Ultraviolet-A Light and Negative-Pressure Wound Therapy to Accelerate Wound Healing and Reduce Bacterial Proliferation.

BACKGROUND: Ultraviolet (UV)-A therapy is a simple, inexpensive, and effective modality for wound healing, with tremendous potential to improve healing and reduce clinical infections in a number of clinical settings. To date, application of UV-A relies on bulky and hard-to-dose lamps that provide inconsistent therapy, thus making it difficult to apply therapy that is appropriate for the patient. METHODS: This study was designed to test the effectiveness of a novel wound therapy device that combines UV-A with traditional negative-pressure wound therapy (NPWT) to promote wound healing. Furthermore, we tested the ability of fiberoptic UV-A delivery to inhibit bacterial proliferation. Finally, we assayed the level of DNA damage that results from UV-A as compared to established UV-C therapies. Wound healing studies were performed in a porcine model using an articulated therapy arm that allows for continued therapy administration over an extended time course. Negative-pressure wound therapy was administered alone or with UV-A fiberoptic therapy for 2 weeks. Dressings were changed twice a week, at which time wound area was assessed. RESULTS: Data demonstrate that UV-A with NPWT treatment of wounds results in greater healing than NPWT alone. Using the same therapy device, we demonstrate that exposure of Staphylococcus aureus and Pseudomonas aeruginosa to fiberoptic UV-A results in decreased colony area and number of both bacterial strains. Finally, we show that UV-A induces minimal DNA damage in human fibroblasts and no more DNA damage in wound tissue as compare to intact skin. CONCLUSIONS: These data demonstrate that UV-A can decrease bacterial proliferation and promote wound healing when coupled with NPWT.

A Comparison of Pathogens in Skin and Soft-Tissue Infections and Pedal Osteomyelitis in Puncture Wound Injuries Affecting the Foot.

BACKGROUND: To compare pathogens involved in skin and soft-tissue infections (SSTIs) and pedal osteomyelitis (OM) in patients with and without diabetes with puncture wounds to the foot. METHODS: We evaluated 113 consecutive patients between June 1, 2011, and March 31, 2019, with foot infection (SSTIs and OM) from a puncture injury sustained to the foot. Eighty-three patients had diabetes and 30 did not. We evaluated the bacterial pathogens in patients with SSTIs and pedal OM. RESULTS: Polymicrobial infections were more common in patients with diabetes mellitus (83.1% versus 53.3%; P = .001). The most common pathogen for SSTIs and OM in patients with diabetes was Staphylococcus aureus (SSTIs, 50.7%; OM, 32.3%), whereas in patients without diabetes it was Pseudomonas (25%) for SSTIs. Anaerobes (9.4%) and fungal infection (3.1%) were uncommon. Pseudomonas aeruginosa was identified in only 5.8% of people with diabetes. CONCLUSIONS: The most common bacterial pathogen in both SSTIs and pedal OM was S aureus in patients with diabetes. Pseudomonas species was the most common pathogen in people without diabetes with SSTIs.

Cost-minimization analysis of negative pressure wound therapy technologies for the treatment of moderate-to-severe foot infections.

Aim: The objective was to estimate the cost of care associated with two negative pressure wound therapy (NPWT) technologies used to treat patients admitted to the hospital with moderate-to-severe foot infections. Materials & methods: A decision tree simulation model was developed to estimate the hospital costs associated with two different NPWT technologies: Cardinal Health™ PRO (NPWT-C) and V.A.C. ULTA™ (NPWT-K). Clinical data were obtained from a previously completed single-site prospective trial. One-way and probabilistic sensitivity analyses were performed to gauge the robustness of the results. Results: The total expected per-patient costs were US$41,206 (SD: US$8,194) for NPWT-C and US$44,439 (SD: US$8,963) for NPWT-K. Conclusion: This study found that NPWT-C was expected to minimize the total costs over the episode of treatment. Larger and more clinically diverse studies are recommended to confirm these findings.

Lyopreserved amniotic membrane is cellularly and clinically similar to cryopreserved construct for treating foot ulcers.

We compared cellular viability between cryopreserved and lyopreserved amniotic membranes and clinical outcomes of the lyopreserved construct in a prospective cohort study of 40 patients with neuropathic foot ulcers. Patients received weekly application of lyopreserved membrane for 12 weeks with standard weekly debridement and offloading. We evaluated the proportion of foot ulcers that closed, time to closure, closure trajectories, and infection during therapy. We used chi-square tests for dichotomous variables and independent t-tests for continuous variables with an alpha of α = .10. Cellular viability was equivalent between cryo- and lyopreserved amniotic tissues. Clinically, 48% of subjects' wounds closed in an average of 40.0 days. Those that did not close were older (63 vs 59 years, P = .011) and larger ulcers at baseline (7.8 vs 1.6 cm2 , P = .012). Significantly more patients who achieved closure reached a 50% wound area reduction in 4 weeks compared with non-closed wounds (73.7% vs 47.6%, P = .093). There was no difference in the slope of the wound closure trajectories between closed and non-closed wounds (0.124 and 0.159, P = .85), indicating the rate of closure was similar. The rate of closure was 0.60 mm/day (SD = 0.47) for wounds that closed and 0.50 mm/day (SD = 0.58) for wounds that did not close (P = .89).

The effect of continuous diffusion of oxygen treatment on cytokines, perfusion, bacterial load, and healing in patients with diabetic foot ulcers.

To evaluate continuous diffusion of oxygen therapy (CDO) on cytokines, perfusion, and bacterial load in diabetic foot ulcers we evaluated 23 patients for 3 weeks. Tissues biopsies were obtained at each visit to evaluate cytokines and quantitative bacterial cultures. Perfusion was measured with hyperspectral imaging and transcutaneous oxygen. We used paired T tests to compare continuous variables and independent T tests to compare healers and nonhealers. There was an increase from baseline to week 1 in TGF-ß (P = .008), TNF-α (P = .014), VEGF (P = .008), PDGF (P = .087), and IGF-1 (P = .058); baseline to week 2 in TGF-ß (P = .010), VEGF (P = .051), and IL-6 (P = .031); and baseline to week 3 with TGF-ß (P = .055) and IL-6 (P = .054). There was a significant increase in transcutaneous oxygen after 1 week of treatment on both medial and lateral foot (P = .086 and .025). Fifty-three percent of the patients had at least a 50% wound area reduction (healers). At baseline, there were no differences in cytokines between healers and nonhealers. However, there was an increase in CXCL8 after 1 week of treatment (P = .080) and IL-6 after 3 weeks of treatment in nonhealers (P = .099). There were no differences in quantitative cultures in healers and nonhealers.

The infected diabetic foot: Can serum biomarkers predict osteomyelitis after hospital discharge for diabetic foot infections?

The aim of this study is to evaluate serum biomarkers to monitor high-risk patients for reinfection of bone. Thirty-five patients were prospectively enrolled with moderate to severe diabetic foot infections with suspicion of osteomyelitis. Bone samples were obtained for culture and histology. Clinical characteristics and outcomes of patients were compared using χ2 square test. Biomarkers (white blood cell count, erythrocyte sedimentation rate, c-reactive protein, procalcitonin, interleukin-6, interleukin-8, and monocyte chemoattractant protein 1) were assessed at baseline, 3, and 6 weeks after treatment initiation and evaluated for correlation with reinfection of bone. After 6 weeks of antibiotic treatment, ESR at 73.5 mm/h (sensitivity 62.5%, specificity 100%, area under the receiver operating characteristic (AUROC) 0.7839, 95% CI 0.54-1.00, P < .01) and IL-8 at 15.09 mg/dL (sensitivity 42.9%, specificity 92.0% AUROC 0.6286, 95% CI 0.36-0.90, P = .0496) were associated with reinfection of bone. An increase in IL-8 from week 0 to 6 >0.95 mg/dL was associated with reinfection (sensitivity 71%, specificity 72% AUROC 0.7057, 95% CI 0.49-0.92, P = .04). An ESR change from week 0-6 of -16.5% (sensitivity 71.4%, specificity 86.4% AUROC 0.7403, 95% CI 0.48-1.00, P = .02), CRP (-)74.4% (sensitivity 66.7%, specificity 91.3% AUROC 0.7174, 95% CI 0.40-1.00, P = .04), IL-6 (-)49.9% (sensitivity 71.4%, specificity 76% AUROC 0.7371, 95% CI 0.47-1.00, P = .04), and IL-8 29% (sensitivity 85.7%, specificity 56.0% AUROC of 0.7343, 95% CI 0.54-0.93, P = .048) were associated with increased risk of reinfection. Pilot data suggest that serum biomarkers (ESR, IL8 and IL6, MCP-1) may be correlated with developing osteomyelitis and could be used to monitor high-risk patients for reinfection.

Does negative pressure wound therapy with irrigation improve clinical outcomes? A randomized clinical trial in patients with diabetic foot infections.

