Activated macrophages for treating skin ulceration: gene expression in human monocytes after hypo-osmotic shock

Abstract

Macrophages play a major role in almost all stages of the complex process of wound healing. It has been previously shown that the incorporation of a hypo-osmotic shock step, in the process of monocyte-concentrate preparation from a blood unit, induces monocyte/macrophage activation. As the macrophages are produced using a unique, closed and sterile system, they are suitable for local application on ulcers in elderly and paraplegic patients. Enhanced phagocytosis by the activated cells, as well as increased secretion of cytokines such as IL-1, IL-6, were detected in a recent study which are in accord with the very encouraging clinical results. In the present study, we used DNA microarrays to analyse the differential gene expressions of the hypo-osmotic shock-activated monocytes/macrophages and compare them to non-treated cells. Of the genes that exhibited differences of expression in the activated cell population, 94% (68/72) displayed increased activity. The mRNA levels of 43/68 of these genes (63%) were found to be 1.5-fold or higher (1.5-7.98) in the activated macrophages cell population as compared to the non-treated cells. Only four genes were found to have lower mRNA levels in the activated cells, with ratios of expression of 0.62-0.8, which may suggest that the changes are insignificant. A significant number of the genes that showed increased levels of expression is known to be directly involved in macrophage function and wound healing. This may correlate with the increased secretion of different cytokines by the activated macrophages depicted previously. Other groups of genes expressed are known to be involved in important pathways such as neuronal growth and function, developmental defects and cancer. The hypo-osmotic shock induces a gene expression profile of cytokines and receptors in the activated cells. These may evoke potential abilities to produce a variety of protein products needed in the wound healing process and may bring to light possibilities for other therapeutic applications of these cells.

Figures

Fig. 1

Differential hybridization of monocytes/macrophages activated by hypo-osmotic shock, to the cytokine/receptor filters.

Fig. 2

Differential hybridization of control monocytes/macrophages to cytokine/receptor filters.

Fig. 3

Comparative hybridization of control and hypo-osmotic shock activated monocytes/macrophages, using the AtlasImageTM software.The blue boxes indicate genes expressed at lower levels in the activated cell population, compared with the controls. The red boxes indicate genes expressed at higher levels in the activated cell population. The green boxes indicate genes with no significant difference in expression levels in both groups and the grey boxes indicate genes expressed at a background level.