detection of intracellular calcium signaling in the magnetically isolated vascular wall cd34+ stem cells

Isolation and Magnetic Separation of Murine CD34&lt;sup&gt;+&lt;/sup&gt; Stem Cells from the Vascular Wall

The vascular wall plays a pivotal role in vascular development, homeostatic regulation, and the progression of vascular diseases. In recent years, numerous studies have unveiled the presence of various stem cell lineages in arteries. In 2004, Professor Qingbo Xu&#39;s group first reported the existence of vascular stem/progenitor cells in the periphery of the adult vascular wall, expressing CD34, Sca-1, c-kit, and Flk-11. These vascular stem cells exhibit multidirectional differentiation and proliferation potential. Under normal conditions, they remain relatively quiescent; however, when activated by specific factors, they can differentiate into smooth muscle cells, endothelial cells, and fibroblasts. Alternatively, they can regulate the perivascular matrix and microvessel formation through paracrine effects to promote the repair or remodeling of injured vessels2,3,4,5,6. Recently, resident CD34+ stem cells in the vascular wall were found to play a role in endothelial cell regeneration after femoral artery guidewire injury2. Consequently, the isolation and quantification of CD34+ VW-SCs and the examination of the basic biological characteristics of CD34+ stem cells are crucial for further studying the signal pathways involved in the regulation of CD34+ VW-SCs.
Various methods for cell separation are currently available, including techniques based on cell culture characteristics or physical properties of cells such as density gradient centrifugation, which results in sorted cells containing many non-target cells and relatively low purity7,8,9,10,11,12. Another commonly used technique is fluorescence/magnetic-assisted cell sorting. Fluorescence-activated cell sorting (FACS) is a complex system with high technical requirements, and it is relatively expensive, time-consuming, and potentially affects the activity of sorted cells13,14. However, magnetic-activated cell sorting (MACS) is more efficient and convenient, with a high recovery rate and cell activity and less impact on downstream applications8. Therefore, in this protocol, we applied MACS to purify CD34+ VW-SCs and further identified the cells by flow cytometry. The establishment of MACS-based isolation methods for studying vascular wall stem cells would be invaluable. Firstly, it permits experimental genetic and cell biological studies. Secondly, efficient isolation and culture of vascular wall resident stem cells allow systematic assessment and screening of signaling factors regulating stem cell functions. Thirdly, identification of crucial phenotypes in stem cells provides important &#39;quality control&#39; in assessing cell status. Thus, identifying methods to purify could be useful for similar applications to analogous stem cells derived from vessels.
This report provides a detailed demonstration of a stable and reliable method for the culture of CD34+ VW-SCs, including cell identification and functional assessment performed by flow cytometry, immunofluorescence staining, and Ca2+ signaling measurement. This study provides a basis for further in-depth research on the function of CD34+ VW-SCs and their regulatory mechanisms in physiological and pathological conditions.

Author Spotlight: Enhanced Isolation and Characterization of Vascular Wall Resident Murine CD34&lt;sup&gt;+&lt;/sup&gt; Stem Cells Using Magnetic Bead Screening-Coupled Flow Cytometry

Immunomagnetic Isolation of the Vascular Wall-Resident CD34+ Stem Cells from Mice

Resident vascular wall CD34+stem cells are increasingly recognized for their crucial role in regulating vascular remodeling post-injury. Establishing a stable and efficient method to culture functional CD34+cells is essential for further investigating the participating mechanisms under various physiological and pathological conditions. This technique combines magnetic bead screening and flow cytometry to purify the primary cultured resident CD34+stem cells.Then, the purified cells can be functionally identified through immunofluorescent staining and calcium imaging. Due to the phenotypical and functional heterogeneity of resident CD34+stem cells in the vascular nerve wall, it will be necessary to identify the specific subcellular type of resident vascular CD34+cells. We present a refined methodology for the culture, identification, and the functional assessment of vascular wall-resident CD34+stem cells.This novel approach encompasses magnetic sorting, flow cytometry, immunofluorescence staining, and calcium signaling measurement. By employing these techniques, our study establishes a solid foundation for the future comprehensive investigations into the function under regulation of recipient CD34+stem cells under both physiological and pathological conditions.

Detection of Intracellular Calcium Signaling in the Magnetically Isolated Vascular Wall CD34+ Stem Cells

To begin, isolate the resident vascular wall CD34-positive stem cells from murine models. Obtain pure cells by magnetic activated cell sorting and characterize them. For detecting calcium signaling, obtain a coverslip pre-seeded with the cells and wash it once with PBS.Then incubate the cells with Fura 2-AM and Tyrode solution for 30 minutes in the dark. To remove the dye, incubate the cells with Tyrode solution for 10 minutes. Then mount the chamber on the stage of an inverted fluorescence microscope, open the main window and go to the grab settings dialogue and camera page.Press the live button for the live image display. To acquire images, draw several freehand lines to circle the cells with different colors and predefine the regions of interest. Fluorescence microscopy demonstrated that ATP administration increased the intracellular calcium levels in the isolated vascular wall CD34-positive stem cells.

