Name: isolation of endothelial progenitor cells from human umbilical cord blood
Uploaded: 2017-09-14T14:00:00
Description: Watch this Scientific Journal Video about Isolation of Endothelial Progenitor Cells from Human Umbilical Cord Blood at JoVE.com

This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1452943 and by the University of Arkansas Honors College. We would also like to acknowledge the Arkansas Cord Blood Bank for providing us with cord blood units.

This research was carried out with the approval of the University of Arkansas Institutional Review Board (Approval number 16-04-722). Umbilical cord blood units were collected in citrate phosphate dextrose (CPD) solution at the Arkansas Cord Blood Bank, and units that did not meet the requirement for storage were donated for research. Cord blood units were couriered to the lab within 24 h of collection at ambient temperatures.
1. Isolation of Endothelial Progenitor Cells from Cord Blood
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As mentioned earlier, adherent EPCs possess a cobblestone morphology. Our isolated MNCs progressed from a spindle-shaped cell colony (Figure 2A-2D) in the early stages to a cobblestone colony (Figure 2E-2F) over a period of ten days in culture. EPCs have been labeled differently by different research groups, namely as late endothelial progenitor cells10, endothelial colony forming cells5...

Several investigators have studied the characteristics and potential of human EPCs5,10,11,12,13. EPCs can be described as circulating cells that have the ability to adhere to endothelial tissue in sites of hypoxia, ischemia, injury, or tumor formation and contribute to the formation of new vascular structures4,14. Their observed involvement in neovascularization, in the form of postnatal vasculogenesis, has led to an understanding of the pathophysiology of these cells and their use in therapeutic applications4,15,16. The number of EPCs in an individual has been shown to be correlated with cardiovascular pathology9,15,16,17,18,19,20. Other studies have also differentiated EPCs into a valve fibroblast-like phenotype and proposed that these cells could be used for tissue-engineering heart valves7,21.
The particular cell surface molecules needed to isolate EPCs have not been clearly identified due to discrepancies between investigations4. The adhesion of MNCs to a certain matrix, with exposure to a variety of culture conditions, has been performed by several groups1,17,22,23, suggesting that putative EPCs may display different phenotypic properties. These properties include a lack of phagocytotic ability, tube formation in Matrigel, and the uptake of Dil-acetylated low-density lipoproteins. The high clonogenic and proliferative potential are two properties with which EPCs can be hierarchized5. EPCs can also form in vitro tubules when cocultured with human fetal lung fibroblasts4. These cells are known to express endothelial cell surface markers and to share some of the hematopoietic markers13,24,25. The positively expressed markers that are widely accepted for phenotyping EPCs are CD31, CD34, vascular endothelial growth factor receptor 2 (VEGFR2), von Willebrand Factor (vWF), CD133, c-Kit, and vascular endothelial cadherin (VE-cadherin)4,18. Cells that co-express CD90, CD45, CD14, CD115, or alpha-smooth muscle actin (&#945;-SMA) are not considered to be EPCs because of their limited proliferative potential, ability to phagocytose bacteria, and inability to form de novo human vessels in vivo4,7. This article outlines a modified protocol for the isolation of endothelial progenitor cells from human umbilical cord blood without the need for any cell sorting protocols. For this article, we used CD31, CD34, and VEGFR2 as the positive markers, with &#945;-SMA as the negative indicator.
In this article, we propose a method of isolating and culturing endothelial progenitor cells from umbilical cord blood without cell sorting using specialized endothelial growth medium supplemented with growth factors (EGM). This EGM contains vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), which enhance the survival, proliferation, and migration of endothelial cells26. It also includes ascorbic acid, which is responsible for maintaining the cobblestone morphology of cells; insulin-like growth factor-1 (IGF-1), which provides angiogenic and migratory function; and heparin, which causes improved long-term stability of growth factors in the medium26. Other growth factors added to the endothelial cell culture medium includes supplementation with epidermal growth factor (EGF), which helps in stimulating cell proliferation and differentiation, and hydrocortisone, which sensitizes the cells to EGF26. We show that the use of this specific growth medium yields higher numbers of EPCs compared to endothelial basal medium (EBM) or Dulbecco&#39;s Modified Eagle Medium (DMEM).

