Collagen/gelatin Sponge Research Articles

Interposition grafting of collagen-gelatin sponge impregnated with basic fibroblast growth factor in primary palatoplasty

IntroductionAn oronasal fistula is a challenging post-operative complication of palatoplasty due to impaired velopharyngeal function or its high recurrence rate. Muscle repositioning, a key procedure in palatoplasty, causes dead space at the junction between the hard and soft palates. Consequently, thin oral and nasal mucosae are prone to break down and form fistulas. In this study, we used basic fibroblast growth factor-impregnated collagen gelatin sponge (bFGF-CGS) in primary palatoplasty to reduce fistula formation. MethodsThis retrospective study assessed the complications and efficacy of bFGF-CGS to reduce fistula formation. Patients who underwent primary palatoplasty with bFGF-CGS were included. The same number of patients who underwent primary palatoplasty without bFGF-CGS was included as a control group. The outcomes included post-operative oronasal fistula formation, delayed healing, bleeding, and infection. ResultsBoth groups included 44 patients. Except for age at palatoplasty, there were no statistically significant demographic differences between the two groups; however, the rates of fistula formation in the study and control group were 2.3% and 13.6%, respectively. There were no infections among the patients. ConclusionsThe grafting of bFGF-CGS in primary palatoplasty was safe and probably effective in reducing post-operative oronasal fistula formation.

Risk of bleeding in anticoagulated patients undergoing dental extraction treated with topical tranexamic acid compared to collagen-gelatin sponge: Randomized clinical trial

This two-arm, parallel-group, double-blind, randomized clinical trial design evaluated the risk of postoperative bleeding in anticoagulated patients undergoing dental extraction treated with topical TXA in comparison to collagen-gelatin sponge. Forty patients were randomly included in one of the study groups: (1) topical use of 4.8% TXA solution; and (2) resorbable hydrolyzed collagen-gelatin sponge applied to the surgical alveolus. Primary outcomes were postoperative bleeding episodes and secondary outcomes were thromboembolic events and postoperative INR values. The relative risk (RR), the absolute risk reduction (RAR) and the number needed to treat (NNT) were used as effect estimates and calculated from the counting of bleeding episodes observed during the first postoperative week. The bleeding rate under the TXA treatment was 22.2%, while in the collagen-gelatin sponge group it was 45.7%, resulting in a RR of 0.49 (95% CI 0.24–099; p = 0.046), RAR 23.5% and NNT 4.3. TXA was more effective in reducing bleeding in surgical sites located in the mandible (RR = 0.10; 95% CI 0.01–0.71; p = 0.021) and the posterior region (RR = 0.39; 95% CI 0.18–0.84; p = 0.016). Within the limitations of the study it seems that topical TXA is more effective in controlling bleeding after tooth extractions in anticoagulated patients than collagen-gelatin sponge. Clinical trial registrationRBR-83qw93.

Two-stage skin grafting using a basic fibroblast growth factor-impregnated artificial dermis.

For traditional artificial dermises, a waiting period of approximately three weeks is required after the first implantation before they are adequately vascularized. The objective of this retrospective case series was to investigate whether full-thickness skin defects, requiring surgical reconstruction, could be successfully treated by implantation of a basic fibroblast growth factor (bFGF)-impregnated artificial dermis and secondary skin grafting with a shorter waiting period. Between January 2019 and January 2021, 19 skin defects in 14 patients (7 male and 7 female) were treated with two-stage skin grafting using bFGF-impregnated collagen-gelatin sponge (CGS). All of them were included in this case series, and the waiting period for skin grafting, success rate of skin grafting, infection during the waiting period, and scar quality 6–12 months postoperatively were retrospectively investigated. As a result, all skin grafting surgeries were successfully performed with a waiting period of 13.3 ± 4.3 days. Infection during the waiting period was observed in three lesions (15.8%); however, all infections were controllable. Postoperative scar quality was acceptable (Vancouver Scar Scale score range, 1–8). In conclusion, compared to traditional artificial dermises, bFGF-impregnated CGSs have the potential to shorten the waiting period without decreasing the success rate of skin grafting. Further studies are required to confirm this finding.

Basic fibroblast growth factor-impregnated collagen gelatin sponge completes formation of dermis-like tissue within 2 weeks: Aprospective cohort study.

