Bone Healing in Critical-Size Defects Treated With Immediate Transplant of Fragmented Autogenous White Adipose Tissue

Abstract

This study analyzed the influence of fragmented autogenous white subcutaneous adipose tissue (WSAT) on bone healing in critical-size defects created in rabbit calvaria. A 15-mm diameter defect was created in the calvaria of 42 rabbits, which were treated with 86 mm3 WSAT grafts or filled only with blood clots (control). Animals were euthanized at 7, 15, and 40 days postsurgery (n = 7), and the data were analyzed using histomorphometry and immunohistochemistry using the anti-CD34 and bone morphogenetic protein-2 (BMP2) antibodies. The calvaria treated with only blood clots demonstrated positivity to CD34 concentrated in endothelial cells, whereas the BMP2 were restricted to the borders of the defects. In contrast, the group treated with WSAT revealed fatty cells exhibiting positivity to BMP2 both in membrane and cytoplasm and intense quantities of stromal spindle cells that exhibited positivity to CD34 simultaneously to BMP2; these results together coincided with a larger bone matrix deposited in all postsurgery periods analyzed. These results revealed that the WSAT may be an alternative to craniofacial bone reconstruction because the adipose tissue exhibited prominent immunoexpression of BMP2, which was coexpressed with stromal CD34+ cells, indicating the plasticity of CD34+ stem cells into osteoblasts, and in the adipocytes, facts that suggest bone tissue development through cellular transdifferentiation from adipocytes.