title: Analysis of the roles of microporosity and BMP-2 on multiple measures of bone regeneration and healing in calcium phosphate scaffolds.
abstract: Osteoinductive agents, such as BMP-2, are known to improve bone formation when combined with scaffolds. Microporosity (<20 μm) 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 scaffolds using multiple measures including bone volume fraction, radial distribution, and specific surface area. These measures were quantitatively compared by analyzing microcomputed tomography data and used to formally define and assess healing. A custom image segmentation 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 4-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.
authors.affiliation: Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Polak
authors.forename: Sheeny K Lan
authors.initials: SK
authors.lastname: Levengood
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Wheeler
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Maki
authors.forename: Sherrie G
authors.initials: SG
authors.lastname: Clark
authors.forename: Amy J Wagoner
authors.initials: AJ
authors.lastname: Johnson
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology; D002130:Calcium Phosphates / Q000494:pharmacology*; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009929:Organ Size / Q000187:drug effects; D016062:Porosity / Q000187:drug effects; D013499:Surface Properties / Q000187:drug effects; D034421:Sus scrofa; D013997:Time Factors; D054457:Tissue Scaffolds / Q000737:chemistry*; D014945:Wound Healing / Q000187:drug effects*; D055114:X-Ray Microtomography
chemical_list: D055396:Bone Morphogenetic Protein 2; D002130:Calcium Phosphates; C020243:calcium phosphate