This work was supported by grant from NIDDK (DK065949 for GG). We thank Dr. Brenda M. Jarvis and Jeff Duryea Jr. for reading the manuscript.

Animal usage follows the procedures specified in protocol M/11/181 approved by the Vanderbilt Institutional Animal Care and Use Committee for Gu. CD1 or CBA/Bl6 mice were purchased from commercial vendors and crossed in the Vanderbilt animal facility to obtain neonatal mice.
1. Preparation of Mice, Stock Solutions, and Equipment
<ol>
	<li>For the mouse cross: set up a mouse cross and record the plugging dates to aid experimental planning. CD1 mice usually give birth around day 19 after mating. Use CD1 or CBA/Bl6 crosses to obtain CD1 or CBA/Bl6 neonates, respectively. Intercrosses between the two lines utilize CD1 females and CBA/Bl6 males.</li>
	<li>For the collagenase stock: weigh 200 mg collagenase Type IV with a high precision balance. Transfer to a 50 mL centrifuge tube. Dissolve in 40 mL HBSS with Ca2+/Mg2+ (1.26 and 0.5 mM, respectively) to make a 5 mg/mL stock solution.
	<ol>
		<li>Allow collagenase to dissolve for ~ 30 min with gentle shaking. Aliquot and keep the solution frozen in -20 &#176;C as stock, which stays active for at least one year.</li>
	</ol>
	</li>
	<li>Autoclave to sterilize several pairs of tweezers, scissors, and P20 tips for dissection and islet picking.</li>
	<li>For the 1 M glucose stock: weigh 9 g glucose in a 50 mL centrifuge tube, add 50 mL RPMI 1640 media to dissolve the glucose. Keep in 4 &#176;C until use, but no more than 6 months.</li>
</ol>
2. Working Solutions
NOTE: The day of islet isolation, prepare the following reagents.
<ol>
	<li>For the collagenase type IV working solution: thaw and dilute collagenase stock on ice. Dispense 0.15 mL stock into each 1.7 mL microfuge tube. Add 1.35 mL HBSS with Ca2+/Mg2+. Invert the tube 5 times. Leave on ice for 15 min.
	<ol>
		<li>Spin at high speed for 3 min in a microcentrifuge. Transfer supernatant to a new tube. Leave on ice until use. Discard the tube with insoluble debris.</li>
	</ol>
	</li>
	<li>For complete RPMI 1640 media: add 2.5 mL 1 M glucose, 50 mL heat inactivated FBS, and 5 mL 100x Pen-strep stock into 500 mL RPMI 1640 media. Leave on ice until use.</li>
</ol>
3. Pancreas Isolation and Digestion
<ol>
	<li>Euthanize neonates with isoflurane, followed by decapitation according to approved protocols.</li>
	<li>Lay the mouse with its belly facing up. Spray with 70% ethanol for sterilization.</li>
	<li>Lift the belly skin up with tweezers and cut the skin and muscle layers longitudinally along the midline with a pair of scissors, from the genital area to the rib cage. This opens the abdominal cavity to expose all internal organs.</li>
	<li>Transfer all the internal organs to a 100 cm dish with a pair of tweezers. Locate the pancreas, which is a scattered-organ with a dorsal portion that clings to the stomach and spleen and a ventral portion that clings to the duodenum11.</li>
	<li>Add HBSS into the dish to submerge the organs. In solution, the pancreatic tissues no longer cling to the duodenum, stomach, or spleen. It is readily recognizable under a dissecting scope because of its typical white color. Use a pair of tweezers to peel the pancreatic tissues away from surrounding tissue and transfer to a new 60 mm dish with HBSS.</li>
	<li>Cut each pancreas with a scissor into pieces smaller than 5 mm across any dimensions. Transfer to a 1.5 mL microcentrifuge tube. Up to five pancreata (younger than P7) can be digested in one tube. For P8-P16 mice, use one tube per pancreas.</li>
	<li>Add 0.5 - 1 mL collagenase working solution to each tube (0.2 mL for each P1-P7 pancreas. Use 0.5 mL for each P8-P16 pancreas). Leave the tube in a 37 &#176;C incubator for up to 15 min. Invert the tube two times every min.</li>
	<li>After ~ 5 min, tap the tube to monitor the digestion status of the pancreatic tissue. Continue the digestion process until most of the pancreatic tissue appears as fragmented cell clusters, with diameter &#60; 2 mm. The lysate will appear cloudy, which is due to normal acinar cell autolysis.</li>
</ol>
4. Lysate Washing
<ol>
	<li>Spin the lysate at 500 x g for 10 s in a microcentrifuge. Remove the supernatant layer with a P1,000 pipetman. The supernatant should appear turbid but devoid of cell clusters. Do not use aspiration, which may quickly aspirate away the tissue fragments at the bottom due to the presence of some sticky DNA.</li>
