic wounds is crucial because they impact ~6.5 million people and cost ~$40 billion per year in the US alone10. Patients with diabetes have increased risks for developing chronic wounds that require amputation in order to contain the spread of infection. These patients have a 50% mortality risk within 5 years of amputation that is attributed to the pathophysiology mechanism of diabetes11. The relationship between the host&#39;s immune system and the microbiome in wound healing is a vital topic of ongoing research because consequences of chronic wounds, if unresolved, include amputation and death12.
Although a significant effort has been invested in understanding how chronic wounds develop in humans, it is still unclear how and why chronic wounds form. Experiments to study the mechanisms of impaired healing is difficult to conduct in humans, and wound healing specialists only see patients with chronic wounds that have already reached chronicity for weeks to months. Thus, specialists are unable to study what processes went wrong that lead the wound to develop to become chronic2. There is a lack of animal models that recapitulate the complexity of human chronic wounds. Until our model was developed, no model for chronic wound studies existed.
The chronic wound model was developed in mice that have a mutation in the leptin receptor (db/db-/-)13. These mice are obese, diabetic, and have impaired healing but do not develop chronic wounds14. Blood glucose levels average around 200 mg/dL, but can be as high as 400 mg/dL15. When high levels of oxidative stress (OS) in the wound tissue are induced immediately after wounding, the wound becomes chronic16. The db/db-/- wounds are considered chronic by 20 days and remain open for 60 days or more. Biofilm produced by bacteria can be seen developing beginning three days after wounding; a mature biofilm can be seen 20 days after wounding and persists until either wound closure. The biofilm-forming bacteria we find in these mice are also found in human diabetic chronic wounds.
Oxidative stress is induced by treating the wounds with two inhibitors of antioxidant enzymes, catalase and glutathione peroxidase, two enzymes with the capacity to break down hydrogen peroxide. Hydrogen peroxide is a reactive oxygen species and can cause cellular damage through the oxidation of proteins, lipids, and DNA. Catalase catalyzes the decomposition of hydrogen peroxide into less harmful chemicals oxygen and water. 3-Amino-1,2,4-triazole (ATZ) inhibits catalase by binding specifically and covalently to the active center of the enzyme, inactivating it17,18,19. ATZ has been used to study the effects of oxidative stress both in vitro and in vivo through the inhibition of catalase20,21,22,23,24. Glutathione peroxidase catalyzes the reduction of hydrogen peroxide through the antioxidant, glutathione, and is an important enzyme that protects the cell against oxidative stress25. Mercaptosuccinic acid (MSA) inhibits glutathione peroxidase by binding to the selenocysteine active site of the enzyme with thiol, inactivating it26. MSA has been used to study the effects of oxidative stress in vitro and in vivo as well20,27,28.
This novel model of chronic wounds is a powerful model to study because it shares many of the same features observed in human diabetic chronic wounds, including prolonged inflammation from increased OS and natural biofilm formation from skin microbiome. The wounds have impaired dermal-epidermal interaction, abnormal matrix deposition, poor angiogenesis and damaged vasculature. Chronic wounds will develop in both male and female mice, so both sexes can be used to study chronic wounds. Therefore, the chronic wound model can contribute significantly to advance fundamental understanding of how such wounds begin. Using this chronic wound model can provide answers to fundamental questions about how chronicity is initiated/achieved through contributions from the physiology of impaired wound healing and the microbiome of the host.

