Biomedical subjects

Vincent Falanga

Publications and source records attributed to Vincent Falanga.

At least 37 records · Page 2Linked to original sources

PubMed2002

The longevity of a bilayered skin substitute after application to venous ulcers.

BACKGROUND: A bilayered skin substitute composed of allogeneic keratinocytes and fibroblasts in a collagen gel has been approved by the US Food and Drug Administration for the treatment of venous and diabetic ulcers. Its mechanism of action has not been fully determined. OBJECTIVE: To determine the longevity of allogeneic fibroblasts and keratinocytes in a bilayered skin substitute in patients with venous leg ulcers. METHODS: Ten patients with venous leg ulcers were treated with a bilayered skin substitute on day 0, days 3 to 5, and weeks 1 through 3. Biopsy specimens of the grafted wound were taken. We used polymerase chain reaction analysis to determine whether allogeneic DNA was present in the biopsy specimens. RESULTS: We detected allogeneic DNA in 2 of 8 specimens at 1 month after initial grafting. Neither of the 2 patients showed persistence of allogeneic DNA at 2 months after initial grafting. CONCLUSIONS: Allogeneic cells from a bilayered skin substitute do not appear to survive permanently after grafting for treatment of venous leg ulcers. Other mechanisms of action might include cytokine release, structural support, or provision of a moist wound environment.

Collagen↗

PubMed2002

Low oxygen tension stimulates collagen synthesis and COL1A1 transcription through the action of TGF-beta1.

Recent findings point to low oxygen tension (hypoxia) as an important mechanism for the expression of several eukaryotic genes. We have previously shown that hypoxia (2% O2), when compared to standard oxygen tension (20% O2), upregulates the mRNA levels of the human alpha1(I) (COL1A1) procollagen gene and transforming growth factor-beta1 (TGF-beta1) in human dermal fibroblasts. In this report, we determined the effect of hypoxia on collagen synthesis and transcription. Exposure of human dermal fibroblasts to hypoxia for 24-72 h led to a threefold, dose-dependent increase in collagenous protein (P < 0.0001; r = 0.9794) and to enhanced type I procollagen deposition, as shown by direct immunofluorescence. Transient transfections with a series of luciferase- and CAT-promoter constructs of the human COL1A1 gene (spanning from -2.5 kb to +113 bp) showed that hypoxia increases the transcriptional activity of constructs having 5' endpoints between -804 bp and -107 bp, with loss of stimulation at -84 bp. Maximal increase in promoter activity in hypoxia was observed between -190 and -174 bp of the proximal promoter, once a cKrox repressor site (-199 to -224 bp) was deleted. Upregulation of COL1A1 mRNA levels in hypoxia was blocked by a TGF-beta1 anti-sense oligonucleotide, and failed to occur in fibroblasts from TGF-beta1 knock-out mice. Co-transfection and overexpression with a Smad7 construct abrogated the increase in COL1A1 promoter activity observed in hypoxia. Upregulated transcriptional activity of the TGF-beta1 promoter in hypoxia was found to be maximal between -453 and -175 bp from the transcriptional start site. Since hypoxia is a critical feature of the early phases of wound repair, we conclude that it may act as a potent physiologic stimulus for collagen synthesis. TGF-beta1 appears to be a critical component of this response.

Adult↗

PubMed2002

Preliminary study of fine changes in the duration of dynamic cooling during 755-nm laser hair removal on pain and epidermal damage in patients with skin types III-V.

