Joong Hyun Shim

Human dermal stem/progenitor cell-derived conditioned medium ameliorates ultraviolet a-induced damage of normal human dermal fibroblasts.

Adult skin stem cells are considered an attractive cell resource for therapeutic potential in aged skin. We previously reported that multipotent human dermal stem/progenitor cells (hDSPCs) can be enriched from (normal human dermal fibroblasts (NHDFs) using collagen type IV. However, the beneficial effects of hDSPCs on aged skin remain to be elucidated. In the present study, we analyzed the growth factors secreted from hDSPCs in conditioned medium (CM) derived from hDSPCs (hDSPC-CM) and found that hDSPCs secreted higher levels of bFGF, IGFBP-1, IGFBP-2, HGF, VEGF and IGF-1 compared with non-hDSPCs. We then investigated whether hDSPC-CM has an effect on ultraviolet A (UVA)-irradiated NHDFs. Real-time RT-PCR analysis revealed that the treatment of UVA-irradiated NHDFs with hDSPC-CM significantly antagonized the UVA-induced up-regulation of the MMP1 and the UVA-induced down-regulation of the collagen types I, IV and V and TIMP1 mRNA expressions. Furthermore, a scratch wound healing assay showed that hDSPC-CM enhanced the migratory properties of UVA-irradiated NHDFs. hDSPC-CM also significantly reduced the number of the early and late apoptotic cell population in UVA-irradiated NHDFs. Taken together, these data suggest that hDSPC-CM can exert some beneficial effects on aged skin and may be used as a therapeutic agent to improve skin regeneration and wound healing.

Enrichment and Characterization of Human Dermal Stem/Progenitor Cells by Intracellular Granularity

Adult stem cells from the dermis would be an attractive cell source for therapeutic purposes as well as studying the process of skin aging. Several studies have reported that human dermal stem/progenitor cells (hDSPCs) with multipotent properties exist within the dermis of adult human skin. However, these cells have not been well characterized, because methods for their isolation or enrichment have not yet been optimized. In the present study, we enriched high side scatter (SSC(high))-hDSPCs from normal human dermal fibroblasts using a structural characteristic, intracellular granularity, as a sorting parameter. The SSC(high)-hDSPCs had high in vitro proliferation properties and expressed high levels of SOX2 and S100B, similar to previously identified mouse SOX2+ hair follicle dermal stem cells. The SSC(high)-hDSPCs could differentiate into not only mesodermal cell types, for example, adipocytes, chondrocytes, and osteoblasts, but also neuroectodermal cell types, such as neural cells. In addition, the SSC(high)-hDSPCs exhibited no significant differences in the expression of nestin, vimentin, SNAI2, TWIST1, versican, and CORIN compared with non-hDSPCs. These cells are therefore different from the previously identified multipotent fibroblasts and skin-derived progenitors. In this study, we suggest that hDSPCs can be enriched by using characteristic of their high intracellular granularity, and these SSC(high)-hDSPCs exhibit high in vitro proliferation and differentiation potentials.

Novel in vitro culture condition improves the stemness of human dermal stem/progenitor cells

Cell therapy using adult stem cells has emerged as a potentially new approach for the treatment of various diseases. Therefore, it is an essential procedure to maintain the stemness of adult stem cells for clinical treatment. We previously reported that human dermal stem/progenitor cells (hDSPCs) can be enriched using collagen type IV. However, hDSPCs gradually lose their stem cell properties as in vitro passages continue. In the present study, we developed optimized in vitro culture condition to improve the stemness of these hDSPCs. To evaluate whether the stemness of hDSPCs is well sustained in various culture conditions, we measured the expression levels of SOX2, NANOG, and S100B, which are well-known representative dermal progenitor markers. We observed that hDSPCs grown in three-dimensional (3D) culture condition had higher expression levels of those markers compared with hDSPCs grown in two-dimensional (2D) culture condition. Under the 3D culture condition, we further demonstrated that a high glucose (4.5 g/L) concentration enhanced the expression levels of the dermal progenitor markers, whereas O2 concentration did not affect. We also found that skin-derived precursor (SKP) culture medium was the most effective, among various culture media, in increasing the dermal progenitor marker expression. We finally demonstrated that this optimized culture condition enhanced the expression level of human telomerase reverse transcriptase (hTERT), the proliferation, and the multipotency of hDSPCs, an important characteristic of stem cells. Taken together, these results suggested that this novel in vitro culture condition improves the stemness of hDSPCs.