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			<td height="42" style="height:42px;width:308px;">B6.BKS(D)-Leprdb/J&#160;</td>
			<td style="width:176px;">The Jackson Laboratory&#160;</td>
			<td style="width:107px;">00697</td>
			<td style="width:204px;">Homozygotes and heterozygotes available&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:308px;">Nair Hair Remover Lotion with Soothing Aloe and Lanolin</td>
			<td style="width:176px;">Nair</td>
			<td style="width:107px;"></td>
			<td style="width:204px;">a chemical depilatory</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:308px;">Buprenex (buprenorphine HCl)</td>
			<td style="width:176px;">Henry Stein Animal Health</td>
			<td style="width:107px;">059122</td>
			<td style="width:204px;">0.3 mg/ml, Class 3</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:308px;">3-Amino-1,2,4-triazole (ATZ)</td>
			<td style="width:176px;">TCI</td>
			<td style="width:107px;">A0432</td>
			<td style="width:204px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Mercaptosuccinic acid (MSA)</td>
			<td style="width:176px;">Aldrich</td>
			<td style="width:107px;">88460</td>
			<td style="width:204px;"></td>
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			<td height="21" style="height:21px;width:308px;">Phosphate buffer solution (PBS)</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;">autoclave steriled</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:308px;">Isoflurane</td>
			<td style="width:176px;">Henry Schein Animal Health</td>
			<td style="width:107px;">029405</td>
			<td style="width:204px;">NDC 11695-6776-2</td>
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			<td height="42" style="height:42px;width:308px;">Oxygen</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;">Tank must be compatible with vaporizing system</td>
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			<td height="21" style="height:21px;width:308px;">Isoflurane vaporizer</td>
			<td style="width:176px;">JA Baulch &#38; Associates&#160;</td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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			<td height="21" style="height:21px;width:308px;">Wahl hair clipper</td>
			<td style="width:176px;">Wahl</td>
			<td style="width:107px;"></td>
			<td style="width:204px;">Lithium Ion Pro</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Acu Punch 7mm skin biopsy punches</td>
			<td style="width:176px;">Acuderm Inc.</td>
			<td style="width:107px;">P750</td>
			<td style="width:204px;"></td>
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			<td height="42" style="height:42px;width:308px;">Tegaderm&#160;</td>
			<td style="width:176px;">3M</td>
			<td style="width:107px;">Ref: 1624W</td>
			<td style="width:204px;">Transparent film dressing (6 cm x 7 cm)</td>
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			<td height="21" style="height:21px;width:308px;">Heating pad</td>
			<td style="width:176px;">Conair</td>
			<td style="width:107px;"></td>
			<td style="width:204px;">Moist Dry Heating Pad</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:308px;">Insulin syringes</td>
			<td style="width:176px;">BD</td>
			<td style="width:107px;">329461</td>
			<td style="width:204px;">0.35 mm (28G) x 12.7 mm (1/2&#34;)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:308px;">70% ethanol</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Kimwipes</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Tweezers</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Sharp surgical scissors</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Thin metal spatula</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
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			<td height="21" style="height:21px;width:308px;">Tubing</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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			<td height="21" style="height:21px;width:308px;">Mouse nose cone</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:308px;">Gloves</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:308px;">small plastic containers</td>
			<td style="width:176px;"></td>
			<td style="width:107px;"></td>
			<td style="width:204px;"></td>
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protocol to create chronic wounds in diabetic mice

Chronic wounds develop as a result of defective regulation in one or more complex cellular and molecular processes involved in proper healing. They impact ~6.5M people and cost ~$40B/year in the US alone. Although a significant effort has been invested in understanding how chronic wounds develop in humans, fundamental questions remain unanswered. Recently, we developed a novel mouse model for diabetic chronic wounds that have many characteristics of human chronic wounds. Using db/db-/- mice, we can generate chronic wounds by inducing high levels of oxidative stress (OS) in the wound tissue immediately after wounding, using a one-time treatment with inhibitors specific to the antioxidant enzymes catalase and glutathione peroxidase. These wounds have high levels of OS, develop biofilm naturally, become fully chronic within 20 days after treatment and can remain open more for more than 60 days. This novel model has many features of diabetic chronic wounds in humans and therefore can contribute significantly to advancing fundamental understanding of how wounds become chronic. This is a major breakthrough because chronic wounds in humans cause significant pain and distress to patients and result in amputation if unresolved. Moreover, these wounds are very expensive and time-consuming to treat, and lead to significant loss of personal income to patients. Advancements in this field of study through the use of our chronic wound model can significantly improve health care for millions who suffer under this debilitating condition. In this protocol, we describe in great detail the procedure to cause acute wounds to become chronic, which has not been done before.

