Labeling stem cells with fluorescent dyes for non-invasive detection with optical imaging

Area of Science:

• Biomedical imaging
• Cell biology
• Regenerative medicine

Background:

• Optical imaging (OI) is a valuable, cost-effective technique for in vivo monitoring of stem cell therapies.
• Current methods involve ex vivo labeling of stem cells with fluorescent dyes for tracking their distribution.
• This study focuses on optimizing fluorescent labeling of human stem cells for enhanced visualization.

Purpose of the Study:

• To demonstrate a straightforward method for fluorescently labeling human mesenchymal stem cells (hMSC) and human embryonic stem cells (hESC).
• To investigate the uptake mechanism of lipophilic fluorescent dyes by stem cells.
• To identify factors that enhance labeling efficiency for improved in vivo tracking.

Main Methods:

• Human mesenchymal stem cells (hMSC) were labeled using the lipophilic dye DiD.
• Human embryonic stem cells (hESC) were labeled using the FDA-approved dye Indocyanine Green (ICG).
• Cell labeling was performed via incubation, with variations in media (serum-free vs. serum-containing) and the addition of Protamine Sulfate.

Main Results:

• Successful labeling of hMSC with DiD and hESC with ICG was achieved.
• Dye uptake occurs through adherence and diffusion across the cell membrane.
• Labeling efficiency was enhanced in serum-free media and with the addition of Protamine Sulfate.

Conclusions:

• Fluorescent labeling of stem cells using DiD and ICG is an effective method for in vivo tracking.
• Optimized labeling conditions, including serum-free media and Protamine Sulfate, significantly improve dye uptake.
• This technique provides a robust tool for monitoring stem cell-based therapies in preclinical research.