Evidence supporting antioxidant action of adipose-derived stem cells: Protection of human dermal fibroblasts from oxidative stress
Introduction
Mesenchymal stem cells within the stromal-vascular fraction of subcutaneous adipose tissue, adipose-derived stem cells (ADSCs), display multi-lineage developmental plasticity and share similarity to bone marrow-derived stem cells (BM-MSCs) with respect to surface markers and gene profiling [1], [2], [3], [4]. In addition, BM-MSCs and ADSCs have some secretory factors in common; collagen, fibronectin, and various cytokines such as vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and fibroblast growth factor (FGF) [5], [6], [7]. Recently, the production and secretion of cytokines has been reported as an essential function of ADSCs and these cytokines exhibit diverse pharmacological effects [7], [8], [9].
Currently, hot topics in the dermatologic field are anatomical–functional damage to the skin and every possible means to counteract the skin defects. Great interest in this issue has been aroused on the study of substances able to prevent skin damage from free radicals. Although there are few reports involving the antioxidant action of stem cells, some evidences support a protective effect of cytokines on the epithelial cells during oxidative injury. For example, insulin like growth factor (IGF) reportedly protects fibroblasts and intestinal epithelial cells from free radicals [10], [11]. HGF has a protective effect on retinal pigment epithelium in oxidative stress induced by glutathione depletion [12]. Pigment epithelium-derived factor (PEDF) is an anti-angiogenic/neurotropic factor and has been shown to mediate antioxidant action [13]. Interleukin 6 (IL-6) has reduced the epithelial cell death induced by hydrogen peroxide [14]. All of these reports indicate the antioxidant effect of stem cells and cytokines, however, their protective mechanism has not been clearly defined.
In a previous study, it was observed that ADSCs had paracrine effects on human dermal fibroblasts (HDFs), activating proliferation/migration of HDFs, which finally accelerated wound healing [15]. In that study, soluble factors in the conditioned medium of ADSCs (ADSC-CM) were examined by enzyme-linked immunosorbent assay (ELISA), which revealed secretions of antioxidant proteins. Although the antioxidant mechanisms of ADSCs are unclear, ADSCs or ADSC-CM are good candidates for control and prevention of skin damage. Therefore, the antioxidant action of ADSC-CM on HDFs is investigated in tert-butyl hydroperoxide (tbOOH) induced oxidative injury model, which imply an important role of ADSCs in the skin biology.
Section snippets
Isolation and culture of ADSCs and HDFs
Human subcutaneous adipose tissue samples were acquired from elective liposuction procedures. The obtained samples were digested with 0.075% collagenase type II (Sigma–Aldrich, St. Louis, MO) under gentle agitation for 45 min at 37 °C, and centrifuged at 300 × g for 10 min to obtain the stromal cell fraction. The pellet was filtered with 70 μm nylon mesh filter, and resuspended in phosphate-buffered saline (PBS). The cell suspension was layered onto histopaque-1077 (Sigma–Aldrich) and centrifuged at
Characterization of ADSCs
In our isolation and culture methods, ADSCs expanded easily in vitro, and exhibited a fibroblast-like morphology similar to that of BM-MSCs. Flow cytometric characterization of ADSCs was performed as described previously [15]. To verify the multipotent differentiation, ADSCs were subjected to media known to induce adipogenic, osteogenic and chondrogenic lineages. Adipogenic differentiation was identified by Oil Red O staining of intracellular lipid droplets (Fig. 1A), osteogenic differentiation
Discussion
From results of the present study, particularly the cell morphology and cell survival rate, it was demonstrated that ADSC-CM aids HDFs to survive in tbOOH-induced oxidative stress. Secretary proteins from ADSC-CM such as SOD and some cytokines may mediate the protective effects and play key roles in the survival and the maintenance of HDF morphology. To our knowledge, this may be the first indication that stem cells have potent antioxidant action and ADSCs protect HDFs through antioxidation,
Acknowledgement
This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (KRF-2005-214-E00060).
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