	<li>Add 1 mL RPMI 1640 complete media. Tap the tube gently to resuspend the fragmented lysate. Invert up and down 10 times. Repeat step 4.1.</li>
	<li>Repeat step 4.2 two more times or until the supernatant appears clear. Re-suspend washed pancreatic fragments in 1 mL complete RPMI 1640 media.</li>
</ol>
5. Islet Isolation
NOTE: For small numbers of pancreata, direct hand-picking as below (5.1) can be used for islet isolation. For large numbers of pancreata (&#62; 6), the method outlined in 5.2 is preferred.
<ol>
	<li>Direct hand-picking:
	<ol>
		<li>Transfer lysate from step 4.3 to a 60 mm dish. Add 5 mL complete RPMI 1640 media. Bring under a dissecting microscope.</li>
		<li>Set up the bright field illumination on the microscope. Adjust the light intensity to ~ 50% of the maximum power. Under this condition, islets appear as slightly pink clusters, whereas acinar cells as dark irregular-shaped clusters (Figure 1A). A magnification of ~ 50X (combining the power of the objective and the eye piece) is recommended to offer the best way of visualizing islets and the pipet tip opening simultaneously for picking.</li>
		<li>Pick up islets with a P20 pipette tip while avoiding acinar clusters. Dispense islets-enriched fractions to a new 60 mm dish with RPMI complete media (Figure 1B).</li>
		<li>Repeat the hand-picking process twice more. Leave pure islets in a new 60 mm dish with 4 mL complete RPMI media (Figure 1C).</li>
	</ol>
	</li>
	<li>Gradient centrifugation:
	<ol>
		<li>Prepare a 15 mL centrifuge tube that is preloaded with 2 mL polysucrose and sodium diatrizoate at a density of 1.077 g/mL. Leave the tube on ice until use.</li>
		<li>Transfer the suspension from step 4.3 onto the top of the polysucrose and sodium diatrizoate solution with a Pasteur pipette. Do not disturb the bottom layer. Tissues from up to 10 newly born or 2 P17 pancreata can be loaded into each 15 mL tube.</li>
		<li>Spin the tube at ~ 600 x g in a swing rotor for 15 min at 4 &#176;C. Use brake-off settings.</li>
		<li>After centrifugation, transfer the media and interphase layers (note that under ideal operation conditions, the islets will be located in the interphase between the polysucrose and culture media after centrifugation) into a new 15 mL tube. Add 10 mL media, mix gently but thoroughly.</li>
		<li>Spin down the islet-enriched fraction at 300 x g for 5 min. Remove the wash media. Repeat the wash one more time with complete RPMI media. Resuspend pellets in to 4 mL media, which contains mostly islets and ducts (Figure 1D).</li>
		<li>Hand-pick the islets as outlined in section 5.1.</li>
	</ol>
	</li>
</ol>
6. GSIS Assays in Isolated Islets
<ol>
	<li>Incubate the islets from step 5.1.4 in complete RPMI media for 2 h in a 37 &#176;C tissue culture incubator.</li>
	<li>Use a pipette to remove RPMI under a dissecting microscope. Add 3 mL KRB solution with 2.8 mM glucose to the plate3. Swirl 10 times to wash the islets. Remove KRB solutions.
	<ol>
		<li>Repeat the washing process once. Incubate the islets with 3 mL KRB solution at 37 &#176;C for 1 h in an incubator.</li>
	</ol>
	</li>
	<li>Aliquot 1 mL KRB into each well of a 12-well plate. Pre-warm the KRB stock and plate to 37 &#176;C in an incubator.</li>
	<li>Wash the islets twice with pre-warmed KRB as in 6.2. Transfer 10 islets to each well of the pre-warmed plates. Incubate in a 37 &#176;C incubator.</li>
	<li>After 45 min, withdraw 50 &#181;L of supernatant. This contains the insulin solution secreted under basal glucose.</li>
	<li>Add 32 &#181;L 500 mM glucose. Swirl the plate 20 times to mix the solution. Incubate in a 37 &#176;C incubator. Swirl the plate 5 times once every 5 min.</li>
	<li>After 45 min, withdraw 50 &#181;L supernatant. This is the insulin secreted under high glucose.</li>
	<li>Transfer all islets to a 1.5 mL tube. Freeze in -20 &#176;C for 30 min. Thaw at room temperature for 5 min. Repeat the freezing and thawing process.</li>
	<li>Add 0.5 mL 70% ethanol with 20 mM HCl. Leave overnight. This is the insulin left in islets.</li>
	<li>Use conventional ELISA to assay insulin levels, described previously3.</li>
</ol>

