Putative roles of Adipose Tissue Derived Stem Cells in Thyroid Associated Orbitopathy

1. Kelvin Chong
2. Gary Yam
3. Richard Choy
4. Clement Tham
5. Dennis Lam
6. Calvin Pang

1. Department of Ophthalmology and Visual Science, the Chinese University of Hong Kong
2. Department of Obstetrics and Gynecology, the Chinese University of Hong Kong

Purpose: To study the roles of adipose tissue derived stem cells (ASC) in patients with Thyroid associated orbitopathy (TAO)

Methods: Orbital fatty tissue explant from patients with TAO undergoing surgical decompression and control subjects during blepharoplasties or socket operations were subject to collagenase digestion. The remaining stromal vascular fraction then underwent red cell lysis, cell strainer passage, gradient selection, negative magnetic cell sorting and cultured at standard plating density with 10% fetal bovine serum in Dulbecco's Modified Eagle Medium: nutrient Mix F-12. Identity of ASC was confirmed with plastic adherence property, formation of colony forming units fibroblasts and specific surface antigens expressions (CD105, CD44, CD90, c-kit, nestin, p21, p75 and SSEA4). Cells were further characterized by immunophenotyping with markers published in TAO literature and cross-over stimulation were performed between ASC from control or TAO subjects using control or TAO plasma.

Results: ASCs were successfully generated from control (n=4) and TAO (n=4) orbital fat. Plating efficiency, growth rate were higher in TAO compared to control. ASC from
TAO patients consistently expressed higher densities of surface thyrotropin receptors (TSHR) and insulin-like growth factor-1 receptors (IGF-1R). Growth and antigen expressions were higher after TAO ASC were supplemented with TAO than control plasma.

Conclusions
ASC were more effectively generated from TAO orbital tissues. They exhibited higher growth rate, surface expression of two putative autoantigens and were readily stimulated by TAO compared with control plasma.