Name: scaffold-supported transplantation of islets in the epididymal fat pad of diabetic mice
Uploaded: 2017-07-23T13:00:00
Description: Watch this Scientific Journal Video about Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice at JoVE.com

The authors would like to thank Wei Zhang from Guanhao Biotech for providing the decellularized scaffolds. We thank Xiao-hong Peng for the helpful discussions. This research was financially supported by the National Natural Science Foundation of China (Project No.31322021).

All experiments were approved by Peking University Institutional Animal Care and Use Committee (IACUC, IACUC no. COE-LuoY-1).
1. Islet Isolation
<ol>
	<li>Preparation of reagents and equipment.
	<ol>
		<li>Reconstitute collagenase P powder (2 U/mg) in HBSS to make a 5 mg/mL solution and filter it through a 0.22 &#181;m filter to remove the bacteria. Prepare 0.6 mL-aliquot solutions of collagenase P in 15-mL conical tubes and store at -20 &#176;C. 
		NOTE: During use, ea...

<ol>
	<li>Shapiro, A. 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=Islet+transplantation+in+seven+patients+with+type+1+diabetes+mellitus+using+a+glucocorticoid-free+immunosuppressive+regimen.">Islet transplantation in seven patients with type 1 diabetes mellitus using a glucocorticoid-free immunosuppressive regimen.</a> N Engl J Med. 343, 230-238 (2000).</li><li>Shapiro, A. M. J., 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=International+Trial+of+the+Edmonton+Protocol+for+Islet+Transplantation.">International Trial of the Edmonton Protocol for Islet Transplantation.</a> N Engl J Med. 355, 1318-1330 (2006).</li><li>Ryan, E. 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=Five-year+follow-up+after+clinical+islet+transplantation.">Five-year follow-up after clinical islet transplantation.</a> Diabetes. 54, 2060-2069 (2005).</li><li>Merani, S., Toso, C., Emamaullee, J., Shapiro, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimal+implantation+site+for+pancreatic+islet+transplantation.">Optimal implantation site for pancreatic islet transplantation.</a> Br J Surg. 95, 1449-1461 (2008).</li><li>Schmidt, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pancreatic+islets+find+a+new+transplant+home+in+the+omentum.">Pancreatic islets find a new transplant home in the omentum.</a> Nat Biotechnol. 35 (1), (2017).</li><li>Dufour, 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=Development+of+an+ectopic+site+for+islet+transplantation,+using+biodegradable+scaffolds.">Development of an ectopic site for islet transplantation, using biodegradable scaffolds.</a> Tissue Eng. 11, 1323-1331 (2005).</li><li>Weaver, J. 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=Controlled+Release+of+Dexamethasone+from+Organosilicone+Constructs+for+Local+Modulation+of+Inflammation+in+Islet+Transplantation.">Controlled Release of Dexamethasone from Organosilicone Constructs for Local Modulation of Inflammation in Islet Transplantation.</a> Tissue Eng Part A. 21, 2250-2261 (2015).</li><li>Wang, K., 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=From+Micro+to+Macro:+The+Hierarchical+Design+in+a+Micropatterned+Scaffold+for+Cell+Assembling+and+Transplantation.">From Micro to Macro: The Hierarchical Design in a Micropatterned Scaffold for Cell Assembling and Transplantation.</a> Adv Mater. 29, (2017).</li><li>Blomeier, H., 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=Polymer+Scaffolds+as+Synthetic+Microenvironments+for+Extrahepatic+Islet+Transplantation.">Polymer Scaffolds as Synthetic Microenvironments for Extrahepatic Islet Transplantation.</a> Transplantation. 82, 452-459 (2006).</li><li>Gibly, R. F., 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=Extrahepatic+islet+transplantation+with+microporous+polymer+scaffolds+in+syngeneic+mouse+and+allogeneic+porcine+models.">Extrahepatic islet transplantation with microporous polymer scaffolds in syngeneic mouse and allogeneic porcine models.</a> Biomaterials. 32, 9677-9684 (2011).</li><li>Moskalewski, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+Culture+of+the+Islets+of+Langerhans+of+the+Guinea+Pig.">Isolation and Culture of the Islets of Langerhans of the Guinea Pig.</a> Gen Comp Endocrinol. 5, 342-353 (1965).</li><li>Lacy, P. E., Kostianovsky, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+the+isolation+of+intact+islets+of+Langerhans+from+the+rat+pancreas.">Method for the isolation of intact islets of Langerhans from the rat pancreas.</a> Diabetes. 16, 35-39 (1967).</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>Li, D. S., Yuan, Y. H., Tu, H. J., Liang, Q. L., Dai, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+protocol+for+islet+isolation+from+mouse+pancreas.">A protocol for islet isolation from mouse pancreas.</a> Nat Protoc. 4, 1649-1652 (2009).</li><li>Stull, N. D., Breite, A., McCarthy, R., Tersey, S. A., Mirmira, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+Islet+of+Langerhans+Isolation+using+a+Combination+of+Purified+Collagenase+and+Neutral+Protease.">Mouse Islet of Langerhans Isolation using a Combination of Purified Collagenase and Neutral Protease.</a> J Vis Exp. (67), (2012).</li><li>Sakata, N., Yoshimatsu, G., Tsuchiya, H., Egawa, S., Unno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+diabetes+mellitus+for+islet+transplantation.">Animal models of diabetes mellitus for islet transplantation.</a> Exp Diabetes Res. , 256707 (2012).</li><li>Schmidt, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pancreatic+islets+find+a+new+transplant+home+in+the+omentum.">Pancreatic islets find a new transplant home in the omentum.</a> Nat Biotech. 35, 8-8 (2017).</li><li>Londono, R., Badylak, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biologic+scaffolds+for+regenerative+medicine:+mechanisms+of+in+vivo+remodeling.">Biologic scaffolds for regenerative medicine: mechanisms of in vivo remodeling.</a> Ann Biomed Eng. 43, 577-592 (2015).</li></ol>

Pancreas perfusion and digestion time are two key parameters that affect islet yield and quality. Moskalewski first reported the use of a crude collagenase mixture to digest minced guinea pig pancreas11. Lacy et al. reported the injection of enzymes into the duct system to perfuse the pancreas, which greatly increased the islet yield12. The ductal perfusion of enzyme allows for the maximal exposure of pancreatic surface area to the enzyme, resulting in a more homog...

Type 1 diabetes mellitus (T1D) is an autoimmune endocrine disorder in which islet cells are ablated by the immune system, rendering patients dependent upon the injection of exogenous insulin for their whole lives. The Edmonton protocol represents a milestone in clinical studies of islet transplantation; islets were infused through the portal vein and transplanted at the intrahepatic site1. However, two main obstacles-inadequate sources of donor islets and poor islet engraftment-prevent the wide success of the islet transplantation2. Usually, islets need to be collected from three cadaveric donors to reverse the hyperglycemic condition of one patient; this is due to the low yield of islet isolation procedures and the islet loss after transplantation. In particular, although the post-transplantation islets were bathed in oxygen-rich blood, the direct contact with blood often evoked the instant blood-mediated inflammatory reaction (IBMIR), which could cause the acute loss of the islets. In the long term, it is thought that the gradual loss of islets in patients accounted for the drop of diabetes reversal rates in the clinical groups, which could reach 90% in the first year and declined to 30% and 10% by 2 and 5 years post-transplantation, respectively3.
Islet transplantation at extrahepatic sites has been an attractive strategy to reduce the direct contact of islets with blood while confining the transplants to more definable locations compared to intrahepatic infusion. Studies have been carried out in the kidney capsule, eye, muscle, fat pads, and subcutaneous spaces over the past years, showing that islets at these sites are able to survive and function to restore normoglycemia4. In addition, the islets at these sites are retrievable, making it possible for biopsy or even for further replacement procedures. Extrahepatic sites therefore demonstrate great potential for clinical transplantation5.
Biomaterial-based scaffolds have been intensively investigated for cell transplantation and tissue engineering. Three-dimensional (3D) scaffolds usually contain porous structures and can serve as cellular templates to generate spatial structure/organization of cells or as reservoirs to provide the controlled release of bioactive cues. Scaffolds have also been fabricated from polymeric materials, such as poly(glycolide-L-lactide)6, poly(dimethylsiloxane)7, and thermoplastic poly(urethane)8, to transplant islets in the EFP. Compared to the direct transplantation of islets, the use of scaffolds was found to reduce islet loss by preventing the leakage of islets into the intraperitoneal cavity9,10, providing mechanical protection and modulating the local inflammatory reaction. The scaffolds thus may be developed to promote islet engraftment at the transplantation sites7.
In this study, we intend to demonstrate a paradigm of islet transplantation in the EFP, carried out in mice models using a DCS. Scaffolds derived from extracellular matrices have attracted great interest in recent years due to the superior biocompatibility and more natural porous structures compared to synthetic products. Here, we describe a robust isolation protocol to obtain pancreatic islets at high yields from C57BL/6J mice. DCSs processed from the bovine pericardium were then seeded with islets, and the grafts were transplanted to the EFP in syngeneic diabetic models. Normoglycemia in mice was achieved within 10 days and was maintained for up to 100 days, until the removal of the grafts.

<table border="0" cellpadding="0" cellspacing="0" width="364">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Dissecting scissor</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Forceps</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">0.5 mm diameter wire mesh</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">70 &#956;m cell strainer</td>
			<td style="width:63px;">Falcon</td>
			<td style="width:91px;">352350</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Artery hemostatic clamp</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Microscopic hemostatic clamp</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Hemostatic forceps</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Absorbable 6-0 PGLA sutures&#160;</td>
			<td style="width:63px;">JINHUAN</td>
			<td style="width:91px;"></td>
