Establishing criteria for human mesenchymal stem cell potency

Area of Science:

• Stem Cell Biology
• Regenerative Medicine
• Biomarker Discovery

Background:

• Mesenchymal stem cells (MSCs) are crucial for tissue regeneration but their therapeutic potency varies significantly between donors.
• Standard criteria, such as adherence to plastic and International Society for Cellular Therapy (ISCT) guidelines, do not reliably predict MSC potency.
• Donor-derived variability in MSC growth capacity necessitates the identification of critical determinants for assessing potency.

Purpose of the Study:

• To identify critical determinants of mesenchymal stem cell (MSC) potency.
• To differentiate between high-growth capacity and low-growth capacity MSCs based on in vitro and in vivo attributes.
• To establish improved criteria for assessing MSC quality for therapeutic applications.

Main Methods:

• Isolation and characterization of bone marrow-derived MSCs from age- and sex-matched donors.
• Assessment of in vitro attributes including adherence to plastic, colony-forming efficiency, and long-term expansion capacity.
• Cell-surface biomarker analysis (including STRO-1 and platelet-derived growth factor receptor alpha) and mRNA transcript expression (TWIST-1, DERMO-1).
• Evaluation of in vivo potency through ectopic bone formation assays.

Main Results:

• MSCs could be categorized into high-growth capacity and low-growth capacity groups, with high-growth cells being smaller, having greater colony-forming efficiency, and longer telomeres.
• ISCT criteria did not distinguish between growth capacities, but STRO-1 and platelet-derived growth factor receptor alpha expression, along with TWIST-1 and DERMO-1 mRNA, were higher in high-growth MSCs.
• Both MSC groups produced similar levels of regenerative factors and exhibited multilineage differentiation, but high-growth MSCs formed double the volume of mineralized tissue in ectopic bone formation assays.
• High-growth capacity MSCs demonstrated superior in vivo bone-forming potential compared to low-growth capacity MSCs.

Conclusions:

• Additional phenotypic criteria beyond current ISCT standards are essential for accurately assessing MSC potency.
• STRO-1, platelet-derived growth factor receptor alpha, TWIST-1, and DERMO-1 show promise as biomarkers for identifying potent MSCs.
• The findings provide a basis for improved quality control of MSCs before therapeutic use, particularly for bone regeneration applications.