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			<td height="20" style="width:204px;height:20px;">A) For isolation and culturing</td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
			<td style="width:807px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">EGM-2 BulletKit</td>
			<td style="width:127px;">Lonza</td>
			<td>CC-3162</td>
			<td>This product comes with all the growth factors needed to make the Endothelial Growth Medium</td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Fetal Bovine Serum</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">26140079</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Pencillin-Streptomycin-Glutamine (100X)</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">10378016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">Ficoll-Paque</td>
			<td style="width:127px;">GE Heatlhcare</td>
			<td style="width:119px;">17-1440-02</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Hank&#39;s Balanced Salt Solution</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">14170-112</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Ammonium Chloride</td>
			<td style="width:127px;">Stem Cell Technologies</td>
			<td style="width:119px;">7850</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">1X Phosphate Buffer Saline</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">14190250</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">Rat Tail I Collagen</td>
			<td style="width:127px;">Corning</td>
			<td style="width:119px;">354236</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">Glacial Acetic Acid</td>
			<td style="width:127px;">Amresco</td>
			<td style="width:119px;">0714-500ML</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">0.05% Trypsin-EDTA</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">25300054</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">HEPES buffer</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">15630080</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Dulbecco&#39;s Modified Eagle&#39;s Medium</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">10566-016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;"></td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
			<td></td>
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			<td height="20" style="width:204px;height:20px;">B) Antibodies and cell lysates</td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">CD31&#160;</td>
			<td style="width:127px;">Abcam</td>
			<td style="width:119px;">ab28364</td>
			<td>1:250 dilution&#160; for Western blotting</td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">CD34</td>
			<td style="width:127px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-7045</td>
			<td>1:100 dilution for Western blotting</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">&#945;-SMA</td>
			<td style="width:127px;">abcam</td>
			<td style="width:119px;">ab5694</td>
			<td>1:100 dilution for Western blotting</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">&#945;-tubulin</td>
			<td style="width:127px;">abcam</td>
			<td style="width:119px;">ab7291</td>
			<td>1:2500 dilution for Western blotting</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">VEGFR2</td>
			<td style="width:127px;">abcam</td>
			<td style="width:119px;">sc504</td>
			<td>1:100 dilution for Western blotting</td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Human umbilical vein endothelial cell lysate</td>
			<td style="width:127px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc24709&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">Valve interstitial cell lysate</td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
			<td style="width:807px;">Primary cell line cultured from own lab and lysed with RIPA buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;"></td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
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			<td height="40" style="width:204px;height:40px;">C) Western blotting and immunostaining</td>
			<td style="width:127px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">10X Tris/Glycine/SDS buffer</td>
			<td style="width:127px;">Biorad</td>
			<td style="width:119px;">161-0772</td>
			<td>Used as running buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">10X Tris/Glycine buffer</td>
			<td style="width:127px;">Biorad</td>
			<td style="width:119px;">161-0771</td>
			<td>Used as transfer buffer</td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Immobilon-FL transfer membrane</td>
			<td style="width:127px;">Merck Millipore</td>
			<td style="width:119px;">IPFL0010</td>
			<td>This is a PVDF transfer membrane that has 45 &#181;m pore size and is mentioned in the protocol as western blot membrane</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">4X Laemmli sample buffer</td>
			<td style="width:127px;">Biorad</td>
			<td style="width:119px;">161-0747</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">2-mercaptoethanol</td>
			<td style="width:127px;">Biorad</td>
			<td style="width:119px;">161-0710</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">10% Criterion TGX precast gel</td>
			<td style="width:127px;">Biorad</td>
			<td style="width:119px;">5671033</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:204px;height:42px;">Prolong Gold antifade</td>
			<td style="width:127px;">Thermofisher Scientific</td>
			<td style="width:119px;">P36930</td>
			<td>Used for mounting immunostained coverslips for long term storage</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:204px;height:21px;">Methanol</td>
			<td style="width:127px;">VWR Analytical</td>
			<td style="width:119px;">BDH1135-4LP</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of endothelial progenitor cells from human umbilical cord blood

The existence of endothelial progenitor cells (EPCs) in peripheral blood and its involvement in vasculogenesis was first reported by Ashara and colleagues1. Later, others documented the existence of similar types of EPCs originating from bone marrow2,3. More recently, Yoder and Ingram showed that EPCs derived from umbilical cord blood had a higher proliferative potential compared to ones isolated from adult peripheral blood4,5,6. Apart from being involved in postnatal vasculogenesis, EPCs have also shown promise as a cell source for creating tissue-engineered vascular and heart valve constructs7,8. Various isolation protocols exist, some of which involve the cell sorting of mononuclear cells (MNCs) derived from the sources mentioned earlier with the help of endothelial and hematopoietic markers, or culturing these MNCs with specialized endothelial growth medium, or a combination of these techniques9. Here, we present a protocol for the isolation and culture of EPCs using specialized endothelial medium supplemented with growth factors, without the use of immunosorting, followed by the characterization of the isolated cells using Western blotting and immunostaining.

Isolation and Expansion of Endothelial Progenitor Cells: 
A schematic (Figure 1) is provided depicting the overall protocol. The different blood component layers were observed following density gradient centrifugation of human umbilical cord blood with density gradient medium. Upon seeding MNCs onto the collagen-treated plates, the outgrowth of colonies was first observed between Days 5 and 7 (Figure 2<stron...