BACKGROUND AND OBJECTIVES: The use of the long-pulsed 755-nm alexandrite laser has been an effective tool in hair removal. A dynamic cooling device (DCD) is commonly used with this laser in order to minimize epidermal damage. No studies have examined how fine changes in DCD duration may affect comfort and epidermal damage during laser hair removal. This study was designed to determine what effect, changes in the duration of dynamic cooling would have on pain and epidermal damage with laser hair removal (755 nm alexandrite) in patients with darker skin types. STUDY DESIGN/MATERIALS AND METHODS: Ten volunteers with Fitzpatrick skin types III-V were enrolled. A 755-nm alexandrite laser with a pulse duration of 3 milliseconds and equipped with a DCD was used with the 12 mm spot size on matched treatment sites. We compared cryogen spurt durations of 0, 20, 40, 60, 80, and 100 milliseconds on pain and epidermal changes. The spray delay was set at 1 millisecond. Pain rating scales and epidermal changes (skin sloughing, hyperpigmentation, hypopigmentation and scarring) were assessed. RESULTS: Overall a decrease in pain was seen with increases in spurt duration. A spurt duration of 20 milliseconds was beneficial for pain reduction in all patients. Longer spurt durations were associated with additional pain relief especially when geographic spacing of pulses was maximized to prevent thermal build-up. In regards to epidermal protection, most patients benefited with shorter cryogen durations of 20-60 milliseconds. There was little advantage with longer spurt durations. Some patients treated at higher fluences without cooling had no detectable side effects. CONCLUSIONS: Increasing DCD spurt duration in laser hair removal provides its strongest benefit in the area of pain reduction, particularly in type V patients. Increasing cryogen spurt durations above a protective threshold shows no significant benefit in terms of epidermal protection. Changing the spurt duration may not be as important in some patients with darker skin types.

Cold Temperature↗

PubMed2002

Leg ulcers.

Skin ulcers of the lower extremities have a chronic, relapsing course and often are difficult to manage. Leg ulcers remain a significant management challenge to health care professionals. This article focuses on the various causes of leg ulcers, with an emphasis on venous disease. Characteristic clinical findings and appropriate treatment options are discussed. Finally, the latest advances in the treatment of venous ulcers and their implications for clinical practice are emphasized.

Collagen↗

PubMed2002

Sustained ability for fibroblast outgrowth from stored neonatal foreskin: a model for studying mechanisms of fibroblast outgrowth.

Fibroblast cultures derived from neonatal foreskin explants have been an important model for understanding the basic mechanisms of fibroblast function and activity. Neonatal foreskin has been routinely used for establishing such fibroblast cultures in vitro. In general, tissue explants and fibroblast cultures are established from freshly harvested neonatal foreskin tissue. It is unknown whether prolonged storage of tissue, even in optimal growth media and conditions would still result in successful explant outgrowth. Specifically, no studies have properly examined the maximal duration of foreskin storage that can produce viable fibroblasts with normal growth and synthetic characteristics. We, therefore, set out to isolate and propagate fibroblast cultures from neonatal foreskin tissue that had been kept in complete culture media at 4 degrees C for various periods of time. We found that outgrowth and propagation of viable fibroblasts in vitro occurred with foreskin samples obtained within 24 days after surgical harvesting. The morphology, cellular proliferative capacity (measured by [3H]-thymidine uptake), steady state levels of alpha1(I) procollagen mRNA, and collagenous protein synthesis were comparable among fibroblast cultures derived from foreskin explants established 3 days (control) and up to 24 days (but not 38 days) after tissue harvesting. These studies demonstrate that viable and functional fibroblasts, with apparently similar in vitro characteristics, can be isolated and propagated from explants of neonatal foreskin tissue that have undergone prolonged storage. Moreover, these findings may be useful in understanding the lack of fibroblast growth in such conditions as found in delayed wound healing and aging.

Cell Division↗

PubMed2002

Wounding of bioengineered skin: cellular and molecular aspects after injury.

Skin substitutes are increasingly being used in the treatment of difficult to heal wounds but their mechanisms of action are largely unknown. In this study, using histology, immunostaining, flow cytometry, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction, we determined the response to injury of a human bilayered skin substitute. Meshing or scalpel fenestration of the construct was found to stimulate keratinocyte migration and to decrease proliferation. By 24 h, flow cytometry of the keratinocyte component showed that meshing was associated with a 33% decrease in the number of cells in S phase (p < 0.01). An approximately 2-fold decrease in staining for Ki67, a proliferation marker, was observed with meshing of human bilayered skin substitute. The process of reepithelialization was apparent by 12 h, however, the wounded human bilayered skin substitute was healed by day 3, and a stratum corneum and fully stratified epithelium were re-established by day 4. Reverse transcription polymerase chain reaction analysis and enzyme-linked immunosorbent assays showed that the expression of acute proinflammatory cytokines (interleukins 1alpha, 6, and 8, tumor necrosis factor alpha) peaked by 12-24 h postinjury. The levels of mRNA of certain growth factors (transforming growth factor beta1, vascular endothelial growth factor, insulin-like growth factor 2) but not others (platelet-derived growth factors A and B, keratinocyte growth factor, fibroblast growth factors 1 and 7, transforming growth factor beta3) increased by 12 h and peaked by 1-3 d after injury, returning to normal by day 6. Immunostaining for tumor necrosis factor alpha and transforming growth factor beta1 paralleled these findings by reverse transcription polymerase chain reaction. We conclude that human bilayered skin substitute, as a prototypic bilayered skin substitute, is a truly dynamic living tissue, capable of responding to physical injury in a staged and specific pattern of cell migration, reepithelialization, and cytokine expression.

