A simple non-destructive method for the fixation and immunostaining of cultured cells encapsulated in alginate

In the present paper we report a simple non-destructive method for the analysis of cells and their proteins encapsulated in alginate. Investigations with a co-culture of the human hepatoma cell line HepG2 and primary human fibroblasts are reported. We studied the expression of three proteins, namely intracellular alpha-foetoprotein and extracellular albumin, expressed by HepG2, and membrane-bound CD90 (Thy-1), expressed by the fibroblasts. Fluorimetric and colorimetric staining methods were evaluated and compared. We optimized the method by investigating a range of concentrations of the washing buffers. The technique protected the capsule and cell structures and enabled the investigated proteins to be clearly and reliably visualized within the encapsulated co-culture in their respective intracellular, membrane-bound and extracellular domains. These results demonstrate that this simple method is suitable for the non-destructive analysis of protein expression by cells encapsulated in alginate.