This study was funded by a Grant-in-Aid for Scientific Research (C) (19K09839, NS) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

The following procedure is performed in three steps. The first step includes the induction of diabetes in the recipient mice and the isolation of donor islets. The second step involves the preparation of islets before transplantation. In the third step, islet transplantation onto epididymal adipose tissue and covering of the islets using the adipose tissue is performed. After that, the therapeutic effects were assessed. The handling of the mice and the experimental procedures performed in this study comply with the &#39;&#39;Principles of Laboratory Animal Care&#39;&#39; (Guide for the Care and Use of Laboratory Animals, National Institutes of Health publication 8th&#160;edition, 2011), and the experimental protocol was approved by the Animal Care and Use Committee of Fukuoka University (approval number: 186018).
1. Surgical preparation
<ol>
	<li>Induction of diabetes: Induce diabetes in 20-25 g body weight, 8-12-week-old recipient male mice through intravenous injection of 18 mg/mL streptozotocin solution prepared in 0.1M citrate buffer (180 mg/kg body weight). Mice with blood glucose levels exceeding 400 mg/dL are considered to be diabetic. Use diabetic mice within 1 week after diabetes induction before excessive atrophy of the epididymal white adipose tissue for covering islets.</li>
	<li>Islet isolation: Perform murine islet isolation one day before transplantation following Gotoh&#39;s method27 for islet isolation.</li>
	<li>In brief, digest pancreatic tissue using collagenase solution. Isolate islets by density gradient centrifugation using an appropriate cell separation solution. Then culture islets overnight in an incubator at 22 &#176;C and 5% CO2 (culture at &#60;37 &#176;C has been reported to prevent islet death28,29,30,31). 
	NOTE:&#160;Handle the purified islet cultures in a safety cabinet. Filter-sterilize all solutions used for islet isolation and culture using a 0.22 &#181;m filter.</li>
</ol>
2. Preparation of islets for transplantation
<ol>
	<li>Gather the appropriate instruments and materials as indicated in Figure 1A.</li>
	<li>As digestive enzymes such as amylase and lipase may result in injury to the isolated and transplanted islets and a loss of islets can occur from being trapped in contaminating fibrous tissues within the culture dish, prior to transplantation, use forceps to handpick any extra-islet components from the pancreas, including acinar and fibrous tissues (Figure 1B), under a dissecting microscope. After picking, use a cell strainer to filter out single acinar cells.</li>
	<li>Transfer the filtered islets to a new culture dish containing any appropriate culture medium or buffer solution (e.g., DMEM with low glucose, RPMI1640, CMRL1066, or HBSS) supplemented with bovine serum or albumin to prevent islet attachment to plastic and swirl the dish to position the islets in the center of the dish (Figure 1C). Using a P200 micropipette and the microscope, pick the individual islets into an appropriate collection tube (Figure 1D).</li>
	<li>Place a new, 40 &#956;m cell strainer on top of a 50 mL plastic tube (Figure 1E left and center) and wash the filter with fresh medium (Figure 1E right).</li>
	<li>Use a 1000 &#956;L pipette to add the islets to the strainer to separate the islets and single acinar cells (Figure 1F1 and Figure 1F2). 
	NOTE: The purified islets on cell strainer will be approximately 100% pure.</li>
	<li>Use forceps to invert the strainer on a new 60- or 100-mm sized non-treated culture dish containing culture medium or an appropriate buffer solution supplemented with bovine serum or albumin (Figure 1F3 and Figure 1F4). Use fresh medium/buffer to flush the islets into a new culture dish. Then add enough medium/buffer to the culture dish to reach a total volume of approximately 20 mL.</li>
	<li>Count the islets under a microscope and divide the number of islets equally between individual 1.5 mL plastic centrifuge tubes according to the number of donor animals (Figure 1G). For example, two hundred, 100-200 &#181;m islet equivalents (IEQ) from two mice would be added to each of two tubes.</li>
	<li>Centrifuge the islets at 2,100 x g within&#160;1 minute at room temperature and discard the supernatant. Around 20-30 &#181;L of residual solution will typically remain in the tube (Figure 1H).</li>
</ol>
3. Islet transplantation onto epididymal adipose tissue and covering with epididymal white adipose tissue
<ol>
