| Costal cartilage is widely used in ear reconstruction because it is obtained and carved easily. Although costal cartilage autograft does not produce rejections, it will cause such poor surgery consequences as deformation, contracture and not symmetry to contralateral ear. Insulin-like growth factor-Ⅰ(IGF-Ⅰ) is one of the important growth factors which regulars the synthesis of cartilage.It is confirmed to stimulate the division growth of cells and increase the synthesis of proteoglycans and typeⅡcollagen in vitro. But there is no record on how IGF-Ⅰwork to autografted costal cartilage in vivo.Objective:To evaluate the function of IGF-Ⅰto autografted costal cartilage which is combined with perichondrium in proliferation and metabolism.Materials and MethodsLaboratory animals and assignment:There are totally 24 healthy New Zealand white rabbits. Twelve of them are young(1 month in age, lkg in weight). And the others are adult(6 month in age,2.5kg in weight). The sex is not care. All of the rabbits are divided into young groug and adult group by age. In each group, the rabbits are randomly divided into surgical control group(surgical CG), 10ng/ml experimental group(10ng/ml EG) and 50ng/ml experimental group(50ng/ml EG).There are 4 rabbits in each group. In surgical CG, the costal cartilage is directly autografted to the back subcutaneous zone. In 10ng/ml EG, the costal cartilage is autografted to the back subcutaneous zone with 0.5ml 10ng/ml IGF-Ⅰgel. In 50ng/ml EG, the costal cartilage is autografted to the back subcutaneous zone with 0.5ml 50ng/ml IGF-Ⅰgel. After 8 weeks, the costal cartilage which is in physiological environment opposite to surgical side is named as blank control group(blank CG). And it will be detected together with the other 3 groups.Preparation of gel and surgical technique:The gel is mixed by fibrinogen(200mg/ml), thrombin(10u/ml) and IGF-Ⅰ(10 or 50ng/ml). And it is better to be made when it is required. First, the rabbits are anesthetized and sterilized. Then the eighth and ninth costal cartilage are removed and divided into 3 parts. Finally, in different groups, the costal cartilages are autografted to the back subcutaneous zone directly or mixed with gels of different concentrations.Data collection and analysis:After 8 weeks, the rabbits are executed. The autografted and physiological costal cartilages are removed and analysed by gross observation, hematoxylin and eosin stain, examination of transmission electron microscopy(TEM) and measurement of the content of hydroxyproline.Statistics:Stata 7.0 is used for statistics. Analysis of variance is used to analyse the content of hydroxyproline among all the 4 groups. And t test is used to analyse the difference between every 2 groups.Results1. Gross observation:After 8 weeks, in young group the grafted cartilages of 50ng/ml EG are combined with surrounding tissues more strongly and can't be separated easily. The grafted cartilages of surgical CG and 10ng/ml EG are combined with surrounding tissues loosely and can be separated easily. The cartilages of surgical CG and 50ng/ml EG are ivory, translucent, flexible and similar with them of blank CG. On the other hand, the cartilages of 10ng/ml EG are yellow, opaque and inelastic. In adult group, there is no apparente difference among the 4 groups. But the elasticity of them is worse to the young's.2. Hematoxylin and eosin stain:In young group, the perichondrium of 50ng/ml EG is complete. There are more osteogenic cells. And the chondrocytes proliferate actively. The perichondrium of surgical CG and lOng/ml EG is littery in structure. There are less osteogenic cells. And the chondrocytes are degenerated. In adult group, the perichondrium cells of 50ng/ml EG are more than those of the other groups. But there exist cavities and segregation of matrix.3. TEM:Young group:There are healthy chondrocytes in blank CG and 50ng/ml EG. And there are little fibroblasts in the junction between cartilages and surrounding tissues. In surgical CG, there are necrotic chondrocytes. And the fibroblasts are active in the junction. In 10ng/ml EG, there are several calcification and no normal chondrocytes. Adult group:There are mature fibroblasts in the junction between cartilages and surrounding tissues in blank CG. In surgical CG, there are necrotic chondrocytes in the junction. In 10ng/ml EG, there are necrotic chondrocytes, too.But the perichondrium cells are normal. In 50ng/ml EG, there are normal chondrocytes. And the matrix is increased obviously.4. Analysis of hydroxyproline:Yong group:The difference between blank CG and 50ng/ml EG is not statistically significant(P>0.05).And the contents of hydroxyproline in these two group are more than them in surgical CG and 10ng/ml EG. The difference of them is statistically significant(P<0.05). The difference between surgical CG and 10 ng/ml EG is not statistically significant(P>0.05). Adult group:The difference among the 4 groups is not statistically significant(P>0.05).Conclusions1.In young group,50ng/ml IGF-Ⅰgel can maintain the proliferation of chondrocytes as physiologic ones and the ability of producing extracellular matrix. And it can keep the normal phenotypes of chondrocytes and perichondrium cells.2. 10ng/ml IGF-Ⅰgel cannot promote the growth of chondrocytes and perichondrium cells. The reason of it maybe that gel inhibit the normal proliferation and metabolism of them.3. In adult group, there is not obvious difference among the 4 groups by gross observation, examinations of histology and TEM and measurement of the content of hydroxyproline. It shows that there are less cell in adult cartilage tissue. And they are in quiescent condition. In the same time, the chondrocytes and perichondrium cells's sensitivity to IGF-Ⅰis lower.4. It can obtain better surgical effect when patients accept costal cartilage autograft in youth than in adult. |
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