Progressive fibrosis is a common pathological finding in various organs, resulting in organ failure. Renal fibrosis is a progressive disease caused by diverse clinical entities. Irrespective and independent of the primary lesion, it is the severity of renal fibrosis that correlates best with the loss of renal function and the risk for progression to renal failure. A circulating population of cells (termed fibrocytes) that display leukocyte markers such as CD45 and CD34 as well as mesenchymal markers including type I collagen has been described. Fibrocytes have been reported to rapidly enter sites of tissue injury and contribute to the pathogenesis of fibrotic conditions. Fibrocytes express CCR7 and migrate in response to secondary lymphoid tissue chemokine (SLC/CCL21). We hypothesized that CCR7-positive fibrocytes contribute to renal fibrosis. To investigate this idea, renal fibrosis was induced by unilateral ureteral obstruction in mice. CD45- and type I collagen-dual positive fibrocytes infiltrated in the fibrotic kidneys and the number of infiltrated fibrocytes increased with the progression of the extent of fibrosis in an experimental murine renal fibrosis model. Most infiltrated fibrocytes in the kidneys were positive for CCR7. In addition, CCL21 protein co-localized with high endothelial venulelike vessels in fibrotic kidneys. The blockade of CCL21/CCR7 signaling reduced the number of infiltrating fibrocytes as well as the extent of renal fibrosis, which was confirmed by the reduction of the amount of hydroxyproline and the levels of renal transcripts of pro α1 chain of type I collagen and transforming growth factor-β1. These results suggest that CCR7-positive fibrocytes infiltrate into the kidney via CCL21-positive vessels, thereby, contributing to the pathogenesis of renal fibrosis. Thus, regulating the recruitment and activation of fibrocytes by modulation of CCL21/CCR7 signaling may provide a novel therapeutic approach for combatting organ fibrosis.

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Psoriasis is a genetically determined, inflammatory, proliferative disease of the skin, and it is often intractable. The most characteristic lesions consist of chronic, sharply demarcated, red, scaly plaques, particularly on the extensor prominences and scalp. The prognosis is benign, however, patients often feel self-conscious regarding the appearance of the lesions and quality of life (QOL) can hence be lower than that for those with cancer or diabetes. At present, the main therapy for psoriasis in Japan is corticosteroids and activated vitamin D₃ analogs as topical treatment, and cyclosporine, etretinate, and methotrexate as systemic therapy. However, topical treatments themselves can be stressful for patients, and long-term administration of medications can cause adverse reactions. Etanercept, infliximab, and adalimumab are biologic preparations with anti-TNFα activities, and these preparations are more effective than the existing treatments and cause fewer adverse reactions. They can also be effective against psoriasis accompanied by joint symptoms that resist other treatments.

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Recent data indicate that the deficiencies of several pro-inflammatory cytokine genes affect skin wound healing processes. Hence, we explored skin wound healing processes in mice deficient in IL-1 receptor antagonist (IL-1ra), a potent endogenous antagonist against a pro-inflammatory cytokine, IL-1. Wound closure was delayed with attenuated collagen accumulation in IL-1ra knockout (KO) mice, compared with wild-type (WT) mice. On the contrary, leukocyte recruitment was exaggerated with augmented IL-1 expression in IL-1ra KO mice, implying that IL-1ra deficiency enhanced local inflammatory reaction at the wound sites. Consistently, nuclear translocation of a pro-inflammatory transcription factor, NF-κB, was significantly enhanced and prolonged in fibroblasts in IL-1ra KO mice, compared with WT mice. Previous in vitro observations demonstrated that NF-κB activation could attenuate transforming growth factor (TGF)-β/Smad signaling pathway, which has crucial roles for collagen deposition in wound healing processes. Indeed, in IL-1ra KO mice, the TGF-β/Smad signaling pathway was suppressed as evidenced by decreases in phosphorylated Smad2/3 and a reciprocal increase in Smad7 at the wound sites, compared with WT mice. These results demonstrated that the absence of IL-1ra resulted in aberrant NF-κB activation and reciprocal diminution in TGF-β/Smad signaling and eventually attenuated collagen deposition during skin wound healing in vivo.

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Tissues and organs are composed of different types of cells and proteins, which interact and express their respective functions based on their three dimensional (3D) structures. Thus, the position and arrangement of those components including cells are critical for tissue engineering, and it is necessary to develop effective technologies for the arrangement of those materials in 3D space. Inkjet printing technology is able to print with small droplets at high resolution that are nearly equal to microscopic tissue structures. We have attempted to use this technology to print with biological cells instead of standard ink and demonstrated that living cells could be safely ejected with the inkjet procedure. Herein, we briefly introduce and review this new approach of inkjet-based cell patterning, which has good potential as an effective tool for tissue engineering.

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Hyaluronan is a ubiquitous, major component of the extracellular matrix. It is involved in cell adhesion and locomotion, and hence in tumor metastasis. We have previously reported that 4-methylumbelliferone (MU) inhibits hyaluronan synthesis and may be a useful tool for examining the functions of hyaluronan. We here demonstrate that MU-mediated inhibition of hyaluronan expression results in suppression of adhesion and locomotion of cultured melanoma cells. Furthermore, MU-treated melanoma cells showed both decreased cell surface hyaluronan formation and suppression of liver metastasis after injection into the mice. Oral administration of MU to mice also decreased tissue hyaluronan content. These hyaluronan knock-down mice displayed suppressed metastasis. Thus, both cell surface hyaluronan of melanoma cells and recipient hyaluronan can promote metastasis, indicating that MU has potential as an anti-metastatic agent.

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Chronic ulcerations are caused by pressure, ischemia or attrition and is a serious problem for long term care. However, little is known about biomolecular markers expressed during the development of pressure ulcerations. In the present study, we examined whether various extracellular matrix components correlate with the development of pressure ulcerations. Examination of wound areas and immunohistological staining showed that pressure ulceration develop following excision of the sciatic nerve from the hindlimbs of mice. Our data reveal that the expression of mRNAs encoding type I collagen (collagen α1 (I)), type IV collagen (collagen α1 (IV)), matrix metalloproteinase (MMP)-2, -3 and -9 correlate with the wound area. But laminin- 5 (laminin-5 α3) does not correlate with the wound area. These results suggest that the expression of those mRNAs provides specific biomolecular markers for pressure ulcerations. The present study will be useful for developing effective therapeutic agents or prophylactic agents against pressure ulcerations.

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