Figure 5 depicts an example of a wound without treatment of inhibitors progressing towards wound closure and a wound with treatment of inhibitors progressing towards chronicity. The transparent dressing has been left in place on the chronic wound so that biofilm and fluid accumulation can be seen.
Chronic wound initiation takes place in less than 6 hours and the wound margin is visibly altered from ...

Watch this Scientific Journal Video about Protocol to Create Chronic Wounds in Diabetic Mice at JoVE.com

Protocol to Create Chronic Wounds in Diabetic Mice

Chronic wounds are developed from acute wounds on a diabetic mouse model by inducing high levels of oxidative stress after a full-thickness cutaneous wound. The wound is treated with inhibitors for catalase and glutathione peroxidase, resulting in impaired healing and biofilm development by bacteria present in the skin microbiome.

Chronic wounds develop as a result of defective regulation in one or more complex cellular and molecular processes involved in proper healing. They impact ...

This mouse model can help answer questions in the medical field of wound chronicity. The major advantage of this model is that the chronic wounds in mice mimic many aspects of the chronic wounds in humans. To begin, place the mouse on a clean surface and hold it in place by pinching the base of its tail.Then prepare the hair clippers and be ready to quickly pull them away if the mouse makes any sudden movements. Shave the whole back from the neck to the tail including all around the tail. Lightly run the blade against the direction of hair growth for the most efficient cut.Do not press the clippers deep into the skin as this can bruise or cut. Next, prepare the skin for an application of depilatory lotion. Moisten the skin with a water soaked paper towel to prevent chemical burns.Press lightly with enough pressure to wet the cut hair down against the skin. Then while the skin is wet, rub a small dollop of depilatory lotion into the shaved region for 15 to 20 seconds. Once applied, let the lotion react with skin for 20 to 45 seconds.Before rinsing off the lotion, lightly wipe away some lotion at various locations to check the reaction. If the skin is pink and hairless, the reaction is complete. Then, grip the mouse to wash it off.Using the nondominant hand with the thumb press down the base of its tail against the palm and close the other fingers. Then with mouse's nose up and away from the water, let water run over the animal's back. Then quickly, but gently, rub the back of the mouse with the other hand to wash away the lotion.After removing all the depilatory cream, dry the skin with a paper towel. It is important to not apply lotion to the ears, tail, or anywhere near the face. If this should happen, immediately wipe away the lotion with a wet towel and then run water over the mouse to prevent damage to these areas.If any dark patches are noticed after using the cream, reapply the cream to those areas. The dark patches of skin will grow hair faster throughout the duration of the experiment. So clip the hair short every three to five days when necessary.A patch or two that are not over the wounding site is acceptable, but if the back of the mouse has more dark patches, do not use it for the chronic wound model. After removing the hair, house the mouse alone for at least one day before wounding because the skin will be too sensitive from the depilatory lotion. 30 minutes before the surgery, inject the mouse with 120 microliters of buprenorphine intraperitoneally in sterile PBS.All the volumes in this procedure assume a 60 gram mouse. 20 minutes before the surgery, inject the mouse with 480 microliters of ATZ intraperitoneally in sterile PBS. Split the volume on either side of the abdomen.After administering the ATZ, place the mouse in a small plastic container on top of a warm heating pad until the surgery begins. Cover the small container with a paper towel to help contain the heat. The mouse should calm down as it warms.After confirming an anesthetized state, proceed with the wounding. To begin the wounding procedure, spray a chem wipe with 70%ethanol to wipe the back of the mouse to clean the wound site and the skin surface. Do not wipe excessively or there will be a risk of killing the bacteria present on the skin.The success of the chronic wound model relies on non-sterile conditions. These mice are not germ free and are housed in a conventional vivarium. The bacterial microbiome that resides on the skin is crucial for the subsequent initiation and development of chronic wounds upon treatment with inhibitors of antioxidant enzymes.Now consider where the place the wound. Ideally, use the dorsal side of the mouse centered and away from dark patches of skin. Now perform the wounding to dressing procedure in 30 to 45 seconds.First lightly press a seven millimeter skin biopsy punch onto the desired wound site and twist the punch around just deep enough to leave an impression of the punch. Then excise the outlined skin by pulling up the center of the punch with tweezers and cutting along the outline with surgical scissors. Once completed, cover the wound firmly with half a piece of transparent film dressing.Within 10 minutes of wounding, apply a 60 microliter aliquot of MSA in sterile PBS and deposit MSA topically onto the wound. Later, six hours after the surgery, administer another does of buprenorphine. Extra doses may be given as needed.Chronic wound initiation takes place in less than six hours and the wound margin is visibly altered from oxidative stress. A chronic wound is a wound that remains open, enlarged comparing to the initial wound and contains biofilm. After 20 days, the wound is at full chronicity.Biofilm forming bacteria that dominate the wound site include Pseudomonas aeruginosa, Enterobacter cloacae, and various Staphylococcus and Corynebacterium species. These bacteria are also found in human chronic wounds. After watching this video you should have a good understanding of how to create chronic wounds in mice.Once you have established these chronic wounds, you can then use them to investigate many of cellular molecular mechanisms involved in the initiation of wound chronicity.

