Effects of Flow Rate on Mesenchymal Stem Cell Oxygen Consumption Rates in 3D Bone-Tissue-Engineered Constructs Cultured in Perfusion Bioreactor Systems

Michael L Felder,Vassilios I Sikavitsas,Robert L Shambaugh,Aaron D Simmons

doi:10.3390/fluids5010030

Michael L Felder, Vassilios I Sikavitsas + Show 2 more

Open Access

https://doi.org/10.3390/fluids5010030

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Journal: Fluids	Publication Date: Mar 8, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: University of Oklahoma, University of Wisconsin–Madison

Abstract

Bone grafts represent a multibillion-dollar industry, with over a million grafts occurring each year. Common graft types are associated with issues such as donor site morbidity in autologous grafts and immunological response in allogenic grafts. Bone-tissue-engineered constructs are a logical approach to combat the issues commonly encountered with these bone grafting techniques. When creating bone-tissue-engineered constructs, monitoring systems are required to determine construct characteristics, such as cellularity and cell type. This study aims to expand on the current predictive metrics for these characteristics, specifically analyzing the effects of media flow rate on oxygen uptake rates (OURs) of mesenchymal stem cells seeded on poly(L-lactic acid) (PLLA) scaffolds cultured in a flow perfusion bioreactor. To do this, oxygen consumption rates were measured for cell/scaffold constructs at varying flow rates ranging from 150 to 750 microliters per minute. Residence time analyses were performed for this bioreactor at these flow rates. Average observed oxygen uptake rates of stem cells in perfusion bioreactors were shown to increase with increased oxygen availability at higher flow rates. The residence time analysis helped identify potential pitfalls in current bioreactor designs, such as the presence of channeling. Furthermore, this analysis shows that oxygen uptake rates have a strong linear correlation with residence times of media in the bioreactor setup, where cells were seen to exhibit a maximum oxygen uptake rate of 3 picomoles O2/hr/cell.

Highlights

Current challenges in tissue engineering include finding reproducible means to create tissue-engineered constructs that are viable for transplants into humans
Previous work completed by Simmons predicted the flow within characteristics on the behavior of mesenchymal stem cells
Previous work completed by Simmons the bioreactor to be well by a to plug dispersion effects

Summary

Introduction

Current challenges in tissue engineering include finding reproducible means to create tissue-engineered constructs that are viable for transplants into humans. Existing methodologies require the destruction of constructs to determine their characteristics, such as cellularity and the development of extracellular matrices and cell phenotypes. The absence of appropriate predictive models has delayed the progress of tissue-engineered products from benchtop to market. While many solutions exist to determine characteristics in 2D systems, 3D systems lack predictive models that can accurately and consistently describe the important factors that will bring tissue-engineered bone constructs to a large-scale production. Several indicators of metabolic activity have shown predictive power, such as glucose consumption and oxygen consumption [1].

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