Cytokines↗

PubMed2002

Human chronic wounds treated with bioengineered skin: histologic evidence of host-graft interactions.

Bioengineered skin is being used to successfully treat a variety of wounds. Randomized controlled clinical trials have shown that a living bilayered skin construct (BSC), consisting of human neonatal keratinocytes and fibroblasts in a collagen matrix, was able to accelerate complete closure of both venous and diabetic ulcers. BSC was particularly effective in difficult-to-heal wounds of long duration. In patients treated with BSC, no obvious signs of gross clinical rejection were observed. Testing of these treated patients showed no BSC-specific immune response and no immune response to bovine collagen or alloantigens expressed on keratinocytes and fibroblasts. However, very little is known about the histologic changes that occur after BSC has been placed on human wounds. We report our preliminary histologic observations in this uncontrolled study of a cohort of 11 patients with 14 wounds treated with BSC in whom biopsy specimens of the grafted sites were obtained at least 2 weeks after application of the construct. The etiology of these ulcers varied from arterial or venous disease to an extensively and poorly healing burn wound. Histologically, thickening of the grafted bioengineered skin was seen in all samples where residual BSC could be identified. Mucin deposition was noted in the dermal layer of the wounds and BSC in 13 of the 14 specimens examined. Unexpectedly, and in spite of good clinical outcome, 4 of the 14 specimens exhibited a foreign body-like granulomatous response. There was no history of prior exposure to BSC in the 4 patients who had a granulomatous response. These early histologic observations suggest that stimulatory interactions develop between BSC and the wound. The consistently found deposition of mucin may point to a fetal pattern of wound repair associated with the neonatal cells in BSC.

Aged↗

PubMed2002

Calciphylaxis with peau d'orange induration and absence of classical features of purpura, livedo reticularis and ulcers.

Calciphylaxis is an ill-defined syndrome that is commonly associated with chronic renal failure. Its heterogeneous clinical features include painful livedo reticularis-like purpuric patches and plaques, vesicles, irregularly shaped ulcers, and black eschars. Despite demonstration of extensive vascular arteriolar calcification in this syndrome, its exact pathogenesis remains unknown. Here, we report a case of calciphylaxis presenting with indurated plaques without the usual clinical picture of livedo reticulate purpura, ulcers or necrotic eschars. This case provides an opportunity to review the clinical spectrum of calciphylaxis and to discuss the therapeutic approaches and pathogenesis of this syndrome from deep intra-wall vascular calcification to the resulting infarctions of adjacent tissues.

Calciphylaxis↗

PubMed2000

Treatment of Venous Ulcers Using a Bilayered Living Skin Construct.

Venous ulcers are a common cause of pain and suffering in the elderly US population. Up to 1 million individuals suffer from this disease, and the true costs in terms of medical care and quality of life are only beginning to be appreciated. Bioengineered skin constructs are being used increasingly to treat venous ulcers with some success and can be used if traditional first-line treatment methods fail.

Journal Article↗

PubMedDate not supplied

Innovative therapies in wound healing.

BACKGROUND: Apligraf is a bioengineered skin product composed of neonatal fibroblasts and keratinocytes. The FDA has approved Apligraf for the treatment of chronic venous ulcers and diabetic ulcers. OBJECTIVE: We review the development of bioengineered skin, examine the cellular activities of various growth factors that may facilitate wound healing, and discuss the results of clinical trials with a particular construct, Apligraf, as proof of principle. CONCLUSION: Bioengineered skin acts as a "smart" delivery system for growth factors and other stimulatory substances. Not only does it present a novel treatment for chronic and diabetic ulcers, but it could also be considered for application to other types of acute wounds.

