title: Bioluminescent and micro-computed tomography imaging of bone repair induced by fibrin-binding growth factors.
abstract: In this work we have evaluated the capacity of bone morphogenetic protein-2 (BMP-2) and fibrin-binding platelet-derived growth factor-BB (PDGF-BB) to support cell growth and induce bone regeneration using two different imaging technologies to improve the understanding of structural and organizational processes participating in tissue repair. Human mesenchymal stem cells from adipose tissue (hAMSCs) expressing two luciferase genes, one under the control of the cytomegalovirus (CMV) promoter and the other under the control of a tissue-specific promoter (osteocalcin or platelet endothelial cell adhesion molecule), were seeded in fibrin matrices containing BMP-2 and fibrin-binding PDGF-BB, and further implanted intramuscularly or in a mouse calvarial defect. Then, cell growth and bone regeneration were monitored by bioluminescence imaging (BLI) to analyze the evolution of target gene expression, indicative of cell differentiation towards the osteoblastic and endothelial lineages. Non-invasive imaging was supplemented with micro-computed tomography (μCT) to evaluate bone regeneration and high-resolution μCT of vascular casts. Results from BLI showed hAMSC growth during the first week in all cases, followed by a rapid decrease in cell number; as well as an increment of osteocalcin but not PECAM-1 expression 3weeks after implantation. Results from μCT show that the delivery of BMP-2 and PDGF-BB by fibrin induced the formation of more bone and improves vascularization, resulting in more abundant and thicker vessels, in comparison with controls. Although the inclusion of hAMSCs in the fibrin matrices made no significant difference in any of these parameters, there was a significant increment in the connectivity of the vascular network in defects treated with hAMSCs.
authors.affiliation: Catalonian Institute for Advanced Chemistry (IQAC-CSIC), Barcelona 08034, Spain; Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza 50018, Spain.
authors.forename: Olaia F
authors.initials: OF
authors.lastname: Vila
authors.affiliation: Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
authors.forename: Mikaël M
authors.initials: MM
authors.lastname: Martino
authors.affiliation: Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich (ETZH), Zürich 8093, Switzerland.
authors.forename: Laura
authors.initials: L
authors.lastname: Nebuloni
authors.affiliation: Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich (ETZH), Zürich 8093, Switzerland.
authors.forename: Gisela
authors.initials: G
authors.lastname: Kuhn
authors.affiliation: Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza 50018, Spain; Institute for Bioengineering of Catalonia (IBEC), Barcelona 08028, Spain.
authors.forename: Soledad
authors.initials: S
authors.lastname: Pérez-Amodio
authors.affiliation: Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich (ETZH), Zürich 8093, Switzerland.
authors.forename: Ralph
authors.initials: R
authors.lastname: Müller
authors.affiliation: Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hubbell
authors.affiliation: Catalonian Institute for Advanced Chemistry (IQAC-CSIC), Barcelona 08034, Spain; Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza 50018, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Rubio
authors.affiliation: Catalonian Institute for Advanced Chemistry (IQAC-CSIC), Barcelona 08034, Spain; Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza 50018, Spain. Electronic address: Jeronimo.Blanco@iqac.csic.es.
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Blanco
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D000077214:Becaplermin; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D001861:Bone Regeneration; D002454:Cell Differentiation; D042783:Endothelial Cells / Q000378:metabolism; D005109:Extracellular Matrix / Q000737:chemistry; D005337:Fibrin / Q000494:pharmacology*; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008163:Luminescent Measurements; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D010006:Osteoblasts / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis / Q000494:pharmacology*; D012886:Skull / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D055114:X-Ray Microtomography
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D005337:Fibrin; D008156:Luciferases
keywords: Angiogenesis; Bioluminescence imaging; Bone regeneration; Fibrin; Mesenchymal stem cell