<ol>
	<li>Matsumoto, S., 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+of+pancreatic+islet+cell+isolation+for+transplantation.">Improvement of pancreatic islet cell isolation for transplantation.</a> Proc (Bayl Univ Med Cent). 20 (4), 357-362 (2007).</li><li>Zmuda, E. J., Powell, C. A., Hai, T. <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+murine+islet+isolation+and+subcapsular+kidney+transplantation.">A method for murine islet isolation and subcapsular kidney transplantation.</a> J Vis Exp. (50), (2011).</li><li>Zhao, 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=Galphao+represses+insulin+secretion+by+reducing+vesicular+docking+in+pancreatic+beta-cells.">Galphao represses insulin secretion by reducing vesicular docking in pancreatic beta-cells.</a> Diabetes. 59 (10), 2522-2529 (2010).</li><li>Planas, 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=Gene+expression+profiles+for+the+human+pancreas+and+purified+islets+in+type+1+diabetes:+new+findings+at+clinical+onset+and+in+long-standing+diabetes.">Gene expression profiles for the human pancreas and purified islets in type 1 diabetes: new findings at clinical onset and in long-standing diabetes.</a> Clin Exp Immunol. 159 (1), 23-44 (2010).</li><li>Tonne, J. 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=Global+gene+expression+profiling+of+pancreatic+islets+in+mice+during+streptozotocin-induced+beta-cell+damage+and+pancreatic+Glp-1+gene+therapy.">Global gene expression profiling of pancreatic islets in mice during streptozotocin-induced beta-cell damage and pancreatic Glp-1 gene therapy.</a> Dis Model Mech. 6 (5), 1236-1245 (2013).</li><li>London, N. J., Swift, S. M., Clayton, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+culture+and+functional+evaluation+of+islets+of+Langerhans.">Isolation, culture and functional evaluation of islets of Langerhans.</a> Diabetes Metab. 24 (3), 200-207 (1998).</li><li>Rorsman, 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=Failure+of+glucose+to+elicit+a+normal+secretory+response+in+fetal+pancreatic+beta+cells+results+from+glucose+insensitivity+of+the+ATP-regulated+K++channels.">Failure of glucose to elicit a normal secretory response in fetal pancreatic beta cells results from glucose insensitivity of the ATP-regulated K+ channels.</a> Proc Natl Acad Sci U S A. 86 (12), 4505-4509 (1989).</li><li>Hellerstrom, C., Swenne, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+maturation+and+proliferation+of+fetal+pancreatic+beta-cells.">Functional maturation and proliferation of fetal pancreatic beta-cells.</a> Diabetes. 40 (Suppl 2), 89-93 (1991).</li><li>Blum, 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=Functional+beta-cell+maturation+is+marked+by+an+increased+glucose+threshold+and+by+expression+of+urocortin+3.">Functional beta-cell maturation is marked by an increased glucose threshold and by expression of urocortin 3.</a> Nat Biotechnol. 30 (3), 261-264 (2012).</li><li>Hegre, O. D., 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=Nonenzymic+in+vitro+isolation+of+perinatal+islets+of+Langerhans.">Nonenzymic in vitro isolation of perinatal islets of Langerhans.</a> In Vitro. 19 (8), 611-620 (1983).</li><li>Dolen&#353;ek, J., Rupnik, M. A., Sto&#382;er, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+similarities+and+differences+between+the+human+and+the+mouse+pancreas.">Structural similarities and differences between the human and the mouse pancreas.</a> Islets. 7 (1), e102445 (2015).</li><li>White, J., White, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Source Book of Enzymes, Source Book of Enzymes. , (1997).</li><li>Bock, T., Pakkenberg, B., Buschard, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+background+determines+the+size+and+structure+of+the+endocrine+pancreas.">Genetic background determines the size and structure of the endocrine pancreas.</a> Diabetes. 54 (1), 133-137 (2005).</li><li>Bouwens, L., Rooman, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+pancreatic+beta-cell+mass.">Regulation of pancreatic beta-cell mass.</a> Physiol Rev. 85 (4), 1255-1270 (2005).</li></ol>

The authors declare no competing financial interests for the described work.