detection-intracellular-calcium-signaling-magnetically-isolated

Research

JoVE Journal

Medicine

Resident CD34+ vascular wall-resident stem and progenitor cells (VW-SCs) are increasingly recognized for their crucial role in regulating vascular injury and repair. Establishing a stable and efficient method to culture functional murine CD34+ VW-SCs is essential for further investigating the mechanisms involved in the proliferation, migration, and differentiation of these cells under various physiological and pathological conditions. The described method combines magnetic bead screening and flow cytometry to purify primary cultured resident CD34+ VW-SCs. The purified cells are then functionally identified through immunofluorescence staining and Ca2+ imaging. Briefly, vascular cells from the adventitia of the murine aorta and mesenteric artery are obtained through tissue block attachment, followed by subculturing until reaching a cell count of at least 1 &#215; 107. Subsequently, CD34+ VW-SCs are purified using magnetic bead sorting and flow cytometry. Identification of CD34+ VW-SCs involves cellular immunofluorescence staining, while functional multipotency is determined by exposing cells to a specific culture medium for oriented differentiation. Moreover, functional internal Ca2+ release and external Ca2+ entry is assessed using a commercially available imaging workstation in Fura-2/AM-loaded cells exposed to ATP, caffeine, or thapsigargin (TG). This method offers a stable and efficient technique for isolating, culturing, and identifying vascular wall-resident CD34+ stem cells, providing an opportunity for in vitro studies on the regulatory mechanisms of VW-SCs and the screening of targeted drugs.

This study has established a stable and efficient method for the isolation, culture, and functional determination of vascular wall-resident CD34+ stem cells (CD34+ VW-SCs). This easy-to-follow and time-effective isolation method can be utilized by other investigators to study the potential mechanisms involved in cardiovascular diseases.

Resident CD34+ vascular wall-resident stem and progenitor cells (VW-SCs) are increasingly recognized for their crucial role in regulating vascular injury ...

Murine Aortal and Mesenteric Arteries Isolation and Culture to Separate CD34+ Stem Cells for Cardiovascular Studies

To begin, place an anesthetized mouse on the operating table. Using sterile ophthalmic scissors and forceps, open the thoracic and abdominal cavities. This will expose the heart and the intestines.Carefully dissect the mesenteric arteries and the aorta separately. Rinse the mesenteric arteries in PBS and transfer them to a 10-centimeter Petri dish containing 1%penicillin-streptomycin-amphotericin B solution. Similarly, rinse the aorta and transfer it to another Petri dish containing the same solution.Quickly remove all the fat around the aorta and the mesenteric arteries. After rinsing twice, place the arteries under a stereo microscope in a tissue culture hood. Carefully make a longitudinal cut along the arteries.Then using fine forceps, peel off the outer layer of the aorta and the first branch of the mesenteric arteries. Place the outer layer in a 3.5 centimeter Petri dish containing 0.1 to 0.2 milliliters of culture medium, and chop it into tiny pieces of about one cubic millimeter. Transfer the tissue pieces into a gelatin-coated T-25 flask.Place the flask vertically in an incubator at 37 degree Celsius with 5%carbon dioxide. After three hours, add five milliliters of DMEM high glucose growth medium to the flask to submerge all the tissue blocks.

Magnetic Separation of Vascular Wall-Resident CD34+ Stem Cells Isolated from Murine Aortal and Mesenteric Arteries for Cardiovascular Studies

To begin, isolate and culture the outer layer of the aorta and the first branch of the mesenteric arteries isolated from the anesthetized mouse. Once the cells become 80%confluent, centrifuge the dissociated cell suspension at 300G for five minutes at room temperature, discard the supernatant completely and resuspend the cell pellet in 98 microliters of sorting buffer per 10 million total cells. After the addition of CD34 antibody, incubate the cells in the dark for 30 minutes at four degrees Celsius.To wash the cells, add two milliliters of sorting buffer to the cells, and centrifuge at 300G for 10 minutes. After discarding the supernatant, resuspend the cells in 80 microliters of sorting buffer. Then add 20 microliters of Anti-FITC MicroBeads to the cell suspension.After washing and centrifuging the cells as demonstrated previously, resuspend the cells in one milliliter of sorting buffer. Next, position a magnetic separation column within the magnetic field of a separator, and place a collection tube beneath the column. After rinsing with 500 microliters of buffer, load the cell suspension into the column and collect the flow through containing unlabeled cells in the collection tube.Remove the column from the separator and place it on a fresh 15 milliliter centrifuge tube. Introduce 500 microliters of sorting buffer into the column and push the plunger into the column to flush out the magnetically labeled cells.

Characterization of the Magnetically Isolated CD34+ Stem Cells for Cardiovascular Studies

To characterize the CD34+stem cells isolated from the murine aorta and mesenteric arteries, perform tissue block culture and obtain the cells by magnetic separation. To detect the endothelial cell in fibroblast cell marker expression after differentiation, observe the cells at 40x magnification with laser excitations of 488 nanometers. After trypsinizing the cells, pellet them by centrifugation and resuspend in 100 microliters of sorting buffer.Then incubate them with anti-mouse CD16/CD32 monoclonal antibodies at four degrees Celsius for five minutes. Then add two microliters of each desired monoclonal antibody for immunofluorescent staining and incubate again at 4 degrees Celsius for 10 minutes. Wash the cells twice with one milliliter of buffer.After centrifuging the cells as demonstrated, remove the supernatant and resuspend the cells in 300 microliters of buffer. Transfer the cells to the flow tubes and place them in an ice box. Run flow cytometry to check the percentage of differentiated cells.Flow cytometric evaluation confirmed the high purity of isolated CD34+vascular wall stem cells. Cellular immunofluorescent staining showed that the isolated CD34+stem cells predominantly expressed stem cell markers, CD34, c-kit, and Flk-1. Flow cytometry also confirmed that the isolated CD34+stem cells possessed the ability to differentiate into endothelial cells as well as fibroblasts in vitro.