protocol-to-create-chronic-wounds-in-diabetic-mice

Research

JoVE Journal

Medicine

Protocol for Long Duration Whole Body Hyperthermia in Mice

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body temperature that is observed during fever. The use of hyperthermia as an adjuvant has emerged as a promising procedure for tumor regression in the field of cancer biology. For this purpose, the most important requirement is to have reliable and uniform heating protocols. We have developed a protocol for hyperthermia (whole body) in mice. In this protocol, animals are exposed to cycles of hyperthermia for 90 min followed by a rest period of 15 min. During this period mice have easy access to food and water. High body temperature spikes in the mice during first few hyperthermia exposure cycles are prevented by immobilizing the animal. Additionally, normal saline is administered in first few cycles to minimize the effects of dehydration. This protocol can simulate fever like conditions in mice up to 12-24 hr. We have used 8-12 weeks old BALB/Cj female mice to demonstrate the protocol.

This paper describes a protocol for whole body hyperthermia in mice that can stimulate fever like conditions up to 12-24 hr.

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body ...

Neo-Islet Formation in Liver of Diabetic Mice by Helper-dependent Adenoviral Vector-Mediated Gene Transfer

Type 1 diabetes is caused by T cell-mediated autoimmune destruction of insulin-producing cells in the pancreas. Until now insulin replacement is still the major therapy, because islet transplantation has been limited by donor availability and by the need for long-term immunosuppression. Induced islet neogenesis by gene transfer of Neuogenin3 (Ngn3), the islet lineage-defining specific transcription factor and Betacellulin (Btc), an islet growth factor has the potential to cure type 1 diabetes.
Adenoviral vectors (Ads) are highly efficient gene transfer vector; however, early generation Ads have several disadvantages for in vivo use. Helper-dependent Ads (HDAds) are the most advanced Ads that were developed to improve the safety profile of early generation of Ads and to prolong transgene expression1. They lack chronic toxicity because they lack viral coding sequences2-5 and retain only Ad cis elements necessary for vector replication and packaging. This allows cloning of up to 36 kb genes.
In this protocol, we describe the method to generate HDAd-Ngn3 and HDAd-Btc and to deliver these vectors into STZ-induced diabetic mice. Our results show that co-injection of HDAd-Ngn3 and HDAd-Btc induces 'neo islets' in the liver and reverses hyperglycemia in diabetic mice.

We describe hepatic neo-islet formation in STZ (streptozotocin)-induced diabetic mice by gene transfer of Neurogenin3 (Ngn3) and Betacellulin (Btc) using helper-dependent adenoviral vector (HDAd) and the reversal of hyperglycemia. Our method takes advantages of helper-dependent adenoviral vectors with their highly efficient in vivo transduction and the long lasting gene expression.

Type 1 diabetes is caused by T cell-mediated autoimmune destruction of insulin-producing cells in the pancreas. Until now insulin replacement is still the ...

