Bone Abstracts

Objectives: The skeleton is not a single functional unit but consists of different, well-organized and mineralized compartments with specific functions, developmental aspects and regulations. Differences in the regulation of spinal and long bone elongation are mirrored clinically by the age course in body proportions. Whereas growth plates (GPs) in long bones can easily be discriminated, vertebral GPs are part of the cartilaginous endplate, which typically shows important species differences. This study aims to describe and compare histological, histomorphometric and regulatory characteristics in the GP of the spine and long bones in a porcine model.

Methods: 2- and 6-week-old piglet GP (GPs) of three vertebral segments (cervical, thoracic, lumbar) and eight long bones (proximal and distal radius, humerus, tibia, femur) were analyzed morphometrically. Further, estrogen receptor (ER), proliferation marker and growth factor expression was examined by immunohistochemistry.

Results: Individual vertebral GPs were smaller in width and contained fewer chondrocytes than long bone GPs, although their proliferation activity was similar. Whereas the expression pattern of growth hormone-associated factors such as Insuline-like Growth Factor (IGF-1) and IGF1-receptor was similar, ERβ and IGF-2 were distinctly expressed in the vertebral samples.

Conclusions: Vertebral GPs display differential growth, with measurements similar to the slowest growing GPs of long bones. Further investigation is needed to decipher the molecular basis of differential growth of the spine and long bones. Knowledge on the distinct mechanism will ultimately improve assessment of clinically essential characteristics of spinal growth, such as vertebral elongation potential and growth plate fusion.

Disclosure: The authors declared no competing interests.