This work was supported by NIDDK grants DK098143 and DK101530 from the NIH (JPA), Stanford's Spectrum Child Health Research Institute (CHRI) and SPARK (UL1 TR001085, JPA).

This protocol was carried out in accordance with the Institutional Animal Care and Use Committee (IACUC) of Stanford University School of Medicine. The described protocol is scaled for islet isolation from six 250 - 300 g (8 - 9 weeks old) male Sprague Dawley rats, which is sufficient to generate 228 wells of a 384-well plate for islet-cell replication assessment.
1. Material Preparation
<ol>
	<li>Prepare coating media prior to initiating islet isolation by collecting the conditioned media of 804G rat b...

<ol>
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The authors declare that they have no competing financial interests.

Experimental methods for studying the molecular pathways that control &#946;-cell growth and regeneration are important tools for diabetes researchers. Herein, a rat-islet-based screening platform to identify and characterize small-molecule stimulators of &#946;-cell replication is presented.
While most aspects of this protocol are easily performed by experienced researchers, a few steps require particular technique. First, during islet isolation, cannulation of the bile-duct without disruptin...

Diabetes encompasses a collection of disorders sharing the common end-point of disrupted glucose homeostasis. Although the pathogenic mechanisms of diabetes subtypes are distinct, they share the consequence of decreased &#946;-cell mass, i.e., loss of insulin production capacity1,2. Presently, diabetes treatment strategies rely upon chronic administration of exogenous insulin, pharmacologic stimulation of insulin production or enhancement of insulin sensitivity, and rarely, the transplantation of pancreatic islets or whole pancreas3,4. Regrettably, the success of these strategies is short-lived and/or fails to sufficiently recapitulate the function of endogenous insulin production. Despite the utility of developing a method to stimulate &#946;-cell regeneration, no such approach exists. Consequently, a major diabetes research goal is to develop methods to generate new &#946;-cells or to expand endogenous &#946;-cell mass5. Although &#946;-cell regeneration from renewable sources such as embryonic stem cells is advancing, safety and efficiency concerns make the pursuit of alternative strategies, including expansion of mature &#946;-cells, a priority6,7. Importantly, the predominant source of new &#946;-cells in vivo is pre-existing &#946;-cells rather than specialized progenitor cells8,9. Although &#946;-cells appear to have limited replication capacity, a small increase in &#946;-cell mass (~ 30%) may be sufficient to restore glucose homeostasis in many diabetics. Furthermore, in situ pharmacologic stimulation of &#946;-cell mass is a potentially inexpensive and scalable treatment strategy. Herein a high-content screening method for identifying and characterizing small molecules that stimulate &#946;-cell growth is presented.
A variety of in vitro experimental methods may be used to identify gene products and/or molecules that promote primary &#946;-cell replication. Early efforts for measuring &#946;-cell replication induction used fetal rodent pancreata culture or intact isolated islet cultures to measure [3H] thymidine incorporation, BrdU incorporation or mitotic bodies within the aldehyde-thionine or insulin stained population in response to specific treatment conditions10,11. These in vitro approaches and close variants thereof have several limitations. Prominent deficiencies include (1) the use of fetal cells which, unlike mature &#946;-cells, display a high basal &#946;-cell replication rate and are growth regulated in a distinct manner12; (2) the subjective nature of experimenter-dependent adjudication of &#946;-cell replication events; (3) the labor and time intensive nature of experimenter-dependent counting of &#946;-cell replication events retards experimental throughput; (4) the use of nuclear incorporation/stain/appearance to identify replication events and a non-overlapping cytoplasmic stain to identify &#946;-cells leads to misattribution of proximate non-&#946;-cell replication events to &#946;-cells.
More recently mature primary &#946;-cells have been used to assess the impact of transgene over-expression as well as gene product or compound treatment on &#946;-cell replication13-16. However, these studies have also relied upon subjective counting of replication events, cytoplasmic staining- or non-specific methods for &#946;-cell identification and/or labor-intensive steps that limit throughput, e.g., individual slide-well plating of cells or intact islet paraffin embedding and processing17. Notably, an image-based human &#946;-cell replication screening methodology, similar to the one presented herein, has been published18; however, successful use of this assay has not been demonstrated and the use of human islets for primary screening may not be broadly feasible.
An alternative strategy for identifying replication-promoting substances is to assess growth induction of &#946;-cell lines. Initial efforts used transformed &#946;-cell-lines such as min6 cells or INS 832/13-cells14,19-21. However, these cell-lines demonstrate unrestrained growth and bear little resemblance to well-differentiated &#946;-cells22. Consequently, growth-induction capacity is minimal, of unclear relevance and sometimes difficult to recapitulate. An improved strategy for cell-line based screening utilizes &#34;reversibly transformed&#34; cells that are growth arrested in the absence of tetracycline (doxycycline)-dependent SV40 T antigen expression23,24. However, it is unclear whether these cells revert to a &#34;normal&#34; &#946;-cell-like state upon doxycycline removal. Unfortunately, use of these cells has yielded generalized growth-promoting compounds that don&#39;t appear to have immediate utility24. Overall, the use of cell-lines to study growth regulation of a cell-type displaying minimal spontaneous replication activity may have limited applicability.
The &#946;-cell replication screening platform presented herein utilizes mature primary rat &#946;-cells to retain in vivo growth regulation to the extent possible, islet-cell cultures of mixed cell-type composition to enable identification of lineage-restricted growth-promoting activities, multi-well formatting to maximize throughput and automated analysis to eliminate bias and facilitate throughput. Successful use of this platform has enabled identification of several compounds that promote &#946;-cell replication25,26. Additionally, the assay has been used for structure-activity relationship studies and chemical epistasis experiments to provide mechanistic insights into the molecular regulation of &#946;-cell replication. The presented platform was successfully adapted for lentiviral RNAi-based investigation of &#946;-cell replication pathways25. Limitations of the assay include restricted scalability (use of primary cells), use of rodent rather than human islet-cells (though the assay may be adapted for human islet studies), expenses associated with antibody-based imaging and primary islet use, the use of dispersed islets (disrupted islet architecture) to facilitate automated image acquisition and dependence upon the availability of an automated microscope with image acquisition and analysis capability. Although a facile in vivo screening methodology for identifying gene products or compounds that stimulate &#946;-cell regeneration in situ would be ideal, such a platform is not yet available27. Consequently, the described platform is appropriate for researcher interested in investigating most aspects of &#946;-cell replication.

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	<tbody>
		<tr height="23">
			<td height="23" style="height:23px;width:364px;">250g male Male Sprague Dawly Rat</td>
			<td style="width:196px;">Charles River</td>
			<td style="width:147px;">Stain # 400</td>
			<td style="width:272px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:364px;">12 cm teeth tisuue forceps</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">11021-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">11.5 cm fine scissors</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">14058-11</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">14.5 cm surgical scissors</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">14001-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">16 cm curved forceps</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">11003-16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">12 cm curved hepostat</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">13011-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">12 cm scalpel handle</td>
			<td style="width:196px;">Fine Science Tools</td>
			<td style="width:147px;">10003-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Tissue sieve-30 mesh</td>
			<td style="width:196px;">Bellco Glass</td>
			<td style="width:147px;">1985-85000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Cizyme RI, 375,000 CDA units</td>
			<td style="width:196px;">VitaCyte</td>
			<td style="width:147px;">005-1030</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:364px;">Hanks&#39; Balanced Salt solution (Ca++ and Mg++)</td>
			<td style="width:196px;">Gibco</td>
			<td style="width:147px;">24020-117</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Ketamine HCl (200 mg/20 ml)</td>
			<td style="width:196px;">JHP Pharmaceuticals</td>
			<td style="width:147px;">NDC# 42023-113-10</td>
			<td>to make anesthetic cocktail&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Xylazine (5 g/50 ml)</td>
			<td style="width:196px;">LLOYD</td>
			<td style="width:147px;">NADA# 139-236</td>
			<td>to make anesthetic cocktail&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Histopaque 1077</td>
			<td style="width:196px;">Sigma</td>
			<td style="width:147px;">H-1077</td>
			<td>to make histopaque 1100</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Histopaque 1119</td>
			<td style="width:196px;">Sigma</td>
			<td style="width:147px;">H-1119</td>
			<td>to make histopaque 1100</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Newborn Calf Serum 500 ml</td>
			<td style="width:196px;">Hyclone</td>
			<td style="width:147px;">SH30118.03</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Hanks&#39; Balanced Salt solution</td>
			<td style="width:196px;">Hyclone</td>
			<td style="width:147px;">SH30268.01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#39;s Modified Eagle Medium/Low Glucose&#160;</td>
			<td style="width:196px;">Hyclone</td>
			<td style="width:147px;">SH30021.01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Functionality/Viability Solution&#160;</td>
			<td style="width:196px;">Mediatech</td>
			<td style="width:147px;">99-768-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">RPMI1640 media&#160;</td>
			<td style="width:196px;">Hyclone</td>
			<td style="width:147px;">SH30096.01</td>
			<td>to make conditioned medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">804G rat bladder carcinoma cell-line</td>
			<td style="width:196px;">Available upon request</td>
			<td style="width:147px;"></td>
			<td>to make conditioned medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Fetal Bovine Serum, Qualified</td>
			<td style="width:196px;">Gibco</td>
			<td style="width:147px;">26160</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">GlutaMax-I</td>
			<td style="width:196px;">Gibco</td>
			<td style="width:147px;">35050-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Penicillin (5,000 IU/ml/Strptomycin (5 mg/ml)&#160;</td>
			<td style="width:196px;">MP Biomedicals</td>
			<td style="width:147px;">1670049</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Formamide 500 mL</td>
			<td style="width:196px;">Fisher BioReagents</td>
			<td style="width:147px;">BP227-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Antigen Unmasking Solution 250 mL (PH 6.0)</td>
			<td style="width:196px;">Vector Laboratories</td>
			<td style="width:147px;">H-3300</td>
			<td>to make 0.15 M Sodium Sitrate solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Dextrose, Anhydrous</td>
