Tomoharu Kiyosawa

Hydrogel blends of chitin/chitosan, fucoidan and alginate as healing-impaired wound dressings.

In order to create a moist environment for rapid wound healing, a hydrogel sheet composed of a blended powder of alginate, chitin/chitosan and fucoidan (ACF-HS; 60:20:2:4 w/w) has been developed as a functional wound dressing. ACF-HS gradually absorbed DMEM without any maceration, and fluid absorption became constant within 18 h. On application, ACF-HS was expected to effectively interact with and protect the wound in rats, providing a good moist healing environment with exudates. In addition, the wound dressing has properties such as ease of application and removal and good adherence. Full-thickness skin defects were made on the backs of rats and mitomycin C solution (1 mg/ml in saline) was applied onto the wound for 10 min in order to prepare healing-impaired wounds. After thoroughly washing out the mitomycin C, ACF-HS was applied to the healing-impaired wounds. Although normal rat wound repair was not stimulated by the application of ACF-HS, healing-impaired wound repair was significantly stimulated. Histological examination demonstrated significantly advanced granulation tissue and capillary formation in the healing-impaired wounds treated with ACF-HS on day 7, as compared to those treated with calcium alginate fiber (Kaltostat; Convatec Ltd., Tokyo, Japan) and those left untreated.

Accelerated wound healing in healing-impaired db/db mice by autologous adipose tissue-derived stromal cells combined with atelocollagen matrix.

Adipose tissue-derived stromal cells (ATSCs) have recently gained widespread attention as a potential alternate source to bone marrow–derived mesenchymal stem cells with a proliferative capacity and a similar ability to undergo multilineage differentiation. In this study, we evaluated the effectiveness of freshly isolated autologous ATSCs-containing atelocollagen matrix with silicon membrane (ACMS) on wound healing of diabetic (db/db) mice. Cultured ATSCs from (db/db) mice secreted significant amounts of growth factors and cytokines, which are suitable for wound repair. Two full thickness round skin defects were made on the backs of healing-impaired db/db mice. Freshly isolated autologous ATSCs-containing ACMS or ACMS alone were applied to the wounds. Twelve mice were treated and then killed at 1 or 2 weeks (n = 6 each). Histologic sections of the wounds were prepared at each time period after treatment. Histologic examination demonstrated significantly advanced granulation tissue formation, capillary formation, and epithelialization in diabetic healing-impaired wounds treated with autologous ATSCs-containing ACMS, compared with mice treated with ACMS alone. These results suggested that transplantation of autologous ATSCs-containing ACMS significantly accelerated wound healing in diabetic healing-impaired db/db mice.

Enhanced Effect of Platelet-Rich Plasma Containing a New Carrier on Hair Growth

BACKGROUND Treatments for alopecia are in high demand, but not all are safe and reliable. Dalteparin and protamine microparticles (D/P MPs) can effectively carry growth factors (GFs) in platelet‐rich plasma (PRP). OBJECTIVE To identify the effects of PRP‐containing D/P MPs (PRP&D/P MPs) on hair growth. METHODS & MATERIALS Participants were 26 volunteers with thin hair who received five local treatments of 3 mL of PRP&D/P MPs (13 participants) or PRP and saline (control, 13 participants) at 2‐ to 3‐week intervals and were evaluated for 12 weeks. Injected areas comprised frontal or parietal sites with lanugo‐like hair. Experimental and control areas were photographed. Consenting participants underwent biopsies for histologic examination. RESULTS D/P MPs bind to various GFs contained in PRP. Significant differences were seen in hair cross‐section but not in hair numbers in PRP and PRP&D/P MP injections. The addition of D/P MPs to PRP resulted in significant stimulation in hair cross‐section. Microscopic findings showed thickened epithelium, proliferation of collagen fibers and fibroblasts, and increased vessels around follicles. CONCLUSION PRP&D/P MPs and PRP facilitated hair growth but D/P MPs provided additional hair growth. The authors have indicated no significant interest with commercial supporters.

Enhanced healing of mitomycin C-treated wounds in rats using inbred adipose tissue-derived stromal cells within an atelocollagen matrix.

The aim of this study was to evaluate the potential accelerating effects of an adipose tissue‐derived stromal cells (ATSC)‐containing atelocollagen matrix with silicone membrane (ACMS) for repairing mitomycin C‐treated healing‐impaired wounds. Mitomycin C was applied to full‐thickness skin incisions in this study to create a healing‐impaired wound model in rat. After thoroughly washing out the mitomycin C from the wound, ACMS alone or ATSC‐containing ACMS was applied to the wounds. Histological sections of the wounds were then prepared at indicated time periods after the treatments. These results indicated significantly advanced granulation tissue and capillary formations in the healing‐impaired wounds treated with ATSC‐containing ACMS compared with those treated with ACMS alone. Thus, this study suggested that transplantation of inbred ATSC‐containing ACMS is effective for repairing healing‐impaired wounds.