Clinical Trials as Topic↗

PubMedDate not supplied

The chronic wound: impaired healing and solutions in the context of wound bed preparation.

In the past few years, a different paradigm for the understanding and treatment of chronic wounds has emerged. The term used to describe this new context in which failure to heal is viewed is "wound bed preparation". This term is revolutionizing the way we approach chronic wounds, and has allowed chronic wounds to gain independence from established models of acute injury. Within the context of wound bed preparation, impaired healing and solutions to it are being addressed in novel ways. In this report, we make use of the diabetic ulcer as an example of a chronic wound, and emphasize the pathophysiological principles, the cellular and molecular abnormalities, and the solutions offered by the new approaches of gene therapy and stem cells. The emerging view is that chronic wounds are characterized by resident cells that have undergone phenotypic changes that need to be corrected for optimal healing to occur. We have established in animal models and in humans that stem cells have the potential to bring about fundamental changes in the repair process and, ultimately, a "quantum" jump in our therapeutic success.

Chronic Disease↗

PubMedDate not supplied

Debridement performance index and its correlation with complete closure of diabetic foot ulcers.

In recent years there has been wider acceptance of aggressive surgical debridement as a means to accelerate closure of diabetic foot ulcers. In a clinical trial by Steed et al.1 involving the use of a topically applied growth factor, thorough surgical debridement of surrounding callus, necrotic ulcer bed, and undermined ulcers' edges was associated with greater incidence of healing and effectiveness of the therapeutic agent. However, at present there is no established way to judge the appropriate extent of debridement and its performance. Here we describe a scoring system to assess whether debridement has been performed adequately. Our scoring system consists of the following three categories: debridement of a) callus; b) ulcer's edge undermining; and c) wound bed necrotic tissue. We assigned a score of 0-2 to each of these categories using the following criteria: 0 = debridement needed but not done, 1 = debridement needed and done, and 2 = debridement not needed. These three scores are then added to give a total ranging from 0 to 6, with the highest number being the optimal score. This instrument, the Debridement Performance Index, evaluates both the adequacy of debridement and whether the ulcer has been or is being properly debrided. To initiate the validation of this scoring system and determine its predictive value for wound closure by week 12, we applied it to 143 patients with diabetic foot ulcers who had been treated in a clinical trial involving either standard therapy (n = 65) or the application of a bioengineered skin construct (n = 78). We blindly evaluated sequential digital photographs of each diabetic foot ulcer and applied the Debridement Performance Index score at day 0, before initiation of either treatment. We found that the lower the baseline Debridement Performance Index the lower the incidence of ultimate wound closure by week 12 ( p = 0.0276). Patients with a Debridement Performance Index between 3 and 6 were 2.4 times more likely to heal than those with a score of 0-2. After controlling for treatment, the Debridement Performance Index was found to be an independent predictor of wound closure (odds ratio = 2.4 95% confidence interval = 1.0-5.6). In conclusion, this novel scoring system for debridement performance appears to be very promising as a predictive tool for determining outcome in clinical trials and, most likely, in clinical practice.

Adolescent↗

PubMedDate not supplied

Full-thickness wounding of the mouse tail as a model for delayed wound healing: accelerated wound closure in Smad3 knock-out mice.