			<td style="width:87px;">With needle</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Wound clip</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Cotton swab</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Gauze</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Sterile drapes</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">10mL syringe</td>
			<td style="width:63px;">JINGHUAN</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">1 mL syringe</td>
			<td style="width:63px;">JINGHUAN</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">27G intravenous needle</td>
			<td style="width:63px;">JINGHUAN</td>
			<td style="width:91px;">0.45x15 RWSB</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">1.5 mL Eppendorf tube</td>
			<td style="width:63px;">Axygen</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">15mL conical tube</td>
			<td style="width:63px;">Corning</td>
			<td style="width:91px;">430791</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">50mL conical tube</td>
			<td style="width:63px;">Corning</td>
			<td style="width:91px;">430829</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">35mm Non-treated&#160; Peri-dishes</td>
			<td style="width:63px;">Corning</td>
			<td style="width:91px;">430588</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Transwell</td>
			<td style="width:63px;">Corning</td>
			<td style="width:91px;">3422</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">0.22 &#956;m filter</td>
			<td style="width:63px;">Pall</td>
			<td style="width:91px;">PN4612</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">10 mL serological pipet</td>
			<td style="width:63px;">Corning</td>
			<td style="width:91px;">4488</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Pipet filler S1</td>
			<td style="width:63px;">Thermo Scientific</td>
			<td style="width:91px;">9501</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:127px;">Pipette (2-20&#956;L)</td>
			<td style="width:63px;">Axygen</td>
			<td style="width:91px;">AP-20</td>
			<td style="width:87px;">AXYPETTM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Dissecting microscope</td>
			<td style="width:63px;">Olympus</td>
			<td style="width:91px;">SZ61</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Centrifuge</td>
			<td style="width:63px;">Eppendorf</td>
			<td style="width:91px;">5810R</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Hank&#8217;s balanced salt solution&#160;</td>
			<td style="width:63px;">Gibco</td>
			<td style="width:91px;">C14175500CP</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Collagenase P</td>
			<td style="width:63px;">Roche</td>
			<td style="width:91px;">COLLP-RO</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Histopaque 1077</td>
			<td style="width:63px;">Sigma</td>
			<td style="width:91px;">10771</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">RPMI 1640</td>
			<td style="width:63px;">Gibco</td>
			<td style="width:91px;">11879-20</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">FBS</td>
			<td style="width:63px;">Gibco</td>
			<td style="width:91px;">16000-044</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">D-glucose</td>
			<td style="width:63px;">Gibco</td>
			<td style="width:91px;">A24940-01</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Glucose meter</td>
			<td style="width:63px;">Roche</td>
			<td style="width:91px;"></td>
			<td style="width:87px;">ACCU-CHEK</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Penicillin-streptomycin</td>
			<td style="width:63px;">Gibco</td>
			<td style="width:91px;">15140-122</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:127px;">Streptozotocin</td>
			<td style="width:63px;">Sigma</td>
			<td style="width:91px;">V900890</td>
			<td style="width:87px;">VetecTM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Chloral hydrate</td>
			<td style="width:63px;">J&#38;K</td>
			<td style="width:91px;">C0073</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Sodium citrate</td>
			<td style="width:63px;">Sigma</td>
			<td style="width:91px;">71497</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:127px;">Citric acid</td>
			<td style="width:63px;">Sigma</td>
			<td style="width:91px;">C2404</td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">Iodophors</td>
			<td style="width:63px;">Ningbo Medical</td>
			<td style="width:91px;"></td>
			<td style="width:87px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:127px;">C57BL/6J, 10-12 weeks old</td>
			<td style="width:63px;">VitalRiver</td>
			<td style="width:91px;"></td>
			<td style="width:87px;">Beijing, China</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:127px;">Decellularized scaffold</td>
			<td style="width:63px;">Guanhao Biotec</td>
			<td style="width:91px;">131102</td>
			<td style="width:87px;">Guangzhou, China</td>
		</tr>
	</tbody>
</table>

