title: Gene-modified adult stem cells regenerate vertebral bone defect in a rat model.
abstract: Vertebral compression fractures (VCFs), the most common fragility fractures, account for approximately 700,000 injuries per year. Since open surgery involves morbidity and implant failure in the osteoporotic patient population, a new minimally invasive biological solution to vertebral bone repair is needed. Previously, we showed that adipose-derived stem cells (ASCs) overexpressing a BMP gene are capable of inducing spinal fusion in vivo. We hypothesized that a direct injection of ASCs, designed to transiently overexpress rhBMP6, into a vertebral bone void defect would accelerate bone regeneration. Porcine ASCs were isolated and labeled with lentiviral vectors that encode for the reporter gene luciferase (Luc) under constitutive (ubiquitin) or inductive (osteocalcin) promoters. The ASCs were first labeled with reporter genes and then nucleofected with an rhBMP6-encoding plasmid. Twenty-four hours later, bone void defects were created in the coccygeal vertebrae of nude rats. The ASC-BMP6 cells were suspended in fibrin gel (FG) and injected into the bone void. A control group was injected with FG alone. The regenerative process was monitored in vivo using microCT, and cell survival and differentiation were monitored using tissue specific reporter genes and bioluminescence imaging (BLI). The surgically treated vertebrae were harvested after 12 weeks and subjected to histological and immunohistochemical (against porcine vimentin) analyses. In vivo BLI detected Luc-expressing cells at the implantation site over a 12-week period. Beginning 2 weeks postoperatively, considerable defect repair was observed in the group treated with ASC-BMP6 cells. The rate of bone formation in the stem cell-treated group was two times faster than that in the FG-treated group, and bone volume at the end point was 2-fold compared to the control group. Twelve weeks after cell injection the bone volume within the void reached the volume measured in native vertebrae. Immunostaining against porcine vimentin indicated that the ASC-BMP6 cells contributed to new bone formation. Here we show the potential of injections of BMP-modified ASCs to repair vertebral bone defects in a rat model. Our results could pave the way to a novel approach for the biological treatment of traumatic and osteoporosis-related vertebral bone injuries.
authors.affiliation: Department of Surgery and Cedars-Sinai Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Sheyn
authors.forename: Ilan
authors.initials: I
authors.lastname: Kallai
authors.forename: Wafa
authors.initials: W
authors.lastname: Tawackoli
authors.forename: Doron
authors.initials: D
authors.lastname: Cohn Yakubovich
authors.forename: Anthony
authors.initials: A
authors.lastname: Oh
authors.forename: Susan
authors.initials: S
authors.lastname: Su
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Da
authors.forename: Amir
authors.initials: A
authors.lastname: Lavi
authors.forename: Nadav
authors.initials: N
authors.lastname: Kimelman-Bleich
authors.forename: Yoram
authors.initials: Y
authors.lastname: Zilberman
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Hyun
authors.initials: H
authors.lastname: Bae
authors.forename: Zulma
authors.initials: Z
authors.lastname: Gazit
authors.forename: Gadi
authors.initials: G
authors.lastname: Pelled
authors.forename: Dan
authors.initials: D
authors.lastname: Gazit
mesh_terms: D053687:Adult Stem Cells / Q000378:metabolism / Q000637:transplantation*; D000818:Animals; D055418:Bone Morphogenetic Protein 6 / Q000235:genetics / Q000378:metabolism / Q000627:therapeutic use*; D001861:Bone Regeneration; D002478:Cells, Cultured; D005337:Fibrin / Q000737:chemistry; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D015675:Osteocalcin / Q000235:genetics; D011401:Promoter Regions, Genetic; D011859:Radiography; D011897:Random Allocation; D051381:Rats; D011923:Rats, Nude; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000627:therapeutic use; D013124:Spinal Injuries / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D013131:Spine / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology*; D050507:Subcutaneous Fat, Abdominal / Q000166:cytology; D013552:Swine; D013556:Swine, Miniature; D013623:Tail; D025801:Ubiquitin / Q000235:genetics
chemical_list: C525816:BMP6 protein, human; D055418:Bone Morphogenetic Protein 6; D011994:Recombinant Proteins; D025801:Ubiquitin; D015675:Osteocalcin; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005337:Fibrin