Image-Based Histological Evaluation of Scaffold-Free 3D Osteoblast Cultures

Abstract

Abstract:The analysis of tissue network characteristics and cell distribution using histological methods is widely used. However, image analysis still relies on manual evaluation methods, known as semi-quantitative analysis, which are time-consuming and to a certain degree user-specific. For this reason, automated imaging processing methods have an enormous potential to increase sample processing and reduce the variation that is caused by a user-specific evaluation. This work demonstrates the feasibility of using a semi-automated image analysis process based on the open source software framework ImageJ and the plug-in Angiogenesis Analyzer to evaluate the quantitative degree of tissue damage within 3D cell constructs after mechanical loading. Within a proof-of-concept study, the semi-automated approach was applied to calculate the Node-to-Free Ratio (N/F-Ratio) and perform a strut analysis for histological evaluation of mechanically compressed samples of human osteoblast-derived 3D constructs. The N/F-Ratio revealed a median value of 1.29 for the control, whereas the values for the mechanically compressed samples decreased to 0.97 for 20% compression, 0.85 for 40%, and 0.86 for 60%. The strut analysis indicated a decrease of the connected branches with increasing compression rate. The newly developed and time-saving processing workflow was successfully established and can be carried out using available, open source software solutions.