AIM: To compare the efficacy of Negative Pressure Wound Therapy (NPWT) with and without irrigation with 0.1% polyhexanide-betaine. METHODS: We randomized 150 subjects in a 16-week RCT to compare healing in patients with diabetic foot infections. NPWT delivered at 125 mm Hg continuous pressure. NPWT-I were administered at 30 cc per hour. RESULTS: There were no differences clinical treatment or outcomes: wound area after surgery (18.5 ± 19.0 vs. 13.4 ± 11.1 cm2, p = 0.50), duration of antibiotics (39.7 ± 21.0 vs. 38.0 ± 24.6 days, p = 0.40), number of surgeries (2.3 ± 0.67 vs. 2.2 ± 0.59, p = 0.85), duration of NPWT (148.1 ± 170.4 vs. 114.5 ± 135.1 h, p = 0.06), healed wounds (58.7% vs. 60.0%, p = 0.86), time to healing (56.3 ± 31.7 vs. 50.7 ± 27.8, p = 0.53), length of stay (13.8 ± 6.4 vs. 14.5 ± 11.2 days, p = 0.42), re-infection (20.0% vs. 22.7%, p = 0.69, and re-hospitalization (17.3% vs. 18.7, p = 0.83). CONCLUSIONS: The addition of irrigation to NPWT did not change clinical outcomes in patients with diabetic foot infections. CLINICAL TRIAL NUMBER: NCT02463487, ClinicalTrials.gov.

Randomized clinical study to compare negative pressure wound therapy with simultaneous saline irrigation and traditional negative pressure wound therapy for complex foot infections.

The aim of this study was to compare the efficacy of different negative pressure wound therapy (NPWT) devices and NPWT with and without simultaneous irrigation in patients admitted to hospital with moderate and severe foot infections. Ninety patients were randomized in a 12-week prospective, randomized noninferiority trial to compare wound healing in patients with moderate and severe infected foot wounds treated with NPWT after surgery. Inclusion criteria included ABI > 0.5 or toe pressures >30 PVR/mmHg, >18 years of age and exclusion included active Charcot arthropathy, collagen vascular disease, HIV, and hypercoagulable state. We compared two different traditional devices, NPWT-K (KCI, VAC Ulta) and NPWT-C (Cardinal, PRO), and NPWT-I with saline irrigation (Cardinal, PRO). All patients had therapy delivered at 125 mmHg continuous pressure. In patients who received simultaneous saline irrigation (NPWT-I), the administration rate was 15 ml per hour. The primary outcome was the proportion of healed wounds in 12 weeks. Secondary outcomes included surgical wound closure, number of surgeries, length of stay, and time to wound healing. Continuous data was presented as mean ± standard deviation. Analysis of variance was used to compare continuous variables and chi-square to compare dichotomous variables with an alpha of 0.05. There were no differences in outcomes among NPWT-I, NPWT-C, and NPWT-K groups in proportion of healed wounds (63.3%, 50.0%, 46.7% p = 0.39), surgical wound closure (83.3%, 80.0%, 63.3%, p = 0.15), number of surgeries (2.0 ± 0.49, 2.4 ± 0.77, 2.4 ± 0.68, p = 0.06), length of stay (16.3 ± 15.7, 14.7 ± 7.4, 15.3 ± 10.5 days, p = 0.87), time to wound healing (46.2 ± 22.8, 40.9 ± 18.8, 45.9 ± 28.3 days, p = 0.78). We did not identify any significant differences in clinical outcomes or adverse events between patients treated with different NPWT devices or NPWT with and without irrigation.

Are We Misdiagnosing Diabetic Foot Osteomyelitis? Is the Gold Standard Gold?

To compare the incidence of osteomyelitis based on different operational definitions using the gold standard of bone biopsy, we prospectively enrolled 35 consecutive patients who met the criteria of ≥21 years of age and a moderate or severe infection based on the Infectious Diseases Society of America classification. Bone samples were obtained from all patients by percutaneous bone biopsy or intraoperative culture if the patient required surgery. Bone samples were analyzed for conventional culture, histology, and 16S ribosomal RNA genetic sequencing. We evaluated 5 definitions for osteomyelitis: 1) traditional culture, 2) histology, 3) genetic sequencing, 4) traditional culture and histology, and 5) genetic sequencing and histology. There was variability in the incidence of osteomyelitis based on the diagnostic criteria. Traditional cultures identified more cases of osteomyelitis than histology (68.6% versus 45.7%, p = .06, odds ratio [OR] 2.59, 95% confidence interval [CI] 0.98 to 6.87), but the difference was not significant. In every case that histology reported osteomyelitis, bone culture was positive using traditional culture or genetic sequencing. The 16S ribosomal RNA testing identified significantly more cases of osteomyelitis compared with histology (82.9% versus 45.7%, p = .002, OR 5.74, 95% CI 1.91 to 17.28) and compared with traditional cultures but not significantly (82.9% versus 68.6%, p = .17, OR 2.22, 95% CI 0.71 to 6.87). When both histology and traditional culture (68.6%) or histology and genetic sequencing cultures (82.9%) were used to define osteomyelitis, the incidence of osteomyelitis did not change. There is variability in the incidence of osteomyelitis based on how the gold standard of bone biopsy is defined in diabetic foot infections.

Erythrocyte sedimentation rate and C-reactive protein to monitor treatment outcomes in diabetic foot osteomyelitis.

This study sought to evaluate the effectiveness of the inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), in monitoring treatment of osteomyelitis in the diabetic foot. We screened 150 charts of patients admitted to our hospital with diabetic foot osteomyelitis (DFO), confirmed by positive results of bone culture and/or histopathology. We included patients who had an initial ESR/CRP within 72 hours of admission and two reported follow-up values. We dichotomised patients based on the outcomes wound healing, re-infection, recurrent ulceration, re-hospitalisation, additional surgery, re-amputation and death, all within 12 months, and analysed the trajectories of the markers over time. Our primary outcome, DFO remission, was defined as wound healing within 12 months of follow-up without re-infection. We included 122 subjects; 65 patients (53·3%) had a combination of positive culture and histopathology. Factors associated with DFO remission (n = 46) were a lower white blood count (WBC) at admission (P = 0·006) and a higher glomerular filtration rate (GFR, P = 0·049). Factors associated with healing were a lower WBC (P = 0·004), a higher GFR (P = 0·01), longer wound duration before admission (P = 0·01), location of the ulcer on the great toe (P = 0·01) and higher glycated haemoglobin (P = 0·03). Logistic regression analysis demonstrated no associations between DFO remission and other variables collected. Trajectories of the inflammatory markers showed an association between stagnating values of ESR and CRP and poor clinical outcomes. In this study population, the trajectories of both ESR and CRP during 12 months follow-up suggest a predictive role of both inflammatory markers when monitoring treatment of DFO.

The fluid dynamics of simultaneous irrigation with negative pressure wound therapy.

Saline irrigation has been shown to be both experimentally and clinically efficacious in decreasing bacterial contamination as well as decreasing infection rates. The dynamics of irrigation delivery fall into two primary categories: simultaneous and intermittent irrigation. An important component to irrigation therapy is distribution of irrigation solution to hard-to-reach areas of a wound bed, including undermining and fissure-like structures. Here we test the effectiveness of simultaneous irrigation to fill the irregular structures of a wound bed. In order to visualise the dynamic movement of irrigation solution, three-dimensional wound models were constructed using clear synthetic ballistic gel. Wounds with the aforementioned characteristics were carved into the ballistic gel with varying area, depth and volume. All three wounds were dressed as per manufacturer's instructions. Data demonstrate that simultaneous irrigation is effective in reaching all parts of a wound bed in wound models that have both undermining and tunnelling, and irrigation effectively saturates bridged wounds. Finally, this study shows that there is constant turnover of irrigation solution in the wound that is driven more by administration volume and less by flow rate. These data show that simultaneous irrigation is an effective technique for delivering irrigation solution to both simple and complex wounds.

Pilot study to evaluate a novel three-dimensional wound measurement device.

As the burden of diabetes continues to grow and treatment standards require careful tracking of wound progress, clinicians increasingly need to rely on technological improvements in wound measurement technologies to track the progress of their treatments. This study aims to determine the accuracy of a new three-dimensional wound measurement (3DWM) device against laser-assisted wound measurement (LAWM) devices and traditional methods of wound measurement. Using several wound models, we demonstrate that the 3DWM device measures wound area, depth and volume similarly to the other methods tested. This is especially apparent when changes in wound measurements were compared between the two devices. Differences between the two technologies were apparent when analysing wound measurement time and measurement repeatability. There was a significantly lower incidence of error in measurements between the 3DWM device and the LAWM device. Finally, the measurement time was significantly faster with the 3DWM device compared to the LAWM device. Together, these data demonstrate that the 3DWM device provides an accurate and reproducible method for measuring changes in wound healing similar to other available technologies. Further, the use of the 3DWM device provides a faster and more consistent measurement, which is critical for clinical application and use.