	<li>Before the surgery, collect an anesthesia machine for small animals, stereo microscope, light source, 50-200 &#181;L micropipette with 200 &#181;L micropipette tips, cotton swabs, a 4-0 suturing set, and disinfected surgical instruments (Figure 2A). Autoclave the cooper scissors, ophthalmic scissors, Pean forceps, tweezers, and needle holders. After autoclaving, immerse the equipment&#160;in a 1% povidone-iodine solution&#160;(Figure 2A). Use cotton swabs for mobilization of the epididymal white adipose tissue and for hemostasis in cases of bleeding. Use a micropipette with a 50-200 &#181;L tips for islet transplantation.</li>
	<li>Deliver anesthesia to the diabetic recipient mouse using an inhaled anesthetic agent (2% isoflurane in oxygen). Apply ophthalmic lubricant to both eyes to prevent drying. Then place the mouse in the supine position (Figure 2B left) and remove the hair from the abdomen to prevent infection using hair clippers and/or depilatory cream.&#160;Disinfect the abdomen and the inguinal region using at least three alternating rounds of a povidone-iodine solution followed by 70% ethanol&#160;(Figure 2B right). Before the surgery, confirm anesthesia depth via the absence of a toe pinch reflex. Provide intra-operative thermal support using a heating pad and use a&#160;surgical drape to secure the sterile surgical area.</li>
	<li>Incise the skin at the lower median area (Figure 2C left). A skin incision that is approximately 2 cm in length is recommended. Clamp the left abdominal wall with the Pean forceps (atraumatic forceps or retractor can also be used) and pull the tissue to the left side of the mouse to secure the surgical field (Figure 2C right). After laparotomy, decrease the percentage of isoflurane to 1.0-1.5% for anesthesia maintenance.</li>
	<li>Use a cotton swab to mobilize the small and large intestine to the right side of the mouse (i.e., left side of the operator). The left epididymal white adipose tissue in the abdominal cavity are located in the left inguinal area. Mobilize the epididymal white adipose tissue and the left testis to outside of the abdomen (Figure 2D left) and stretch out the tissue (2D right).</li>
	<li>Use a P200 micropipette equipped with a 200 &#181;L pipette tip to collect the entire volume of islets from one 1.5 mL tube with gentle pipetting (Figure 2E left), taking care that no islets are left in the tube upon collection. Allow the collected islets to settle to the tip of the pipette by gravity (Figure 2E right).</li>
	<li>Place the micropipette tip lightly onto the distended adipose tissue. Taking care to prevent excessive flushing of the medium/buffer in the tip, carefully seed the islets onto the tissue (Figure 2F left). After seeding, confirm a correct placement of the islets under a dissecting microscope (Figure 2F right).</li>
	<li>Cover the islets with the epididymal white adipose tissue (Figure 2G). The use of sutures or biobinding agents is not needed.</li>
	<li>Place the left testis under the epididymal white adipose tissue and return the tissues to the intraperitoneal cavity (Figure 2H). Close the skin in two layers (peritoneum, then muscle and skin) using a 4-0 suture (any sutures such as nylon&#160;or absorbable sutures can be used) (Figure 2I). Inject&#160;acetylsalicylic acid (300 mg/kg; SQ)&#160;near the wound for postoperative analgesia.&#160;Then place the mouse under a heat lamp and&#160;monitor until full recovery.</li>
</ol>
4. Monitoring after Islet transplantation (Summary)
<ol>
	<li>Assess the therapeutic effects of islet transplantation by monitoring blood glucose, glucose tolerance test and histological assessment at postoperative day (POD) 28.
	<ol>
		<li>Monitor the blood glucose, including the measurements of blood glucose at glucose tolerance test, using a small glucose meter.</li>
		<li>Collect the blood samples (a little microliters) from tail vein. Regarding histological assessment, murine insulin (for detecting engrafted islets) and von Willebrand factor (for detection of vessels, which is an evidence for islet engraftment) were detected in transplanted islets in the recovered epididymal adipose tissue by immunohistochemistry.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Barton, F. B., 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=Improvement+in+outcomes+of+clinical+islet+transplantation:+1999-2010.">Improvement in outcomes of clinical islet transplantation: 1999-2010.</a> Diabetes Care. 35 (7), 1436-1445 (2012).