Katsuya Kawai

Accelerated tissue regeneration through incorporation of basic fibroblast growth factor-impregnated gelatin microspheres into artificial dermis.

The objective of this study was to evaluate the effect of incorporation of basic fibroblast growth factor (bFGF)-impregnated gelatin microspheres into an artificial dermis on the regeneration of dermis-like tissues. When used in the free form in vivo, bFGF cannot induce sufficient wound healing activity, because of its short half-life. Therefore, sustained release of bFGF was achieved by impregnation into biodegradable gelatin microspheres. A radioisotope study revealed that incorporation of bFGF-impregnated gelatin microspheres significantly prolonged in vivo retention of bFGF in the artificial dermis. Artificial dermis with incorporated bFGF-impregnated gelatin microspheres or bFGF in solution was implanted into full-thickness skin defects on the back of guinea pigs (1.5 cm x 1.5 cm) (n = 4). Incorporation of bFGF into the artificial dermis accelerated fibroblast proliferation and capillary formation in a dose-dependent manner. However, the accelerated effects were more significant with the incorporation of bFGF-impregnated gelatin microspheres than with free bFGF at doses of 50 microg or higher. We conclude that the gelatin microsphere is a promising tool to accelerate bFGF-induced tissue regeneration in artificial dermis.

Enhanced wound healing by topical administration of mesenchymal stem cells transfected with stromal cell-derived factor-1.

The objective of this study was to investigate the ability of mesenchymal stem cells (MSC) genetically engineered with stromal cell-derived factor-1 (SDF-1) to heal skin wounds. When transfected with SDF-1 plasmid DNA, MSC which were isolated from the bone marrow of rats, secreted SDF-1 for 7 days. In vitro cell migration assay revealed that the SDF-1-engineered MSC (SDF-MSC) enhanced the migration of MSC and dermal fibroblasts to a significantly greater extent than MSC. The SDF-MSC secreted vascular endothelial growth factor, hepatocyte growth factor, and interleukin 6 at a significantly high level. A skin defect model of rats was prepared and MSC and SDF-MSC were applied to the wound to evaluate wound healing in terms of wound size and histological examinations. The wound size decreased significantly faster with SDF-MSC treatment than with MSC and PBS treatments. The length of the neoepithelium and the number of blood vessels newly formed were significantly larger. A cell-tracing experiment with fluorescently labeled cells demonstrated that the percent survival of SDF-MSC in the tissue treated was significantly high compared with that of MSC. It was concluded that SDF-1 genetic engineering is a promising way to promote the wound healing activity of MSC for a skin defect.

Collagen-Gelatin Scaffold Impregnated with bFGF Accelerates Palatal Wound Healing of Palatal Mucosa in Dogs

BACKGROUND We have developed a collagen-gelatin sponge (CGS) as a scaffold capable of the sustained release of bFGF to improve the healing process of the existing collagen scaffold. The aim of this study was to evaluate the efficacy of CGS impregnated with basic fibroblast growth factor (bFGF) in palatal wound healing in beagles. MATERIALS AND METHODS Four standardized 6 mm diameter full-thickness wounds were made in the palate of each dog and covered with CGS impregnated with normal saline or bFGF at concentrations of 1 μg/cm2, 7 μg/cm2 and 14 μg/cm2. One and 2 wk after surgery, the wound area, neoepithelium length, thickness, area of regenerated submucosal tissue, and the number and total area of neoformed capillaries were evaluated. RESULTS Two weeks after implantation, wounds treated with bFGF 7 μg/cm2 and 14 μg/cm2 were completely epithelized, while the length of the neoformed epithelium was significantly longer in the 7 μg/cm2 group. Groups impregnated with bFGF 7 μg/cm2 and 14 μg/cm2 showed promoted regeneration of submucosal tissue 2 wk later. The number and area of neoformed capillaries were significantly higher in the bFGF 7 μg/cm2 group than in other groups. We conclude that palatal wound healing in the bFGF 7 μg/cm2 group was promoted with good neovascularization and showed less contracture than other groups. CONCLUSIONS Our new collagen-gelatin scaffold, CGS, impregnated with bFGF, could be a promising treatment to accelerate the regeneration of palatal mucosa.