Validation of a laser-assisted wound measurement device in a wound healing model.

In the treatment and monitoring of a diabetic or chronic wound, accurate and repeatable measurement of the wound provides indispensable data for the patient's medical record. This study aims to measure the accuracy of the laser-assisted wound measurement (LAWM) device against traditional methods in the measurement of area, depth and volume. We measured four 'healing' wounds in a Play-Doh(®) -based model over five subsequent states of wound healing progression in which the model was irregularly filled in to replicate the healing process. We evaluated the LAWM device against traditional methods including digital photograph assessment with National Institutes of Health ImageJ software, measurements of depth with a ruler and weight-to-volume assessment with dental paste. Statistical analyses included analysis of variance (ANOVA) and paired t-tests. We demonstrate that there are significantly different and nearly statistically significant differences between traditional ruler depth measurement and LAWM device measurement, but there are no statistically significant differences in area measurement. Volume measurements were found to be significantly different in two of the wounds. Rate of percentage change was analysed for volume and depth in the wound healing model, and the LAWM device was not significantly different than the traditional measurement technique. While occasionally inaccurate in its absolute measurement, the LAWM device is a useful tool in the clinician's arsenal as it reliably measures rate of percentage change in depth and volume and offers a potentially aseptic alternative to traditional measurement techniques.

Barbed sutures and wound complications in plastic surgery: an analysis of outcomes.

BACKGROUND: Barbed sutures may expedite dermal approximation and improve tissue support while requiring less time and material than conventional sutures. Several types of barbed sutures are available, each with unique advantages. OBJECTIVES: The authors sought to determine whether the incidence of complications differed after wound approximation in plastic surgery when various brands of barbed vs nonbarbed traditional sutures were employed. METHODS: The authors conducted a retrospective review of outcomes in body contouring, free flap, and breast reconstruction. Suture type and closure method were noted for each case. The number of complications after traditional 2-layer closure with nonbarbed sutures was compared with the number of complications after closure via 1- and 2-layer techniques with several brands of barbed sutures, and the brands of barbed sutures were compared with each other. RESULTS: A total of 1011 unique surgical procedures, including 298 procedures with barbed sutures and 713 procedures with nonbarbed sutures, were performed by 5 members of the plastic surgery faculty. The 2-layer technique with barbed sutures was associated with significantly higher rates of wound separation than traditional methods. Excessive erythema along the incision site was significantly more frequent with Quill barbed sutures than with V-Loc barbed sutures. CONCLUSIONS: Barbed sutures were associated with significantly higher rates of minor wound complications, specifically when the 2-layer closure technique was performed. Significantly higher rates of erythema were associated with Quill barbed sutures than with V-Loc barbed sutures. LEVEL OF EVIDENCE 4: Risk.

The impact of perioperative hypothermia on plastic surgery outcomes: a multivariate logistic regression of 1062 cases.

BACKGROUND: Perioperative hypothermia has been associated with increased rates of infection, prolonged recovery time, and coagulopathy. OBJECTIVES: The authors assessed the impact of hypothermia on patient outcomes after plastic surgery and analyzed the impact of prewarming on postoperative outcomes. METHODS: The medical charts of 1062 patients who underwent complex plastic surgery typically lasting at least 1 hour were reviewed. Hypothermia was defined as a temperature at or below 36°C. Postoperative complication data were collected for outcomes including infection, delayed wound healing, seroma, hematoma, dehiscence, deep venous thrombosis, and overall wound problems. Odds ratios (ORs) were estimated from 3 multivariate logistic regression models of hypothermia and one model of body contouring procedures that included prewarming as a parameter. RESULTS: Perioperative hypothermia was not a significant predictor of wound problems (OR = 0.83; P = .28). In the stratified regression model, hypothermia did not significantly impact wound problems. The regression model measuring the interaction between hypothermia and operating time did not show a significantly increased risk of wound problems. Prewarming did not significantly affect perioperative hypothermia (P = .510), and in the model of body contouring procedures with prewarming as a categorical variable, massive weight loss was the most significant predictor of wound complications (OR = 2.57; P = .003). Prewarming did not significantly affect outcomes (OR = 1.49; P = .212). CONCLUSIONS: Based on univariate and multivariate models in our study, mild perioperative hypothermia appears to be independent of wound complications. LEVEL OF EVIDENCE 4: Risk.

The role of estrogen in the modulation of autologous fat graft outcomes.

BACKGROUND: Autologous fat grafting is a widely used procedure, yet the mechanisms that regulate graft outcomes are poorly understood. Estrogen signaling is a potent regulator of lipid handling, inflammation, fibrosis, and adipocyte progenitor recruitment in adipose tissues. To date, no studies have investigated the effect of circulating estrogens on fat graft outcomes. METHODS: Immunosuppressed (Nu/Nu) mice underwent ovariectomy or sham surgery. Forty-five days later, half the mice (donors) were killed, and adipose tissue was taken and transplanted into the remaining cohort (recipients). Forty-five days after transplantation, grafts were dissected, weighed, and assessed for expression of vascular endothelial growth factor, estrogen receptor-α, and vascular density. RESULTS: Grafts harvested from and transplanted into sham environments are smaller but more highly vascularized compared with ovariectomy environments. The estrogenic effects on grafts are more critical at the site of the donor tissue than the recipient. Finally, expression of estrogen receptor-α in the grafted tissue correlates with the observed graft characteristics, which is altered by both the donor and recipient environments. CONCLUSIONS: Circulating estrogens have significant effects on fat graft outcomes, primarily at the site of the donor tissue. As there are well-established depot-specific estrogenic responses, the choice of adipose depot used as a donor for fat grafting may affect outcomes. In addition, outcomes may be confounded by the patient's hormonal status. Understanding the mechanisms by which estrogen signaling regulates graft outcomes is important in refining this commonly used clinical procedure.

Effectiveness of prophylactic antibiotics in outpatient plastic surgery.

BACKGROUND: The effectiveness of prophylactic antibiotics has not been established for patients who undergo plastic surgery as outpatients, and consensus guidelines for antibiotic administration in clean-contaminated plastic surgery are not available. OBJECTIVES: In a retrospective study of outpatients, the authors examined preoperative timing of prophylactic antibiotics, whether postoperative antibiotics were administered, and whether any correlations existed between these practices and surgical complications. METHODS: The medical records of 468 plastic surgery outpatients were reviewed. Collected data included preoperative antibiotic timing, postoperative antibiotic use, comorbidities, and complications. Rates of complications were calculated and compared with other data. RESULTS: All 468 patients received antibiotics preoperatively, but only 93 (19.9%) received them ≥1 hour before the initial incision. Antibiotics were administered 15 to 44 minutes before surgery in 217 patients (46.4%). There was no significant difference in complication rates between the 315 patients who received postoperative prophylactic antibiotics (16.2%) and the 153 who did not (20.9%). Comorbidities had no bearing on postoperative complications. CONCLUSIONS: Postoperative antibiotic prophylaxis may be unnecessary for outpatient plastic surgery patients. LEVEL OF EVIDENCE: 3.

Genome editing of mouse fibroblasts by homologous recombination for sustained secretion of PDGF-B and augmentation of wound healing.

BACKGROUND: Exogenous cytokines, such as platelet-derived growth factor (PDGF)-B, can augment wound healing, but sustained delivery to maintain therapeutic levels remains a problem. "Genome editing" is a new technology in which precise genome modifications are made within cells using engineered site-specific nucleases. Genome editing avoids many of the complications associated with traditional gene therapy and the use of viral vectors, including random integration, imprecise gene expression, and inadvertent oncogene activation. METHODS: This study demonstrates site-specific nuclease-mediated integration of a PDGF-B transgene into a predefined locus within the genome of primary mouse fibroblasts. Engineered fibroblasts were applied to splinted mouse wounds and evaluated after 14 days and 5 months for the retention of engineered fibroblasts, wound healing morphology, angiogenesis, and systemic PDGF-B expression. RESULTS: The application of engineered PDGF-B-expressing fibroblasts enhanced wound healing compared with controls. Low-level, constitutive expression of PDGF-B was achieved without detectable levels of systemic PDGF-B. The mechanism of improved wound healing is, at least in part, the result of increased wound vascularization, as the wounds treated with PDGF-B fibroblasts had a blood vessel density 2.5 times greater than controls. After 5 months, the engineered fibroblasts persisted in the wound bed. No adverse effects were detected from the application of these fibroblasts after 5 months as assessed by hematoxylin and eosin staining of wounds and by mouse necropsy. CONCLUSIONS: These data support that site-specific genome editing allows for sustained cell-based cytokine delivery. Furthermore, sustained release of PDGF-B increases the speed and quality of wound healing after a single application.