Collecting And Measuring Wound Exudate Biochemical Mediators In Surgical Wounds

We describe a methodology by which we are able to collect and measure biochemical inflammatory and nociceptive mediators at the surgical wound site. Collecting site-specific biochemical markers is important to understand the relationship between levels in serum and surgical wound, determine any associations between mediator release, pain, analgesic use and other outcomes of interest, and evaluate the effect of systemic and peripheral drug administration on surgical wound biochemistry. This methodology has been applied to healthy women undergoing elective cesarean delivery with spinal anesthesia. We have measured wound exudate and serum mediators at the same time intervals as patient's pain scores and analgesics consumption for up to 48 hours post-cesarean delivery. Using this methodology we have been able to detect various biochemical mediators including nerve growth factor (NGF), prostaglandin E2 (PG-E2) substance P, IL-1&#x03B2;, IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, TNF&alpha;, INF&#x03B3;, G-CSF, GM-CSF, MCP-1 and MIP-1&#x03B2;. Studies applying this human surgical wound bioassay have found no correlations between wound and serum cytokine concentrations or their time-release profile (J Pain. 2008; 9(7):650-7).1 We also documented the utility of the technique to identify drug-mediated changes in wound cytokine content (Anesth Analg 2010; 111:1452-9).2

This article provides a detailed and visual description of a methodology for collecting and measuring biochemical inflammatory and nociceptive mediators at the surgical wound site following cesarean delivery. This human bioassay has been used to determine correlations between wound and serum cytokine concentrations and drug-mediated changes in wound cytokines, chemokines and neuropetides.

We describe a methodology by which we are able to collect and measure biochemical inflammatory and nociceptive mediators at the surgical wound site. ...

Assessment of Gastric Emptying in Non-obese Diabetic Mice Using a [13C]-octanoic Acid Breath Test

Gastric emptying studies in mice have been limited by the inability to follow gastric emptying changes in the same animal since the most commonly used techniques require killing of the animals and postmortem recovery of the meal1,2. This approach prevents longitudinal studies to determine changes in gastric emptying with age and progression of disease. The commonly used [13C]-octanoic acid breath test for humans3 has been modified for use in mice4-6 and rats7 and we previously showed that this test is reliable and responsive to changes in gastric emptying in response to drugs and during diabetic disease progression8. In this video presentation the principle and practical implementation of this modified test is explained. As in the previous study, NOD LtJ mice are used, a model of type 1 diabetes9. A proportion of these mice develop the symptoms of gastroparesis, a complication of diabetes characterized by delayed gastric emptying without mechanical obstruction of the stomach10.
This paper demonstrates how to train the mice for testing, how to prepare the test meal and obtain 4 hr gastric emptying data and how to analyze the obtained data. The carbon isotope analyzer used in the present study is suitable for the automatic sampling of the air samples from up to 12 mice at the same time. This technique allows the longitudinal follow-up of gastric emptying from larger groups of mice with diabetes or other long-standing diseases.

Assessment of Gastric Emptying in Non-obese Diabetic Mice Using a [13C]-octanoic Acid Breath Test

Determination of gastric emptying with a non-invasive [13C]-octanoic acid breath test for tracking gastroparesis in female NOD LtJ mice.

Gastric emptying studies in mice have been limited by the inability to follow gastric emptying changes in the same animal since the most commonly used ...

Parabiosis in Mice: A Detailed Protocol

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 18641, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival2. In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.

Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of ...

Urinary Bladder Distention Evoked Visceromotor Responses as a Model for Bladder Pain in Mice

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized by increased urgency and frequency of urination, as well as nocturia and general pelvic pain, especially upon bladder filling or voiding. Despite years of research, the cause of IC/BPS remains elusive and treatment strategies are unable to provide complete relief to patients. In order to study nervous system contributions to the condition, many animal models have been developed to mimic the pain and symptoms associated with IC/BPS. One such murine model is urinary bladder distension (UBD). In this model, compressed air of a specific pressure is delivered to the bladder of a lightly anesthetized animal over a set period of time. Throughout the procedure, wires in the superior oblique abdominal muscles record electrical activity from the muscle. This activity is known as the visceromotor response (VMR) and is a reliable and reproducible measure of nociception. Here, we describe the steps necessary to perform this technique in mice including surgical manipulations, physiological recording, and data analysis. With the use of this model, the coordination between primary sensory neurons, spinal cord secondary afferents, and higher central nervous system areas involved in bladder pain can be unraveled. This basic science knowledge can then be clinically translated to treat patients suffering from IC/BPS.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized in part by pelvic pain. In order to study nervous system contributions to the condition, a physiological model of urinary bladder pain is used in mice and rats.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition ...

