Stem cells from human fat as cellular delivery vehicles in an athymic rat posterolateral spine fusion model.
BACKGROUND
Mesenchymal stem cells derived from human liposuction aspirates, termed processed lipoaspirate cells, have been utilized as cellular delivery vehicles for the induction of bone formation in tissue engineering and gene therapy strategies. In this study, we sought to evaluate the efficacy of bone morphogenetic protein (BMP)-2-producing adipose-derived stem cells in inducing a posterolateral spine fusion in an athymic rat model.


METHODS
Single-level (L4-L5) intertransverse spinal arthrodesis was attempted with use of a type-I collagen matrix in five groups of athymic rats, with eight animals in each group. Group I was treated with 5 x 10(6) adipose-derived stem cells transduced with an adenoviral vector containing the BMP-2 gene; group II, with 5 x 10(6) adipose-derived stem cells treated with osteogenic media and 1 microg/mL of recombinant BMP-2 (rhBMP-2); group III, with 10 microg of rhBMP-2; group IV, with 1 microg of rhBMP-2; and group V, with 5 x 10(6) adipose-derived stem cells alone. The animals that showed radiographic evidence of healing were killed four weeks after cell implantation and were examined with plain radiographs, manual palpation, microcomputed tomography scanning, and histological analysis.


RESULTS
All eight animals in group I demonstrated successful spinal fusion, with a large fusion mass, four weeks postoperatively. Furthermore, group-I specimens consistently revealed spinal fusion at the cephalad level (L3 and L4), where no fusion bed had been prepared surgically. In contrast, despite substantial BMP-2 production measured in vitro, group-II animals demonstrated minimal bone formation even eight weeks after implantation. Of the groups treated with the application of rhBMP-2 alone, the one that received a relatively high dose (group III) had a higher rate of fusion (seen in all eight specimens) than the one that received the low dose (group IV, in which fusion was seen in four of the eight specimens). None of the group-V animals (treated with adipose-derived stem cells alone) demonstrated successful spine fusion eight weeks after the surgery.


CONCLUSIONS
Adipose-derived stem cells show promise as gene transduction targets for inducing bone formation to enhance spinal fusion in biologically stringent environments.
Hsu
Wellington K
WK
K4/703, 600 Highland Avenue, Box 7375 Clinical Science Center-H4, Madison, University of Wisconsin, WI 53792-3284, USA. wkhsu@yahoo.com
Wang
Jeffrey C
JC
Liu
Nancy Q
NQ
Krenek
Lucie
L
Zuk
Patricia A
PA
Hedrick
Marc H
MH
Benhaim
Prosper
P
Lieberman
Jay R
JR
D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage* / Q000096:biosynthesis / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D045164:Mesenchymal Stem Cell Transplantation; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D011897:Random Allocation; D051381:Rats; D011923:Rats, Nude; D011994:Recombinant Proteins / Q000008:administration & dosage; D013123:Spinal Fusion; D023822:Tissue Engineering / Q000379:methods; D014161:Transduction, Genetic / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000008:administration & dosage* / Q000096:biosynthesis / Q000235:genetics
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta