The fate of hypertrophic chondrocytes in growth plates transplanted intramuscularly in the rabbit

Area of Science:

• Skeletal Biology
• Developmental Biology
• Tissue Engineering

Background:

• Endochondral ossification is a key process in bone development.
• The origin of cells contributing to bone formation after cartilage transplantation is not fully understood.

Purpose of the Study:

• To investigate the cellular origin of bone formed via endochondral ossification from transplanted fetal growth cartilage.
• To determine the fate of chondrocytes within the transplanted cartilage.

Main Methods:

• Fetal growth cartilage from New Zealand white rabbits was implanted intramuscularly into adult rabbits of the opposite sex.
• Sex chromatin analysis was used to identify the origin of osteoblasts and chondrocytes.
• Feulgen-Schiff staining assessed nuclear DNA integrity in chondrocytes.

Main Results:

• Endochondral ossification occurred in 11 out of 16 implants.
• The majority of newly formed bone was of recipient origin (p < 0.01).
• Chondrocytes showed decreased DNA stainability with maturation, indicating cell death.

Conclusions:

• Transplanted fetal growth cartilage can undergo endochondral ossification.
• The bone formed is predominantly derived from the recipient's cells.
• Growth plate chondrocytes likely undergo apoptosis and are replaced by recipient osteoblasts.