Watch this Scientific Journal Video about Isolation of Endothelial Progenitor Cells from Human Umbilical Cord Blood at JoVE.com

Isolation of Endothelial Progenitor Cells from Human Umbilical Cord Blood

The goal of this protocol is to isolate endothelial progenitor cells from umbilical cord blood. Some of the applications include using these cells as a biomarker for identifying patients with cardiovascular risk, treating ischemic diseases, and creating tissue-engineered vascular and heart valve constructs.

The existence of endothelial progenitor cells (EPCs) in peripheral blood and its involvement in vasculogenesis was first reported by Ashara and ...

The overall goal of this procedure is to isolate endothelial progenitor cells from human umbilical cord blood. This method describes the isolation of endothelial progenitor cells from cord blood for their potential use as autologous cells for the tissue engineering of vascular grafts. The main advantage of this technique is that the isolation procedure can be done in specialized media without the need for any amino sorting.The isolated endothelial progenitor cells can be used to study neovascularization, and reports have also suggested that these cells can be used as biomarkers to identify patients with risk for cardiovascular diseases. Before beginning the isolation procedure, pre-coat six well plates with two milliliters of freshly prepared rat tail one collagen solution per well. Equilibrate the plate in a 37 degree Celsius and 5%CO2 incubator for at least one hour.Then dilute approximately 25 milliliters of cord blood with HBSS at a one-to-one concentration. Next add 20 milliliters of density gradient medium reagent to a 50 milliliter conical tube, and carefully dispense 20 milliliters of diluted cord blood down the wall of the tube to layer the blood onto the medium. Separate the cells by centrifugation, followed by careful removal of the plasma layer.Using a syringe fitted with an 18-gauge needle, collect the mononuclear cell containing buffy coat into a new 50 milliliter tube. And add an equal volume of endothelial basal medium to the cells. Wash the cells by centrifugation and lyse the red blood cells in the resulting palate with five milliliters of ammonium chloride solution on ice.After five to 10 minutes with occasional shaking, collect the cells by centrifugation and resuspend the white pellet in fresh endothelial growth medium. After counting, aspirate the collagen from each well of the six well plate, and wash the wells three times in PBS. Seed the mononuclear cells at a one times 10 to the seventh cells per two milliliters of medium per well concentration.And return the plate to the incubator for 24 hours. The next day, rinse the cells one time with fresh endothelial growth medium. Then replace the wash with three milliliters of fresh endothelial growth medium, and return the cells to the cell culture incubator.Using a bright field microscope, obtain daily images of the cells to monitor the progression of the endothelial cell colonies, marking the plates where the colonies arise to track their growth. When the endothelial cell colonies reach about three millimeters in size, coat a T25 culture flask with fresh rat tail one collagen for at least one hour in the cell culture incubator. Then harvest the cells with 150 microliters of 0.05%Trypsin-EDTA per well in the cell culture incubator for two to three minutes.Gently tapping the plate to dislodge the attached cells. When the cells begin to detach, immediately add two milliliters of fresh endothelial growth medium, and pull the cells in a single 15 milliliter conical tube. Collect the cells by centrifugation, and resuspend the pellet in fresh endothelial growth medium.After counting, seed the cells in the collagen coated flask at a five times 10 to the fifth cells in three milliliters of medium per flask density, and mark the flask as passage one. Then return the flask to the incubator, reseeding the cells whenever the colony reaches 90%confluency. After seeding onto the collagen treated plates, the first colony outgrowth is typically observed between days five to nine.The colonies continue to grow and to acquire a spindle-shaped cell morphology in the early stages of culture, which later progresses to a cobblestone-like morphology. The total number of cells harvested at each passage increases in direct correlation to the total number of days in culture. Western blot analysis reveals an early expression of CD 31 and CD 34 by the cultured endothelial cells, which appears to decrease with subsequent passaging.The expression of vascular endothelial growth factor receptor two, however, is maintained over time, although at a slightly lower level of expression than that observed after the first passage. Of note, endothelial progenitor cells are not positive for the mesenchymal cell marker alpha smooth muscle actin, unlike for example, valvular interstitial cell lysates, which can be included as a positive control. The entire isolation procedure can be completed in less than five hours depending on the cord blood unit obtained.After isolating and seeding the mononuclear cells in endothelial growth medium, it usually takes between five and nine days for the EPC colonies to show up in the culture. The proposed method of isolation uses specialized media for culturing the endothelial progenitor cells, and avoids the usage of a flow cytometer, as far as the requirement for having endothelial markers. This method also provides an efficient protocol for obtaining high quantities of endothelial progenitor cells over a short span of time.After watching this video, you should have a good understanding of how to isolate endothelial progenitor cells from human umbilical cord blood units. Don't forget that human umbilical cord blood can be hazardous, and proper disposal of waste blood and cell culture products should be followed.

Research

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