IntroductionThis study included patients who underwent full-thickness skin reconstruction using a two-stage procedure comprising basic fibroblast growth factor-impregnated collagen gelatin sponge (bFGF-CGS) implantation and autologous skin grafting, and the take rate of skin grafts was compared between groups of patients who underwent autologous skin grafting after a waiting period of <2 weeks or ≥2 weeks.MethodsAn acute, full-thickness skin defect was treated with thorough debridement of contaminated/necrotic tissue, followed by washing with saline and hemostasis with electrocautery. Then, an FGF-CGS was fixed to the skin defect wound using non-absorbable sutures, and after confirming regeneration of sufficient dermis-like tissue, the second-stage autologous skin grafting was performed for wound closure. Patients were divided into two groups according to the waiting period before the second operation, namely, <2 weeks (early group) and ≥2 weeks (late group), and the take rate of skin grafts was compared.ResultsWe enrolled and treated 25 cases (18 men, 7 women; mean age: 49 [range 2–86] years). The mean take rate of skin grafts was 93% (range 80%–100%) in the early group and 92% (range 65%–100%) in the late group, with no significant difference between the two groups. There was a significant difference between the groups in mean time to complete healing: 25.2 ± 9.7 days in the early group vs 44.7 ± 27 days in the late group (p < 0.05).ConclusionOur data suggest that bFGF-CGF can form dermis-like granulation tissue with sufficient quality as a graft bed for skin transplantation within 2 weeks.

Fibroblast Growth Factor-Impregnated Collagen-Gelatin Sponge Improves Keratinocyte Sheet Survival.

Commercially available cultured epithelial keratinocyte sheets (KSs) have played an essential role in wound healing over the past four decades. Despite the initial uptake by the dermal elements, the survival rate of KS on the dermis-like tissue generated by conventional artificial dermis (AD) is low, making this method unsuitable for standard treatments. Therefore, an innovative AD such as collagen-gelatin sponge (CGS) that maintains the release of human recombinant basic fibroblast growth factor (bFGF) may promote wound healing. In this study, we examined whether combination therapy with KSs and CGS with bFGF (bFGF-CGS) could enhance KS survival by heterologous grafting by transplantation of human-derived KSs in an athymic nude rat wound model of staged skin reconstruction. The CGSs were implanted into skin defect wounds on athymic nude rats, which were then divided into two experimental groups: the bFGF group (CGSs containing bFGF, n = 8) and the control group (CGSs with saline, n = 8). Two weeks after implantation, human epithelial cell-derived KSs were grafted onto the dermis-like tissue, followed by assessment of the survival and morphology at 1 week later using digital imaging, histology (hematoxylin and eosin and Masson's trichrome staining), immunohistology (von Willebrand factor), immunohistochemistry (cytokeratin 1-5-6, Ki-67), and immunofluorescence (collagen IV, pan-cytokeratins) analyses. The bFGF group showed a significantly higher KS survival area (86 ± 58 mm2 vs. 32 ± 22 mm2; p < 0.05) and increased epidermal thickness (158 ± 66 μm vs. 86 ± 40 μm; p < 0.05) compared with the control group, along with higher dermis-like tissue regeneration, neovascularization, epidermal maturation, and basement membrane development. These results indicate that the survival rate of KSs in the dermis-like tissue formed by bFGF-CGS was significantly increased. Therefore, combination treatment of bFGF-CGS and KSs shows potential for full-thickness skin defect reconstruction in clinical situations. Impact statement This study highlights how using a combination of cultures, keratinocyte sheets, and collagen-gelatin sponge containing basic fibroblast growth factors can significantly improve cell survival in athymic nude rats with staged skin reconstruction. Our study makes a significant contribution to the literature because it highlights a novel and improved strategy for treating a very common condition such as skin wounds arising from many conditions. Clinical translation of this study may be useful for treating skin wounds.

Coverage of Free Flap Vascular Pedicles by Basic Fibroblast Growth Factor-impregnated Collagen-Gelatin Sponge Without Skin Graft

Coverage of Free Flap Vascular Pedicles by Basic Fibroblast Growth Factor-impregnated Collagen-Gelatin Sponge Without Skin Graft

Effects of Fibroblast Growth Factor-2 Combined With a Collagen/Gelatin Sponge for Adipogenesis in the Mouse Subcutis.