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.

Our clamping method, performed using a microscopic hemostatic clamp, is straightforward and time-saving compared with the suture ligation technique. It took roughly 4 h to isolate and purify about 1,200 islets from 6 mice. The freshly isolated islets typically had a rough periphery under an optical microscope (Figure 3A). Once the islets recovered from the isolation process, they looked bright and tight and acquired a smooth surface. However, the stressful is...

Watch this Scientific Journal Video about Scaffold-supported Transplantation of Islets in the Epididymal Fat Pad of Diabetic Mice at JoVE.com

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

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 ...

Hello everyone, I'm Kai Wang from Department of Biomedical Engineering in Peking University at Dr.Lowe's laboratory. Currently, individuals with type one diabetes are treated mainly with insulin injections which do not perfectly simulate the insulin secretion from islets. Replacing the lost islets by islet transportation can show you stable blood glucose control without severe fluctuation.However, the requirement of producing large numbers of high quality islets and the poor engraftment efficiency compromised the widespread clinical use. Today, I'm gonna show you the process of islet isolation and the transplanting scaffold-supported islets into the epididymal fat pad of diabetic mice. These steps require good knowledge of tissue structures and the skilled hands to perform the surgery.Spray the whole body with ethanol. Make a V-incision starting from the genital area. Remove the bowel through the right side of the mouse.Clamp the portal vein and the bile duct with hemostatic clamp. Grip the duodenum carefully with forceps and pull the duodenum until the bile duct is taught. Insert the intravenous needle into the common bile duct through the ampulla.Clamp the duct segment containing the needle using an ultra hemostatic clamp. Dispense the collagenic solution at a slow and constant rate. After complete inflation of the pancreas, push the bowel through the left side of the mouse.You can see the pancreatic duct is fully inflated. Remove the pancreas by starting end of descending colon. Use the forceps to lift the bowel and to separate it from the pancreas with another forceps.Continue to remove the pancreas until it is unattached from the top of the stomach. Finally, lift the pancreas out of the abdomen and cut it free from the remaining spleen. Place a pancreas in the conical tube and deliver on ice.Incubate the perfused pancreas. Terminate the digestion by adding neutralization solutions. Dissociate the two soup by shaking the tubes vigorously.Filter the digestive tissue samples through the wire mesh. Collect the islet suspensions into a new conical tube. Centrifuge the tubes.Pour off the supernatant carefully without disturbing the tissue palettes. Resuspend the palettes with Histopaque by pipetting the suspension up and down for a few times. Slowly pipette HBSS down the side of the tube to the top of the Histopaque solutions.The two solutions should be well separated layers with a sharp interface. Centrifuge the suspension for 20 minutes. Most of the islets migrate to the interface of the Histopaque and HBSS layers.Remove the entire supernatant solutions, and pass the solutions through an inverted strainer. The islets will be retained by the strainer. Dip the surface retaining the islets into the solution and gently shake to release the islets.Hand pick the isolated islets under the microscope. Collect islets into a new culture dish. If the tissue surrounding the duct begins to inflate, it means that the