Here, we provide a step-by-step protocol on islet isolation from pancreata that are too small for conventional perfusion. It is expected to yield islets ready for all islet-based studies such as beta-cell purification, gene expression analysis, islet beta-cell maturation, proliferation, cell stress responses, cell survival, metabolism, and functional GSIS maintenance, etc. This will be, to the best of our knowledge, the first detailed visual protocol that guides new researchers to perform islet isolation from ne...

Isolating pure pancreatic islets is essential for assaying glucose stimulated insulin secretion (GSIS) of beta cells and for islet transplantation from cadaveric donors 1-3. It is also necessary to establish endocrine gene expression in islet cells 4, 5. For this purpose, detailed protocols have been established to allow for isolation of pancreatic islets from large pancreata (6 and references therein). These methods are based on enzymatic perfusion to dissociate acinar from islet tissues, coupled with gradient separation and hand picking. Thus, islet isolation from large pancreas can be performed readily in most laboratories. On the other hand, no detailed step-by-step protocol exists to allow for the isolation of islets from pancreata that are too small to perfuse.
Studying gene expression and function of neonatal islets is important. Neonate islets have different properties from adults in insulin secretion and proliferation capability 7, 8. However, isolating islets from newly born animals, especially mice is challenging due to the small size of the newly born pancreas. The size prevents the usual perfusion process when collagenase is injected though the pancreatic duct. Indeed, several papers have presented studies along these lines, with enzyme or non-enzyme aided isolation procedures 7, 9, 10. However, detailed description of the islet isolation process with visual aid is lacking 7, 9, making it a challenge for most researchers to perform similar studies. 
We have explored several different conditions that yield high quality islets from neonatal mice. Here we present a protocol that is expected to help researchers learn the key details in the islet isolation process. This protocol is applicable to mouse pancreas up to two weeks of age, after which perfusion can be performed for routine islet isolation. Islets can be directly used for insulin secretion and gene expression assays.

<table><tbody><tr><td>Collagenase Type IV</td><td>Sigma Aldrich, St Louis, MO</td><td>C5138</td><td></td></tr><tr><td>1x HBSS with Ca&lt;sup&gt;2+&lt;/sup&gt;/Mg&lt;sup&gt;2+&lt;/sup&gt;</td><td>Mediatech/Cellgro, Manassas, VA</td><td>MT21020CV</td><td>If HBSS wihout Ca&lt;sup&gt;2+&lt;/sup&gt;/Mg&lt;sup&gt;2+&lt;/sup&gt; is obtained, CaCl&lt;sub&gt;2&lt;/sub&gt; and MgSO&lt;sub&gt;4&lt;/sub&gt; can be added to 1.26 and 0.5 mM, respectively.&amp;nbsp;</td></tr><tr><td>RPMI 1640 w/o glucose</td><td>Thermo Fisher Scientific/Life Technologies, Waltham, MA</td><td>11879-020</td><td>Glucose needs to be added to specific levels to not interfere with subsequent islet usage.&amp;nbsp;</td></tr><tr><td>Glucose</td><td>Sigma Aldrich, St Louis, MO</td><td>G-7021&amp;nbsp;</td><td></td></tr><tr><td>polysucrose and sodium diatrizoate solution</td><td>Sigma Aldrich, St Louis, MO</td><td>Histopaque-10771</td><td></td></tr><tr><td>Stereoscope</td><td>Carl-Zeiss, Oberkochen, Germany</td><td>Stemi2000</td><td></td></tr><tr><td>Stereoscope</td><td>Leica, Wetzlar, Germany</td><td>Leica M165</td><td></td></tr><tr><td>Microcentrifuge</td><td>Eppendorf, Hauppauge, NY</td><td>Centrifuge 5417C</td><td></td></tr><tr><td>Centrifuge</td><td>Eppendorf, Hauppauge, NY</td><td>Centrifuge 5810R</td><td></td></tr><tr><td>15-mL centrfuge tubes</td><td>VWR, Radnor, PA</td><td>89039-666</td><td></td></tr><tr><td>50-mL centrfuge tubes</td><td>VWR, Radnor, PA</td><td>89039-658</td><td></td></tr><tr><td>Precision balance</td><td>VWR, Radnor, PA</td><td>VWR-225AC</td><td></td></tr><tr><td>Microfuge tubes</td><td>VWR, Radnor, PA</td><td>87003-294</td><td></td></tr><tr><td>Pipetman P1000</td><td>Fisher Scientific,&amp;nbsp; Waltham, MA</td><td>F123602</td><td></td></tr><tr><td>Pipetman P20</td><td>Fisher Scientific,&amp;nbsp; Waltham, MA</td><td>F123600</td><td></td></tr><tr><td>100 x 15 mm dish</td><td>VWR, Radnor, PA</td><td>25384-088</td><td></td></tr><tr><td>60 x 15 mm dish</td><td>VWR, Radnor, PA</td><td>25384-168</td><td></td></tr><tr><td>12-well plates</td><td>VWR, Radnor, PA</td><td>665-180</td><td></td></tr><tr><td>Scissor</td><td>Fine Scientific Tools, Foster City, CA</td><td>14080-11</td><td></td></tr><tr><td>Tweezers</td><td>Fine Scientific Tools, Foster City, CA</td><td>5708-5</td><td></td></tr><tr><td>CD1 mice</td><td>Charles River Laboratories, Wilminton, MA&amp;nbsp;</td><td>CD-1</td><td></td></tr><tr><td>C57BL/6J</td><td>The Jackson laboratory, Farmington, CT&amp;nbsp;</td><td>C57BL/6J</td><td></td></tr><tr><td>B6CBAF1/J</td><td>The Jackson laboratory, Farmington, CT&amp;nbsp;</td><td>B6CBAF1/J</td><td></td></tr></tbody></table>