A collagen/gelatin sponge (CGS) is a new scaffold that promotes wound healing by slowly releasing fibroblast growth factor (FGF)-2. FGF-2 induces mitogenesis, angiogenesis, and adipogenesis. In this study, the adipogenesis-inducing effects of CGS combined with FGF-2 in the subcutis of mice were evaluated. Collagens/gelatin sponges (10 × 5 mm) were impregnated with 50 μL of FGF-2 solution (10 or 100 μg/mL). A CGS (Gunze Corp, Osaka, Japan) combined with FGF-2 was implanted subcutaneously into the thoracic region of mice. At 1, 2, 3, and 4 weeks, samples were collected for hematoxylin and eosin staining, von Willebrand factor immunostaining, and perilipin immunostaining to examine adipose tissue localization and angiogenesis. A CGS with only saline solution was prepared as a control. Adipocytes in the collagen fibers appeared at 3 weeks, and a zonal fat layer was noted under the panniculus carnosus at 4 weeks in the FGF-2-combined CGS groups. The fat layer was significantly thicker in the FGF-2 (100 μg/mL) group than in the FGF-2 (10 μg/mL) group. In the control group, no fat pad was newly formed. The number of newly formed vessels in the FGF (10 μg/mL) and (100 μg/mL) groups was significantly greater in the FGF-2 group than in the control group. This study presents a promising method to enhance adipogenic effects in the murine subcutis using CGS combined with FGF-2, representing a potential technique for soft tissue reconstruction.

Full-thickness skin reconstruction with basic fibroblast growth factor-impregnated collagen-gelatin sponge

IntroductionThis study examined the usefulness of basic fibroblast growth factor impregnated collagen-gelatin sponge (bFGF-CGS) in reconstructive surgery for various acute skin defects including deep dermal burns, facial full-thickness skin defects, and finger amputations as the first clinical application.MethodsReconstructive surgery was performed in two stages with bFGF-CGS in 8 male subjects, ranging in age from 6 to 84 years, with acute full-thickness skin defects. Following the adequate debridement of the defect, surgeons prepared a bFGF-CGS with bFGF solution at a dose of 7–14 mg/cm2 approximately 10 min just before application and then secured the bFGF-CGS in place with non-absorbable sutures. Second-stage wound closure was performed with autologous skin grafting following adequate dermis-like tissue regeneration at the site postoperatively. Follow-up was continued for 6 months.ResultsOf the 8 subjects, the mean duration from the adequate vascularization of the dermis-like tissue until the second-stage autologous skin graft was 22 ± 4 days. Wound closure was achieved in all cases; the mean duration until wound closure was 32 ± 8 days. During the 6-month follow-up period, no wound infection, recurrent skin ulceration, and no exposure of tendon, bone, and cartilage were observed, and there were no cases of indirectly restricted range of motion from postoperative scar contracture and none with disfiguring scars.ConclusionThe authors achieved favorable outcomes following reconstructive surgery with a hybrid artificial dermis impregnated with bFGF for treating acute full-thickness skin defects. bFGF-CGS serves as a convenient regenerative device requiring no specialized medical facilities.

The sustained release of basic fibroblast growth factor accelerates angiogenesis and the engraftment of the inactivated dermis by high hydrostatic pressure.

We developed a novel skin regeneration therapy combining nevus tissue inactivated by high hydrostatic pressure (HHP) in the reconstruction of the dermis with a cultured epidermal autograft (CEA). The issue with this treatment is the unstable survival of CEA on the inactivated dermis. In this study, we applied collagen/gelatin sponge (CGS), which can sustain the release of basic fibroblast growth factor (bFGF), to the inactivated skin in order to accelerate angiogenesis. Murine skin grafts from C57BL6J/Jcl mice (8 mm in diameter) were prepared, inactivated by HHP and cryopreserved. One month later, the grafts were transplanted subcutaneously onto the back of other mice and covered by CGS impregnated with saline or bFGF. Grafts were harvested after one, two and eight weeks, at which point the engraftment was evaluated through the histology and angiogenesis-related gene expressions were determined by real-time polymerase chain reaction. Histological sections showed that the dermal cellular density and newly formed capillaries in the bFGF group were significantly higher than in the control group. The relative expression of FGF-2, PDGF-A and VEGF-A genes in the bFGF group was significantly higher than in the control group at Week 1. This study suggested that the angiogenesis into grafts was accelerated, which might improve the engraftment of inactivated dermis in combination with the sustained release of bFGF by CGSs.

Collagen/Gelatin Sponges (CGSs) Provide Both Protection and Release of bFGF: An In Vitro Study.

It has been reported that collagen/gelatin sponges (CGSs) are able to sustain the release of basic fibroblast growth factor (bFGF) for approximately 10 days via the formation of ion complexes between bFGF and gelatin. CGSs impregnated with bFGF have been proven to promote dermis-like tissue formation in various in vivo studies and clinical trials. However, the bioactivities of bFGF released from CGSs have not been explored in vitro. In this study, we explored the ability of CGS impregnated with bFGF, stored at 37°C for up to 14 days, to promote fibroblast proliferation and the sustained release of bFGF. We analyzed the cellular viability and proliferation in 2D and in 3D cell cultures, by a CCK-8 assay. Furthermore, in order to characterize the morphological alteration of fibroblasts, we studied 3D cultures by microscopy with a scanning electron microscope (SEM) and a confocal microscope. Our analyses revealed that the fibroblasts were elongated and flanked each other. They infiltrated and migrated inside the CGSs and were oriented along the CGS structure. Thus, these data prove that CGSs protect and sustain the efficient release of growth factor for more than 7 days.