</li><li>Balamurugan, A. N., 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=Islet+product+characteristics+and+factors+related+to+successful+human+islet+transplantation+from+the+Collaborative+Islet+Transplant+Registry+(CITR)+1999-2010.">Islet product characteristics and factors related to successful human islet transplantation from the Collaborative Islet Transplant Registry (CITR) 1999-2010.</a> American Journal of Transplantation. 14 (11), 2595-2606 (2014).</li><li>Collaborative Islet Transplant Registry. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Collaborative Islet Transplant Registry. 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V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Survival+and+metabolic+function+of+syngeneic+rat+islet+grafts+transplanted+in+the+omental+pouch.">Survival and metabolic function of syngeneic rat islet grafts transplanted in the omental pouch.</a> American Journal of Transplantation. 3 (3), 281-285 (2003).</li><li>Kasoju, N., 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=Bioengineering+a+pre-vascularized+pouch+for+subsequent+islet+transplantation+using+VEGF-loaded+polylactide+capsules.">Bioengineering a pre-vascularized pouch for subsequent islet transplantation using VEGF-loaded polylactide capsules.</a> Biomaterials Science. 8 (2), 631-647 (2020).</li><li>Sakata, N., Yoshimatsu, G., Kodama, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White+Adipose+Tissue+as+a+Site+for+Islet+Transplantation.">White Adipose Tissue as a Site for Islet Transplantation.</a> Transplantology. 1 (2), 55-70 (2020).</li><li>Osama Gaber, A., Chamsuddin, A., Fraga, D., Fisher, J., Lo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+independence+achieved+using+the+transmesenteric+approach+to+the+portal+vein+for+islet+transplantation.">Insulin independence achieved using the transmesenteric approach to the portal vein for islet transplantation.</a> Transplantation. 77 (2), 309-311 (2004).</li><li>Fujita, M., 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=Technique+of+endoscopic+biopsy+of+islet+allografts+transplanted+into+the+gastric+submucosal+space+in+pigs.">Technique of endoscopic biopsy of islet allografts transplanted into the gastric submucosal space in pigs.</a> Cell Transplantation. 22 (12), 2335-2344 (2013).</li><li>Sakata, N., 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=Strategy+for+clinical+setting+in+intramuscular+and+subcutaneous+islet+transplantation.">Strategy for clinical setting in intramuscular and subcutaneous islet transplantation.</a> Diabetes/Metabolism Research and Reviews. 30 (1), 1-10 (2014).</li><li>Cantarelli, E., 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=Transplant+Site+Influences+the+Immune+Response+After+Islet+Transplantation:+Bone+Marrow+Versus+Liver.">Transplant Site Influences the Immune Response After Islet Transplantation: Bone Marrow Versus Liver.</a> Transplantation. 101 (5), 1046-1055 (2017).</li><li>White, S. A., 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+risks+of+total+pancreatectomy+and+splenic+islet+autotransplantation.">The risks of total pancreatectomy and splenic islet autotransplantation.</a> Cell Transplantation. 9 (1), 19-24 (2000).</li><li>Itoh, T., Nishinakamura, H., Kumano, K., Takahashi, H., Kodama, 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+Spleen+Is+an+Ideal+Site+for+Inducing+Transplanted+Islet+Graft+Expansion+in+Mice.">The Spleen Is an Ideal Site for Inducing Transplanted Islet Graft Expansion in Mice.</a> PLoS One. 12 (1), 0170899 (2017).</li><li>Sakata, N., Yoshimatsu, G., Kodama, 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+Spleen+as+an+Optimal+Site+for+Islet+Transplantation+and+a+Source+of+Mesenchymal+Stem+Cells.">The Spleen as an Optimal Site for Islet Transplantation and a Source of Mesenchymal Stem Cells.</a> International Journal of Molecular Sciences. 19 (5), (2018).</li><li>Sakata, N., 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=Effect+of+rat-to-mouse+bioartificial+pancreas+xenotransplantation+on+diabetic+renal+damage+and+survival.">Effect of rat-to-mouse bioartificial pancreas xenotransplantation on diabetic renal damage and survival.</a> Pancreas. 32 (3), 249-257 (2006).</li><li>Nagaya, M., 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=Effectiveness+of+bioengineered+islet+cell+sheets+for+the+treatment+of+diabetes+mellitus.">Effectiveness of bioengineered islet cell sheets for the treatment of diabetes mellitus.</a> Journal of Surgical Research. 227, 119-129 (2018).</li><li>Weaver, J. 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We have no conflict of interests.