Platelet-rich Plasma (prp) Promotes Survival of Fat-grafts in Rats

This study evaluated the effects of platelet-rich plasma (PRP) on resorption and adipocyte survival in autologous fat-graft of rats prepared with isogenous PRP. Fat grafts prepared without PRP (control group) became united to the tissue adjacent to the implantation site and were significantly resorbed from 30 days. On the other hand, fat grafts prepared with PRP (PRP group) demonstrated little resorption from 30 to 120 days and appeared pink, had a soft, supple feel, and were easily compressible. Histologic sections of grafts in the control and PRP groups at 10 days exhibited similar consolidation of the grafted tissue, which contained morphologically normal adipocytes with different degrees of granulation and capillary formation. From 20 days normal adipocytes were obviously decreased in the control group, while the PRP group demonstrated increased granulation tissue and capillary formation and good maintenance of normal adipocytes for at least 120 days.

Controlled release of FGF-2 using fragmin/protamine microparticles and effect on neovascularization

Water-insoluble fragmin/protamine microparticles of about 0.5-1 mum in diameter were prepared by simple mixing of low-molecular-weight heparin (fragmin) with protamine. We investigated the capability of these microparticles to immobilize fibroblast growth factor (FGF)-2, to protect FGF-2 against degradation, to enhance FGF-2 activity, and to facilitate controlled release of FGF-2. FGF-2 bound to the fragmin/protamine microparticles with high affinity (Kd = 2.08 x 10(-9) M) and the half-life of FGF-2-activity was prolonged substantially through binding of FGF-2 to the microparticles, by protection of FGF-2 from inactivation by heat and proteolysis. After subcutaneous injection into the back of mice, the fragmin/protamine microparticles underwent biodegradation and disappeared in about 2 weeks. A similar injection of FGF-2-containing microparticles resulted in significant neovascularization and fibrous tissue formation near the injection site after 1 week. These results indicate that controlled release of biologically active FGF-2 occurs through both slow diffusion and biodegradation of the microparticles, with subsequent induction of neovascularization. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.

Vascularized free nail grafts nourished by arterial inflow from the venous system.

Three patients underwent successful transplantation of the great toenails to their index fingers using the method of vascularization from venous pedicles. We have found that this procedure is easy and reliable.

Detection of skin perforators by indocyanine green fluorescence nearly infrared angiography.

Perforator-based island flaps are widely used to reconstruct skin defects. For this procedure to succeed, a perforator with adequate blood flow must be selected, and precise preoperative prediction of the location of the perforators is required. To identify perforators, a variety of methods have bee

Controlled releases of FGF-2 and paclitaxel from chitosan hydrogels and their subsequent effects on wound repair, angiogenesis, and tumor growth.

A photocrosslinkable chitosan (Az-CH-LA) aqueous solution resulted in an insoluble hydrogel like a soft rubber within 30 sec of ultraviolet light (UV)-irradiation. The photocrosslinked chitosan hydrogel showed strong sealing strength and potential use as a new tissue adhesive in surgical application. Paclitaxel, which is an anti-tumor reagent and a vascularization-inhibitor, retained in the photocrosslinked chitosan hydrogel, and were gradually released from the photocrosslinked chitosan hydrogel in vivo upon the degradation of the hydrogel. The paclitaxel-incorporated photocrosslinked chitosan hydrogels effectively inhibited tumor growth and angiogenesis in mice. On the other hand, the fibroblast growth factor (FGF)-2 molecules also retained in both the photocrosslinked chitosan and an injectable chitosan/IO(4)-heparin hydrogels, and were gradually released from the hydrogels upon their in vivo biodegradations. The activity of FGF-2 in the hydrogels was stable for long time (more than 14 days). The controlled release of biologically active FGF-2 molecules from the hydrogels caused an induction of the angiogenesis and, possibly, collateral circulation occurred in the healing-impaired diabetic (db/db) mice and the ischemic limbs of rats. The purpose of this review is to describe the effectiveness of the chitosan hydrogels (photocrosslinkable chitosan hydrogel and chitosan/IO(4)-heparin hydrogel) as a local drug delivery carrier for FGF-2 and paclitaxel to control wound repair, tumor growth, and angiogenesis. It is thus proposed that the chitosan hydrogels may be a promising new local carrier for drugs such as FGF-2 and paclitaxel.

Enhancement of vascularization and granulation tissue formation by growth factors in human platelet‐rich plasma‐containing fragmin/protamine microparticles

The purpose of this study was to evaluate effects of human platelet-rich plasma (PRP)-containing fragmin/protamine microparticles (F/P MPs) as a protein carrier on neovascularization and granulation tissue formation. Frozen and thawed PRP contains high concentrations of various growth factors (GFs) and F/P MPs effectively adsorb those GFs. Human microvascular endothelial cells (MVECs) and dermal fibroblast cells (DFCs) were optimally grown in medium containing 4% PRP and the addition of F/P MPs significantly maintained and protected the proliferative activity of PRP incubated at 37°C for more than 10 days. When PRP-containing F/P MPs were subcutaneously injected into the back of mice, significant neovascularization was induced near the injected site with enhanced filtration of inflammatory cells from day 3 to day 30, compared with controls (injections of PRP, F/P MPs, and saline). Both PRP-containing F/P MPs and PRP alone induced significant formation of granulation tissue at the injected site. However, thickness of induced granulation tissues was well maintained for 30 days only in PRP-containing F/P MP-injected group. Those bound GFs may be gradually diffused and released from F/P MPs in vitro and in vivo. Thereby, PRP-containing F/P MPs offer significantly higher inductions of vascularization and fibrous tissue formation in vivo than PRP alone.