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Standard Operating Procedure

SOP-LB-004: Flow Cytometry Characterization

Version1.0
Effective Date2026-02-21
Review Date2027-02-21
DepartmentAnalytical
Approved ByLab Director
Page1 of 5

1. Purpose

This procedure describes the immunophenotypic characterization of menstrual blood-derived mesenchymal stem cells (MenSCs) by flow cytometry according to ISCT minimal criteria.

2. Antibody Panels

Required Positive Markers (≥95%)

  • CD73 (APC or PE)
  • CD90 (FITC or PerCP)
  • CD105 (PE or APC)

Required Negative Markers (≤2%)

  • CD34 (FITC)
  • CD45 (PerCP or APC)
  • HLA-DR (PE)
Additional Markers (Optional)
  • CD44, CD29, CD13, CD166 - Additional MSC markers
  • CD14, CD19, CD11b - Hematopoietic lineage exclusion
  • CD106 (VCAM-1) - Activation marker

3. Materials

4. Sample Preparation

1

Harvest Cells

Harvest MenSCs using standard trypsinization (SOP-LB-003). Wash twice with PBS. Resuspend in FACS buffer at 1-5 × 10⁶ cells/mL.

Target cell count: 1 × 10⁶ cells per staining condition

2

Single Cell Suspension

Pass cells through 40 μm cell strainer to remove clumps. This is critical for accurate flow cytometry analysis.

3

Aliquot Samples

Distribute 100 μL cell suspension per tube:

  • Tube 1: Unstained control
  • Tube 2: Isotype control
  • Tube 3: Positive panel (CD73, CD90, CD105)
  • Tube 4: Negative panel (CD34, CD45, HLA-DR)
  • Tube 5: Full panel (all markers)

5. Staining Protocol

4

Add Antibodies

Add antibodies according to manufacturer's recommended dilution (typically 1:50 to 1:200). Mix gently.

MarkerFluorochromeTypical Dilution
CD73APC1:100
CD90FITC1:100
CD105PE1:100
CD34FITC1:50
CD45PerCP1:100
HLA-DRPE1:100
5

Incubate

Incubate in the dark at 4°C for 30 minutes. Protect from light throughout remaining steps.

6

Wash

Add 2 mL FACS buffer to each tube. Centrifuge at 300 × g for 5 minutes. Aspirate supernatant. Repeat wash once.

7

Resuspend

Resuspend cells in 300-500 μL FACS buffer. Add viability dye (7-AAD or DAPI) 5 minutes before analysis if required.

6. Flow Cytometry Acquisition

  1. Perform compensation using single-stain controls or compensation beads
  2. Set forward scatter (FSC) and side scatter (SSC) voltages using unstained control
  3. Create gates: FSC-A vs FSC-H for singlets, then SSC vs FSC for cell population
  4. Acquire minimum 10,000 events in the live cell gate
  5. Record mean fluorescence intensity (MFI) and % positive cells for each marker

7. Acceptance Criteria

MarkerISCT StandardAcceptance
CD73≥95%≥90%
CD90≥95%≥90%
CD105≥95%≥90%
CD34≤2%≤5%
CD45≤2%≤5%
HLA-DR≤2%≤5%

8. Reporting

Generate report including:

9. Revision History

VersionDateDescription
1.02026-02-21Initial release