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Updated: Jul 10, 2026
Magnetic-Activated Cell Sorting Strategies to Isolate and Purify Synovial Fluid-Derived Mesenchymal Stem Cells from a Rabbit Model
Published on: August 10, 2018
Autofluorescence and cell size-based sorting eliminates senescent cells in synovial mesenchymal stem cells from
Kurea Sakuma1, Kentaro Endo1, Nobutake Ozeki1
1Center for Stem Cell and Regenerative Medicine, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Introduction:
The presence of senescent cells in synovial mesenchymal stem cell (MSC) preparations reduces the therapeutic efficacy of MSCs as a treatment for osteoarthritis (OA). Senolytic drugs can selectively kill senescent cells; however, their safety profiles remain a major concern. This study investigated whether cell sorting based on the increased autofluorescence (AF) and cell size of senescent MSCs could selectively eliminate senescent cells from human synovial MSC preparations derived from OA patients.
Methods:
Synovial MSCs isolated from six OA patients undergoing total knee arthroplasty were divided into three fractions using a fluorescence-activated cell sorter according to their AF and forward scatter (FSC) intensity: AFhigh, AFlowFSChigh, and AFlowFSClow. The cell diameter, morphology, and senescence-associated β-galactosidase (SA-β-gal) activity were evaluated as indicators of cellular senescence, and colony-forming ability and trilineage differentiation potentials (adipogenesis, osteogenesis, and chondrogenesis) were assessed as indicators of stem cell function.
Results:
The AFlowFSClow fraction had a smaller cell diameter, less enlarged and flattened morphology, and lower SA-β-gal positivity rate when compared with the AFhigh and AFlowFSChigh fractions. The AFlowFSClow cells formed more colonies and exhibited enhanced chondrogenic differentiation ability, as indicated by stronger safranin O staining, higher glycosaminoglycan/DNA ratios, and upregulation of chondrogenic genes. Adipogenic and osteogenic potentials were comparable among the three fractions.
Conclusions:
Sorting human synovial MSCs based on AF and cell size effectively eliminated senescent cells and enhanced the stem cell function of the MSC preparation. This drug-free strategy will improve both the safety and therapeutic efficacy of synovial MSC-based treatments for OA.
Insights
This study developed a drug-free method to remove senescent cells from mesenchymal stem cell (MSC) therapies for osteoarthritis (OA). Cell sorting based on autofluorescence and size effectively eliminated senescent cells, improving MSC function and therapeutic potential.
Area of Science:
- Biomedical Engineering
- Regenerative Medicine
- Cell Biology
Background:
- Senescent cells in mesenchymal stem cell (MSC) preparations reduce therapeutic efficacy for osteoarthritis (OA).
- Existing senolytic drugs raise safety concerns.
- A novel method to eliminate senescent MSCs is needed for OA treatment.
Purpose of the Study:
- To investigate cell sorting based on autofluorescence (AF) and cell size to selectively eliminate senescent cells from human synovial MSCs.
- To assess the impact of this sorting method on MSC stem cell function.
Main Methods:
- Human synovial MSCs from OA patients were sorted into three fractions (AFhigh, AFlowFSChigh, AFlowFSClow) using fluorescence-activated cell sorting based on AF and forward scatter (FSC).
- Senescence was evaluated by cell diameter, morphology, and SA-β-gal activity.
- Stem cell function was assessed by colony-forming ability and trilineage differentiation potential.
Main Results:
- The AFlowFSClow fraction exhibited reduced SA-β-gal activity, smaller cell diameter, and less enlarged morphology, indicating successful elimination of senescent cells.
- AFlowFSClow cells showed enhanced colony-forming ability and superior chondrogenic differentiation.
- Adipogenic and osteogenic differentiation potentials were similar across all fractions.
Conclusions:
- Cell sorting based on AF and size effectively removes senescent cells from human synovial MSCs.
- This drug-free approach enhances MSC stem cell function, improving potential for OA therapy.
- This method offers a safer and more effective strategy for MSC-based OA treatments.
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