effective isolation of functional islets from neonatal mouse pancreas

Perfusion-based islet-isolation protocols from large mammalian pancreata are well established. Such protocols are readily conducted in many laboratories due to the large size of the pancreatic duct that allows for ready collagenase injection and subsequent tissue perfusion. In contrast, islet isolation from small pancreata, like that of neonatal mice, is challenging because perfusion is not readily achievable in the small pancreata. Here we describe a detailed simple procedure that recovers substantial numbers of islets from newly born mice with visual assistance. Freshly dissected whole pancreata were digested with 0.5 mg/mL collagenase IV dissolved in Hanks&#39; Balanced Salt Solution (HBSS) at 37 &#176;C, in microcentrifuge tubes. Tubes were tapped regularly to aid tissue dispersal. When most of the tissue was dispersed to small clusters around 1 mm, lysates were washed three to four times with culture media with 10% fetal bovine serum (FBS). Islet clusters, devoid of recognizable acinar tissues, can then be recovered under dissecting stereoscope. This method recovers 20 - 80 small- to large-sized islets per pancreas of newly born mouse. These islets are suitable for most conceivable downstream assays, including insulin secretion, gene expression, and culture. An example of insulin secretion assay is presented to validate the isolation process. The genetic background and degree of digestion are the largest factors determining the yield. Freshly made collagenase solution with high activity is preferred, as it aids in endocrine-exocrine isolation. The presence of cations [calcium (Ca2+) and magnesium (Mg2+)] in all solutions and fetal bovine serum in the wash/picking media are necessary for good yield of islets with proper integrity. A dissecting scope with good contrast and magnification will also help.

Under optimal conditions, the presented method can yield 20 - 80 islets from each small mouse pancreas. This number depends on the genetic background, age of mice, and the size of islets to be recovered. Among the commonly used, CD1 out-bred and C57BL/6J pure-bred mice produce less islets with smaller size than hybrids between CD1 and C57BL/6 or commercial B6CBAF1/J mice do. Direct hand picking generally gave a smaller number of islets, likely due to the exclusion of small islets that cou...

Watch this Scientific Journal Video about Effective Isolation of Functional Islets from Neonatal Mouse Pancreas at JoVE.com

Effective Isolation of Functional Islets from Neonatal Mouse Pancreas

We describe a protocol herein for isolating intact islets from neonatal mice. Pancreata were partially digested with collagenase, followed by washing and hand picking. 20 - 80 islet clusters can be obtained per pancreas from newly born mice, which are suitable for several islet studies.

Perfusion-based islet-isolation protocols from large mammalian pancreata are well established. Such protocols are readily conducted in many laboratories ...

effective-isolation-of-functional-islets-from-neonatal-mouse-pancreas

Universidad San Sebastian

Research

JoVE Journal

Developmental Biology

10.0K Views.  Vanderbilt University Medical School. We describe a protocol herein for isolating intact islets from neonatal mice. Pancreata were partially digested with collagenase, followed by washing and hand picking. 20 - 80 islet clusters can be obtained per pancreas from newly born mice, which are suitable for several islet studies.

Video: Effective Isolation of Functional Islets from Neonatal Mouse Pancreas

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 ...

