Standard Guide for Micro-computed Tomography of Tissue-Engineered Scaffolds

Importancia y uso:

4.1 X-ray microcomputed tomography (microCT) is a nondestructive three-dimensional imaging method that can be used to reconstruct the microarchitecture of a tissue-engineered medical product (TEMP) scaffold that may or may not contain ingrown tissue. MicroCT was first developed to study ceramics for the auto industry and adapted for bone morphology at the microscale (Feldkamp et al., 1989) (2). More recently, the imaging method has been adapted for in vivo applications and studies of multiple natural and synthetic materials.

4.2 Alternate characterization methods for assessing scaffold microarchitecture and tissue ingrowth are limited by their two-dimensional nature (e.g., microscopy) and low depth of penetration (e.g., optical coherence tomography), even though their resolution may be increased over microCT. However, microCT is an ideal imaging choice for studying scaffold microarchitecture and tissue ingrowth because it is nondestructive, provides scaffold assessments based on direct measurements rather than stereological methods, offers the ability to perform longitudinal imaging, and can be conducted at length scales relevant to cells and cell attachment (i.e., 1 micron to hundreds of microns).

4.3 The microarchitecture of tissue-engineered scaffolds plays a critical role in providing structural support and/or facilitating cell adhesion, proliferation, and phenotype as well as matrix deposition. These parameters are essential elements of the tissue engineering strategy. During scaffold degradation, either in vitro or in vivo, changes to the microarchitecture continue to influence the eventual tissue repair. Therefore, it is critical to characterize the microarchitecture over time. Such characterization can aid the optimal design of TEMP scaffolds, establishment of manufacturing consistency, and monitoring of scaffold structure and/or tissue response.

4.4 This guide provides a compendium of information related to the use of microCT for the structural assessment of scaffold microarchitecture and tissue ingrowth. While the microarchitecture of tissue-engineered scaffolds as well as changes to it over time can be assessed using multiple methods (e.g., such as those described in Guide F2450), this guide focuses on unique considerations for conducting the microCT analyses.

4.5 The user of this guide is provided with considerations for each aspect of a complete microCT study including sample preparation, image acquisition, assessing image quality and artifacts, post-processing, and image interpretation based on the specific application.

4.6 This standard provides imaging and analysis considerations for the following broad types of applications: (a) scaffold microarchitecture analysis in vitro either before or after different stages of degradation, (b) ex vivo analysis of scaffold microarchitecture following partial degradation in an in vivo animal model, (c) deriving microarchitectural information when multiple materials are used in the scaffold, and (d) differentiating between scaffold microarchitectural changes and new tissue ingrowth.

4.7 The information provided in this standard guide is not intended as a test method for microCT characterization because the user’s specific application and experimental design will significantly influence the imaging methodology and interpretation.

Subcomité:

F04.42

Referida por:

F3510-21, F2952-22, F3659-24

Volúmen:

13.02

Número ICS:

11.100.99 (Other standards related to laboratory medicine)

Palabras clave:

image analysis; microarchitecture; microCT; scaffold;