The fat-covered islet transplantation method incorporates techniques from two different transplant techniques: intraperitoneal islet transplantation and intra-adipose tissue islet transplantation. As the surface membrane of epididymal white adipose tissue is considered to be the white adipose tissue that is covered by the peritoneum and that is attached to the epididymis, the fat-covered islet transplantation method can be anatomically categorized as a type of intraperitoneal islet transplantation. The technique by which...

Islet transplantation is a cellular replacement therapy for patients with severe diabetes mellitus. Recent reports have shown that rates of insulin-independence at three years after transplantation improve up to 44%1 and that approximately 80% of recipients who receive more than 600,000 total islet equivalents achieve insulin independence2. Furthermore, in the most recent Collaborative Islet Transplant Registry report, it was revealed that fasting blood glucose levels were maintained at 60-140 mg/dL for over a period of 5 years in over 70% of patients who underwent islet transplant alone. The study also determined that around 90% of the patients who received islet transplant alone or islet transplantation after kidney transplant did not develop any severe hypoglycemic events for over 5 years3.
Although the clinical outcomes of this treatment have been improving, some limitations must still be addressed, including the necessity of establishing an optimal transplant site. The liver is a typical transplant site for clinical islet transplantation because it is the largest organ that can accommodate a high volume of islets. However, in some patients the liver is unavailable (e.g., due to portal hypertension, hepatitis, and/or cirrhosis4) and therefore other sites, including the renal subcapsular space5,6, omental pouch7,8,9,10, mesentery11, gastrointestinal tract12, skeletal muscle13, subcutaneous tissue13, bone marrow14, and spleen15,16,17, have been considered as alternative transplant sites.
Although intraperitoneal islet transplantation can be performed easily under local anesthesia, making the intraperitoneal cavity an appealing site for clinical islet transplantation, upon transplant, the islets are dispersed throughout the entire intraperitoneal cavity, making islet engraftment detection and successful engraftment confirmation difficult. Therefore, the intraperitoneal cavity is not widely recognized as an ideal clinical transplant site. Instead, it is frequently utilized as a control model for preclinical studies to investigate the effectiveness of transplanted encapsulated18 and bioengineered islets19. However, an exact comparison between bioengineered and control islets is difficult to achieve due to the challenges in performing an accurate engraftment assessment.
In contrast, the use of intraperitoneal white adipose tissue in the omental pouch8, mesentery, and other extrahepatic locations has been well reported10,20,21,22,23 and many of the studies investigating the function of bioengineered islets transplanted using white adipose tissue were able to report promising therapeutic outcomes20,24,25,26. As the use of epididymal adipose tissue facilitates the detection of transplanted islets, the &#34;fat-covered islet transplantation method&#34;, utilizing epididymal adipose tissue, was developed to overcome the limitations of intraperitoneal islet transplantation. In this paper, fat-covered islet transplantation using epididymal adipose tissue is described.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4-0 Nylon</td>
			<td>Alfresa</td>
			<td>ER2004NA45-KF2</td>
			<td>Closing abdomen</td>
		</tr>
		<tr>
			<td>Alexa 488-conjugated donkey anti-guinea pig</td>
			<td>Jackson Immunoresearch</td>
			<td>706-546-148</td>
			<td>Secondary antibody for insulin antibody</td>
		</tr>
		<tr>
			<td>Alexa 647-conjugated donkey anti-rabbit</td>
			<td>Jackson Immunoresearch</td>
			<td>711-606-152</td>
			<td>Secondary antibody for von Willebrand factor antibody</td>
		</tr>
		<tr>
			<td>DMEM, low glucose, pyruvate</td>
			<td>ThermoFisher Scientific</td>
			<td>11885084</td>
			<td>Culturing islets, transplanting islets</td>
		</tr>
		<tr>
			<td>Eosin</td>
			<td>Fujifilm Wako Chemicals</td>
			<td>051-06515</td>
			<td>Using for staining tissue by eosin</td>
		</tr>
		<tr>
			<td>Eppendorf Safe-Lock Tubes, 1.5 mL</td>
			<td>Eppendorf</td>
			<td>30120086</td>
			<td>Collecting islets&#160;</td>
		</tr>
		<tr>
			<td>Falcon 15 mL Conical Centrifuge Tubes</td>
			<td>Corning</td>
			<td>352095</td>
			<td>Collecting islets</td>
		</tr>
		<tr>
			<td>Falcon 40 &#181;m Cell Strainer</td>
			<td>Falcon</td>
			<td>352340</td>
			<td>Using for separating islets from other pancreatic tissue</td>
		</tr>
		<tr>
			<td>Falcon 50 mL Conical Centrifuge Tubes</td>
			<td>Corning</td>
			<td>352070</td>
			<td>Discarding excessive medium/buffer</td>
		</tr>
		<tr>
			<td>Guinea pig anti-insulin</td>
			<td>Agilent Technologies Japan, Ltd. (Dako)</td>
			<td>IR002</td>
			<td>Primary antibody for murine insulin</td>
		</tr>
		<tr>
			<td>Hematoxylin</td>
			<td>Muto Pure Chemicals Co., Ltd.</td>
			<td>30002</td>
			<td>Using for staining tissue by hematoxylin</td>
		</tr>
		<tr>
			<td>Isodine solution 10%</td>
			<td>Shionogi&#38;Co., Ltd.</td>
			<td>no catalog number</td>
			<td>Using for disinfection</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Fujifilm Wako Chemicals</td>
			<td>095-06573</td>
			<td>Using for anesthesia</td>
		</tr>
		<tr>
			<td>Labcon 1000 &#181;L ZapSilk Low Retention Pipette Tips</td>
			<td>Labcon</td>
			<td>1177-965-008</td>
			<td>Using for separating islets from other pancreatic tissue</td>
		</tr>
		<tr>
			<td>Labcon 200 &#181;L ZapSilk Low Retention Pipette Tips</td>
			<td>Labcon</td>
			<td>1179-965-008</td>
			<td>Using for seeding islets onto epididymal white adipose tissue</td>
		</tr>
		<tr>
			<td>Mintsensor</td>
			<td>Sanwa Kagaku Kenkyusho Co. Ltd.,</td>
			<td>8AEB02E</td>
			<td>Using for monitoring blood glucose</td>
		</tr>
		<tr>
			<td>Pipetteman P-1000</td>
			<td>Gilson</td>
			<td>F123602</td>
			<td>Using for separating islets from other pancreatic tissue</td>
		</tr>
		<tr>
			<td>Pipetteman P-200</td>
			<td>Gilson</td>
			<td>F123601</td>
			<td>Using for seeding islets onto epididymal white adipose tissue</td>
		</tr>
		<tr>
			<td>Rabbit anti-vWF</td>
			<td>Abcam</td>
			<td>ab6994</td>
			<td>Primary antibody for murine von Willebrand factor</td>
		</tr>
	</tbody>
</table>

