Effect of recombinant human BMP-2 on the repair of cricoid cartilage defects in young and adult rabbits: a comparative study.
OBJECTIVE
The study evaluated the possible differences in the repair of cricoid cartilage defects treated with recombinant human BMP-2 in young and adult rabbits.


METHODS
A cricoid defect rabbit model was used. Thirty rabbits were randomly divided into eight groups. Two groups of young rabbits and two groups of adult rabbits were treated with rhBMP-2 delivered on an absorbable collagen sponge, while the other two groups of young rabbits and two groups of adult rabbits were used as controls. The rabbits were killed at 1 week or 4 weeks after surgery. A histomorphometric analysis and an evaluation of the expression of collagen types I, II, and X, and proliferating cell nuclear antigen as well as a study of distribution of calcified matrix, were performed.


RESULTS
rhBMP-2 induced a marked chondrogenesis in both experimental age groups. However, in young rabbits the newly formed cartilage appeared more elongate, and the length of perichondrium involved was greater. The host cricoid cartilage of adult rabbits was calcified in large areas and displayed a strong matrix expression of collagen type X as well as collagen type I in the perichondrium, compared to the cricoid of young rabbits. In spite of these differences no immunohistochemical differences were found in the newly formed cartilage of both age groups treated with rhBMP-2. The cricoid cartilage defect was filled with new bone at 4 weeks in both age groups treated with rhBMP-2. New bone tissue had a well-defined trabecular structure.


CONCLUSIONS
rhBMP-2 triggers appositional cartilage growth from the cricoid perichondrium of young rabbits more easily than from that of adult rabbits. The new bone induced by rhBMP-2 showed a similar immunohistochemical and morphological pattern in both age groups of rabbits.
Tcacencu
Ion
I
Department of Otorhinolaryngology, Karolinska University Huddinge Hospital, Karolinska Institutet, Stockholm, Sweden. tcacencu@yahoo.co.uk
Carlsöö
Bengt
B
Stierna
Pontus
P
D000328:Adult; D000367:Age Factors; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects*; D024042:Collagen Type I / Q000096:biosynthesis; D024043:Collagen Type II / Q000096:biosynthesis; D024121:Collagen Type X / Q000096:biosynthesis; D003413:Cricoid Cartilage / Q000187:drug effects* / Q000293:injuries* / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008297:Male; D010012:Osteogenesis / Q000187:drug effects; D011817:Rabbits; D011897:Random Allocation; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000008:administration & dosage / Q000494:pharmacology*; D014945:Wound Healing / Q000187:drug effects*; D014947:Wounds and Injuries / Q000188:drug therapy
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D024042:Collagen Type I; D024043:Collagen Type II; D024121:Collagen Type X; D019394:Ki-67 Antigen; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta