This research was supported by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, Center for Cancer Research.

Note: The following protocol describes the necessary steps to eliminate specific cells using NIR-PIT. Controls and other details about NIR-PIT and cell viability can be found elsewhere18.
1. Conjugation of IR700 to Monoclonal Antibodies (mAb)
<ol>
	<li>Prepare mAb of interest at 2-5 mg/ml in 0.1 M Na2HPO4 (pH 8.6) solution.</li>
	<li>Mix 6.8 nmol of mAb with 30.8 nmol of 10 mM IR700 in 0.1 M Na2HPO4 solution (pH 8.6) in a microcentrifuge tube and incubate at...

<ol>
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The authors have nothing to disclose.

We demonstrate a method of specific cell elimination from a mixed 3D cell culture without damage to non-target cells by using NIR-PIT. So far, there is no practical method of cell elimination once the tissue is established or after transplantation. Thus, NIR-PIT is a promising method to accomplish this. This technique could also be utilized in vivo18,22, since APCs show similar pharmacokinetics as mAb itself. The target cell type can be adapted with various APC. Various antibodies or antibody...

Eliminating specific cells without damaging other cells is extremely difficult, especially in established tissue, and there is an urgent need for a cell elimination method in the tissue engineering field. Nowadays in the field of regenerative medicine, tissue cultures using embryonic stem cells (ES), pluripotent stem cells (PSCs), or induced pluripotent stem cell (iPS) are promising materials1-3.
Although this tissue regeneration is promising, contamination with unwanted cells is a major concern. Moreover, there is a safety concern of tumorigenicity after transplantation4,5. Although many studies have focused on these issues to eliminate specific cells, especially in regenerative medicine6-8, no practical method has been developed.
Near infrared photoimmunotherapy (NIR-PIT) is a treatment based on an antibody-photoabsorber conjugate (APC). An APC consists of a cell-specific monoclonal antibody (mAb) and a photoabsorber, IR700. IR700 is a hydrophilic silica-phthalocyanine derivative and does not induce phototoxicity by itself9. IR700 is covalently conjugated to the antibody via amide residues on the side chain of lysine molecules. The APC binds target molecules on the cell membrane and then induces nearly immediate cell necrosis after exposure to NIR light at 690 nm. During the exposure to NIR-light, the cellular membrane ruptures leading to cell death9-14. NIR-PIT has proven to be effective with multiple antibodies or antibody fragments, including anti-EGFR, anti-HER2, anti-PSMA, anti-CD25, anti-mesothelin, anti-GPC3, and anti-CEA15-21. Therefore, NIR-PIT can be used against a wide variety of target molecules. Moreover, NIR-PIT is a well-controlled treatment that allows selective treatment of specific regions by restricting the NIR-light irradiation18,22.
Here, we present a method of specific cell elimination using NIR-PIT from mixed 3D cultures.

<table border="0" cellpadding="0" cellspacing="0" width="1083">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:424px;">IRDye 700DX Ester Infrared Dye</td>
			<td style="width:364px;">LI-COR Bioscience (Lincoln, NE, USA)</td>
			<td style="width:191px;">929-70011</td>
			<td style="width:104px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Na2HPO4</td>
			<td>SIGMA-ALDRICH (St. Louis, MO, USA)</td>
			<td>S9763</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sephadex G25 column (PD-10)&#160;</td>
			<td>GE Healthcare (Piscataway, NJ, USA)</td>
			<td>17-0851-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Coomassie (bradford) Plus protein assay</td>
			<td>Thermo Fisher Scientific Inc (Waltham, MA, USA)</td>
			<td>PI-23200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perfecta3D 96-Well hanging Drop Plates</td>
			<td>3D Biomatrix Inc (Ann Arbor, MI, USA)</td>
			<td>HDP1096-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Optical power meter</td>
			<td>Thorlabs (Newton, NJ, USA)</td>
			<td>PM100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LED: L690-66-60</td>
			<td>Marubeni America Co. (Santa Clara, CA, USA)</td>
			<td>L690-66-60</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vectibix (panitumumab)</td>
			<td>Amgen (Thousand Oaks, CA, USA)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">35mm glass bottom dish, dish size 35mm, well size 10mm</td>
			<td>Cellvis (Mountain View, CA, USA)</td>
			<td>D35-10-0-N</td>
			<td></td>
		</tr>
	</tbody>
</table>

selective cell elimination from mixed 3d culture using a near infrared photoimmunotherapy technique

Recent developments in tissue engineering offer innovative solutions for many diseases. For example, tissue engineering using induced pluripotent stem cell (iPS) emerged as a new method in regenerative medicine. Although this tissue regeneration is promising, contamination with unwanted cells during tissue cultures is a major concern. Moreover, there is a safety concern regarding tumorigenicity after transplantation. Therefore, there is an urgent need for eliminating specific cells without damaging other cells that need to be protected, especially in established tissue. Here, we present a method for specific cell elimination from a mixed 3D cell culture in vitro with near infrared photoimmunotherapy (NIR-PIT) without damaging non-targeted cells. This technique enables the elimination of specific cells from mixed cell cultures or tissues.

