# Imaging Oxygen Concentrations in Bone Scaffolds during Cellular Activity and Fluid Perfusion

## TL;DR

This study uses imaging to track oxygen levels in bone scaffolds during cell activity and fluid flow, aiming to improve large-scale tissue engineering.

## Contribution

A novel method for modulating and imaging oxygen concentrations in bone scaffolds during perfusion and cellular activity is introduced.

## Key findings

- Yeast cells in scaffolds significantly deplete oxygen in the center, matching reaction-diffusion model predictions.
- Pumping fresh medium through scaffolds restores oxygen levels in a reproducible manner.
- The method provides a foundation for future in vivo oxygen imaging studies using localized light sources and perfusion.

## Abstract

Developing bone replacement scaffolds has been a driving
ambition
of regenerative medicine. Although great progress has been achieved
for small scaffolds, the real clinical need is for large scaffolds
>5 mm. Oxygenating these scaffolds is challenging, as slow diffusion
rates lead to necrotic regions in the scaffold core. In this work,
we modulate in vitro oxygen concentration in a scaffold
in a flow chamber using an external perfusion pump while imaging oxygen
concentrations below the scaffolds. With no external flow, yeast cells
growing in the scaffold deplete oxygen, especially from the center,
with concentrations reaching a steady state consistent with reaction-diffusion
models. The oxygen is restored via pumping fresh medium through the
scaffold. The oxygen profiles are highly reproducible from cycle to
cycle. This lays the groundwork for future in vivo oxygen imaging studies using localized light sources and external
perfusion pumps for modulation.