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Background Skin flap necrosis is a problem encountered postoperatively. The purpose of this study was to evaluate the effects of platelet-rich plasma containing fragmin/protamine microparticles (PRP&F/P MPs) on viability in a rat dorsal paired pedicle skin (DPPS) flap. Materials and Methods Two symmetrical adjoining rectangular flaps (8 × 2 cm each) were drawn on the rat dorsum. Two days after PRP&F/P MPs-, PRP-, F/P MPs-, and saline (control)-injections ( n = 8 each), flaps were elevated as a random pattern flap without the lateral thoracic, posterior intercostal, and deep circumflex iliac vessels. The flaps were immediately sutured back and the flap survival area was measured 7 d after flap elevation. Results The flap survival rate in PRP&F/P MPs-injected groups (73.1% ± 4.2%) was significantly higher than those in PRP (64.9% ± 4.0%), F/P MPs (59.4 ± 4.5%), and control (61.2% ± 4.2%) groups. Histologic observation of the flaps showed survived thick granulation tissue and neovascularization in PRP&F/P MPs-injected groups. Conclusions When PRP&F/P MPs are administered 2 d before the flap elevation, the improved flap survivals are observed. The pre-injection of PRP&F/P MPs may thus represent a promising treatment to prevent skin flap necrosis in reconstructive surgery.

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.

We evaluated the effects of fragmin/protamine micro-particles (F/P MPs) containing FGF-2 (F/P MP-F) as carriers for the controlled release of FGF-2 for adipocyte-survival and capillary formation in inbred rats with subdivided free fat grafts. F/P MPs could immobilize FGF-2, thereafter gradually releasing the bound FGF-2. Inbred Fisher 344 rats weighing around 150 g were anesthetized and implanted with paste comprising harvested fat combined with F/P MP-F. The effect of F/P MP-F on the survival, granulation, and capillary formation in fat grafts was histologically compared with control grafts containing either FGF-2, F/P MPs or PBS. The control fat grafts became attached to tissues adjacent to the implantation site and were significantly resorbed after 30 days. In contrast, pink, soft, supple grafts were compressible and were little resorbed in the group given F/P FP MP-F at 30-120 days. Normal adipocytes were obviously decreased in the control groups with increased granulation tissues, whereas normal adipocytes with capillary formations were maintained in the F/P MP-F group. Thus, adding F/P MP-F to subdivided fat grafts helps to improve graft volume retention and survival in soft-tissue reconstruction through accelerating adipocyte-survival rates and angiogenesis.

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.

To create a moist environment for wound healing, a hydrocolloid-sheet composed of alginate, chitin/chitosan and fucoidan (ACF-HS) has been developed as a functional wound dressing. ACF-HS gradually adsorbed medium without any maceration and the medium adsorption in vitro reached constant after 18 h. ACF-HS could effectively interact with and protect a healing-impaired wound in diabetic db/db mice, providing a good moist healing environment with exudate. Furthermore, the wound dressing could have other properties like ease of application and removal, and proper adherence. The aim of this study was to evaluate an accelerating effect of ACF-HS on wound healing for healing-impaired wounds in diabetic db/db mice. Round full-thickness skin defects (12 mm in diameter) were made on the back of db/db mice to prepare healing-impaired wounds. After applying ACF-HS to the wounds, the mice were later killed and histological sections of the wound were prepared. Histological examinations showed significantly advanced granulation tissue and capillary formations in the wounds treated with ACF-HS on days 4, 9 and 14 compared with those in commercially available hydrocolloid wound dressing and non-treatment (control). Thus, ACF-HS may serve as a new wound dressing for diabetic healing-impaired wounds.

We examined the effects of prostaglandin E₁ (PGE₁) on radiation-induced proliferation inhibition and apoptosis in keratinocytes and healing of radiation-induced skin injury in a rat model. PGE₁ had a protective effect on radiation-induced growth inhibition in keratinocytes in vitro, but not in fibroblasts. Varying concentrations of PGE₁ were subcutaneously administered into the posterior neck region. X-irradiation at a dose of 20 Gy was administrated to the lower part of the back using a lead sheet with two holes 30 min to 1 h before or after the administration of PGE₁. Although X-irradiation induced epilation, minor erosions, or skin ulcers in almost all rats, PGE₁ administration prior to irradiation reduced these irradiation injuries. Staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling showed that proportions of apoptotic keratinocytes in the X-irradiated skin of PGE₁-administered rats were significantly lower than for those in the skin of rats which did not receive PGE₁. Cutaneous full-thickness defective wounds were then formed in X-irradiated areas to examine the time course of wound healing. Wound healing was significantly delayed because of X-irradiation, but PGE₁ administration prior to irradiation led to a significantly shorter delay in wound healing compared with controls. Decreasing delay in wound healing was correlated with concentration of PGE₁ administrated. Thus, PGE₁-administration may potentially alleviate the radiation-induced skin injury.

Our aim was to provide a new animal model for intractable skin ulcers in irradiated rats. Twenty-four rats were irradiated with total single radiographic irradiation doses of 10, 15, 20, and 30 Gy. The skin was observed for 6 months. In the 10-Gy group, there were no visible changes to the skin. In the 15-Gy group, epilation and depigmentation were seen about 2 weeks after irradiation. In the groups over 20-Gy, minor erosion or skin ulcers appeared in most rats. The wounds healed in the 20-Gy group, but many in the 30-Gy group could not be healed. A further 36 rats were irradiated with 20 Gy, and this was followed by the creation of cutaneous full-thickness defects at different periods. The size of the wounds was measured on days 0, 3, 5, 7, 10, and 14. Delayed wound healing was found in the irradiated groups compared with the unirradiated group (p = 0.01). There were no differences in the time of ulceration, except in the Day 7 group (p = 0.03).

To create a moist environment for rapid wound healing, a hydrosheet composed of alginate, chitin/chitosan, and fucoidan (ACF-HS) has been developed as a functional wound dressing. The aim of this study was to evaluate the accelerating effect of ACF-HS on wound healing for rat mitomycin C-treated healing-impaired wounds. Full-thickness skin defects were made on the back of rats and mitomycin C was applied onto the wound for 10 minutes to prepare a healing-impaired wound. After thoroughly washing out the mitomycin C, ACF-HS was applied to the healing-impaired wounds. The rats were later euthanized and histological sections of the wounds were prepared. The histological examinations showed significantly advanced granulation tissue and capillary formations in the healing-impaired wounds treated with ACF-HS on days 7 and 14, in comparison with that in alginate fiber (Kaltostat), hydrogel wound dressing (DuoACTIVE), and nontreatment (negative control). Furthermore, in cell culture studies, ACF-HS-absorbed serum and fibroblast growth factor-2 was found to be proliferative for fibroblasts and endothelial cells, respectively, and ACF-HS-absorbed serum was found to be chemoattractive for fibroblasts. However, our results may not be strictly comparable with general healing-impaired wound models in humans because of the cell damage by mitomycin C. In addition, more biocompatibility studies of fucoidan are essential due to the possibility of renal toxicity.

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.

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.