needle passes through the wall of the bile duct.It is necessary to reposition the needle and try cannulating the bile duct again. As the solutions fill up the pancreas, the tissue near the duodenum inflates first, followed by the region near the pancreatic tail. If the duodenum begins to inflate as shown here with blue stain, adjust the artery clamp and reclamp the bile duct.Place mouse in supine position. Shave the abdomen. Then swab with iodophors to sterilize the skin.Cover the mouse with a sterile drape. Make a small incision through the peritoneal wall in the middle close to the genital area. Gently grab and pull out the epididymal fat pad from the abdominal cavity.Spread the fat pad on a wetted gauze. Place a scaffold containing islets on the fat pad and fold the fat pad to wrap the transplant. Suture the fat pad to secure the islets encapsulated in the fat pad.Gently place the fat pad back into the abdominal cavity. Close the mouse by suturing the peritoneal wall. Clamp the dermal layer with wound clips.Inject appropriate doses of pain killers and antibiotics subcutaneously. The fresh isolated islets typically had a rough periphery under optical microscope. Once islets recovered from the isolation process, they looked bright, tight, and acquired a smooth surface.The calculated mean islet diameter was about 130 micrometers. The decelerized scaffolds are mechanically robust enough to be handled by tweezer. The porous scaffold-supported islets were then transferred onto the surface of the spread fat pad, and then encapsulated by the fat pad.In a syngeneic transplantation model, typically 500 islets reverse hypoglycemia within 10 days. Normal glycemia was maintained before about 100 days till the retrieval of the grafts. The histological studies show that the islets were revascularized and surrounded by the fat pad tissue and the scaffold.After watching this video, with practice, you should learn the key steps involved in the islet's isolation and transportation. Firstly, cannulating the common bile duct and dilating the pancreas is the most difficult part of this protocol. Secondly, encapsulate the islet-laden scaffold with a fat pad completely, as the incomplete encapsulation might lead to the failure of the transplantation.

scaffold-supported-transplantation-islets-epididymal-fat-pad-diabetic

Research

JoVE Journal

Bioengineering

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Gene Transfection toward Spheroid Cells on Micropatterned Culture Plates for Genetically-modified Cell Transplantation

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. The cell spheroids are prepared in a culture system on micropatterned plates coated with a thermosensitive polymer. A number of spheroids are formed on the plates, corresponding to the cell adhesion areas of 100 &#181;m diameter that are regularly arrayed in a two-dimensional manner, surrounded by non-adhesive areas that are coated by a polyethylene glycol (PEG) matrix. The spheroids can be easily recovered as a liquid suspension by lowering the temperature of the plates, and their structure is well maintained by passing them through injection needles with a sufficiently large caliber (over 27 G). Genetic modification is achieved by gene transfection using the original non-viral gene carrier, polyplex nanomicelle, which is capable of introducing genes into cells without disrupting the spheroid structure. For primary hepatocyte spheroids transfected with a luciferase-expressing gene, the luciferase is sustainably obtained in transplanted animals, along with preserved hepatocyte function, as indicated by albumin expression. This system can be applied to a variety of cell types including mesenchymal stem cells.

This protocol describes a cell transplantation system using genetically modified, injectable spheroids. Cell spheroids are cultured on micropatterned culture plates and recovered after gene introduction using polyplex nanomicelles. This system facilitates prolonged transgene expression from the transplanted cells in host animals while maintaining the innate function of the cells.

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. ...

Procedure for Decellularization of Rat Livers in an Oscillating-pressure Perfusion Device

Decellularization and recellularization of parenchymal organs may enable the generation of functional organs in vitro, and several protocols for rodent liver decellularization have already been published. We aimed to improve the decellularization process by construction of a proprietary perfusion device enabling selective perfusion via the portal vein and/or the hepatic artery. Furthermore, we sought to perform perfusion under oscillating surrounding pressure conditions to improve the homogeneity of decellularization. The homogeneity of perfusion decellularization has been an underestimated factor to date. During decellularization, areas within the organ that are poorly perfused may still contain cells, whereas the extracellular matrix (ECM) in well-perfused areas may already be affected by alkaline detergents. Oscillating pressure changes can mimic the intraabdominal pressure changes that occur during respiration to optimize microperfusion inside the liver. In the study presented here, decellularized rat liver matrices were analyzed by histological staining, DNA content analysis and corrosion casting. Perfusion via the hepatic artery showed more homogenous results than portal venous perfusion did. The application of oscillating pressure conditions improved the effectiveness of perfusion decellularization. Livers perfused via the hepatic artery and under oscillating pressure conditions showed the best results. The presented techniques for liver harvesting, cannulation and perfusion using our proprietary device enable sophisticated perfusion set-ups to improve decellularization and recellularization experiments in rat livers.

The presented techniques for liver harvesting, cannulation and perfusion using our proprietary device enable sophisticated perfusion set-ups to improve decellularization and recellularization experiments in rat livers.

Decellularization and recellularization of parenchymal organs may enable the generation of functional organs in vitro, and several protocols for rodent ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

An Ultrasonic Tool for Nerve Conduction Block in Diabetic Rat Models

Nerve conduction block with a high intensity-focused ultrasound (HIFU) transducer has been performed in normal and diabetic animal models recently. HIFU can reversibly block the conduction of peripheral nerves without damaging the nerves while using an appropriate ultrasonic parameter. Temporary and partial block of the action potentials of nerves shows that HIFU has the potential to be a useful clinical treatment for pain relief. This work demonstrates the procedures for suppressing the action potentials of neuropathic nerves in diabetic rats in vivo using an HIFU transducer. The first step is to generate adult male diabetic neuropathic rats by streptozotocin (STZ) injection. The second step is to evaluate the peripheral diabetic neuropathy in STZ-induced diabetic rats by an electronic von Frey probe and a hot plate. The final step is to record in vivo extracellular action potentials of the nerve exposed to HIFU sonication. The method showed here may benefit the study of ultrasound analgesic applications.

This work presents the methodology of applying high intensity-focused ultrasound to block the action potentials of diabetic neuropathic nerves.

Nerve conduction block with a high intensity-focused ultrasound (HIFU) transducer has been performed in normal and diabetic animal models recently. HIFU ...