			<td style="width:196px;">EMD Chemicals</td>
			<td style="width:147px;">DX0145-1</td>
			<td>to make 1 M glucose solution</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:364px;">Nomal Donkey Serum (Powder)</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">017-000-121</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Triton X-100</td>
			<td style="width:196px;">Sigma</td>
			<td style="width:147px;">T8787-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Mouse anti-human Ki67 antibody</td>
			<td style="width:196px;">BD Biosciences</td>
			<td style="width:147px;">556003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Goat anti-human PDX-1 antibody</td>
			<td style="width:196px;">R&#38;D Systems</td>
			<td style="width:147px;">AF2419</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Polyclonal Guinea Pig anti-insulin antibody</td>
			<td style="width:196px;">Dako</td>
			<td style="width:147px;">2016-08</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Polyclonal Rabbit anti-glucagon antibody</td>
			<td style="width:196px;">Dako</td>
			<td style="width:147px;">2014-06</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Polyclonal Rabbit anti-somatostatin antibody</td>
			<td style="width:196px;">Dako</td>
			<td style="width:147px;">2011-08</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Polyclonal chicken anti-vimentin antibody</td>
			<td style="width:196px;">abcam</td>
			<td style="width:147px;">ab24525</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Biotin-SP-conjugated, Donkey Anti-Mouse IgG</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">715-065-150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">StreptAvidin, Alex Flour 488 conjugated&#160;</td>
			<td style="width:196px;">Invitrogen</td>
			<td style="width:147px;">S32354</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Rhodamine-conjugated Donkey Anti-Goat IgG&#160;</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">705-025-147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Rhodamine-conjugated Donkey Anti-Guinea Pig IgG&#160;</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">706-025-148</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Rhodamine-conjugated Donkey Anti-Rabbit IgG</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">711-025-152</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Cy 5-conjugated Donkey Anti-Guinea Pig IgG&#160;</td>
			<td style="width:196px;">Jackson ImmunoResearch</td>
			<td style="width:147px;">706-175-148</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cy 5-conjugated Donkey Anti-Goat IgG</td>
			<td>Jackson ImmunoResearch</td>
			<td>705-175-147</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cy 5-conjugated Donkey Anti-Rabbit IgG</td>
			<td>Jackson ImmunoResearch</td>
			<td>711-175-152</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cy 5-conjugated Donkey Anti-Chicken IgG</td>
			<td>Jackson ImmunoResearch</td>
			<td style="width:147px;">703-175-155</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">DAPI</td>
			<td style="width:196px;">Millipore</td>
			<td style="width:147px;">S7113</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Disposable Reagent Reservoir 25 mL</td>
			<td style="width:196px;">Sorenson BioScience</td>
			<td style="width:147px;">39900</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">384 well, black/clear, tissue culture treated plate</td>
			<td style="width:196px;">BD Falcon</td>
			<td style="width:147px;">353962</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">96 well, black/clear, tissue culture treated plate</td>
			<td style="width:196px;">Costar</td>
			<td style="width:147px;">3603</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Multi-channel pipettor</td>
			<td style="width:196px;">Costar</td>
			<td style="width:147px;">4880</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">12-channel vaccume aspirator</td>
			<td style="width:196px;">Drummond</td>
			<td style="width:147px;">3-000-096</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Cell Scraper</td>
			<td style="width:196px;">Falcon</td>
			<td style="width:147px;">353085</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">Isotemp Water Bath Model 2223&#160;</td>
			<td style="width:196px;">Fisher Scientific</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:364px;">High-content screening instrument: ArrayScan VTI</td>
			<td style="width:196px;">Thermo Scientific</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

