[Human chondrocyte responsiveness to bone morphogenetic protein-2 after their in vitro dedifferentiation: potential use of bone morphogenetic protein-2 for cartilage cell therapy].
OBJECTIVE
Cartilage has a limited capacity for healing after trauma. Autologous chondrocyte implantation is widely used for the treatment of patients with focal damage to articular cartilage. Chondrocytes are isolated from biopsy specimen, cultured in monolayers on plastic then transplanted over the cartilage defect. However, chondrocyte amplification on plastic triggers their dedifferentiation. This phenomenon is characterized by loss of expression of type II collagen, the most abundant cartilage protein. The challenge for autologous chondrocyte implantation is to provide patients with well-differentiated cells. The aim of the present study was to test the capability of bone morphogenetic protein (BMP)-2 to promote redifferentiation of human chondrocytes after their expansion on plastic.


METHODS
Chondrocytes extracted from nasal cartilage obtained after septoplasty were serially cultured in monolayers. After one, two or three passages, BMP-2 was added to the culture medium. The cellular phenotype was characterized at the gene level by using RT-PCR. The expression of genes coding for type II procollagen with the ratio of IIB/IIA forms, aggrecan, Sox9, osteocalcin and type I procollagen was monitored.


RESULTS
Our results show that BMP-2 can stimulate chondrogenic expression of the chondrocytes amplified on plastic, without inducing osteogenic expression. However, this stimulatory effect decreases with the number of passages.


CONCLUSIONS
The efficiency of autologous chondrocyte implantation could be improved by using chondrocytes treated with BMP-2 during their in vitro preparation.
Salentey
V
V
CNRS UMR5086, institut de biologie et chimie des protéines, université de Lyon-1, 69003 Lyon, France.
Claus
S
S
Bougault
C
C
Paumier
A
A
Aubert-Foucher
E
E
Perrier-Groult
E
E
Ronzière
M-C
MC
Freyria
A-M
AM
Galéra
P
P
Beauchef
G
G
Duterque-Coquillaud
M
M
Piperno
M
M
Damour
O
O
Herbage
B
B
Mallein-Gerin
F
F
D000293:Adolescent; D000328:Adult; D053674:Aggrecans / Q000096:biosynthesis / Q000235:genetics; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D054337:Cell Dedifferentiation / Q000187:drug effects; D064987:Cell- and Tissue-Based Therapy / Q000379:methods; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D024043:Collagen Type II / Q000096:biosynthesis / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics; D011347:Procollagen / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D055815:Young Adult
D053674:Aggrecans; D055396:Bone Morphogenetic Protein 2; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D011347:Procollagen; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D015675:Osteocalcin