Medicine

Isolation of Human Islets from Partially Pancreatectomized Patients

Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction 1 have been hampered by the limited availability of type 2 diabetic islets from organ donors2. Here we share our protocol for isolating islets from human pancreatic tissue obtained from type 2 diabetic and non-diabetic patients who have undergone partial pancreatectomy due to different pancreatic diseases (benign or malignant pancreatic tumors, chronic pancreatitis, and common bile duct or duodenal tumors). All patients involved gave their consent to this study, which had also been approved by the local ethics committee. The surgical specimens were immediately delivered to the pathologist who selected soft and healthy appearing pancreatic tissue for islet isolation, retaining the damaged tissue for diagnostic purposes. We found that to isolate more than 1,000 islets, we had to begin with at least 2 g of pancreatic tissue. Also essential to our protocol was to visibly distend the tissue when injecting the enzyme-containing media and subsequently mince it to aid digestion by increasing the surface area.
To extend the applicability of our protocol to include the occasional case in which a large amount (&gt;15g) of human pancreatic tissue is available , we used a Ricordi chamber (50 ml) to digest the tissue. During digestion, we manually shook the Ricordi chamber3 at an intensity that varied by specimen according to its level of tissue fibrosis. A discontinous Ficoll gradient was then used to separate the islets from acinar tissue. We noted that the tissue pellet should be small enough to be homogenously resuspended in Ficoll medium with a density of 1.125 g/ml. After isolation, we cultured the islets under stress free conditions (no shaking or rotation) with 5% CO2 at 37 &deg;C for at least 48 h in order to facilitate their functional recovery. Widespread application of our protocol and its future improvement could enable the timely harvesting of large quantities of human islets from diabetic and clinically matched non-diabetic subjects, greatly advancing type 2 diabetes research.

The supply of type 2 diabetic islets for research is insufficient. Here we share our protocol for isolating islets from patients undergoing partial pancreatectomy. This approach represents a unique venue for obtaining islets from type 2 diabetic and clinically matched non-diabetic subjects in adequate numbers for basic and clinical studies.

Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction 1 have been hampered by the limited availability of type 2 ...

Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice

Islet transplantation has been clinically proven to be effective at treating type 1 diabetes. However, the current intrahepatic transplantation strategy may incur acute whole blood reactions and result in poor islet engraftment. Here, we report a robust protocol for the transplantation of islets at the extrahepatic transplantation site-the epididymal fat pad (EFP)-in a diabetic mouse model. A protocol to isolate and purify islets at high yields from C57BL/6J mice is described, as well as a transplantation method performed by seeding islets onto a decellularized scaffold (DCS) and implanting them at the EFP site in syngeneic C57BL/6J mice rendered diabetic by streptozotocin. The DCS graft containing 500 islets reversed the hyperglycemic condition within 10 days, while the free islets without DCS required at least 30 days. The normoglycemia was maintained for up to 3 months until the graft was explanted. In conclusion, DCS enhanced the engraftment of islets into the extrahepatic site of the EFP, which could easily be retrieved and might provide a reproducible and useful platform for investigating the scaffold materials, as well as other transplantation parameters required for a successful islet engraftment.

This protocol demonstrates murine islet isolation and seeding onto a decellularized scaffold. Scaffold-supported islets were transplanted into the epididymal fat pad of streptozotocin (STZ)-induced diabetic mice. Islets survived at the transplantation site and reversed the hyperglycemic condition.

Islet transplantation has been clinically proven to be effective at treating type 1 diabetes. However, the current intrahepatic transplantation strategy ...

Bioengineering

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, the role of beta-cell dysfunction in type 2 diabetes has been clearly established 2. Research progress has required methods for the isolation of pancreatic islets. The protocol of the islet isolation presented here shares many common steps with protocols from other groups, with some modifications to improve the yield and quality of isolated islets from both the wild type and diabetic Leprdb (db/db) mice. A live-cell 2-photon imaging method is then presented that can be used to investigate the control of insulin secretion within islets.

Leprdb Mouse Model of Type 2 Diabetes: Pancreatic Islet Isolation and Live-cell 2-Photon Imaging Of Intact Islets

We present here a protocol for the isolation of islets from the mouse model of type 2 diabetes, Leprdb and details of a live-cell assay for measurement of insulin secretion from intact islets that utilizes 2 photon microscopy.

Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 1. During the past 2 decades, ...