Cathepsin G Inhibitor Prevents Ultraviolet B- Induced Photoaging in Hairless Mice via Inhibition of Fibronectin Fragmentation

Background: Cathepsin G, a serine protease that is activated by ultraviolet (UV) radiation, increases matrix metalloproteinase-1 (MMP-1) expression in fibroblasts through fibronectin (Fn) fragmentation and promotes the conversion of proMMP-1 to active MMP-1. Objectives: This study investigated whether [2-[3-[[(1-benzoyl-4-piperidinyl)methylamino]carbonyl]-2-naphthalenyl]-1-(1-naphthalenyl)-2-oxoethyl]-phosphonic acid (KPA), a cathepsin G inhibitor, plays any role in extracellular matrix (ECM) damage in an in vitro 3D dermal equivalent (DE) and an in vivo ultraviolet B (UVB)-irradiated hairless mice. Methods: We examined the potential ECM-protective effects of a cathepsin G inhibitor in an in vitro 3D DE model and an in vivo UVB-irradiated hairless mouse skin model. Results: Among five known serine protease inhibitors, KPA showed the strongest potency and selectivity against cathepsin G. KPA inhibited the cathepsin G-mediated MMP-1 increase and alleviated the downregulation of mRNAs encoding collagen and tissue inhibitor of matrix metalloproteinase-1 in an in vitro 3D DE model. Most importantly, topical application of KPA (0.025%) to the dorsal skin of hairless mice enhanced collagen expression and attenuated UVB-induced Fn fragmentation and upregulation of MMP-2 and MMP-9 activities. Conclusions: Cathepsin G inhibitors may be useful for the prevention of UVB-induced photoaging through amelioration of ECM damage and MMP upregulation.

The retinoic acid-induced up-regulation of insulin-like growth factor 1 and 2 is associated with prolidase-dependent collagen synthesis in UVA-irradiated human dermal equivalents.

BACKGROUND Ultraviolet (UV) A irradiation causes the degeneration of extracellular matrix in the skin dermis, mainly due to disrupted collagen homeostasis, resulting in the photo-aging of human skin. All-trans retinoic acid (ATRA) improves photo-aged human skin in vivo. OBJECTIVES Although the effects of ATRA on collagen synthesis and MMP regulation are well known, the effects of ATRA on other collagen homeostasis-associated genes have not been elucidated. This study was aimed to study the factors that are pharmacologically associated with the effect of ATRA on collagen homeostasis. METHODS The gene transcription profile of collagen homeostasis-associated genes was systematically evaluated in three-dimensional human dermal equivalents (HDEs) following UVA-irradiation and/or ATRA treatment. RESULTS In addition to the expected changes in MMPs and collagen synthesis in HDEs in response to ATRA, prolidase, an important enzyme in the recycling of proline and hydroxyproline from degraded collagen molecules, was significantly decreased by UVA irradiation, and its down-regulation was antagonized by ATRA. Transfection with a prolidase-specific siRNA led to a significant decrease in procollagen synthesis in human fibroblasts. ATRA inhibited the UVA irradiation-induced decrease in prolidase activity through an insulin-like growth factor (IGF) receptor signaling pathway in HDEs. ARTA increased IGF1 and IGF2 production in HDEs, and neutralizing IGFs with anti-IGF antibodies abolished the effect of ATRA on proliase activity. CONCLUSIONS These data demonstrate that ATRA regulates prolidase activity in HDEs via IGF receptor signaling, suggesting one of the pharmacological mechanisms by which improves photo-aged human skin.

Human Dermal Stem/Progenitor Cell-Derived Conditioned Medium Improves Senescent Human Dermal Fibroblasts

Adult skin stem cells are recognized as potential therapeutics to rejuvenate aged skin. We previously demonstrated that human dermal stem/progenitor cells (hDSPCs) with multipotent capacity could be enriched from human dermal fibroblasts using collagen type IV. However, the effects of hDSPCs on cellular senescence remain to be elucidated. In the present study, we investigated whether conditioned medium (CM) collected from hDSPC cultures (hDSPC-CM) exhibits beneficial effects on senescent fibroblasts. We found that hDSPC-CM promoted proliferation and decreased the expression level of senescence-associated β-galactosidase in senescent fibroblasts. In addition, p53 phosphorylation and p21 expression were significantly reduced in senescent fibroblasts treated with hDSPC-CM. hDSPC-CM restored the expression levels of collagen type I, collagen type III, and tissue inhibitor of metalloproteinase, and antagonized the increase of matrix metalloproteinase 1 expression. Finally, we demonstrated that hDSPC-CM significantly reduced reactive oxygen species levels by specifically up-regulating the expression level of superoxide dismutase 2. Taken together, these data suggest that hDSPC-CM can be applied as a potential therapeutic agent for improving human aged skin.