fat-covered islet transplantation using epididymal white adipose tissue

Islet transplantation is a cellular replacement therapy for severe diabetes mellitus. The intraperitoneal cavity is typically the transplant site for this procedure. However, intraperitoneal islet transplantation has some limitations, including poor transplant efficacy, difficult graft detection ability, and a lack of graftectomy capability for post-transplant analysis. In this paper, "fat-covered islet transplantation", an intraperitoneal islet transplantation method that utilizes epididymal white adipose tissue, is used to assess the therapeutic effects of bioengineered islets. The simplicity of the method lies in the seeding of islets onto epididymal white adipose tissue and using the tissue to cover the islets. While this method can be categorized as an intraperitoneal islet transplantation technique, it shares characteristics with intra-adipose tissue islet transplantation. The fat-covered islet transplantation method demonstrates more robust therapeutic effects than intra-adipose tissue islet transplantation, however, including the improvement of blood glucose and plasma insulin levels and the potential for graft removal. We recommend the adoption of this method for assessing the mechanisms of islet engraftment into white adipose tissue and the therapeutic effects of bioengineered islets.

To compare the transplant efficacy of fat-covered islet transplantation to that after intraperitoneal islet transplantation, the same number of islets was implanted onto the peritoneum at the left paracolic space of control recipient diabetic animals. The blood glucose levels of mice with fat-covered islet transplantation were observed to gradually and significantly decrease compared to intraperitoneal islet transplanted mice (p = 0.0023; Figure 3A). One month after transplantation, the bloo...

Watch this Scientific Journal Video about Fat-Covered Islet Transplantation Using Epididymal White Adipose Tissue at JoVE.com

Fat-Covered Islet Transplantation Using Epididymal White Adipose Tissue

This fat-covered islet transplantation method is suitable for the detection of engrafted islets in the intraperitoneal cavity. Notably, it does not require the use of biobinding agents or suturing.

Islet transplantation is a cellular replacement therapy for severe diabetes mellitus. The intraperitoneal cavity is typically the transplant site for this ...

fat-covered-islet-transplantation-using-epididymal-white-adipose

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JoVE Journal

Medicine

1.9K Views.  Fukuoka University. This fat-covered islet transplantation method is suitable for the detection of engrafted islets in the intraperitoneal cavity. Notably, it does not require the use of biobinding agents or suturing.

Video: Fat-Covered Islet Transplantation Using Epididymal White Adipose Tissue

A Method for Murine Islet Isolation and Subcapsular Kidney Transplantation

Since the early pioneering work of Ballinger and Reckard demonstrating that transplantation of islets of Langerhans into diabetic rodents could normalize their blood glucose levels, islet transplantation has been proposed to be a potential treatment for type 1 diabetes 1,2. More recently, advances in human islet transplantation have further strengthened this view 1,3. However, two major limitations prevent islet transplantation from being a widespread clinical reality: (a) the requirement for large numbers of islets per patient, which severely reduces the number of potential recipients, and (b) the need for heavy immunosuppression, which significantly affects the pediatric population of patients due to their vulnerability to long-term immunosuppression. Strategies that can overcome these limitations have the potential to enhance the therapeutic utility of islet transplantation.
Islet transplantation under the mouse kidney capsule is a widely accepted model to investigate various strategies to improve islet transplantation. This experiment requires the isolation of high quality islets and implantation of islets to the diabetic recipients. Both procedures require surgical steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol. We also briefly discuss different transplantation models: syngeneic, allogeneic, syngeneic autoimmune, and allogeneic autoimmune.

