Initial cell plating density affects properties of human primary synovial mesenchymal stem cells

Area of Science:

• Orthopedics and Regenerative Medicine
• Stem Cell Biology
• Biotechnology

Background:

• Synovial mesenchymal stem cells (MSCs) are promising for cartilage and meniscus regeneration due to their proliferative and chondrogenic capacities.
• Current methods for preparing primary synovial MSCs involve either low-density or high-density cell plating.
• The impact of initial cell density on synovial MSC properties requires further investigation.

Purpose of the Study:

• To investigate the effects of initial cell plating density on the proliferation, surface markers, and multipotentiality (including chondrogenesis) of primary synovial MSCs.
• To determine the optimal plating density for obtaining synovial MSCs with high chondrogenic potential for regenerative applications.

Main Methods:

• Human synovial tissue from osteoarthritis patients was processed to isolate nucleated cells.
• Cells were plated at three different densities (10^3, 10^4, or 10^5 cells/60-cm^2 dish) and cultured for 14 days.
• Proliferation, surface marker expression (including CD105), chondrogenesis (pellet weight), adipogenesis (oil red-O staining), and calcification (alizarin red staining) were assessed.

Main Results:

• Cell proliferation and fold increase were negatively correlated with plating density.
• Low-density plating (10^3 cells/dish) resulted in distinct cell colonies and higher chondrogenic potential (indicated by cartilage pellet weight).
• High-density plating (10^5 cells/dish) promoted adipogenesis and calcification, with CD105 expression negatively related to plating density.

Conclusions:

• Initial cell plating density significantly influences the characteristics of primary synovial MSCs.
• Low-density plating is superior for enhancing synovial MSC proliferation and chondrogenic potential, making it ideal for cartilage regeneration.
• High-density plating favors osteogenic and adipogenic differentiation, suggesting differential applications for MSCs based on initial culture conditions.