Effects of Delta12-prostaglandin J2 on bone regeneration and growth factor expression in rats.
OBJECTIVE
Cyclopentenone prostaglandins have been shown to promote osteoblast differentiation in vitro. The aim of this study was to examine in a rat model the effects of local delivery of Delta(12)-prostaglandin J(2) (Delta(12)-PGJ(2)) on new bone formation and growth factor expression in (i) cortical defects and (ii) around titanium implants.


METHODS
Standardized transcortical defects were prepared bilaterally in the femur of 28 male Wistar rats. Ten microliters of Delta(12)-PGJ(2) at 4 concentrations (10(-9), 10(-7), 10(-5) and 10(-3) mol/l) in a collagen vehicle were delivered inside a half-cylindrical titanium chamber fixed over the defect. Contralateral defects served as vehicle controls. Ten days after surgery, the amount of new bone formation in the cortical defect area was determined by histomorphometry and expression of platelet-derived growth factor (PDGF)-A and -B, insulin-like growth factor (IGF)-I/II, bone morphogenetic protein (BMP)-2 and -6 was examined by immunohistochemistry. In an additional six rats, 24 titanium implants were inserted into the femur. Five microliters of carboxymethylcellulose alone (control) or with Delta(12)-PGJ(2) (10(-5) and 10(-3) mol/l) were delivered into surgically prepared beds prior to implant installation.


RESULTS
Delta(12)-PGJ(2) (10(-5) and 10(-3) mol/l) significantly enhanced new bone formation (33%, P<0.05) compared with control cortical defects. Delivery of Delta(12)-PGJ(2) at 10(-3) mol/l significantly increased PDGF-A and -B and BMP-2 and -6 protein expression (P<0.05) compared with control defects. No significant difference was found in IGF-I/II expression compared with controls. Administration of Delta(12)-PGJ(2) also significantly increased endosteal new bone formation around implants compared with controls.


CONCLUSIONS
Local delivery of Delta(12)-PGJ(2) promoted new bone formation in the cortical defect area and around titanium implants. Enhanced expression of BMP-2 and -6 as well as PDGF-A and -B may be involved in Delta(12)-PGJ(2)-induced new bone formation.
Damrongsri
Damrong
D
Department of Anatomy, School of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Geva
Sarah
S
Salvi
Giovanni E
GE
Cooper
Lyndon F
LF
Limwongse
Visaka
V
Offenbacher
Steven
S
D020341:Absorbable Implants; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis; D001861:Bone Regeneration / Q000187:drug effects*; D015921:Dental Implants; D005269:Femur / Q000601:surgery; D015870:Gene Expression / Q000187:drug effects; D048091:Guided Tissue Regeneration / Q000295:instrumentation / Q000379:methods; D007155:Immunologic Factors / Q000494:pharmacology*; D020007:Implants, Experimental; D008297:Male; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis; D015230:Prostaglandin D2 / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D019485:Bone Morphogenetic Proteins; D015921:Dental Implants; D007155:Immunologic Factors; D010982:Platelet-Derived Growth Factor; C499810:delta(12)-prostaglandin J(2); D015230:Prostaglandin D2