Surface Engineering of Pancreatic Islets with a Heparinized StarPEG Nanocoating

Cell surface engineering can protect implanted cells from host immune attack. It can also reshape cellular landscape to improve graft function and survival post-transplantation. This protocol aims to achieve surface engineering of pancreatic islets using an ultrathin heparin-incorporated starPEG (Hep-PEG) nanocoating. To generate the Hep-PEG nanocoating for pancreatic islet surface engineering, heparin succinimidyl succinate (Heparin-NHS) was first synthesized by modification of its carboxylate groups using N-(3-dimethylamino propyl)-N'-ethyl carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The Hep-PEG mixture was then formed by crosslinking of the amino end-functionalized eight-armed starPEG (starPEG-(NH2)8) and Heparin-NHS. For islet surface coating, mouse islets were isolated via collagenase digestion and gradient purification using Histopaque. Isolated islets were then treated with ice cold Hep-PEG solution for 10 min to allow covalent binding between NHS and the amine groups of islet cell membrane. Nanocoating with the Hep-PEG incurs minimal alteration to islet size and volume and heparinization of the islets with Hep-PEG may also reduce instant blood-mediated inflammatory reaction during islet transplantation. This "easy-to-adopt" approach is mild enough for surface engineering of living cells without compromising cell viability. Considering that heparin has shown binding affinity to multiple cytokines, the Hep-PEG nanocoating also provides an open platform that enables incorporation of unlimited functional biological mediators and multi-layered surfaces for living cell surface bioengineering.

This protocol aims to achieve surface engineering of pancreatic islets using a heparin-incorporated starPEG nanocoating via pseudo-bioorthogonal chemistry between the N-hydroxysuccinimide groups of the nanocoating and the amine groups of islet cell membrane.

Cell surface engineering can protect implanted cells from host immune attack. It can also reshape cellular landscape to improve graft function and ...

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver engineering, including in vivo organ decellularization followed by repopulation, has emerged as a promising approach over ex vivo liver engineering. However, postoperative survival was not achieved. The aim of this study is to develop a novel surgical technique of in vivo selective liver lobe perfusion in rats as a prerequisite for in vivo liver engineering. We generate a circuit bypass only through the left lateral lobe. Then, the left lateral lobe is perfused with heparinized saline. The experiment is performed with 4 groups (n = 3 rats per group) based on different perfusion times of 20 min, 2 h, 3 h, and 4 h. Survival, as well as the macroscopically visible change of color and the histologically determined absence of blood cells in the portal triad and the sinusoids, is taken as an indicator for a successful model establishment. After selective perfusion of the left lateral lobe, we observe that the left lateral lobe, indeed, turned from red to faint yellow. In a histological assessment, no blood cells are visible in the branch of the portal vein, the central vein, and the sinusoids. The left lateral lobe turns red after reopening the blocked vessels. 12/12 rats survived the procedure for more than one week. We are the first to report a surgical model for in vivo single liver lobe perfusion with a long survival period of more than one week. In contrast to the previously published report, the most important advantage of the technique presented here is that perfusion of 70% of the liver is maintained throughout the whole procedure. The establishment of this technique provides a foundation for in vivo partial liver engineering in rats, including decellularization and recellularization.

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

We establish a novel surgical technique for an in vivo single liver lobe perfusion model in rat as a prerequisite for further studying in vivo partial liver engineering in the future.

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver ...

A Tripeptide-Stabilized Nanoemulsion of Oleic Acid

We describe a method to produce a nanoemulsion composed of an oleic acids-Pt(II) core and a lysine-tyrosine-phenylalanine (KYF) coating (KYF-Pt-NE). The KYF-Pt-NE encapsulates Pt(II) at 10 wt. %, has a diameter of 107 &#177; 27 nm and a negative surface charge. The KYF-Pt-NE is stable in water and in serum, and is biologically active. The conjugation of a fluorophore to KYF allows the synthesis of a fluorescent nanoemulsion that is suitable for biological imaging. The synthesis of the nanoemulsion is performed in an aqueous environment, and the KYF-Pt-NE forms via self-assembly of a short KYF peptide and an oleic acids-platinum(II) conjugate. The self-assembly process depends on the temperature of the solution, the molar ratio of the substrates, and the flow rate of the substrate addition. Crucial steps include maintaining the optimal stirring rate during the synthesis, permitting sufficient time for self-assembly, and pre-concentrating the nanoemulsion gradually in a centrifugal concentrator.

