Oxygen-distribution within 3-D collagen I hydrogels for bone tissue engineering

Paul Wolff*, Laura Heimann, Gregor Liebsch, Robert J Meier, Martin Gutbrod, Martijn van Griensven, Elizabeth R Balmayor

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Web of Science)

Abstract

Tissue engineering (TE) approaches typically envisage the structural and functional reconstitution of previously damaged tissue in situ. An adequate three-dimensional environment is therefore of fundamental importance for the designated cells associated to the scaffold material. The sufficient supply with nutrients and oxygen in vitro and in vivo mark thereby critical challenges of TE. In this study, we intended to analyse the level of locally dissolved oxygen within 3-D cell-loaded collagen I gels in vitro. For the analysis of the oxygen levels in situ, we employed an optical fibre-based micro sensor setup, as well as a camera supported non-invasive optical sensor foil based technique. These complementary analytical tools enable the identification, localization, and temporal follow-up investigation of specified regions of interest within TE constructs. Human adipose-derived mesenchymal stem cells (hAdMSCs) cultured in collagen I gels under normoxic conditions were analysed periodically and kinetically up to 70 days - thereby revealing dynamic changes of the level of dissolved oxygen inside the gel constructs. Dependent on the applied cell concentration, the in vitro oxygen concentration (cO2) within the gels reached physiological ranges (7-9%) after 21 days, or 35 days of culture. The minimal cO2 was measured after 35 days in vitro, featuring an oxygen level of 4.8 ± 1.3%. Upon prolonged culture, a plateau-like status of the cO2 around 8-9% established, indicating a change in the physiological activity of the cells under investigation. The expression patterns of BCL2, CASP3 and MCM5 revealed significant differences among the proliferative and apoptotic stages of the cell-loaded samples at the investigated time points of 7 and 70 days in culture. In summary, these data show the temporary dynamic nature of the oxygen distribution in cell-loaded gel constructs. The applied technique is an ideal tool for the evaluation of multiple parameters affecting the oxygen distribution in vitro. We conclude that it takes 5 weeks for establishing an equilibrium of cO2. Levels reached in a 3-D gel construct are comparable with physiological oxygenation ranges in bone-associated tissues.

Original languageEnglish
Pages (from-to)422-427
Number of pages6
JournalMaterials Science & Engineering C-Materials for Biological Applications
Volume95
DOIs
Publication statusPublished - 1 Feb 2019
Externally publishedYes

Keywords

  • Animals
  • Apoptosis/physiology
  • Cattle
  • Cell Proliferation/physiology
  • Cells, Cultured
  • Collagen Type I/chemistry
  • Humans
  • Hydrogels/chemistry
  • Mesenchymal Stem Cells/cytology
  • Oxygen/chemistry
  • Tissue Engineering/methods
  • APOPTOSIS
  • TENSION
  • PROLIFERATION
  • MARROW HEMATOPOIETIC COMPARTMENT
  • HYPOXIA
  • GRADIENTS
  • Mesenchymal stem cells
  • 3-D gel construct
  • Collagen I
  • STEM-CELLS
  • MODELING PO(2) DISTRIBUTIONS
  • Bone tissue engineering
  • In vitro oxygenation level
  • DIFFERENTIATION
  • ADIPOSE

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