Development of an artificial dermis preparation capable of silver sulfadiazine release

This article describes the antibacterial effects of an artificial dermis impregnated with silver sulfadiazine (Ag-SD) in vitro as well as in vivo. In the in vitro test, silver release from the artificial dermis impregnated with Ag-SD, by immersion in collagenase solution was controlled by the degradation of the collagen sponge. The artificial dermis impregnated with 3% or higher doses of Ag-SD completely suppressed the growth of Pseudomonas aeruginosa (Ps.) or Staphylococcus aureus (St.). The cytotoxicity test revealed that impregnation of 5% or higher doses of Ag-SD suppressed the growth of fibroblasts. However, when the artificial dermis impregnated with Ag-SD was implanted into full-thickness skin defects on the backs of guinea pigs, no tissue damage was histologically observed around the implanted site of the dermis. In the in vivo test, the artificial dermis impregnated with 10% Ag-SD, which was grafted on experimentally contaminated wounds in the backs of guinea pigs, macroscopically suppressed degradation of the collagen sponge, and significantly reduced the growth of both Ps. and St., compared with artificial dermis without Ag-SD. We conclude that collagen sponge impregnated with Ag-SD is a promising artificial dermis applicable to treat contaminated wounds.

Evaluation of a novel collagen–gelatin scaffold for achieving the sustained release of basic fibroblast growth factor in a diabetic mouse model

The objective of this study was to evaluate the ability of a scaffold, collagen–gelatin sponge (CGS), to release basic fibroblast growth factor (bFGF) in a sustained manner, using a pressure‐induced decubitus ulcer model involving genetically diabetic mice. We confirmed that CGSs impregnated with a bFGF concentration of up to 50 µg/cm2 were able to sustain the release of bFGF throughout their biodegradation. We prepared decubitus ulcers on diabetic mice. After debriding the ulcers, we implanted CGSs (diameter 8 mm) impregnated with normal saline solution (NSS) or bFGF solution (7, 14, 28 or 50 µg/cm2). At 1 and 2 weeks after implantation, the mice were sacrificed and tissue specimens were obtained. The wound area, neoepithelium length and numbers and total area of newly formed capillaries were evaluated. The CGSs impregnated with NSS became infected and degraded, whereas the CGSs impregnated with 7 or 14 µg/cm2 bFGF displayed accelerated dermis‐like tissue formation and the CGSs impregnated with 14 µg/cm2 bFGF produced significant improvements in the remaining wound area, neoepithelium length and numbers and total area of newly formed capillaries compared with the NSS group. No significant difference was observed between the NSS and 50 µg/cm2 bFGF groups. CGSs impregnated with 7–14 µg/cm2 bFGF accelerated wound healing, and an excess amount of bFGF did not increase the wound‐healing efficacy of the CGSs. Our CGS is a scaffold that can release positively charged growth factors such as bFGF in a sustained manner and shows promise as a scaffold for skin regeneration. Copyright

Efficacy of novel collagen/gelatin scaffold with sustained release of basic fibroblast growth factor for dermis-like tissue regeneration.

Abstract We have developed collagen/gelatin sponges (CGS) with a gelatin concentration of 10 wt% to sustain the release of basic fibroblast growth factor (bFGF). The objective of this study is to elucidate the efficacy of CGS impregnated with different concentrations of bFGF, using mouse skin defects. CGSs impregnated with normal saline solution (NSS) or bFGF solution (1, 7, 14, or 50 &mgr;g/cm2) were implanted into full-thickness skin defects on the backs of mice. The wound area, neoepithelium length, and total area of newly formed capillaries in CGS were evaluated. The group of CGS with 7-&mgr;g/cm2 bFGF was significantly superior to the NSS group in all evaluated items. CGS impregnated with the appropriate dosage of bFGF accelerates dermis-like tissue formation 2 or 3 times earlier than existing artificial dermis. The combination of CGS and bFGF could solve the problem of the existing artificial dermis and be very promising for the treatment of skin defects.

Treating a collagen scaffold with a low concentration of nicotine promoted angiogenesis and wound healing.

BACKGROUND Nicotine, one of the major pharmacologically active agents of cigarette smoke, has various effects on cell proliferation, and it has recently been reported to have angiogenic effects. In our previous study, we showed that the topical administration of nicotine at a low concentration accelerated wound healing. This study aimed to evaluate the efficacy of nicotine and synergistic effects of combination treatment with nicotine and basic fibroblast growth factor (bFGF) in a murine excisional wound model treated with artificial dermis. METHODS Full-thickness defects (8 mm in diameter) were created on the backs of mice, and artificial dermis was sutured to the defects. Phosphate-buffered saline (10 μL), nicotine (10(-3), 10(-4), or 10(-5) M), bFGF (0.5 μg), and both bFGF and 10(-4) M nicotine were topically administered to the artificial dermal tissue for 7 d. The mice were killed on day 14, and the wound area, neoepithelium length, and area of newly formed capillaries in the artificial dermis were evaluated. RESULTS The wound areas treated with 10(-4) M nicotine, bFGF, or bFGF plus 10(-4) M nicotine were significantly smaller than those in the control group. In these three groups, the neoepithelium in the bFGF plus 10(-4) M nicotine group was significantly longer than that in the other groups. There was no significant difference between the neoepithelium lengths of the control and 10(-5) M nicotine groups. The 10(-3) M nicotine group displayed the least re-epithelization among the groups. CONCLUSIONS In this study, 10(-4) M nicotine induced angiogenesis in, and accelerated the healing of, wounds treated with artificial dermis. bFGF and nicotine had synergistic effects, and the combined use of nicotine and bFGF is an effective wound healing method.