Experimentally induced wounds in animal models are useful in gaining a better understanding of the cellular and molecular processes of wound healing, and in the initial evaluation of the safety and effectiveness of potential therapeutic agents. However, studying delayed healing has proved difficult in animals, whose wounds heal within a few days. In this report, we describe a novel method for establishing mouse wounds that require up to 3 weeks or more for complete closure, and we show the validity of this model in Smad3 null mice, which are known to display accelerated healing. Full-thickness wounds, measuring 0.3 by 1.0 cm, were made down to fascia on the dorsal aspect of the mouse tail in Smad3 knock-out mice and control littermates, approximately 1 cm distal to the body of the animal. The wounds were left to heal by secondary intention and were assessed histologically by computerized planimetry for wound closure at various times after wounding. The wounds in wild-type mice displayed delayed healing, with full closure occurring between 14 and 25 days after wounding. Complete closure of similar wounds in Smad3 null mice healed 30 percent faster (p < 0.01). By immunostaining for ki67, a marker for proliferation, Smad3 null animals also showed increased proliferation of dermal wound cells by day 4 after wounding. Cultured dermal fibroblasts from Smad3 null mice had increased baseline DNA synthesis and, interestingly, an enhanced response to transforming growth factor-beta1. By Western blot analysis, Smad3 null mice fibroblasts showed a compensatory increase in mitogen-activated protein kinase phosphorylation in response to transforming growth factor-beta1, suggesting that mitogen-activated protein kinase overcompensation together with loss of Smad3 may be involved in the modulation of faster healing. We conclude that this novel tail-wounding model may be useful for studying delayed wound closure.

Animals↗

PubMedDate not supplied

Human beta-defensin-2 expression is increased in chronic wounds.

First identified in psoriatic epidermis and subsequently in other inflammatory cutaneous lesions, human beta-defensin-2 (hbetaD-2) is one of two endogenous antimicrobial peptides related to defensins in plants and animals. Our objective was to determine the expression of hbetaD-2 after injury and in chronic wounds. Biopsies of normal ipsilateral thigh skin and wound edges were taken from nine consecutive patients with venous leg ulcers (day 1) and from the same biopsy sites 2 days later (day 3). Sequential samples were also obtained from intact or meshed bilayered bioengineered skin consisting of neonatal human keratinocytes and dermal fibroblasts in a collagen matrix. Specimens were processed and immunostained for hbetaD-2 using a polyclonal rabbit antibody. In both human tissues and bioengineered skin, staining for hbetaD-2 was confined to the upper epidermal layers, sparing the basal cells. Analysis of 26 tissue samples from patients showed that normal skin had no hbetaD-2 expression but that marked up-regulation occurred after wounding by day 3. Conversely, chronic ulcers showed moderate-to-strong immunostaining for hbetaD-2 at baseline on day 1, with little or no change in intensity after wounding by day 3. In vitro, bioengineered skin showed increased distribution of cytoplasmic hbetaD-2 immunostaining after meshing. We conclude that the expression of hbetaD-2 is up-regulated after injury. Chronic wounds uniformly show a constitutively high baseline expression of hbetaD-2, possibly due to ongoing tissue injury and bacterial colonization.

Chronic Disease↗

PubMedDate not supplied

Wound bed score and its correlation with healing of chronic wounds.

Adequate wound bed preparation is essential for healing of leg ulcers, and consists of controlling exudate and edema, decreasing the bacterial burden, promoting healthy granulation tissue, and removing necrotic tissue. Currently, there is no classification system for wound bed preparation that has predictive value. Based on past work and the authors' experience, we have now developed and tested a new classification system that scores the following parameters: healing edges (wound edge effect), presence of eschar, greatest wound depth/granulation tissue, amount of exudate amount, edema, peri-wound dermatitis, peri-wound callus and or fibrosis, and a pink/red wound bed. Each parameter receives a score from 0 (worst score) to 2 (best score), and all the parameter scores are added for a total score. Each wound can have a maximum score of 16 (the best score possible), to a minimum score of 0 (the worst score possible). We used this wound bed score (WBS) system in a study of 177 patients with venous ulcers who had been prospectively treated with and randomized to either conventional therapy (compression alone) or a living bilayered skin construct (BSC). We evaluated serial photographs at baseline to determine whether the results would be predictive of complete wound closure and could validate the WBS. We found that wounds that ultimately achieved full closure had a statistically significant higher WBS than those that did not heal (p = 0.0012). This was also true when separating wounds by treatment modality: standard therapy (p = 0.044) and treatment with a BSC (p = 0.011). When dividing the WBS in the following quartile groups: scores 4-10, 10-12, 12-13, and 13-16, the percentage of healed wounds correlated with the WBS (p = 0.0008). For all wounds, a one unit increase in total WBS resulted on average in a 22.8% increase in odds of healing (OR = 1.228). This WBS seems to have validity in predicting complete wound closure in wounds treated with either standard therapy or advanced modalities, such as BSC. If confirmed and widely adopted in this and other types of wounds, it could be a useful tool in both the clinical and research setting.

