Bone morphogenetic protein gene therapy using a fibrin scaffold for a rabbit spinal-fusion experiment.
OBJECTIVE
To observe the feasibility of using fibrin gel as a scaffold during rabbit spinal fusion with rat kidney cells carrying bone morphogenetic protein-2 (BMP-2) expression vector.


METHODS
Normal Rattusnorvegicus (rat) kidney (NRK) cells were transfected with pCMV-BMP2 vectors by using a nonviral reagent (FuGENE6), following which the transfected cells (1.5 x 10(7)) were encapsulated and evenly suspended in a fibrin scaffold, and implanted to either side of the L5-L6 intertransverse space for six test rabbits. For the control group (six rabbits), the transfected cells (1.5 x 10(7)) were added on and absorbed in a surgical gelatin sponge, and implanted in an analogous location. Radiographs of the spine of all animals were taken at six, ten, and 12 weeks subsequent to fusion surgery. Gross and histological examination of the fusion masses for all the animals were performed subsequent to animals having been sacrificed at 12 weeks.


RESULTS
Expression of BMP-2 was verified in the pCMV-BMP2 transfected NRK cells which were used for the subsequent rabbit experiment. For all 12 rabbits, no evidence of implanted-tissue rejection was seen during the postoperative course. Neither residual scaffold nor inflammatory granulation tissue was seen in the harvested spinal segments. For the six study-group rabbits, radiographic examinations revealed that four individuals (67%) featured prominent new-bone formation (good fusion), and two (33%) revealed moderate new-bone formation (fair fusion) at the implanted sites, whereas all six control-group rabbits revealed no evidence of new-bone formation (nonfusion) at the implanted sites. For the histological examinations, all animals in the study group revealed the presence of osseous tissue at the sites corresponding to the sites of radiographically demonstrated new-bone formation, whereas for the control group, no osseous tissue was seen at the implanted sites for any animal


CONCLUSIONS
Fibrin gel, being a biocompatible and biodegradable matrix, can encapsulate pCMV-BMP2 transfected NRK cells and adhere to the intertransverse lumbar-spine spaces of test rabbits. With the above characteristics, it plays an important role in the successful delivery of pCMV-BMP2-transfected cells for this rabbit spinal-fusion experiment. Being a natural matrix and able to be obtained readily from patients' own blood, fibrin gel seems to be a promising scaffold for future gene therapy in human trials.
Lee
Tao-Chen
TC
Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan. leetc@adm.cgmh.org.tw
Ho
Jih-Tsun
JT
Hung
Kuo-Sheng
KS
Chen
Wu-Fu
WF
Chung
Yueh-Hua
YH
Yang
Yu-Lin
YL
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D001861:Bone Regeneration / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D005337:Fibrin / Q000008:administration & dosage*; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000601:surgery; D011817:Rabbits; D051381:Rats; D013123:Spinal Fusion / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta; D005337:Fibrin