Abstract/Summary

The adrenal gland is a small endocrine organ with inherent regenerative capacity. Numerous studies proposed a stem cell niche located in the capsule of adrenal cortex. This project investigated mRNA and protein spatial expression of potential stem cell markers in the adrenal cortex. One of these markers (Thy-1) was used to isolate potential stem cells from dispersed primary adrenal cortex cells using magnetic-activated cell sorting (MACS). Thy-1 positive cells were monitored while they survived in vitro for over one year. Thy-1 cells were demonstrated to be undifferentiated fibroblastic-like cells with characteristics similar to those of mesenchymal stem cells in vitro such as plastic adherent, can form colonies, the confluent cells have a whirlpool-like formation and the significant (P< 0.05) increase of Thy-1 expression during cultivation in vitro. Thy-1 positive cells showed the expression of other stem cell markers such as Wt1, Etv5 and ID4. The monitoring of Thy-1 positive cells behavioural changes in vitro showed slow division rate, slow cell migration and the coexistence of senescent cells in their early months of cultivation. In comparison, in the late months of cultivation, the cells showed a significant (P< 0.05) increase in cell division rate and cell migration similar to cancer cell behaviour in vitro. As these cells were generally undifferentiated and they have characteristics of mesenchymal stem cells, differentiation attempts were first conducted using external differentiation factors (forskolin, ACTH and AT20 cell line media). However, the results showed non-significant responses to these treatments. The second differentiation experiments were conducted by forcing expression of Sf1 protein in Thy-1 positive cells using a cloning vector. Transfection with Sf1caused a significant (P< 0.05) reduction in ID4 mRNA expression and significantly (P< 0.05) elevated the expression of the progenitor marker Gli1 and the expression of steroidogenic enzyme genes (Cyp11A1 and 3βHSD) consistent with previous reports for several mesenchymal stem cell types.