To optically monitor the effect of NIR-PIT, the A431 cell line, which overexpresses EGFR, was genetically modified to also express GFP and luciferase (A431-luc-GFP). As a non-target of NIR-PIT, the Balb/3T3 cell line was optically modified to express RFP (3T3-RFP). The APC, panitumumab-IR700 (pan-IR700), was synthesized. Mixed spheroids, which were composed of various ratios of cells (A431-luc-GFP and 3T3-RFP) were fabricated according to this protocol (Figure 1). Repeate...

Watch this Scientific Journal Video about Selective Cell Elimination from Mixed 3D Culture Using a Near Infrared Photoimmunotherapy Technique at JoVE.com

Selective Cell Elimination from Mixed 3D Culture Using a Near Infrared Photoimmunotherapy Technique

Eliminating specific cells without damaging other cells is extremely difficult, especially in established tissue, yet there is an urgent need for a cell elimination method in the tissue engineering field. Here, we present a method for specific cell elimination from a mixed 3D cell culture using near infrared photoimmunotherapy (NIR-PIT).

Recent developments in tissue engineering offer innovative solutions for many diseases. For example, tissue engineering using induced pluripotent stem ...

The overall goal of this experimental procedure is to demonstrate the elimination of specific cells of interest from a mixed 3D cell culture using near infrared photoimmunotherapy. This method can help answer key questions in the tissue-engineering field about regenerating medicine. The main advantage of this technique that it can be used against a variety of target molecules and that the treatment can be restricted to specific lesions of interest.Thus can minimize the side effect. For IR700 conjugation to monoclonal antibodies, incubate the antibodies of interest with IR700 in Disodium Phosphate in a microcentrefuge tube at room temperature for one hour covered in aluminum foil. At the end of the incubation, wash a PD10 column two times with 15 milliliters of PBS.Then, load the antibody solution onto the column and purify the mixture by PBS elution according to the manufacturer's instructions. To confirm the number of fluoro-4 molecules conjugated to each monoclonal antibody molecule, use a spectrophotometer to determine the monoclonal antibody protein concentration. Then, store the conjugate at 4-degree Celsius.To prepare the mixed 3D cell culture, add 1 milliliter of sterile water into the plate reservoir section of a 96-well hanging drop plate. Then, plate various ratios of the cell types of interest in the appropriate cell culture medium at at least 5, 000 cells per 50 microliters of medium per well for five to seven days in a humidified incubator at 37-degree Celsius and 5%carbon dioxide. Change the culture medium every two days and observe the morphology and size of the spheroids daily with an inverted bright-field microscope at 10 to 40 times magnification.When the spheroids have reached 400 to 600 microns in diameter, replace the hanging drop plate medium with antibody photoabsorber conjugate-containing medium, and return the plate to the incubator for six hours. At the end of the incubation, wash the spheroids two times with fresh phenol red free-culture medium. Then use a 200-microliter pipette tip with a cut-off end to transfer one spheroid at a time into individual glass-bottom 50-millimeter dishes containing 100 microliters of fresh phenol red free-culture medium per dish.Use the inverted microscope to observe changes in the spheroid morphology. To irradiate the spheroids, place a light-emitting diode no higher than 5 inches above the glass-bottom dishes. And use an optical power meter to confirm the emission of a 670 to 710 nanometer wavelength at 2 joules per centimeter squared.After the NIR infrared photoimmunotherapy, transfer the spheroids into a new hanging drop plate with 50 microliters of fresh-culture medium per well for one day in the cell-culture incubator. Then, using another 200-microliter pipette tip with a cut-off end, gently transfer the spheroids into new glass-bottom dishes containing 100 microliters of phenol red free-culture medium, and assess the optical reporter expression under the flourescent microscope. Finally, detect the dead cells by the addition of propidium iodide to the medium.Or by the loss of cytoplasmic GFP flourescence. In this representative experiment, mixed spheroids composed of various ratios of A431-luc-GFP and 3T3-RFP cells were prepared as just demonstrated. Repeated NIR infrared photoimmunotherapy was then performed with the incubation of panitumumab-IR700 as illustrated.And the target cell elimination was monitored through the assessment of the flourescent and luciferase activities within the hanging drop cultures. Once mastered, this technique can be completed in one hour if it is performed properly. While attempting this procedure, it's important to remember that light energy decreases according to inverse-square law.

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7.8K Görüntüleme.  National Cancer Institute. The overall goal of this experimental procedure is to demonstrate the elimination of specific cells of interest from a mixed 3D cell culture using near infrared photoimmunotherapy. This method can help answer key questions in the tissue-engineering field about regenerating medicine. The main advantage of this technique that it can be used against a variety of target molecules and that the treatment can be restricted to specific lesions of interest.Thus can minimize the side effect. For...