Effects of low concentrated BMP-7 administered by co-cultivation or plasmid transfection on human osteoarthritic chondrocytes.
BACKGROUND
While BMP-7 has proven to be one of the most potent growth factors in cartilage tissue engineering, protein concentration and route of administration remain a matter of debate. Here we investigated the effects of a low concentration of BMP-7 on human osteoarthritic chondrocytes administered by protein co-cultivation and plasmid transfection.


METHODS
Freshly released (P0) or in vitro propagated chondrocytes (P2) were cultivated in a collagen type-I gel for 3 weeks in vitro or in nude mice. Seeded chondrocytes were treated with 50 ng/mL BMP-7 directly added to the medium or were subject to transient BMP-7 plasmid transfection prior to gel cultivation. Untreated specimens served as a control. After recovery, samples were investigated by histological and immunohistochemical staining and real-time PCR.


RESULTS
In vitro, collagen type-II protein production was enhanced, and it was stored mainly pericellularly. Collagen type-II and aggrecan gene expression were enhanced in both treatment groups. After nude mouse cultivation, col-II protein production was further enhanced, but specimens of the BMP-7 transfection group revealed a clustering of col-II positive cells. Gene expression was strongly upregulated, chondrocyte number was increased and the differentiated phenotype prevailed. In general, freshly released chondrocytes (P0) proved to be superior to chondrocytes pre-amplified in vitro (P2).


CONCLUSIONS
Both BMP-7 co-cultivation and plasmid transfection of human osteoarthritic chondrocytes led to improved cartilage repair tissue. Nevertheless, the col-II distribution following BMP-7 co-cultivation was homogeneous, while samples produced by transient transfection revealed a col-II clustering.
Gavenis
Karsten
K
Department of Orthopedic Surgery, Aachen University Hospital, Aachen, Germany. kgavenis@ukaachen.de
Schneider
Ulrich
U
Wallich
Reinhard
R
Mueller-Rath
Ralf
R
Schmidt-Rohlfing
Bernhard
B
Andereya
Stefan
S
D000818:Animals; D055419:Bone Morphogenetic Protein 7 / Q000008:administration & dosage*; D018929:Cell Culture Techniques; D019902:Chondrocytes / Q000187:drug effects* / Q000473:pathology*; D018920:Coculture Techniques; D006801:Humans; D008055:Lipids; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010003:Osteoarthritis / Q000473:pathology*; D010957:Plasmids; D014162:Transfection
D055419:Bone Morphogenetic Protein 7; D008055:Lipids; C086724:Lipofectamine