Continuous negative-pressure wound therapy improves the survival rate of skin grafts and shortens the time required for skin graft survival.

BACKGROUND: The effectiveness of negative-pressure wound therapy (NPWT) in skin graft fixation has been demonstrated in several clinical studies. However, in vitro and in vivo studies on skin graft fixation with NPWT have been scarce. In this in vivo study, we aimed to determine whether NPWT fixation enhances skin graft survival and how it contributes to improving skin graft survival biologically. MATERIALS AND METHODS: We harvested skin from the bilateral abdominal wall of 88 mice after anesthetizing them. Full-thickness skin grafts (FTSGs) were performed on contralateral harvest sites, and grafts were fixed using NPWT (continuous and intermittent modes), conventional compression methods, and wrapping with polyurethane foam as a control group. On days 5 and 10 of grafting, the survival rates of the FTSGs were evaluated. Immunohistopathological analysis and measurement of the expression levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2), and epidermal growth factor (EGF) were performed. RESULTS: The survival rates of FTSG in the continuous NPWT group were significantly higher than those in the other groups. The number of capillaries in the dermis was significantly higher in the continuous NPWT group than in the other groups. In the wound bed, VEGF levels were significantly higher in both NPWT groups than in the other groups. CONCLUSION: Continuous NPWT increases the survival rate of FTSGs and shortens the duration of skin graft survival.

An intrinsically semi-permeable PDMS nanosheet encapsulating adipose tissue-derived stem cells for enhanced angiogenesis.

Cell encapsulation devices are expected to be promising tools that can control the release of therapeutic proteins secreted from transplanted cells. The protein permeability of the device membrane is important because it allows the isolation of transplanted cells while enabling the effectiveness of the device. In this study, we investigated free-standing polymeric ultra-thin films (nanosheets) as an intrinsically semi-permeable membrane made from polydimethylsiloxane (PDMS). The PDMS nanosheet with a thickness of 600 nm showed intrinsic protein permeability, and the device fabricated with the PDMS nanosheet showed that VEGF secreted from implanted adipose tissue-derived stem cells (ASCs) could be released for at least 5 days. The ASC encapsulation device promoted angiogenesis and the development of granulation tissue 1 week after transplantation to the subcutaneous area of a mouse. This cell encapsulation device consisting of PDMS nanosheets provides a new method for pre-vascularization of the subcutaneous area in cell transplantation therapy.

Superficial Temporal Artery Island Flap Combined With Laser Hair Removal for Inadequate Skin Expansion Following Tissue Expansion: A Case Report of Congenital Melanocytic Nevus of the Forehead in an Adult.

Tissue expansion is a handy reconstructive technique for the head and neck region; however, its implementation requires careful planning and surgical experience. If tissue expansion is inadequate, forced closure results in wound tension and risks complications, such as postoperative deformity, wide scarring, and wound dehiscence. We report a case of adult forehead melanocytic nevus excision using a tissue expander (TE) where complications caused by insufficient tissue expansion were avoided by creating a flap using a dog ear. The patient was a male in his 20s who underwent surgery with a TE for a congenital melanocytic nevus sized 15 × 10 cm on the left forehead. Resection was performed by tissue expansion using two TEs; however, simple advancement flaps led to excessive wound tension, risk of elevation of the eyebrow on the affected side, and postoperative scarring. Hence, a superficial temporal artery fasciocutaneous island flap with left superficial temporal vessels as a pedicle was raised at the dog ear and moved to the site of strong tension, and the wound was closed without difficulty. Although postoperative laser hair removal was required, both the appearance and functional results were satisfactory. Using anatomical flaps obtained from the surroundings during tissue expansion helps avoid complications associated with forced wound closure.

Urosymphyseal fistula development following treatment for radiation-induced urethral stenosis in three patients with prostate cancer.

Introduction: Urosymphyseal fistula is a rare and devastating complication that develops after radiation therapy for prostate cancer and is often triggered by the treatment of radiation-induced urethral stenosis. Here, we report our experience with urosymphyseal fistulas in three patients with prostate cancer. Case presentation: Three patients with prostate cancer developed urethral stenosis after radiotherapy. The management of urethral stenosis was suprapubic tube placement in case 1, direct vision internal urethrotomy in case 2, and excision with primary anastomosis in case 3. All patients presented with severe suprapubic or thigh pain or both. Urosymphyseal fistulas were detected on magnetic resonance imaging. Conservative treatment was unsuccessful, and all patients required debridement of the necrotic pubic symphysis and simple cystectomy. In cases 1 and 2, ileal conduit urinary diversion was performed. Conclusion: Urologists need to be aware that urosymphyseal fistulas can occur in irradiated patients with prostate cancer, especially after urethral stenosis treatment.

Mixed lesion of traumatic pseudoaneurysm and pyogenic granuloma on a digit.

Traumatic aneurysms occurring in the digit are extremely rare. We report a case of a traumatic pseudoaneurysm arising from a terminal branch of the finger artery and presenting as a mixed lesion with pyogenic granuloma that was exposed to the outside of the body and treated surgically.

Lymphoscintigraphy with single-photon emission computerized tomography/computed tomography for evaluating lymphatic leakage following pelvic and para-aortic lymphadenectomy.

Lymphatic ascites following pelvic and para-aortic lymphadenectomy is a well-known complication. Surgical treatment and interventional radiology are required in a few cases. To determine the appropriate treatment strategy, it is important to preoperatively detect the presence and location of lymphatic leakage. However, the methods have yet to be established. We report a case in which lymphoscintigraphy with single-photon emission computerized tomography/computed tomography (SPECT/CT) was performed to evaluate pelvic lymphorrhea that occurred following total hysterectomy with pelvic and para-aortic lymphadenectomy for stage IIIA uterine sarcoma. Lymphoscintigraphy with SPECT/CT showed leakage of radioisotopes into the pelvic space, and intranodal lymphangiography was performed based on these findings. Following the procedure, the pelvic lymphorrhea improved, and no radioisotope leakage was confirmed by re-evaluation with lymphoscintigraphy with SPECT/CT. Our case indicates that lymphoscintigraphy with SPECT/CT may be useful for detecting the precise site of lymphatic leakage before interventional radiology or surgery.

Negative-Pressure Wound Therapy: What We Know and What We Need to Know.

Negative-pressure wound therapy (NPWT) promotes wound healing by applying negative pressure to the wound surface. A quarter of a century after its introduction, NPWT has been used in various clinical conditions, although molecular biological evidence is insufficient due to delay in basic research. Here, we have summarized the history of NPWT, its mechanism of action, what is currently known about it, and what is expected to be known in the future. Particularly, attention has shifted from the four main mechanisms of NPWT to the accompanying secondary effects, such as effects on various cells, bacteria, and surgical wounds. This chapter will help the reader to understand the current status and shortcomings of NPWT-related research, which could aid in the development of basic research and, eventually, clinical use with stronger scientific evidence.

Novel cell culture system for monitoring cells during continuous and variable negative-pressure wound therapy.

BACKGROUND: Although the clinical efficacy of negative-pressure wound therapy (NPWT) is well known, many of its molecular biological mechanisms remain unresolved, mainly due to the difficulty and paucity of relevant in vitro studies. We attempted to develop an in vitro cell culture system capable of real-time monitoring of cells during NPWT treatment. MATERIALS AND METHODS: A novel negative-pressure cell culture system was developed by combining an inverted microscope, a stage-top incubator, a sealed metal chamber for cell culture, and an NPWT treatment device. Human keratinocytes, PSVK-1, were divided into ambient pressure (AP), continuous negative-pressure (NPc), and intermittent negative-pressure (NPi) groups and cultured for 24 h with scratch assay using our real-time monitoring system and device. Pressure inside the device, medium evaporation rate, and the residual wound area were compared across the groups. RESULTS: Pressure in the device was maintained at almost the same value as set in all groups. Medium evaporation rate was significantly higher in the NPi group than in the other two groups; however, it had negligible effect on cell culture. Residual wound area after 9 h evaluated by the scratch assay was significantly smaller in the NPc and NPi groups than in the AP group. CONCLUSION: We developed a negative-pressure cell culture device that enables negative-pressure cell culture under conditions similar to those used in clinical practice and is able to monitor cells under NPWT. Further experiments using this device would provide high-quality molecular biological evidence for NPWT.

Optimal blue light irradiation conditions for the treatment of acne vulgaris in a mouse model.

BACKGROUND: Although blue light is one of the therapeutic approaches used to treat acne vulgaris (AV), there is no consensus on its effectiveness. As a result, it is not recommended in the major acne vulgaris treatment guidelines. OBJECTIVE: The goal of this study was to look into the mechanism, safety, and efficacy of blue light therapy. We achieved this by examining the pathological response, inflammation, and depth of light penetration in a mouse model of cystic AV. METHODS: The aims of the study were addressed by exposing the mice to light with a wavelength of 415 nm under four different irradiation conditions. The exposure was done for five consecutive days followed by a no irradiation period of 72 h. RESULTS: Blue light treatment was most effective when irradiation was performed at 100 mW/cm2 for 20 min for five consecutive days. Inflammatory responses emerged 72 h after the final irradiation dose was administered. These responses were not associated with apoptosis as cleaved caspase-3 staining revealed no significant increases in apoptosis in the skin under any of the tested conditions. Blue light reached the superficial layer of the acne cyst at 5% of the total irradiation power and was attenuated by half for every 50 µm of progress through the cyst. CONCLUSION: In conclusion, blue light could control severe dermatologic inflammatory responses; therefore, it can be used to irradiate AV with high inflammation levels on a daily basis until improvement is observed. In addition, porphyrin, a metabolite of Cutibacterium acnes, and reactive oxygen species generated by the surrounding skin tissue may have essential roles in AV treatment.

Myofibroblast-dominant proliferation associated with severe fibrosis in bulbar urethral strictures.

OBJECTIVES: Myofibroblast-dominant proliferation (relative to fibroblast proliferation) is the key process in urethral fibrosis, but its association with clinical features is not understood. We conducted a histological analysis of urethral strictures and examined the association between myofibroblast proliferation and stricture characteristics. METHODS: Formalin-fixed, paraffin-embedded urethral sections sliced axially from 175 male patients with bulbar urethral strictures were retrospectively analyzed. All patients underwent excision and primary anastomosis between September 2008 and January 2021 by a surgeon (AH). Masson's trichrome stain was used to estimate the area of fibrosis. Corresponding unstained slides with the largest area of fibrosis were selected and double-immunostained with anti-smooth muscle actin (SMA) and anti-TE-7 mouse monoclonal antibodies for the assessment of myofibroblasts and fibroblasts, respectively. The ratio of the number of SMA-positive cells to the number of TE-7-positive cells (SMA/TE-7 ratio) was calculated. RESULTS: The area of fibrosis in strictures due to perineal trauma (n = 85, median 108.9 mm2 ) was significantly larger than that in non-traumatic strictures (n = 90, median 42.9 mm2 , p < 0.0001). The area of fibrosis positively correlated with SMA expression (r = 0.35, p < 0.0001) and the SMA/TE-7 ratio (r = 0.36, p < 0.0001), but not with TE-7 expression (r = -0.01, p = 0.75). In a multivariate linear regression model, traumatic etiology (standard coefficient 0.37, t value 3.9, p < 0.0001) and increased SMA expression (standard coefficient 0.17, t value 2.1, p = 0.03) were the predictors of wide fibrosis area. CONCLUSIONS: Myofibroblast-dominant proliferation may contribute to the pathogenesis of severe urethral fibrosis.

Transperineal bulbovesical anastomosis for extensive posterior urethral stenoses after treatment of prostatic disease.

OBJECTIVES: We report our surgical experience of transperineal bulbovesical anastomosis (BVA) for extensive posterior urethral stenosis (PUS). METHODS: Six male patients who had extensive PUS extending from the bulbomembranous urethra to the bladder neck due to prostatic disease treatment and underwent transperineal BVA between 2014 and 2020 were retrospectively reviewed. BVA was performed according to the elaborate perineal approach for pelvic fracture urethral repair with minor modifications. After confirming the absence of recurrent stenosis 6 months postoperatively, the patients were offered artificial urinary sphincter (AUS) placement for subsequent urinary incontinence (UI). RESULTS: Median patient age was 68, and the etiology of PUS was radical prostatectomy for prostate cancer in four patients, brachytherapy for prostate cancer in one, and transurethral resection of the prostate for benign prostatic hyperplasia in one. All patients had been previously treated with multiple transurethral procedures such as urethrotomy and dilation. Median operative time and blood loss were 211 min and 154 ml, respectively. Five cases (83.3%) had no recurrent stenosis with a median follow-up of 45 months, but a single direct vision internal urethrotomy was performed in one (16.7%) due to restenosis. Four (66.7%) patients underwent AUS placement via transcorporal approach for subsequent UI, but two had it removed due to urethral erosion. CONCLUSION: Transperineal BVA could effectively manage extensive PUS after prostatic disease treatment. Staged AUS placement could be a viable option for subsequent UI, but the risk of urethral erosion seemed high.

Efficacy of urethral reconstruction for urethral stricture associated with hypospadias surgery in adults.

OBJECTIVES: We report our experience with urethral reconstruction for hypospadias surgery-related urethral stricture in terms of surgical and patient-reported outcomes. METHODS: Twenty-nine adult males who underwent urethral reconstruction for hypospadias surgery-related urethral stricture between August 2008 and January 2022 were retrospectively reviewed. Uroflowmetry and patient-reported outcomes were evaluated at 3, 6, and 12 months, and annually thereafter. Surgical success was defined as the absence of additional procedures. Patients were asked to rate their satisfaction with urethral reconstruction as "very satisfied", "satisfied", "unsatisfied", or "very unsatisfied". RESULTS: The median patient age at referral was 43 years. The median number of previously performed hypospadias surgeries was three, and 18 patients (62.8%) had been treated with repeated transurethral procedures. The median stricture length was 54 mm (interquartile range 36-81). Performed urethral reconstruction included staged urethroplasty in 22 (75.9%), one-stage onlay augmentation in 3 (10.2%), and perineal urethrostomy in 4 (13.8%) cases. Urethral reconstruction was successful in 26 patients (89.7%) over a median postoperative period of 31 months. Patient-reported outcomes were assessed in 25 (86.2%) patients. The mean maximum flow rate, international prostate symptom score total score, international prostate symptom score quality of life score, and EuroQol-5 dimensions index significantly improved postoperatively. Twenty-three patients (92%) were "very satisfied" or "satisfied" with the outcome of their urethral reconstruction. CONCLUSIONS: Urethral reconstruction is a highly successful and patient-satisfying treatment for hypospadias surgery-related urethral stricture in adult patients. Perineal urethrostomy is a reasonable alternative for elderly patients and for patients with complicated hypospadias surgery-related urethral strictures.

Metachronous lesions in the orbit, retroperitoneum, and pleura of mucosa-associated lymphoid tissue lymphoma: A case report.

BACKGROUND: Mucosa associated lymphoid tissue (MALT) lymphoma of the orbit is rare, often indolent, but can recur, and spread to extra-nodal sites. Pleural and retroperitoneum recurrences of MALT lymphoma are rare. CASE: A 65-year-old man was referred to our hospital due to right pleural effusion and difficulty in breathing. He had a medical history of having undergone surgery for MALT lymphoma of the left orbit. A chest computed tomography (CT) scan showed right pleural thickness, pleural effusion, and a retroperitoneal mass, spreading from the muscular layer to the subcutaneous layer. The thickened pleural lesion was surgically biopsied and diagnosed as a recurrence of MALT lymphoma. CONCLUSION: Pleural effusion should be carefully examined and monitored for the possibility of recurrence in MALT lymphoma patients.

Urethral reconstruction for iatrogenic urethral stricture after transurethral prostate surgery: An analysis of surgical and patient-reported outcomes.

OBJECTIVES: We investigated the efficacy of urethral reconstruction in male patients with iatrogenic urethral stricture after transurethral prostate surgery. METHODS: We retrospectively reviewed the cases of 82 patients who underwent urethral reconstruction for iatrogenic urethral stricture caused by transurethral prostate surgery between August 2011 and July 2021. Patients were followed up postoperatively with uroflowmetry, postvoid residual urine measurement, and questionnaires using Peeling's picture score, International Prostate Symptom Score, International Consultation on Incontinence Questionnaire Short Form, Sexual Health Inventory for Men, EuroQol-5 dimensions, and EuroQol-5 dimensions visual analog scores. Successful urethral reconstruction was defined as the absence of a postoperative decrease in urinary force and any additional treatment. RESULTS: The median patient age was 72 years, and the stricture site was the urethral meatus in eight (9.8%) patients, penoscrotal junction in 42 (51.2%), and proximal bulbar urethra in 26 (31.7%). Six patients (7.3%) had synchronous urethral strictures. Urethral reconstruction was successful in 78 patients (95.1%), with a median follow-up of 43 months. The mean maximum flow rate (P < 0.0001), postvoid residual urine (P = 0.004), Peeling's picture score (P < 0.0001), the score for each question and total International Prostate Symptom Score and International Prostate Symptom Score-quality of life scores (P < 0.0001 for all comparisons), and EuroQol-5 dimensions and EuroQol-5 dimensions visual analog scores (P < 0.0001 for both) significantly improved postoperatively. However, the Sexual Health Inventory for Men and International Consultation on Incontinence Questionnaire Short Form scores remained unchanged (P = 0.09 and 0.70, respectively). CONCLUSIONS: Urethral reconstruction was effective for urethral stricture due to transurethral prostate surgery in both subjective and objective aspects.

Surgical and Patient-Reported Outcomes of Delayed Anastomotic Urethroplasty for Male Pelvic Fracture Urethral Injury at a Japanese Referral Center.

We aimed to assess the surgical and patient-reported outcomes of delayed anastomotic urethroplasty (DAU) for pelvic fracture urethral injury (PFUI). We included 211 male patients who underwent DAU for PFUI. DAU success was considered when the urethral lumen was sufficiently large for the passage of a flexible cystoscope, without additional treatment required. The patients completed the lower urinary tract symptoms (LUTS)-related quality of life (QOL) questionnaire (scores: 0, not at all; 1, a little; 2, somewhat; 3, a lot), EuroQol-5 dimensions (EQ-5D), and EQ-5D visual analog scale (EQ-VAS). Postoperative overall satisfaction was evaluated using the following responses: "very satisfied," "satisfied," "unsatisfied," or "very unsatisfied." DAU was successful in 95.3% cases, with a median postoperative follow-up duration of 48 months. Multivariate logistic regression analysis revealed that "greater blood loss" was an independent predictor of failed urethroplasty. Questionnaire responses were obtained from 80.1% patients. The mean LUTS-related QOL, EQ-5D score and EQ-VAS improved significantly from 2.8, 0.63 and 54.4 at baseline to 0.9, 0.81 and 76.6 postoperatively (p < 0.0001 for all parameters). Moreover, 35.5% and 59.2% of the patients responded being "satisfied" and "very satisfied," respectively, with their DAU outcomes. DAU not only had a high surgical success rate, but also a significant beneficial effect on both LUTS-related QOL and overall health-related QOL.

Blue Laser Irradiation Decreases the ATP Level in Mouse Skin and Increases the Production of Superoxide Anion and Hypochlorous Acid in Mouse Fibroblasts.

Photobiomodulation studies have reported that blue light irradiation induces the production of reactive oxygen species. We investigated the effect of blue laser (405 nm) irradiation on the ATP levels in mouse skin and determined the types of reactive oxygen species and reactive nitrogen species using cultured mouse fibroblasts. Blue laser irradiation caused a decrease in the ATP level in the mouse skin and triggered the generation of superoxide anion and hypochlorous acid, whereas nitric oxide and peroxynitrite were not detected. Moreover, blue laser irradiation resulted in reduced cell viability. It is believed that the decrease in the skin ATP level due to blue light irradiation results from the increased levels of oxidative stress due to the generation of reactive oxygen species. This method of systematically measuring the levels of reactive oxygen species and reactive nitrogen species may be useful for understanding the effects of irradiation conditions.

Impact of urethroplasty on overactive bladder symptoms in patients with anterior urethral strictures.

OBJECTIVES: To investigate the incidence of overactive bladder in men with anterior urethral stricture and to evaluate the impact of urethroplasty on its improvement. METHODS: A total of 104 men with anterior urethral stricture who underwent urethroplasty between 2016 and 2020 completed a validated urethral stricture surgery patient-reported outcome measure comprising six lower urinary tract symptoms questions on voiding symptoms and overactive bladder symptom score before and 3, 6, and 12 months after urethroplasty. Patients with an urgency score of ≥2 for overactive bladder symptom score question 3, and a total overactive bladder symptom score of ≥3 were considered to have overactive bladder. An improvement in overactive bladder was defined as a decrease in the total overactive bladder symptom score by at least three points. RESULTS: Thirty-nine patients (37.5%) were considered to have overactive bladder, and improvement in overactive bladder after urethroplasty was found in 30 (76.9%). Maximum flow rate on uroflowmetry, postvoid residual urine volume, lower urinary tract symptoms total score, and total overactive bladder symptom score were all significantly improved after urethroplasty (P < 0.0001 for all variables). There was a positive correlation between changes in lower urinary tract symptoms total score and total overactive bladder symptom score (Spearman's correlation 0.48, P < 0.0001). Multivariate logistic regression analysis showed that greater change in lower urinary tract symptoms score was an independent predictor of improvement in overactive bladder (odds ratio 1.30, 95% confidence interval 1.06-1.59; P = 0.002). CONCLUSIONS: Overactive bladder is prevalent in patients with anterior urethral stricture, and can be effectively improved after urethroplasty. Improvement of voiding symptoms are key for improving overactive bladder symptoms.

Ability of photocurable gelatin to prevent stricture recurrence after urethral dilation in rabbits.

OBJECTIVES: To evaluate the ability of photocurable gelatin to prevent stricture recurrence after urethral dilation in a rabbit urethral stricture model. METHODS: We created urethral strictures in the bulbar urethras of 10 male Japanese white rabbits using electrocoagulation. After 1 month, the rabbits were randomly divided into Group A (n = 5; urethral stricture dilation and the local application of photocurable gelatin using a ruthenium photoinitiator and irradiation with a light-emitting diode light [λ = 455 nm, 50 mW/cm2 ] for 1 min) and Group B (n = 5; dilation only). Urethral stricture status was evaluated 1-2 months later by retrograde urethrography and urethroscopy. The lumen ratio (urethral width at the stricture site to the normal urethral width on retrograde urethrography) was calculated. Urethral patency was considered to be improved when the urethral lumen could accommodate a 10-Fr urethroscope without resistance. Urethral specimens were harvested for histopathological examination. RESULTS: The mean lumen ratio did not differ significantly between Groups A and B before dilation (25.8% vs 23.4%; P = 0.40), but differed significantly after dilation (65.5% vs 27.3%, respectively; P = 0.03). Urethral patency improved in all rabbits in Group A (100%) versus one rabbit in Group B (20%; P = 0.02). The mean circumference of the regenerated urethral epithelium at the stricture site was larger in Group A than in Group B (14 mm vs 6.6 mm; P = 0.06). CONCLUSIONS: Photocurable gelatin can reduce urethral stricture recurrence after dilation in a rabbit model.

Membranous urethral length on magnetic resonance imaging as a novel predictor of urinary continence after delayed anastomotic urethroplasty for pelvic fracture urethral injury.

PURPOSE: We studied the impact of membranous urethral length (MUL) on magnetic resonance imaging (MRI) on post-urethroplasty continence in male patients with pelvic fracture urethral injury (PFUI). METHODS: Of 169 male patients with PFUI who underwent delayed anastomotic urethroplasty between 2008 and 2020, 85 who underwent preoperative MRI, had no recurrent stenosis on cystoscopy, and underwent a 1-h pad test 1 year after surgery were included. MUL was defined as the distance from the distal end of the disrupted proximal urethra to the apex of the prostate, as measured using T2-weighted MRI. Urinary incontinence (UI) was defined as a 1-h pad test weight > 2.0 g. RESULTS: None of the patients had UI before a pelvic fracture. Eighty-two patients (96.5%) had a measurable MUL, and the median length was 8.1 (interquartile range [IQR], 5.2-10.8) mm. The median weight of the 1-h pad test was 1.0 (IQR, 0.0-4.0) g, and 26 (30.6%) patients had UI. An open bladder neck (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.0-22.0; p = 0.04) and a short measurable membranous urethra (for every extra mm: OR, 1.2; 95% CI, 1.0-1.3; p = 0.04) were significant UI predictors on multivariate analysis. CONCLUSIONS: A long MUL is significantly positively associated with urinary continence in male patients with PFUI. This could be of potential value to reconstructive urologists when counseling patients regarding post-urethroplasty continence before urethroplasty.

Photocrosslinked gelatin hydrogel improves wound healing and skin flap survival by the sustained release of basic fibroblast growth factor.

Biomaterials traditionally used for wound healing can act as a temporary barrier to halt bleeding, prevent infection, and enhance regeneration. Hydrogels are among the best candidates for wound healing owing to their moisture retention and drug-releasing properties. Photo-polymerization using visible light irradiation is a promising method for hydrogel preparation since it can easily control spatiotemporal reaction kinetics and rapidly induce a single-step reaction under mild conditions. In this study, photocrosslinked gelatin hydrogels were imparted with properties namely fast wound adherence, strong wet tissue surface adhesion, greater biocompatibility, long-term bFGF release, and importantly, ease of use through the modification and combination of natural bio-macromolecules. The production of a gelatin hydrogel made of natural gelatin (which is superior to chemically modified gelatin), crosslinked by visible light, which is more desirable than UV light irradiation, will enable its prolonged application to uneven wound surfaces. This is due to its flexible shape, along with the administration of cell growth factors, such as bFGF, for tissue regeneration. Further, the sustained release of bFGF enhances wound healing and skin flap survival. The photocrosslinking gelatin hydrogel designed in this study is a potential candidate to enhance wound healing and better skin flap survival.