A Simple Mechanical Procedure to Create Limbal Stem Cell Deficiency in Mouse

Limbal stem cell deficiency (LSCD) is a state of malfunction or loss of limbal epithelial stem cells, after which the corneal epithelium is replaced with conjunctiva. Patients suffer from recurrent corneal defects, pain, inflammation, and loss of vision.
Previously, a murine model of LSCD was described and compared to two other models. The goal was to produce a consistent mouse model of LSCD that both mimics the phenotype in humans and lasts long enough to make it possible to study the disease pathophysiology and to evaluate new treatments. Here, the technique is described in more detail.
A motorized tool with a rotating burr has been designed to remove the rust rings from the corneal surface or to smooth the pterygium bed in patients. It is a suitable device to create the desired LSCD model. It is a readily available, easy-to-use tool with a fine tip that makes it appropriate for working on small eyes, as in mice. Its application prevents unnecessary trauma to the eye and it does not result in unwanted injuries, as often is the case with chemical injury models. As opposed to a blunt scraper, it removes the epithelium with the basement membrane. In this protocol, the limbal area was abraded two times, and then the whole corneal epithelium was shaved from limbus to limbus. To avoid stroma injury, care was taken not to brush the corneal surface once the epithelium was already removed.

The following article provides an easy, reproducible technique to effectively create a sustainable mouse model of limbal stem cell deficiency (LSCD). This animal model is useful in testing and comparing the efficacy of treatments for limbal stem cell diseases.

Limbal stem cell deficiency (LSCD) is a state of malfunction or loss of limbal epithelial stem cells, after which the corneal epithelium is replaced with ...

Two Techniques to Create Hypoparathyroid Mice: Parathyroidectomy Using GFP Glands and Diphtheria-Toxin-Mediated Parathyroid Ablation

Hypoparathyroidism (HP) is a disorder characterized by low levels of PTH which lead to hypocalcemia, hyperphosphatemia, and low bone turnover. The most common cause of the disease is accidental removal of the parathyroid glands during thyroid surgery. Novel therapies for HP are needed, but testing them requires reliable animal models of acquired HP. 
Here, we demonstrate the generation of two mouse models of acquired HP. In the GFP-PTX model, mice with green fluorescent protein (GFP) expressed specifically in the parathyroids (PTHcre-mTmG) were created by crossing PTHcre+ mice with Rosa-mTmGfl/fl mice. Green fluorescing parathyroid glands are easily identified under a fluorescence dissecting microscope and parathyroidectomy is performed in less than 20 min. After fluorescence-guided surgery, mice are profoundly hypocalcemic. Contrary to the traditional thyro-parathyroidectomy, this precise surgical approach leaves thyroid glands and thyroid function intact. The second model, which does not require surgery, is based on a diphtheria-toxin approach. PTHcre-iDTR mice, which express the diphtheria toxin (DT) receptor specifically in the parathyroids, were generated by crossing the inducible DTR mouse with the PTHcre mouse. Parathyroid cells are thus rendered sensitive to diphtheria toxin (DT) and can be selectively destroyed by systemically injecting mice with DT. The resulting hypocalcemic phenotype is stable.

Mice with acquired hypoparathyroidism would be useful for studying novel drug therapies for hypoparathyroidism. Two procedures to create such mice are demonstrated. The GFP-PTX mouse is generated by surgical parathyroidectomy guided by green fluorescing parathyroid glands. A second, non-surgical approach is based on parathyroid-specific expression of the diphtheria toxin receptor.

Hypoparathyroidism (HP) is a disorder characterized by low levels of PTH which lead to hypocalcemia, hyperphosphatemia, and low bone turnover. The most ...

