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Blake V. Acohido, Nahyoung G. Lee, Eric Steele, David J. Wilson; Increased Cell Proliferation in Pediatric Orbital Dermis Fat Graft Implants. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4072.
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Without intervention, the loss of intraorbital soft tissue volume associated with enucleation, can lead to severe and disfiguring facial hypoplasia, particularly in young children. To address this known complication, various methods of intraorbital volume replacement have been employed. Of these, intraorbital dermis fat graft implantation (IODFG) has proven to be quite successful, owing to the graft’s intrinsic ability to grow within the orbit, facilitating improved symmetry of facial growth. One drawback to IODFG is the propensity for overly exuberant growth of the adipose component of the graft, a complication that requires surgical debulking to maintain symmetry. The aim of this study is to elucidate whether adipocyte cell proliferation contributes to the vigorous expansion of adipose tissue that occurs in pediatric IODFG.
Tissue was collected from 5 patients who underwent IODFG debulking (median age 3). 5 resident orbital fat specimens with a diagnosis of normal adipose tissue were used as control (median age 62.6). Immunohistochemistry was performed on paraffin embedded sections of these specimens to assay for Ki-67, a surrogate marker for active cell proliferation. Tissue sections were examined under light microscopy. The area of highest concentration of positive adipocyte nuclear staining was identified, and positively staining nuclei were counted under a 40X, high-power objective.
We found in normal orbital fat that there were 2.2 Ki-67 positive adipocyte nuclei per high power field. In comparison we observed 18.2 Ki-67 positive nuclei per high power field in our DFG specimens. This apparent increase in Ki-67 positive approached statistical significance with p-value of 0.057 (unpaired t-test). Of note, the Ki-67 positive staining in our DFG group was patchy in distribution, with isolated areas of intense staining surrounded by large expanses of unstained nuclei.
Our data demonstrates a trend toward increased cell proliferation within the adipocytes of expansile IODFG, suggesting that adipocyte hyperplasia may play a significant role in the robust growth of graft tissue within the pediatric orbit. At the present time it is unclear whether these proliferating adipocytes originated from the graft, the resident intraorbital adipose tissue, or from both. It is also unknown, whether the signal for cell proliferation originates from the graft, the orbit, or both. These unanswered questions warrant future investigation.
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