To assess &#946;-cell or &#945;-cell replication, a four-color assay protocol is required. First, objects are identified by DAPI staining (Channel 1, 386 nm). Next, &#946;-cells (event 1) are counted: objects that co-express PDX-1+ (channel 2, 650 nm) and peri-nuclear insulin (channel 3, 549 nm). Subsequently, replicating &#946;-cells (event 2) are counted: &#946;-cells (event 1) that co-express Ki-67 (channel 4, 485 nm) (Figure 3). The percentage of replicatin...

Watch this Scientific Journal Video about A High-content In Vitro Pancreatic Islet Î²-cell Replication Discovery Platform at JoVE.com

A High-content In Vitro Pancreatic Islet &amp;#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.

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 ...

The overall goal of this high content beta cell replication screening platform, is to facilitate the investigation of the molecular pathways that restrict beta cell growth. This method can help answer important questions in the beta cell biology field. Such as one of the key signaling molecules and pathways that control beta cell regeneration.The main advantages of this technique are that it enables increasing the throughput cell lining to a specific assessment and the automated data analyst of a primary islet cell replication. The employment of this technique has the potential to extend toward the development of the regenerative therapy for diabetes. A disease with major health and economic cost to our society.Begin by using a pancreatic digestive solution loaded 10 milliliter syringe equipped with a 22 gauge needle to chemulate the common bile duct at or just distal to the junction of the cystic and common hepatic ducts. Supporting the common bile duct with a scalple handle, slowly inject 10 milliliters of the solution. After all of the collagenase has been administered, used curved forceps and scissors to separate the inflated pancreas from the descending colon, intestines, stomach, and spline.Then place up to two pancreata in a 50 milliliter tube on ice containing five milliliters of pancreatic digestion solution. When all of the pancreata have been collected, place the digestion tubes in a 37 degree Celsius water bath for 15 minutes with gentle swirling every three minutes. At the end of the digestion, vigorously shake the tubes vertically 10 times.And add 10 milliliters of cold wash buffers to the specimens. Vigorously shake the tubes five more times and place them on ice. Next fill the tubes to a final volume of 50 milliliters with cold wash buffer and invert the tubes five times.Then spin down the tissues and pour off the supernatants, taking care not to dislodge the pellets. Re-suspend the tissue slurry in 25 milliliters of wash buffer followed by gentle vortexing. Repeat the spinning and re-suspension steps two more times.The pour the tissue suspensions through a 30 mesh tissue sieve into a sterile 250 milliliter beaker. Rinse the digestion tubes with an additional 20 milliliters of wash buffer and pour the washes onto the mesh to remove the undigested pancreatic and fat tissues. Divide the filtered material between two new 50 milliliter tubes and pellet the tissue by centrifugation.Then decant the supernatant and invert the tubes to drain the excess buffer. To purify the islets, add 20 milliliters of cold density gradient to the pancreatic tissue pellets and gently pipet up and down five times to homogeneously re-suspend the contents. Next slowly overlay 10 milliliters of HBSS down the wall of each tube of gradient taking care to maintain a sharp liquid interface and separate the pancreatic cells by centrifugation.Use a 10 milliliter pipet to transfer the islet layer from the interface into new 50 milliliter conical tubes. Then wash the islets in 40 to 50 milliliters of wash buffer three times. Inverting their tubes to re-suspend the pellets between each centrifugation.After the final wash, bring the tubes