Generation of a Chronic Obstructive Pulmonary Disease Model in Mice by Repeated Ozone Exposure

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and lung parenchymal destruction. It has a very high incidence in aging populations. The current conventional therapies for COPD focus mainly on symptom-modifying drugs; thus, the development of new therapies is urgently needed. Qualified animal models of COPD could help to characterize the underlying mechanisms and can be used for new drug screening. Current COPD models, such as lipopolysaccharide (LPS) or the porcine pancreatic elastase (PPE)-induced emphysema model, generate COPD-like lesions in the lungs and airways but do not otherwise resemble the pathogenesis of human COPD. A cigarette smoke (CS)-induced model remains one of the most popular because it not only simulates COPD-like lesions in the respiratory system, but it is also based on one of the main hazardous materials that causes COPD in humans. However, the time-consuming and labor-intensive aspects of the CS-induced model dramatically limit its application in new drug screening. In this study, we successfully generated a new COPD model by exposing mice to high levels of ozone. This model demonstrated the following: 1) decreased forced expiratory volume 25, 50, and 75/forced vital capacity (FEV25/FVC, FEV50/FVC, and FEV75/FVC), indicating the deterioration of lung function; 2) enlarged lung alveoli, with lung parenchymal destruction; 3) reduced fatigue time and distance; and 4) increased inflammation. Taken together, these data demonstrate that the ozone exposure (OE) model is a reliable animal model that is similar to humans because ozone overexposure is one of the etiological factors of COPD. Additionally, it only took 6 - 8 weeks, based on our previous work, to create an OE model, whereas it requires 3 - 12 months to induce the cigarette smoke model, indicating that the OE model might be a good choice for COPD research.

This study describes the successful generation of a new chronic obstructive pulmonary disease (COPD) animal model by repeatedly exposing mice to high concentrations of ozone.

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and lung parenchymal destruction. It has a very high ...

Application of Lucilia sericata Larvae in Debridement of Pressure Wounds in Outpatient Settings

Biological therapy using Lucilia sericata larvae has numerous advocates worldwide, yet it is still fairly unknown and not commonly applied in daily practice because of the limited awareness and insufficient experience of medical and nursing personnel. There are case reports suggesting that maggot therapy can be applied and supported by lay caregivers, provided they are supervised and informed by physicians/nurses. The foregoing observation suggests that the method should be considered for implementation by a wider group of caregivers if accepted and meticulously supervised by trained and experienced medical staff. The concerns related to the therapeutic use of maggots in certain regions seem understandable, but are not supported by scientific facts. It should be noted that many therapeutic agents (including brood) used in medicine are of natural origin, and are associated with low production costs and high possibilities of implementation in the course of therapy. By analyzing the literature and using our own clinical and research experience, we have come to conclusions related to using larvae therapy, as a quick and safe method providing cleaning and revitalization in the process of treating wounds of various etiologies, especially pressure ulcers. In the current study, medical-grade Lucilia sericata maggots were applied to remove necrotic tissue from deep pressure sores. The treatment is mostly accepted by both caregivers and patients. In most cases, it is conducted by trained and experienced medical personnel in home and outpatient settings. Over the course of the conducted analyzes involving the collected specimens, there were no statistically significant relationships (p&gt; 0.05) confirmed between the wound surface successfully cleared by brood and variables, such as time from wound formation, location, surface size, and the depth of damage to the tissue structure. The lack of statistical dependence may result from the small size of the studied group. Based on the current findings, we have formulated the following conclusions: Maggot Debridement Therapy (MDT) is a fast and effective method enabling the preparation of the wound bed. The use of MDT in outpatient settings is safe and acceptable for patients and their caregivers.

Application of Lucilia sericata Larvae in Debridement of Pressure Wounds in Outpatient Settings

Maggots of Lucilia sericata were used in the debridement of deep pressure sores in outpatient settings for the treatment of pressure sores involving the complete skin thickness. The technique presented in the article does not pose risks for the patient.

Biological therapy using Lucilia sericata larvae has numerous advocates worldwide, yet it is still fairly unknown and not commonly applied in daily ...