Endocrine Abstracts

Background: The plasticity of adrenal cortex suggests the presence of adrenocortical stem cells (ACSC) but the exact in vivo identity of ACSC remains elusive. A few studies have demonstrated the differentiation of adipose or bone marrow-derived mesenchymal stem cells (MSC) into steroid-producing cells. We therefore investigated the direct isolation of MSC from human adrenal cortex.

Methods: Adrenals were obtained as discarded surgical material. Single cell suspensions from human adrenal cortex (n=3) were cultured onto either complete growth medium (CM) or mesenchymal stem cell growth promotion medium (MGPM). Following ex-vivo expansion, the adipogenic, chondrogenic and osteogenic differentiation potential of these cells were evaluated. Cells were analysed by flow cytometry for cell-surface antigens associated with bone marrow-MSCs and adrenocortical-specific phenotype. Multipotent differentiation was assessed by immunocytochemistry.

Results: The formation of colony forming unit-fibroblasts consisting of adherent cells with fibroblast morphology were observed from the monolayer cell culture of human adrenal cortex in both CM and MGPM. Cells derived and cultured in MGPM revealed differentiation toward osteogenic and adipogenic cell lineages as determined by positive staining for Alizarin Red and Oil Red-O, respectively. Chondrogenic staining could not be demonstrated. These cells expressed cell-surface MSC markers (CDs: 44, 90, 105, 166) but did not express the haematopoietic and lymphocytic markers (CD19 and CD45). The proportion of MSC-positive cells was lower in CM compared to those from MGPM (mean 90.5 vs 70.2%; P=0.001). These cells also demonstrated higher expression of GLI1 (P=0.035) and DAX1 (P=0.009) antigens. More than 90% of the cells in MGPM were shown to co-express SF1 and MSC markers. They were highly proliferative as judged by GLI/SHH expression.

Conclusion: Our study demonstrates, for the first time, that cells derived from human adrenal cortex cells have the capacity to differentiate into mesenchymal lineages. Understanding the cell biology of adrenal-cortex derived MSCs will inform regenerative medicine approaches in Addison’s disease.