Quantitative image analysis of in vivo microstructure and growth factor effects in hydroxyapatite bone scaffolds

Osteoinductive agents, such as BMP-2, are known to improve bone formation when combined with scaffolds. Microporosity (<20µm) has also been shown to influence bone regeneration in calcium phosphate (CaP) scaffolds. However, many studies use only the term “osteoconductive” to describe the effects of BMP-2 and microporosity on bone formation, and do not assess the degree of healing that occurred. The objective of this study was to quantify the influence of BMP-2 and microporosity on bone regeneration and healing in biphasic calcium phosphate (BCP) scaffolds using multiple measures including bone volume fraction (BF), radial distribution (RBD), and specific surface area (SSA). These measures were quantitatively compared by analyzing micro-computed tomography data and used to formally define and assess healing. An accurate custom image segmentation program was developed that utilizes grayscale values, the periodicity of the scaffold, and 3D spatial features to segment background, bone, and scaffold pixels. This program was used to segment >100 samples, with 900 images each, that were implanted in porcine mandibular defects for 3, 6, 12, and 24 weeks. The assessment of healing presented in this work demonstrates the level of detail possible in evaluating scaffold-guided bone regeneration. The analysis shows that BMP-2 and microporosity accelerate healing up to four-fold. BMP-2 and microporosity were shown to have different and complementary roles in bone formation that effect the time needed for a defect to heal.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Bioengineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Polak, Samantha J.

Contributors dc:contributor

• Wagoner Johnson, Amy J.

• Hydroxyapatite
• Bone scaffold
• Bone morphogenetic protein 2 (BMP-2)
• Microporosity
• Micro computed tomography (Micro-CT)

Statement dc:rights

• © 2010 Samantha Jane Polak

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/18409

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/18409