Expression of progenitor markers is associated with the functionality of a bioartificial adrenal cortex

Abstract

Encapsulation of primary bovine adrenocortical cells in alginate is an efficacious model of a bioartificial adrenal cortex. Such a bioartificial adrenal cortex can be used for the restoration of lost adrenal function in vivo as well as for in vitro modeling of the adrenal microenvironment and for investigation of cell–cell interactions in the adrenals. The aim of this work was the optimization of a bioartificial adrenal cortex, that is the generation of a highly productive, self-regenerating, long-term functioning and immune tolerant bioartificial organ. To achieve this, it is necessary that adrenocortical stem and progenitor cells are present in the bioartificial gland, as these undifferentiated cells play important roles in the function of the mature gland. Here, we verified the presence of adrenocortical progenitors in cultures of bovine adrenocortical cells, studied the dynamics of their appearance and growth and determined the optimal time point for cell encapsulation. These procedures increased the functional life span and reduced the immunogenicity of the bioartificial adrenal cortex. This model allows the use of the luteinizing hormone-releasing hormone (LHRH) agonist triptorelin, the neuropeptide bombesin, and retinoic acid to alter cell number and the release of cortisol over long periods of time.

Isolation and characterization of adrenocortical progenitors involved in the adaptation to stress

“…We have been able to isolate the adrenocortical Nestin + progenitors and culture them in vitro. The differential expression of various progenitor markers in adrenocortical cells, isolated from mice, is similar to what we observed in cultures of bovine adrenocortical cells, in which we also saw the highest expression on days 6–7 of culture (27). On day 7 of differentiation, the cells were highly reactive to Ang II and ACTH, indicating that, at this point, there is a mixture of zG and zF cells.…”

“…To elucidate if Nestin marks a known population of progenitors to steroidogenic cells, we performed immunohistochemistry with a range of progenitor/stem cell and steroid markers. DAX1 is critical for the maintenance of adrenocortical progenitor cells (15), and we have previously shown that DAX1 is expressed in progenitors of the bovine adrenal cortex (27). In adult mice, double-positive cells were rarely observed (Fig.…”

“…Previously, we tested various pharmacological agents for their ability to influence the properties of a bioartificial bovine adrenal cortex. In this former study, two peptides, triptorelin and bombesin, were shown to increase cell functionality and proliferative potential when applied to bovine adrenocortical cells encapsulated in alginate (27). When we applied bombesin to our differentiating cells, the production of corticosterone was unchanged.…”

“…Lineage-specific stem cells from adult tissues are important sources for cell-replacement therapies. Recently, we have shown that the expression of progenitor markers is associated with the functionality of a bioartificial adrenal cortex (27). Our demonstration that Nestin + progenitors can be cultured in vitro and differentiated into mineralocorticoid- and glucocorticoid-producing cells therefore provides a source of cells to address, for example, adrenal insufficiency, which makes this study very relevant clinically.…”

The clinical relevance of necroinflammation—highlighting the importance of acute kidney injury and the adrenal glands

“…This particular material allows diffusion of adrenal hormones whereas immune cells cannot enter this artificial tissue, and the xenotransplanted adrenal cells thus cannot be rejected [130]. Recent data suggest that this approach is not limited to single cell types [130] but may be employed to generate a bioartificial adrenal cortex [131]. However, it is currently unclear to which extent alginate may prevent the necroinflammatory stimulus to enter the systemic vasculature.…”