This protocol describes an efficient method to synthesize a nanoemulsion of an oleic acids-platinum(II) conjugate stabilized with a lysine-tyrosine-phenylalanine (KYF) tripeptide. The nanoemulsion forms under mild synthetic conditions via self-assembly of the KYF and the conjugate.

We describe a method to produce a nanoemulsion composed of an oleic acids-Pt(II) core and a lysine-tyrosine-phenylalanine (KYF) coating (KYF-Pt-NE). The ...

Transplantation of a 3D Bioprinted Patch in a Murine Model of Myocardial Infarction

Testing regenerative properties of 3D bioprinted cardiac patches in vivo using murine models of heart failure via permanent left anterior descending (LAD) ligation is a challenging procedure and has a high mortality rate due to its nature. We developed a method to consistently transplant bioprinted patches of cells and hydrogels onto the epicardium of an infarcted mouse heart to test their regenerative properties in a robust and feasible way. First, a deeply anesthetized mouse is carefully intubated and ventilated. Following left lateral thoracotomy (surgical opening of the chest), the exposed LAD is permanently ligated and the bioprinted patch transplanted onto the epicardium. The mouse quickly recovers from the procedure after chest closure. The advantages of this robust and quick approach include a predicted 28-day mortality rate of up to 30% (lower than the 44% reported by other studies using a similar model of permanent LAD ligation in mice). Moreover, the approach described in this protocol is versatile and could be adapted to test bioprinted patches using different cell types or hydrogels where high numbers of animals are needed to optimally power studies. Overall, we present this as an advantageous approach which may change preclinical testing in future studies for the field of cardiac regeneration and tissue engineering.

This protocol aims to transplant a 3D bioprinted patch onto the epicardium of infarcted mice modeling heart failure. It includes details regarding anesthesia, the surgical chest opening, permanent ligation of the left anterior descending (LAD) coronary artery and application of a bioprinted patch onto the infarcted area of the heart.

Testing regenerative properties of 3D bioprinted cardiac patches in vivo using murine models of heart failure via permanent left anterior descending (LAD) ...

Doxycycline Loaded Collagen-Chitosan Composite Scaffold for the Accelerated Healing of Diabetic Wounds

One major complication of diabetes mellitus is diabetic wounds (DW). The prolonged phase of inflammation in diabetes obstructs the further stages of an injury leading to delayed wound healing. We selected doxycycline (DOX), as a potential drug of choice, due to its anti-bacterial properties along with its reported anti-inflammatory properties. The current study aims to formulate DOX loaded collagen-chitosan non-crosslinked (NCL) &amp; crosslinked (CL) scaffolds and evaluate their healing ability in diabetic conditions. The characterization result of scaffolds reveals that the DOX-CL scaffold holds ideal porosity, a low swelling &amp; degradation rate, and a sustained release of DOX compared to the DOX-NCL scaffold. The in vitro studies reveal that the DOX-CL scaffold was biocompatible and enhanced cell growth compared with CL scaffold treated and control groups. The anti-bacterial studies have shown that the DOX-CL scaffold was more effective than the CL scaffold against the most common bacteria found in DW. Using the streptozotocin and high-fat diet-induced DW model, a significantly (p&#8804;0.05) faster rate of wound contraction in the DOX-CL scaffold treated group was observed compared to those in CL scaffold treated and control groups. The use of the DOX-CL scaffold can prove to be a promising approach for local treatment for DWs.

The prepared DOX-CL scaffold satisfied the prerequisites of an ideal DW dressing in mechanical strength, porosity, water absorption, degradation rate, sustained release, anti-bacterial, biocompatibility, and anti-inflammatory properties, which are considered to be essential for the recovery of damaged tissue in DWs.

One major complication of diabetes mellitus is diabetic wounds (DW). The prolonged phase of inflammation in diabetes obstructs the further stages of an ...