Photoconvertible markers for study individual myoblast migration into the macrophage's colony

The success of myoblasts transplantation for regeneration in ischemic heart disease is largely determined by their interactions with resident macrophages. Studying their complex, contradictory, and poorly understood interactions requires the development of effective and reliable approaches for labeling and tracking myoblasts. Here, we present a useful approach for studying myoblast migration into macrophage colonies using cell-internalizable thermally treated polyelectrolyte microcapsules containing Rhodamine B (average size is approximately 3.2 ± 0.8 μm). The presented capsules exhibited fluorescence photoconversion properties, allowing for individual fluorescence coding of myoblast cells based on the number of converted and unconverted microcapsules when several capsules were internalized simultaneously. More than 70 % of C2C12 cells internalized the capsules (74 % of which contained more than two). The metabolic activity did not decrease to below 80 %, and proliferation and mobility did not change significantly. The initial cell density during the incubation with the capsules had a significant effect on the uptake efficiency. We tracked the migration of individually labeled myoblasts and their daughter cells into a macrophage colony (Raw 264.7) over 96 h. The marked cells purposefully moved with other myoblasts towards the macrophage colony, while the macrophages did not shorten the distance, despite their ability to migrate. This proposed approach may provide valuable insights for future research into the role and interaction of macrophages and myoblasts in cardiac muscle repair and regeneration.