A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic &#946; cells which will lead to the development of type 2 diabetes mellitus (T2DM). Although the mechanisms for the chemical-induced &#946; cell damage were unclear and likely to be complex, one recurring finding is that these chemicals induce oxidative stress leading to the generation of excessive reactive oxygen species (ROS) which induce damage to the &#946; cell. To identify potential diabetogenic environmental chemicals, we isolated pancreatic islet cells from C57BL/6 mice and cultured islet cells in 96-well cell culture plates; then, the islet cells were dosed with chemicals and the ROS generation was detected by 2',7'-dichlorofluorescein (DCFH-DA) fluorescent dye. Using this method, we found that bisphenol A (BPA), Benzo[a]pyrene (BaP), and polychlorinated biphenyls (PCBs), could induce high levels of ROS, suggesting that they may potentially induce damage in islet cells. This method should be useful for screening diabetogenic xenobiotics. In addition, the cultured islet cells may also be adapted for in vitro analysis of chemical-induced toxicity in pancreatic cells.

Here we present a protocol to isolate mouse pancreatic islet cells for screening the ROS inductions by the xenobiotics in order to identify the potential diabetogenic xenobiotic chemicals.

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic &#946; cells which will lead to ...

Immunology and Infection

A High-content In Vitro Pancreatic Islet &#946;-cell Replication Discovery Platform

Loss of insulin-producing &#946;-cells is a central feature of diabetes. While a variety of potential replacement therapies are being explored, expansion of endogenous insulin-producing pancreatic islet &#946;-cells remains an attractive strategy. &#946;-cells have limited spontaneous regenerative activity; consequently, a crucial research effort is to develop a precise understanding of the molecular pathways that restrain &#946;-cell growth and to identify drugs capable of overcoming these restraints. Herein an automated high-content image-based primary-cell screening method to identify &#946;-cell replication-promoting small molecules is presented. Several, limitations of prior methodologies are surmounted. First, use of primary islet cells rather than an immortalized cell-line maximizes retention of in vivo growth restraints. Second, use of mixed-composition islet-cell cultures rather than a &#946;-cell-line allows identification of both lineage-restricted and general growth stimulators. Third, the technique makes practical the use of primary islets, a limiting resource, through use of a 384-well format. Fourth, detrimental experimental variability associated with erratic islet culture quality is overcome through optimization of isolation, dispersion, plating and culture parameters. Fifth, the difficulties of accurately and consistently measuring the low basal replication rate of islet endocrine-cells are surmounted with optimized immunostaining parameters, automated data acquisition and data analysis; automation simultaneously enhances throughput and limits experimenter bias. Notable limitations of this assay are the use of dispersed islet cultures which disrupts islet architecture, the use of rodent rather than human islets and the inherent limitations of throughput and cost associated with the use of primary cells. Importantly, the strategy is easily adapted for human islet replication studies. This assay is well suited for investigating the mitogenic effect of substances on &#946;-cells and the molecular mechanisms that regulate &#946;-cell growth.

A High-content In Vitro Pancreatic Islet &#946;-cell Replication Discovery Platform

Critical challenges for the diabetes research field are to understand the molecular mechanisms that regulate islet &#946;-cell replication and to develop methods for stimulating &#946;-cell regeneration. Herein a high-content screening method to identify and assess the &#946;-cell replication-promoting activity of small molecules is presented.

Loss of insulin-producing &#946;-cells is a central feature of diabetes. While a variety of potential replacement therapies are being explored, expansion ...

Mouse Islet of Langerhans Isolation using a Combination of Purified Collagenase and Neutral Protease

The interrogation of beta cell gene expression and function in vitro has squarely shifted over the years from the study of rodent tumorigenic cell lines to the study of isolated rodent islets. Primary islets offer the distinct advantage that they more faithfully reflect the biology of intracellular signaling pathways and secretory responses. Whereas the method of islet isolation using tissue dissociating enzyme (TDE) preparations has been well established in many laboratories1-4, variations in the consistency of islet yield and quality from any given rodent strain limit the extent and feasibility of primary islet studies. These variations often occur as a result of the crude partially purified TDEs used in the islet isolation procedure; TDEs frequently exhibit lot-to-lot variations in activity and often require adjustments to the dose of enzyme used. A small number of reports have used purified TDEs for rodent cell isolations5, 6, but the practice is not widespread despite the routine use and advantages of purified TDEs for human islet isolations. In collaboration with VitaCyte, LLC (Indianapolis, IN), we developed a modified mouse islet isolation protocol based on that described by Gotoh7, 8, in which the TDEs are perfused directly into the pancreatic duct of mice, followed by crude tissue fractionation through a Histopaque gradient9, and isolation of purified islets. A significant difference in our protocol is the use of purified collagenase (CIzyme MA) and neutral protease (CIzyme BP) combination. The collagenase was characterized by the use of a6 fluorescence collagen degrading activity (CDA) assay that utilized fluorescently labeled soluble calf skin fibrils as substrate6. This substrate is more predictive of the kinetics of collagen degradation in the tissue matrix because it relies on native collagen as the substrate. The protease was characterized with a sensitive fluorescent kinetic assay10. Utilizing these improved assays along with more traditional biochemical analysis enable the TDE to be manufactured more consistently, leading to improved performance consistency between lots. The protocol described in here was optimized for maximal islet yield and optimal islet morphology using C57BL/6 mice. During the development of this protocol, several combinations of collagenase and neutral proteases were evaluated at different concentrations, and the final ratio of collagenase:neutral protease of 35:10 represents enzyme performance comparable to Sigma Type XI. Because significant variability in average islet yields from different strains of rats and mice have been reported, additional modifications of the TDE composition should be made to improve the yield and quality of islets recovered from different species and strains.