Efficacy of the dual controlled release of HGF and bFGF impregnated with a collagen/gelatin scaffold

BackgroundWe previously developed collagen/gelatin sponges (CGS) able to sustain and release basic fibroblast growth factor (bFGF) and reported that this CGS impregnated with bFGF promoted dermis-like tissue formation. We herein confirmed the single-sustained release of hepatocyte growth factor (HGF) and the dual sustained release of HGF and bFGF from CGSs, and explored its efficacy using a murine model of skin defects. Materials and methodsThe sustained release of HGF alone and both HGF and bFGF from CGSs were evaluated in vitro. CGSs (8 mm in diameter) impregnated with normal saline solution (NSS) (NSS group), HGF solution (10 or 50 μg/cm2) (HGF-L or HGF-H group), bFGF solution (7 μg/cm2) (bFGF group), or HGF (10 μg/cm2) and bFGF (7 μg/cm2) solution (HGF + bFGF group) were implanted into full-thickness skin defects on the backs of mice. The wound area, neoepithelium length, dermis-like tissue formation and newly formed capillaries were evaluated. ResultsThe single release of HGF and the dual release of HGF and bFGF from CGSs were confirmed. At week 1, the wound closure and neoepithelium length were promoted in the HGF-L group compared with the NSS group. At week 2, the wound closure, neoepithelium length, dermis-like tissue formation and newly formed capillary formation were promoted in the bFGF and HGF + bFGF groups compared with the NSS and HGF-H groups. Newly formed capillary formation was superior in the HGF + bFGF group compared with the bFGF group. ConclusionsThe dual release of HGF and bFGF from CGS was a promising treatment for full-thickness skin defects.

A Comparison of Conventional Collagen Sponge and Collagen-Gelatin Sponge in Wound Healing.

The objective of this study was to compare the effectiveness of the collagen-gelatin sponge (CGS) with that of the collagen sponge (CS) in dermis-like tissue regeneration. CGS, which achieves the sustained release of basic fibroblast growth factor (bFGF), is a promising material in wound healing. In the present study, we evaluated and compared CGSs and conventional CSs. We prepared 8 mm full-thickness skin defects on the backs of rats. Either CGSs or CSs were impregnated with normal saline solution (NSS) or 7 μg/cm2 of bFGF solution and implanted into the defects. At 1 and 2 weeks after implantation, tissue specimens were obtained from the rats of each group (n = 3, total n = 24). The wound area, neoepithelial length, dermis-like tissue area, and the number and area of capillaries were evaluated at 1 and 2 weeks after implantation. There were no significant differences in the CGS without bFGF and CS groups. Significant improvements were observed in the neoepithelial length, the dermis-like tissue area, and the number of newly formed capillaries in the group of rats that received CGSs impregnated with bFGF. The effects on epithelialization, granulation, and vascularization of wound healing demonstrated that, as a scaffold, CGSs are equal or superior to conventional CSs.

The efficacy of a novel collagen-gelatin scaffold with basic fibroblast growth factor for the treatment of vocal fold scar.

Vocal fold scar remains a therapeutic challenge. Basic fibroblast growth factor (bFGF) was reported to have regenerative effects for vocal fold scar, although it has the disadvantage of rapid absorption in vivo. A collagen-gelatin sponge (CGS) can compensate for the disadvantage by providing a sustained release system. The current study evaluated the efficacy of CGS combined with bFGF on vocal fold scar, using rat fibroblasts for an in vitro model and a canine in vivo model. We prepared fibroblasts from scarred vocal folds (sVFs) in rats and showed that bFGF accelerated cell proliferation and suppressed expression levels of cleaved caspase 3 and α-smooth muscle actin. Has 1, Has 3, Fgf2, Hgf and Vegfa mRNA levels were significantly upregulated, while Col1a1 and Col3a1 were dose-dependently downregulated, with a maximum effect at 100 ng/ml bFGF. In an in vivo assay, 6 weeks after lamina propria stripping, beagles were divided into three groups: CGS alone (CGS group); CGS with bFGF (7 µg/cm2 ; CGS + bFGF group); or a sham-treated group. Vibratory examination revealed that the glottal gap was significantly reduced in the bFGF group and the two implanted groups, whereas the CGS + bFGF group showed higher mucosal wave amplitude. Histological examination revealed significantly restored hyaluronic acid and elastin redistribution in the CGS + bFGF group and reductions in dense collagen deposition. These results provide evidence that CGS and bFGF combination therapy may have therapeutic potential and could be a promising tool for treating vocal fold scar. Copyright © 2015 John Wiley & Sons, Ltd.

