In situ positron emission tomography monitoring of endothelial cells embedded in perfused fibrin gels

• A PET imaging protocol for perfused 3D cell cultures has been devised.
• PET imaging allowed repeated thick 3D culture monitoring over long periods.
• 3D culture sample perfusion, viability and metabolism could be assessed with 18FDG.
• We tested the potential of PET imaging as a monitoring tool in tissue engineering.
• We examined PET imaging as an instrument for perfused bioreactor culture monitoring.

In tissue engineering, the continuous monitoring of cell and tissue cultures in vitro is crucial to assess their functional status over time. However, these constructs can be large, thick and non-transparent. Medical imaging techniques can allow real-time in situ monitoring of cell and tissue cultures in thick solid scaffolds. Here, human endothelial cells were embedded in fibrin gels that were continuously perfused by a culture medium. Positron emission tomography (PET) imaging was used to assess cell viability non-destructively over periods extending up to a few weeks. PET imaging protocols were adapted and validated to measure culture perfusion and cell metabolism using [18F]-fluorodeoxyglucose (18FDG). Cell densities down to 100,000 cells/mL were detectable after 12 h of culture and cell structures were localized within the fibrin gels after 1–2 weeks of culture. PET is a promising tool to investigate a wide range of cellular properties and reveal information on tissue development.