A detailed description of mouse islet isolation is described using the technique of in situ pancreatic ductal cannulation and perfusion of a combination of purified collagenase and neutral protease.

The interrogation of beta cell gene expression and function in vitro has squarely shifted over the years from the study of rodent tumorigenic cell lines ...

Biology

Intraportal Transplantation of Pancreatic Islets in Mouse Model

Pancreatic islet transplantation to reduce hyperglycemia is highly successful in rodents with chemically-induced diabetes. The most common transplantation site in experimental islet transplantation is the kidney capsule. However, as less is known about the interaction of pancreatic islets with blood constituents, it also makes sense to utilize the portal vein approach in experimental islet transplantation.
This protocol demonstrates an intraportal islet transplantation technique in NMRI nude mice. Streptozotocin (180 mg/kg) is injected intraperitoneally to induce hyperglycemia in recipient mice. They are considered as diabetic at a non-fasting blood glucose level greater than 20 mmol/L. One day prior to transplantation, mouse pancreatic islets are isolated from the donor pancreas by collagenase digestion; a minimum of 350 islets are utilized per diabetic recipient. Depending upon the islet isolation yield, two or more donor mice are utilized per recipient. After overnight culture at 37 &#176;C, islets are administered into the recipient liver via the portal vein. After surgery, the mice are protected in red Makrolon houses and observed until are awake. This protocol maintains glycemic control for 120 days in syngeneic mice and 15 days in allogeneic mice.

Pancreatic islet transplantation is a way to achieve normoglycemia in type 1 diabetes. This article focuses on the transplantation technique through the intraportal route to maintain normal glucose levels in diabetic mice.

Pancreatic islet transplantation to reduce hyperglycemia is highly successful in rodents with chemically-induced diabetes. The most common transplantation ...

A Method for Mouse Pancreatic Islet Isolation and Intracellular cAMP Determination

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing prevalence of diabetes, both immune-mediated type 1 and obesity-linked type 2, studies aimed at delineating diabetes pathophysiology and therapeutic mechanisms are of critical importance. The &#946;-cells of the pancreatic islets of Langerhans are responsible for appropriately secreting insulin in response to elevated blood glucose concentrations. In addition to glucose and other nutrients, the &#946;-cells are also stimulated by specific hormones, termed incretins, which are secreted from the gut in response to a meal and act on &#946;-cell receptors that increase the production of intracellular cyclic adenosine monophosphate (cAMP). Decreased &#946;-cell function, mass, and incretin responsiveness are well-understood to contribute to the pathophysiology of type 2 diabetes, and are also being increasingly linked with type 1 diabetes. The present mouse islet isolation and cAMP determination protocol can be a tool to help delineate mechanisms promoting disease progression and therapeutic interventions, particularly those that are mediated by the incretin receptors or related receptors that act through modulation of intracellular cAMP production. While only cAMP measurements will be described, the described islet isolation protocol creates a clean preparation that also allows for many other downstream applications, including glucose stimulated insulin secretion, [3H]-thymidine incorporation, protein abundance, and mRNA expression.

Assaying in vitro &#946;-cell function using isolated mouse islets of Langerhans is an important component in the study of diabetes pathophysiology and therapeutics. While many&#160;downstream applications are available, this protocol specifically describes the measurement of intracellular cyclic adenosine monophosphate (cAMP) as an essential parameter determining &#946;-cell function.

Uncontrolled glycemia is a hallmark of diabetes mellitus and promotes morbidities like neuropathy, nephropathy, and retinopathy. With the increasing ...

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.

Effective Isolation of Functional Islets from Neonatal Mouse Pancreas

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