title: Effects of Immobilized BMP-2 and Nanofiber Morphology on In Vitro Osteogenic Differentiation of hMSCs and In Vivo Collagen Assembly of Regenerated Bone.
abstract: Engineering bone tissue is particularly challenging because of the distinctive structural features of bone within a complex biochemical environment. In the present study, we fabricated poly(L-lactic acid) (PLLA) electrospun nanofibers with random and aligned morphology immobilized with bone morphogenic protein-2 (BMP-2) and investigated how these signals modulate (1) in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs) and (2) in vivo bone growth rate, mechanical properties, and collagen assembly of newly formed bone. The orientation of adherent cells followed the underlying nanofiber morphology; however, nanofiber alignment did not show any difference in alkaline phosphate activity or in calcium mineralization of hMSCs after 14 days of in vitro culture in osteogenic differentiation media. In vivo bone regeneration was significantly higher in the nanofiber implanted groups (approximately 65-79%) as compared to the defect-only group (11.8 ± 0.2%), while no significant difference in bone regeneration was observed between random and aligned groups. However, nanoindentation studies of regenerated bone revealed Young's modulus and contact hardness with anisotropic feature for aligned group as compared to random group. More importantly, structural analysis of collagen at de novo bone showed the ability of nanofiber morphology to guide collagen deposition. SEM and TEM images revealed regular, highly ordered collagen assemblies on aligned nanofibers as compared to random fibers, which showed irregular, randomly organized collagen deposition. Taken together, we conclude that nanofibers in the presence of osteoinductive signals are a potent tool for bone regeneration, and nanofiber alignment can be used for engineering bone tissues with structurally assembled collagen fibers with defined direction.
authors.forename: Sajeesh Kumar Madhurakkat
authors.initials: SK
authors.lastname: Perikamana
authors.forename: Jinkyu
authors.initials: J
authors.lastname: Lee
authors.forename: Taufiq
authors.initials: T
authors.lastname: Ahmad
authors.affiliation: §Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, Ohio 43210, United States.
authors.forename: Yonghoon
authors.initials: Y
authors.lastname: Jeong
authors.affiliation: §Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, Ohio 43210, United States.
authors.forename: Do-Gyoon
authors.initials: DG
authors.lastname: Kim
authors.affiliation: ∥Division of Bioengineering, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea.
authors.forename: Kyobum
authors.initials: K
authors.lastname: Kim
authors.forename: Heungsoo
authors.initials: H
authors.lastname: Shin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D048430:Cell Shape / Q000187:drug effects; D003094:Collagen / Q000378:metabolism*; D006801:Humans; D055767:Immobilized Proteins / Q000494:pharmacology; D020007:Implants, Experimental; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008813:Mice, Inbred ICR; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D010012:Osteogenesis / Q000187:drug effects*; D011859:Radiography; D012038:Regeneration / Q000187:drug effects; D012886:Skull / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D055396:Bone Morphogenetic Protein 2; D055767:Immobilized Proteins; D003094:Collagen
keywords: bone morphogenic proteins; bone tissue engineering; collagen assembly; contact guidance; electrospun nanofibers