title: Marrow stromal cell-based cyclooxygenase 2 ex vivo gene-transfer strategy surprisingly lacks bone-regeneration effects and suppresses the bone-regeneration action of bone morphogenetic protein 4 in a mouse critical-sized calvarial defect model.
abstract: This study evaluated whether the murine leukemia virus (MLV)-based cyclooxygenase-2 (Cox-2) ex vivo gene-transfer strategy promotes healing of calvarial defects and/or synergistically enhances bone morphogenetic protein (BMP) 4-mediated bone regeneration. Gelatin scaffolds impregnated with mouse marrow stromal cells (MSCs) transduced with MLV-expressing BMP4, Cox-2, or a control gene were implanted into mouse calvarial defects. Bone regeneration was assessed by X-ray, dual-energy X-ray absorptiometry, and histology. In vitro, Cox-2 or prostanglandin E(2) enhanced synergistically the osteoblastic differentiation action of BMP4 in mouse MSCs. In vivo, implantation of BMP4-expressing MSCs yielded massive bone regeneration in calvarial defects after 2 weeks, but the Cox-2 strategy surprisingly did not promote bone regeneration even after 4 weeks. Staining for alkaline phosphatase (ALP)-expressing osteoblasts was strong throughout the defect of animals receiving BMP2/4-expressing cells, but defects receiving Cox-2-expressing cells displayed weak ALP staining along the edge of original intact bone, indicating that the Cox-2 strategy lacked bone-regeneration effects. The Cox-2 strategy not only lacked bone-regeneration effects but also suppressed the BMP4-induced bone regeneration. In vitro coculture of Cox-2-expressing MSCs with BMP4-expressing MSCs in gelatin scaffolds reduced BMP4 mRNA transcript levels, suggesting that Cox-2 may promote BMP4 gene silencing in BMP4-expressing cells, which may play a role in the suppressive action of Cox-2 on BMP4-mediated bone formation. In summary, the Cox-2 ex vivo gene-transfer strategy not only lacks bone-regeneration effects but also suppresses the bone-regeneration action of BMP4 in healing of calvarial defects.
authors.affiliation: Musculoskeletal Disease Center (151), Jerry L. Pettis Memorial VA Medical Center, 11201 Benton Street, Loma Linda, CA 92357, USA. William.Lau@med.va.gov
authors.forename: K-H William
authors.initials: KH
authors.lastname: Lau
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gysin
authors.forename: Shin-Tai
authors.initials: ST
authors.lastname: Chen
authors.forename: Jon E
authors.initials: JE
authors.lastname: Wergedal
authors.forename: David J
authors.initials: DJ
authors.lastname: Baylink
authors.forename: Subburaman
authors.initials: S
authors.lastname: Mohan
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism*; D001861:Bone Regeneration / Q000502:physiology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D018014:Gene Transfer Techniques; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D012333:RNA, Messenger / Q000378:metabolism; D012886:Skull / Q000293:injuries / Q000378:metabolism*; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: C525718:BMP2 protein, human; C525809:BMP4 protein, human; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; D015232:Dinoprostone