Adolescent↗

PubMedDate not supplied

Basic approach to inflammatory ulcers.

Cutaneous ulcers are a difficult problem. A multidisciplinary approach is often adapted in caring for patients with nonhealing wounds. Internists, surgeons, dermatologists, and nurses must work together to provide a patient with the most comprehensive care possible. Dermatologists are consulted for a number of reasons, particularly if the ulcers are secondary to an inflammatory process. In this discussion, we describe a basic and useful approach to the diagnosis and management of inflammatory ulcers. The spectrum of these conditions is wide, ranging from vasculitis, to pyoderma gangrenosum, to ulcers resulting from the antiphospholipid syndrome and cryoprecipitates. The present authors will emphasize that the approach needs to be all-encompassing, and not focused on the ulceration alone. Certain clues are critical to diagnosis. The management, whereas often difficult, can be very rewarding.

Humans↗

PubMedDate not supplied

Best-practice algorithms for the use of a bilayered living cell therapy (Apligraf) in the treatment of lower-extremity ulcers.

Tissue-engineered skin substitutes such as Apligraf have emerged over the past 20 years as among the most carefully studied and efficacious of the advanced wound modalities. These products have been proven as effective enhancements to general wound care, promoting wound closure particularly in instances where conventional wound care fails. Marketed for hard-to-heal wounds since 1998, Apligraf has become part of standard wound care in many wound centers across the United States. Despite this situation, few general wound care guidelines incorporate advanced and active wound-healing technologies, such as tissue-engineered skin products. Because of this deficiency, appropriate patient selection and proper use of these product remain largely unaddressed within the general wound care community. Here, we describe the development of guidelines surrounding optimal use of the bilayered living cell therapy, Apligraf, in the treatment of the two types of lower extremity ulcers for which the product is FDA approved: venous leg ulcer and diabetic foot ulcer. The guidelines detailed in this article focus on the identification and selection of patients who are at risk for failure of standard wound care therapy and thus appropriate for Apligraf treatment. The intended audience for these guidelines is the general wound care practitioner, for whom the developed treatment algorithms and accompanying figure legends should provide practical, user-friendly direction simplifying both patient selection and appropriate use of Apligraf within the context of good wound-healing practice.

Algorithms↗

PubMedDate not supplied

Evaluation of Apligraf persistence and basement membrane restoration in donor site wounds: a pilot study.

Apligraf is a bilayered tissue-engineered product consisting of a bovine collagen matrix with neonatal fibroblasts, overlaid by a stratified epithelium containing living keratinocytes. The United States Food and Drug Administration has approved its use for venous leg ulcers and neuropathic diabetic foot ulcers. Apligraf provides a dermal matrix and produces cytokines similar to the human skin. However, its mechanism of action and ultimate fate in host wounds are unclear. The aim of this study was to evaluate the persistence of Apligraf fibroblasts and keratinocytes in human acute partial-thickness wounds (split-thickness donor sites) treated with Apligraf. In an open-label, within-patient, three-centered, controlled pilot study, 10 patients were treated with Apligraf, Apligraf dermis only (without epidermis), and a polyurethane film for donor site wounds of the same size, depth, and anatomical location. Apligraf DNA persistence was the primary outcome measure. Basement membrane components, cosmetic outcome, time to wound healing, and safety parameters were secondary outcome measures. One week after the initial treatment, reverse transcription polymerase chain reaction analysis found that two Apligraf and two Apligraf dermis-only-treated sites had Apligraf DNA present. Four weeks posttreatment, only one Apligraf and one Apligraf dermis-only sites showed the presence of Apligraf DNA. There was no difference between the three treatment modalities in establishing basement membrane in donor site wounds. No differences in other secondary outcomes were found. Apligraf DNA persisted in a minority of patients at 4 weeks in acute partial-thickness wounds. Apligraf's success in speeding healing of acute wounds appears to be related to factors other than the persistence of donor DNA or effect on basement membrane restoration.

Adult↗