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

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. 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. 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. 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.

Novel Collagen/Gelatin Scaffold with Sustained Release of Basic Fibroblast Growth Factor: Clinical Trial for Chronic Skin Ulcers

Chronic skin ulcers such as diabetic ulcers and venous leg ulcers are increasing and are a costly problem in healthcare. We have developed a novel artificial dermis, collagen/gelatin sponge (CGS), which is capable of sustained release of basic fibroblast growth factor (bFGF) for more than 10 days. The objective of this study was to investigate the safety and efficacy of CGS impregnated with bFGF in the treatment of chronic skin ulcers. Patients with chronic skin ulcers that had not healed in at least 4 weeks were treated with CGS impregnated with bFGF at 7 or 14 μg/cm(2) after debridement, and the wound bed improvement was assessed 14 days after application. Wound bed improvement was defined as a granulated and epithelialized area on day 14 with a proportion to the baseline wound area after debridement of 50% or higher. The wound area, the wound area on day 14, and the granulation area on day 14 were independently measured by blinded reviewers in a central review using digital images of wounds taken with a calibrator. Patients were followed up until 28 days after application to observe the adverse reactions related to the application of CGS. From May 2010 to June 2011, 17 patients were enrolled and, in 16 patients, the wound bed improved. Among the randomized patients in step 2, no significant difference was seen between the low-dose group and the high-dose group. No serious adverse reactions were observed. Adverse reactions with a clear causal relationship to the study treatment were mild and patients quickly recovered from them. This study is the first-in-man clinical trial of CGS and showed the safety and efficacy of CGS impregnated with bFGF in the treatment of chronic skin ulcers. This combination therapy could be a promising therapy for chronic skin ulcers.

Efficacy of Novel Collagen/Gelatin Scaffold With Sustained Release of Basic Fibroblast Growth Factor for Dermis-like Tissue Regeneration

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 μg/cm) 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-μg/cm 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.

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/cm(2) ) or normal saline solution. Then the labelled cells were disseminated (passage 3) on CGSs at a seeding density of 1 × 10(5) cells/cm(2) 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/cm(2) 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.

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/cm(2) 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/cm(2)). 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/cm(2) bFGF displayed accelerated dermis-like tissue formation and the CGSs impregnated with 14 µg/cm(2) 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/cm(2) bFGF groups. CGSs impregnated with 7-14 µg/cm(2) 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.

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

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. 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. 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. Our new collagen-gelatin scaffold, CGS, impregnated with bFGF, could be a promising treatment to accelerate the regeneration of palatal mucosa.

Following the fate of murine epidermal stem cells in a syngeneic dermal equivalent in vivo

Background Stem cells in healthy epidermis have the capacity to produce structures, such as interfollicular epidermis, hair follicle, and sebaceous glands. Embryonic stem (ES) cells can be induced to differentiate into epidermal stem cells in vitro. These ESCs (epidermal or epidermoid stem cells derived from ES cells) have the potential to be an ideal replacement of those stem cells destroyed in severe injury, such as in deep and extensive burn. The aim of this study was to follow the fate of murine ESCs which were seeded in a syngeneic dermal equivalent and implanted into syngeneic recipient mice subcutaneously. Methods ES cells were induced in vitro to differentiate into ESCs. Stained with a fluorescent dye Hoechst 33342, these ESCs were seeded into a fibroblast–collagen–gelatin sponge complex, functioning as a dermal equivalent model, and then implanted subcutaneously into 129/J mice, which were syngeneic to these stem cells. Results These ESCs were clearly visible in the implant by fluorescent microscopy 3 weeks or longer after implantation. These cells remained viable, differentiating into hair follicle-like structures, glandular structures, and gave rise to additional structures resembling native dermis. A number of markers were expressed in the differentiated structures, including CD29 (integrin β1 subunit) and cytokeratin 18 (CK18). No apparent rejection or severe side effects were observed at least during the 10 weeks following implantation. Conclusions Now that ESCs can survive in vivo in this dermal equivalent model and differentiate into hair follicle-like structures as well as glandular structures, it is feasible to use these cells as seed cells in studies to fabricate dermal equivalents that have the potential to develop dermal appendages.