Transplantation of isolated islets has been proposed to be a potential treatment for type 1 diabetes. Here we describe a method to isolate islets from mouse pancreata and transplant them to the subcapsular space of the kidney.

Since the early pioneering work of Ballinger and Reckard demonstrating that transplantation of islets of Langerhans into diabetic rodents could normalize ...

Transplantation of Pulmonary Valve Using a Mouse Model of Heterotopic Heart Transplantation

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed results. However, the cellular and molecular mechanisms of the neotissue development, valve thickening, and stenosis development are not researched extensively. To answer the above questions, we developed a murine heterotopic heart valve transplantation model. A heart valve was harvested from a valve donor mouse and transplanted to a heart donor mouse. The heart with a new valve was transplanted heterotopically to a recipient mouse. The transplanted heart showed its own heartbeat, independent of the recipient&#8217;s heartbeat. The blood flow was quantified using a high frequency ultrasound system with a pulsed wave Doppler. The flow through the implanted pulmonary valve showed forward flow with minimal regurgitation and the peak flow was close to 100 mm/sec. This murine model of heart valve transplantation is highly versatile, so it can be modified and adapted to provide different hemodynamic environments and/or can be used with various transgenic mice to study neotissue development in a tissue engineered heart valve.

In order to understand the cellular and molecular mechanisms underlying neotissue formation and stenosis development in tissue engineered heart valves, a murine model of heterotopic heart valve transplantation was developed. A pulmonary heart valve was transplanted to recipient using the heterotopic heart transplantation technique.

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed ...

Cerenkov Luminescence Imaging of Interscapular Brown Adipose Tissue

Brown adipose tissue (BAT), widely known as a &#8220;good fat&#8221; plays pivotal roles for thermogenesis in mammals. This special tissue is closely related to metabolism and energy expenditure, and its dysfunction is one important contributor for obesity and diabetes. Contrary to previous belief, recent PET/CT imaging studies indicated the BAT depots are still present in human adults. PET imaging clearly shows that BAT has considerably high uptake of 18F-FDG under certain conditions. In this video report, we demonstrate that Cerenkov luminescence imaging (CLI) with 18F-FDG can be used to optically image BAT in small animals. BAT activation is observed after intraperitoneal injection of norepinephrine (NE) and cold treatment, and depression of BAT is induced by long anesthesia. Using multiple-filter Cerenkov luminescence imaging, spectral unmixing and 3D imaging reconstruction are demonstrated. Our results suggest that CLI with 18F-FDG is a practical technique for imaging BAT in small animals, and this technique can be used as a cheap, fast, and alternative imaging tool for BAT research.

In this video report, we show the application of Cerenkov Luminescence Imaging (CLI) for interscapular brown adipose tissue in mice under activated and depressed conditions.

Brown adipose tissue (BAT), widely known as a &#8220;good fat&#8221; plays pivotal roles for thermogenesis in mammals. This special tissue is closely ...

Encapsulation Thermogenic Preadipocytes for Transplantation into Adipose Tissue Depots

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular weight metabolites in tissues of the treated host to achieve long-term survival. The semipermeable membrane allows engrafted encapsulated cells to avoid rejection by the immune system. The encapsulation procedure was designed to enable a controlled release of bioactive compounds, such as insulin, other hormones, and cytokines. Here we describe a method for encapsulation of catabolic cells, which consume lipids for heat production and energy dissipation (thermogenesis) in the intra-abdominal adipose tissue of obese mice. Encapsulation of thermogenic catabolic cells may be potentially applicable to the prevention and treatment of obesity and type 2 diabetes. Another potential application of catabolic cells may include detoxification from alcohols or other toxic metabolites and environmental pollutants.

Here, we present a protocol for encapsulation of catabolic cells, which consume lipids for heat production in intra-abdominal adipose tissue and increase energy dissipation in obese mice.

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular ...