Adipogenesis using human adipose tissue-derived stromal cells combined with a collagen/gelatin sponge sustaining release of basic fibroblast growth factor

We have developed a collagen/gelatin sponge (CGS) that can provide a sustained release of basic fibroblast growth factor (bFGF). In our previous study, it was shown that CGS impregnated with the appropriate dosage of bFGF accelerates dermis‐like tissue formation two or three times earlier than an existing collagen sponge. In this study, adipogenesis was evaluated using CGSs disseminated with adipose tissue‐derived stem cells (ASCs). Human ASCs were primarily isolated from human adipose tissue that was obtained during breast cancer surgery with informed consent at Kyoto University Hospital. ASCs were isolated from collagenase digests of adipose tissue. ASCs were labelled with PKH26. CGSs (8 mm diameter × 3 mm thickness) were impregnated with bFGF (0.1, 1, 7, 14 µg/cm2) or normal saline solution. Then the labelled cells were disseminated (passage 3) on CGSs at a seeding density of 1 × 105 cells/cm2 and implanted into the back subcutis of nude mice. Six weeks after implantation, adipogenesis at the administered site was evaluated. Immunohistological staining with von Willebrand factor (vWf) was performed to evaluate newly formed capillaries. Newly formed adipose tissue was observed macroscopically and histologically in all groups. The weight and area of regenerated adipose tissue were largest in the 1 µg/cm2 bFGF group. Under a fluorescent microscope, newly formed adipose tissue in the bFGF‐administered group was PKH‐positive. These findings show that ASCs differentiated and formed adipose tissue. In this study, we showed that our CGSs impregnated with bFGF could be used as scaffolds with ASCs for adipogenesis. Copyright

Biocompatibility and efficacy of collagen/gelatin sponge scaffold with sustained release of basic fibroblast growth factor on vocal fold fibroblasts in 3-dimensional culture.

Objective: Treatment of vocal fold scarring remains challenging. We have previously reported the therapeutic effects of local injection of basic fibroblast growth factor (bFGF) in animal models and humans. A novel collagen/gelatin sponge (CGS) is capable of sustained release of bFGF, which compensates for its quick absorption in vivo, avoiding multiple injections. This study aimed to evaluate the biocompatibility and efficacy of the CGS in rat vocal fold fibroblasts prior to human trials. Methods: Fibroblasts extracted from Sprague-Dawley rat vocal folds were seeded onto a CGS and then cultivated with bFGF at concentrations of 0, 10, and 100 ng/mL. Vocal fold fibroblast morphology, adhesion, proliferation, and gene expression were measured under these 3-dimensional conditions. Results: Cells adhered to the CGS from day 1. Although no significant differences in cell morphology were detected, cell proliferation was accelerated by bFGF administration. Expression of endogenous bFGF and hepatocyte growth factor was significantly up-regulated at 10 ng/mL bFGF. The expression of procollagen I and procollagen III was significantly suppressed, whereas HAS-1 and HAS-2 were up-regulated at 10 and 100 ng/mL bFGF. Conclusion: The collagen/gelatin sponge is biocompatible with vocal fold fibroblasts and may be useful as a bFGF drug delivery system for the treatment of scarred vocal folds.

A case of giant naevus followed up for 22 years after treatment with artificial dermis

We present an ultra-long followed-up case in which an artificial dermis was used for the treatment of a giant naevus. A 5-year-old boy had a giant naevus on his lower back and both buttocks. The light black pigmentation extended to the lower abdomen and both upper thighs. The lesions on the lower back and both buttocks were treated using the artificial dermis Pelnac in three operative series every 2 years. After removal of the lesion, Pelnac was placed onto the skin defect. Three weeks postoperatively, the silicone film was peeled off and a thin split-thickness skin graft (STSG) taken from the upper-middle back was placed on the regenerated dermis-like connective tissue. Thin STSGs were harvested from the same upper back area repeatedly. The lesions on both posteromedial upper thighs and the lower abdomen were treated in three operative series using tissue expanders. Finally, tissue expanders were inserted subcutaneously in both buttocks where Pelnac had been used 5 years or 7 years before. The lesions around the anus were reconstructed using the expanded skin and local skin flaps. Twenty-two years after the first operation, both grafted and donor sites keep good condition not only cosmetically but also functionally.