Mammosphere Formation Assay from Human Breast Cancer Tissues and Cell Lines

The overall goal of the following experiment is to estimate the proportion of stem-like cells within a cancer cell line or tumor tissue sample, and assess their capacity for self-renew over successive passages. To do this, a cancer cell line or tumor tissue is processed to generate a single cell suspension, which is then sorted to isolate CD 44 positive and CD 24 negative cellular subsets. The cells are seeded onto low attachment plates, allowed time for growth, and then examined by light microscopy sphere.

Forming efficiency is quantified by determining the number of spheres that have formed relative to the number of cells originally seeded. The process of generating a single cell suspension, allowing time for growth and determining sphere forming efficiency is repeated over successive passages, ultimately providing a measure of the capacity of the cells for self-renewal over time. This method provides a simple perspective assay to identify cells exhibiting functional properties of stem cells such as self-renew, as well as a quantitative estimate of the number of stem cells coming from in vivo tumors.

A central tenet of sphere forming assays is that each sphere is derived from a single cell is there for clonal. For these reasons, cell density is the most important parameter this assay, because it has a critical impact on ality Working under a sterile culture hood. Begin this procedure with MCF seven or MDA MB 2 3 1 cells that are 70 to 80%cofluent.

Aspirate the medium from the flask, wash the cells twice with PBS. Then add tripsin EDTA and incubate for two to six minutes following detachment winch by adding mammos sphere medium containing 10%FBS. Once the cells have detached, transfer them to a 15 milliliter conical centrifuge tube and spin it 200 times G at room temperature for five minutes.

Following the centrifugation, decant the senna. Then resus suspend the cells in one to five milliliters of manosphere medium, pipette up and down 10 times to break up the cell pellet. Next, run further the cell suspension to a 40 micron cell training cap filter and collect the flow through in the attached tube.

To obtain a single cell suspension, I pet a 20 microliter aliquot of the resuspended cells onto a hemo cytometer and use a microscope to examine it. If cell clusters are observed as seen here, use a syringe to massage the suspension in and out of a 25 gauge needle one or two times. Once the cells have been dispersed into a single cell suspension as shown here, recede to isolate CD 44 positive CD 24 negative cellular subsets via fluorescence activated cell sourcing or magnetic activated cell sourcing.

Use an LS column to positively select the CD 44 positive cells. Since the desired cells attached to the walls of the LS column, discard the flow through, then remove cells from the column. Apply five milliliters of buffer and apply and depress the plunger supplied with the column to flush out the desired cells.

Next, use an LD column to further purify the population by negative selection. Here the CD 24 positive cells attached to the LD columns. Collect the flow through which contains the CD 24 negative cells.

Next, using flow cytometry, confirm the phenotypes of all isolated cells. Using the Trian blue exclusion method, calculate the density of viable cells after appropriately diluting the cell suspension. Seed each well of a six well ultralow attachment plate with 500 to 4, 000 cells centimeter square in two milliliters of complete mammos sphere.Medium.

Incubate the plates taking care not to disturb them for five to 10 days until spheres are observed. Continue culturing until the spheres are at least 40 microns in diameter but have not yet started to turn.Apoptotic. Obtain human breast cancer tissue from patients undergoing surgery for the removal of breast tumors.

Store the tissue on ice for up to 24 hours in 50 milliliters. Sterile tubes in DMEM containing 100 units per milliliter, penicillin and 100 units per milliliter. Streptomycin working under a sterile tissue culture hood.

Transfer the sample into a 100 millimeter tissue culture dish containing a small volume of medium using sterile scissors, a scalpel and tweezers. Remove the adipose tissue. Add two to three milliliters of D-M-E-M-F 12 and using a sterile scalpel or razor blade, mince the sample until no large pieces remain.

Reeses bend the tissue pieces and 10 milliliters of prewarm DMEM containing proteolytic enzymes and incubated 37 degrees Celsius in a rotary shaker for one to three hours. When a stacking viable primate tumor cells using digestive enzymes, there is a critical trade off between cell death and sufficient extraction from cellular matrix to ins. Ensure success is essential to regularly monitor this digestion Every half an hour, pipet 20 microliters of suspension onto a hemo cytometer, and use a microscope to assess the degree of digestion.

Once the digestion is complete. Allow the fragments to sediment for five minutes. Then transfer the supinate to a 15 milliliter conical polypropylene tube.

Centrifuge your 200 times G for 10 minutes at room temperature. After the spin, carefully decant the supine agent and resuspend the cells in one to five milliliters of mammos sphere medium. Then prepare and plate single cell suspensions as described in the previous section.

At this video, ask the cells up and down through a 25 gauge syringe at a maximum of two times to disperse the cells if necessary. After the culture period, observe the cells at 40 times magnification under a microscope equipped with a digital camera. Acquire images of five random fields.

Once all of the images have been taken, use the acquisition software to determine the number of microspheres that are larger than 40 microns in diameter. Finally, calculate the metasphere forming efficiency By dividing the number of mamos spheres in each well by the number of cells seeded in each well times 100, I bet the medium containing the mamos spheres from each well into a 15 milliliter tube. Wash each well with PBS and add it to the collected medium.

Then centrifuge the cells at 115 times G for 10 minutes of room temperature. After the spin, discard the supinate andries. Suspend the pellet in 500 microliters of prewarm tryin EDTA incubate for two to three minutes.

Following the incubation, add 500 microliters of FBS to neutralize the tryin then centrifuge at 500 times G for five minutes. Once the spin has completed, discard the supinate and there spin the pellet in 100 microliters of mammos sphere, medium pipette up and down to disaggregate any spheres. Again, using a hemo cytometer, count the cells and determine whether they have dispersed into a single cell suspension.

If not, pass them through a 25 gauge syringe up to two times to obtain single cells, seed the cells into a new ultralow. Attachment six, well plate at the same density used in the primary generation after five to 10 days, count spheres larger than 40 microns and calculate calculates fear forming efficiency as before to estimate sphere forming efficiency. Atmospheres were grown from an epithelial estrogen positive CF seven and am mesenchymal triple negative MDA 2 3 1 cell line as described in this video, counts of mammos spheres larger than 40 microns provide an estimate of sphere forming efficiency for each cell line.

Note that the minimal cell fusion aggregation seen here was attained by low density plating here at 500 cells per centimeter square for MCF seven and 1000 cells per centimeter square for MDA 2 3 1. After watching this video, you should have a good understanding how to grow and count mammo spheres derived from a different cell lines or from surgical tumor samples. While attempting this procedure, it's important to remember to seed cells at low densities to ensure clonality and to ensure a high proportion of cells are viable when extracting cells from surgical samples.

In addition to this procedure, other methods like xenograft cell populations into immunocompromised mice should be performed in order to determine in vivo tumor genicity of tissues of interest.