Creation and Transplantation of an Adipose-derived Stem Cell (ASC) Sheet in a Diabetic Wound-healing Model

Artificial skin has achieved considerable therapeutic results in clinical practice. However, artificial skin treatments for wounds in diabetic patients with impeded blood flow or with large wounds might be prolonged. Cell-based therapies have appeared as a new technique for the treatment of diabetic ulcers, and cell-sheet engineering has improved the efficacy of cell transplantation. A number of reports have suggested that adipose-derived stem cells (ASCs), a type of mesenchymal stromal cell (MSC), exhibit therapeutic potential due to their relative abundance in adipose tissue and their accessibility for collection when compared to MSCs from other tissues. Therefore, ASCs appear to be a good source of stem cells for therapeutic use. In this study, ASC sheets from the epididymal adipose fat of normal Lewis rats were successfully created using temperature-responsive culture dishes and normal culture medium containing ascorbic acid. The ASC sheets were transplanted into Zucker diabetic fatty (ZDF) rats, a rat model of type 2 diabetes and obesity, that exhibit diminished wound healing. A wound was created on the posterior cranial surface, ASC sheets were transplanted into the wound, and a bilayer artificial skin was used to cover the sheets. ZDF rats that received ASC sheets had better wound healing than ZDF rats without the transplantation of ASC sheets. This approach was limited because ASC sheets are sensitive to dry conditions, requiring the maintenance of a moist wound environment. Therefore, artificial skin was used to cover the ASC sheet to prevent drying. The allogenic transplantation of ASC sheets in combination with artificial skin might also be applicable to other intractable ulcers or burns, such as those observed with peripheral arterial disease and collagen disease, and might be administered to patients who are undernourished or are using steroids. Thus, this treatment might be the first step towards improving the therapeutic options for diabetic wound healing.

Creation and Transplantation of an Adipose-derived Stem Cell ASC Sheet in a Diabetic Wound-healing Model

Adipose-derived stem cells (ASCs) are easily isolated and harvested from the fat of normal rats. ASC sheets can be created using cell-sheet engineering and can be transplanted into Zucker diabetic fatty rats exhibiting full-thickness skin defects with exposed bone and then covered with a bilayer of artificial skin.

Artificial skin has achieved considerable therapeutic results in clinical practice. However, artificial skin treatments for wounds in diabetic patients ...

A Technique for Subcutaneous Abdominal Adipose Tissue Biopsy via a Non-diathermy Method

Adipose tissue biopsies offer tissue samples that, upon analysis, may provide insightful overviews of mechanisms relating to metabolism and disease. To obtain subcutaneous adipose tissue biopsies in the abdominal area, researchers and physicians use either a surgical or a needle-based technique. However, surgical subcutaneous fat biopsies can offer tissue samples that may provide a more comprehensive overview of the complexities of biological indices in white adipose tissue. Usually, a surgical adipose tissue biopsy includes a diathermy treatment for cauterizing blood vessels to prevent excessive bleeding. Nevertheless, side effects, such as flash fires and skin lesions in the tissue, have been reported after diathermy. Therefore, we aimed to standardize a surgical abdominal adipose tissue biopsy performed under local anesthesia using a non-diathermy method. We conducted 115 subcutaneous adipose tissue biopsies in healthy men using a non-diathermy abdominal surgical biopsy method. Our results showed three cases of excessive post-operation bleeding out of 115 operations (2.61%).In conclusion, our standardized subcutaneous abdominal adipose tissue surgical biopsy using a non-diathermy method can be safely applied to healthy men at the bedside, with minimal side effects.

We standardized an abdominal adipose tissue biopsy using a non-diathermy method performed under local anesthesia. Three cases of excessive post-operation bleeding out of 115 operations (2.61%) occurred.We conclude that an abdominal adipose tissue surgical biopsy using a non-diathermy method can be safely applied to healthy men.

Adipose tissue biopsies offer tissue samples that, upon analysis, may provide insightful overviews of mechanisms relating to metabolism and disease. To ...

Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. It is hypothesized that pro-atherogenic mediators released from fat tissues particularly in association with central/visceral adiposity may promote pathogenic vascular changes locally and systemically, and the notion that cardiovascular disease may be the consequence of adipose tissue dysfunction continues to evolve. Here, we describe a unique method of videomicroscopy that involves analysis of vasodilator and vasoconstrictor responses of intact small human arterioles removed from the adipose depot of living human subjects. Videomicroscopy is used to examine functional properties of isolated microvessels in response to pharmacological or physiological stimuli using a pressured system that mimics in vivo conditions. The technique is a useful approach to gain understanding of the pathophysiology and molecular mechanisms that contribute to vascular dysfunction locally within the adipose tissue milieu. Moreover, abnormalities in the adipose tissue microvasculature have also been linked with systemic diseases. We applied this technique to examine depot-specific vascular responses in obese subjects. We assessed endothelium-dependent vasodilation to both increased flow and acetylcholine in adipose arterioles (50 - 350 &#181;m internal diameter, 2 - 3 mm in length) isolated from two different adipose depots during bariatric surgery from the same individual. We demonstrated that arterioles from visceral fat exhibit impaired endothelium-dependent vasodilation compared to vessels isolated from the subcutaneous depot. The findings suggest that the visceral microenvironment is associated with vascular endothelial dysfunction which may be relevant to clinical observation linking increased visceral adiposity to systemic disease mechanisms. The videomicroscopy technique can be used to examine vascular phenotypes from different fat depots as well as compare findings across individuals with different degrees of obesity and metabolic dysfunction. The method can also be used to examine vascular responses longitudinally in response to clinical interventions.