into a tissue culture hood. Aspirate the supernatant. And re-suspend the pellets in six milliliters of islet medium.Sieve the islets from each tube in individual wells of six well tissue culture plate. And swirl the plate to collect the islets in the middles of the wells. Evaluate islet purity under the microscope.To further purify the islets, collect them using a one milliliter pipet and transfer to the adjacent well using six milliliters of islet medium. Repeat islet swirling, collection, transfer and microscopic evaluation until greater than 90 percent purity is achieved. Next, transfer the islets to a single 10 centimeter tissue culture dish containing 20 milliliters of islet medium.After all of the islets have been harvested, place the culture dish in a tissue culture incubator overnight. Then coat the wells of a 384 well plate with 40 microliters of 804G, conditioned medium per well and place the plate in the incubator overnight. The next day, use a cell scraper to gently detach the islets.Then transfer the islets into a 50 milliliter tube. Collect the islets by centrifugation. Then wash them with 20 milliliters of warm p, b, s.Centrifuge for one minute. Aspirate the supernatant. And re-suspend the pellet in zero point two, five percent Trypsin.Incubate the islets for 10 minutes at 37 degrees Celsius using a one milliliter pipet to aspirate and dispense the islets 10 times at five and 10 minutes. After the second triteration, count a 20 microliter sample of the trypsinized islet cells. If the tissues are fully digested, suspend the dissociative islet cells at a four point five times ten to the four cell per milliliter concentration in islet function medium.Then use a 12 well manifold aspirator to remove the 804G condition medium from the previously prepared 384 well plate. And sieve 70 microliters of islets per well into rows c to n in columns four to 21. Allow the islets to adhere in the tissue culture incubator for 48 hours.After two day, use the 12 well manifold aspirator to carefully remove the islet medium and use a 12 channel pipet to add 35 microliters of islet function medium to each well. Then transfer 35 microliters of the freshly prepared two, x compound solutions of interest to each well. And return the islets to the incubator for another 48 hours.After 48 hours, fix, stain, and analyze the compound treated islets cultures using an automated high content imaging platform. In a typical experiment, the replication rate of the DAPI, PD-1 and insulin positive beta cells is determined by the percentage of beta cells co-expressing Ki-67. Alpha cell replication is measured as the percentage of DAPI positive, PD negative, Glucagon positive, Ki-67 co-expressing cells.For example in this representative experiment, Dipryridamole was observed to promote the replication of beta but not alpha cells. This technique can be completed in seven days. Following this procedure compounds that in the beta cell replication can be studied further to reveal the mechanisms of action.This technique has enabled researches in the field of beta cell biology to identify new signaling factors and pathways that regulate beta cell growth. After watching this video, you should have a good understanding of how to test the ability of small molecules to selective stimulate beta cell regeneration.

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11.1K Görüntüleme.  Stanford University School of Medicine. The overall goal of this high content beta cell replication screening platform, is to facilitate the investigation of the molecular pathways that restrict beta cell growth. This method can help answer important questions in the beta cell biology field. Such as one of the key signaling molecules and pathways that control beta cell regeneration.The main advantages of this technique are that it enables increasing the throughput cell lining to a specific assessment and the automated data a...