Videomicroscopy systems are used to examine functional properties of isolated adipose tissue arterioles in response to physiological and pharmacological stimuli. This technique can be used to examine microvascular phenotypes in different adipose tissue domains in obese humans.

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. ...

Transplantation of Adipose Tissue-Derived Stem Cell Sheet to Reduce Leakage After Partial Colectomy in A Rat Model

Anastomotic leakage is a disastrous complication after colorectal surgery. Although current methods for leakage prevention have different levels of clinical efficacy, they are until now imperfect solutions. Stem cell therapy using ASC sheets could provide a solution to this problem. ASCs are considered as promising candidates for promoting tissue healing because of their trophic and immunomodulatory properties. Here, we provide methods to produce high-density ASC sheets, that are transplanted onto a colorectal anastomosis in a rat model to reduce the leakage. ASCs formed cell sheets in thermo-responsive culture dishes that could be easily detached. On the day of the transplantation, a partial colectomy with a 5-suture colorectal anastomosis was performed. Animals were immediately transplanted with 1 ASC sheet per rat. ASC sheets adhered spontaneously to the anastomosis without any glue, suture, or any biomaterial. Animal groups were sacrificed 3 and 7 days postoperatively. Compared to transplanted animals, the incidence of anastomotic abscesses and leakage was higher in control animals. In our model, the transplantation of ASC sheets after colorectal anastomosis was successful and associated with a lower leakage rate.

The preparation and transplantation of adipose tissue derived stem cell (ASC) sheets onto insufficiently sutured colorectal anastomoses in a rat model is presented. This novel application shows that ASC sheets can reduce colorectal anastomosis leakage.

Anastomotic leakage is a disastrous complication after colorectal surgery. Although current methods for leakage prevention have different levels of ...

Characterization of Immune Cells in Human Adipose Tissue by Using Flow Cytometry

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the development of obesity-associated complications such as type 2 diabetes. To quantitatively and qualitatively investigate the immune cell subsets in human AT deposits, we have developed a flow cytometry approach. The stromal vascular fraction (SVF), containing the immune cells, is isolated from subcutaneous and visceral AT biopsies by collagenase digestion. Adipocytes are removed after centrifugation. The SVF cells are stained for multiple membrane-bound markers selected to differentiate between immune cell subsets and analyzed using flow cytometry. As a result of this approach, pro- and anti-inflammatory macrophage subsets, dendritic cells (DCs), B-cells, CD4+ and CD8+ T-cells, and NK cells can be detected and quantified. This method gives detailed information about immune cells in AT and the amount of each specific subset. Since there are numerous fluorescent antibodies available, our flow cytometry approach can be adjusted to measure various other cellular and intracellular markers of interest.

This article describes a method to analyze immune cell content of adipose tissue by isolation of immune cells from adipose tissue and subsequent analysis using flow cytometry.

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the ...

Whole Body and Regional Quantification of Active Human Brown Adipose Tissue Using 18F-FDG PET/CT

In endothermic animals, brown adipose tissue (BAT) is activated to produce heat for defending body temperature in response to cold. BAT&#39;s ability to expend energy has made it a potential target for novel therapies to ameliorate obesity and associated metabolic disorders in humans. Though this tissue has been well studied in small animals, BAT&#39;s thermogenic capacity in humans remains largely unknown due to the difficulties of measuring its volume, activity, and distribution. Identifying and quantifying active human BAT is commonly performed using 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET/CT) scans following cold-exposure or pharmacological activation. Here we describe a detailed image-analysis approach to quantify total-body human BAT from 18F-FDG PET/CT scans using an open-source software. We demonstrate the drawing of user-specified regions of interest to identify metabolically active adipose tissue while avoiding common non-BAT tissues, to measure BAT volume and activity, and to further characterize its anatomical distribution. Although this rigorous approach is time-consuming, we believe it will ultimately provide a foundation to develop future automated BAT quantification algorithms.

Whole Body and Regional Quantification of Active Human Brown Adipose Tissue Using 18F-FDG PET/CT

Using free, open-source software, we have developed an analytical approach to quantify total and regional brown adipose tissue (BAT) volume and metabolic activity of BAT using 18F-FDG PET/CT.

In endothermic animals, brown adipose tissue (BAT) is activated to produce heat for defending body temperature in response to cold. BAT&#39;s ability to ...