Treatment of keloids by surgical excision and immediate postoperative single-fraction radiotherapy

The authors report the outcomes of patients with keloid scars treated with a protocol of extralesional excision and immediate single-fraction adjuvant radiotherapy. The design of the study was a retrospective analysis with up to 5-year outcome data. The setting was a single treatment team, University Teaching Hospital in London, United Kingdom. Participants (n = 80) were treated for 80 keloid scars (59 percent female patients, 76 percent nonwhite), and 44 percent of keloids were located on earlobes. For all patients, prior treatment without radiotherapy had failed. The salvage treatment reported in this article is combined extralesional excision and immediate postoperative external-beam radiotherapy. A 10-Gy dose of superficial 60-kV or 100-kV photon irradiation was given within 24 hours of the operation. The main outcome measure was freedom from recurrence of keloid scars. Results were that all keloid scars were controlled at 4-week follow-up. Probability of relapse at 1 year was 9 percent; at 5 years, probability of relapse was 16 percent. The earlobe showed no greater chance of relapse than other sites on the body. The authors' report shows that extralesional excision of keloid followed by early, single-fraction, postoperative radiotherapy is both simple and effective in preventing recurrence at excision sites.     

Low-dose enalapril in the treatment of surgical cutaneous hypertrophic scar and keloid--two case reports and literature review

Hypertrophic scars and keloids are 2 forms of excessive cutaneous scarring that occur in predisposed individuals. The healing process varies greatly among patients, and the risk of a bad scar evolution is unpredictable. Keloids create disfiguring scars with associated erythema and pain or pruritus or restricted range of motion, and are a major cause of morbidity. A fortuitous observation was made by the first author of this study who, at age 54, developed an erythematous and painful postsurgical abdominal keloid scar after undergoing left colectomy for colon adenocarcinoma. Four months later, after treatment with low-dose enalapril (10 mg, once a day) for mild arterial hypertension, her keloid scar rapidly improved and she eventually made a complete recovery. second case involved a 70-year-old female with diabetes who was affected by a long-standing postsurgical abdominal keloid scar of 2 years' duration. She was intentionally treated with the same low dose of enalapril, and, after 6 months of therapy, the bad scar showed marked improvement. We conducted an exhaustive search of the literature pertaining to the wound healing process, specifically to determine whether angiotensin-converting enzyme (ACE) inhibitors have a healing effect on wounds. ACE inhibitors are known to induce reduction of left ventricular collagen content and to attenuate remodeling during the postinfarctual period (thus improving ventricular function), and they have been shown to exert a pulmonary antifibrotic effect. After conducting this literature search, it became apparent that no data on cutaneous scars and ACE inhibitors are available. During the posttraumatic or postoperative stage, it is useful to achieve the best possible aesthetic results and to decrease the risk of a disfiguring keloid scar, thereby avoiding revision surgery; to this purpose, an early treatment with a low dose of enalapril is a possible solution, even if further confirmatory observations are needed.     

Keloid skin scars: the influence of hyperbaric oxygenation on fibroblast growth and on the expression of messenger RNA for insulin like growth factor and for transforming growth factor

Wound healing can result in the development of keloid scars that contain atypical fibroblasts and an overabundance of extracellular matrix components. Hyperbaric oxygenation (HBO) refers to exposure to pure oxygen under increased atmospheric pressure and is recognized as a valuable supplementary method of treatment for problematic wounds. The effect of HBO in the expression of insulin-like growth factor type 1 (ILGF-1) and transforming growth factor β (TGF-β) messenger RNAs was determined by semiquantitative RT-PCR in fibroblasts obtained from keloid scars and nonwound involved skin fibroblast from the same patient. ILGF-1 and TGF-β are the principal mitogens during wound regeneration. We found a decrease in the growth of fibroblasts and in the expression of ILGF-1 and TGF-β messengers in keloid and nonkeloid fibroblast after chronic exposition to hyperbaric oxygenation compared with normal oxygen partial pressure.     

瘢痕疙瘩中TIEG1的高表达

转化生长因子-β1(TGF-β1/Smads)信号转导通路的持续激活是瘢痕疙瘩形成的重要机制.研究发现这条通路重要的负反馈调节信号分子Smad7表达明显下调,Smad2/3的磷酸化水平和蛋白质量并无明显改变.但是,Smad7下调的机制尚不清楚.采用生物信息学方法对Smad7的启动子进行分析;用RT-PCR和蛋白质印迹分别检测了正常皮肤、正常瘢痕及瘢痕疙瘩组织中的Sp1样转录因子TIEG1mRNA及蛋白质的表达水平;体外培养正常皮肤、正常瘢痕及瘢痕疙瘩成纤维细胞,检测TIEG1 mRNA及蛋白的表达水平.研究结果显示,Smad7启动子上有Sp1的位点,TIEG1 mRNA及蛋白质水平在瘢痕疙瘩组织及瘢痕疙瘩成纤维细胞中表达明显高于正常瘢痕和正常皮肤(P<0.05).说明瘢痕疙瘩中TIEG1可能是Smad7下调的重要原因,有必要进一步研究TIEG1对Smad7的调控作用机制.     

The role of the activin system in keloid pathogenesis

Keloid scars represent a pathological response to cutaneous injury under the regulation of many growth factors. Activin-A, a dimeric protein and a member of the transforming growth factor- superfamily, has been shown to regulate various aspects of cell growth and differentiation in the repair of the skin mesenchyme and the epidermis. Thus our aim was to study the role of activin and its antagonist, follistatin, in keloid pathogenesis. Increased mRNA expression for activin was observed in keloid scar tissue by performing RNase protection assay. Immunohistochemistry showed increased localization of both activin-A and follistatin in the basal layer of epidermis of keloid tissue compared with normal tissue. ELISA demonstrated a 29-fold increase in concentration of activin-A and an 5-fold increase in follistatin in conditioned media in keloid fibroblasts compared with normal fibroblasts. Although keloid keratinocytes produced 25% more follistatin than normal keratinocytes, the amounts of activin-A, in contrast, was 77% lower. Proliferation of fibroblasts was stimulated when treated with exogenous activin-A (46% increase in keloids fibroblasts) or following co-culture with hAHaCaT cells (66% increase). Activin-A upregulated key extracellular matrix components, namely collagen, fibronectin, and -smooth muscle actin, in normal and keloid fibroblasts. Co-treatment of follistatin with activin-A blocked the stimulatory effects of activin on extracellular matrix components. These findings emphasize the importance of the activin system in keloid biology and pathogenesis and suggest a possible therapeutic potential of follistatin in the prevention and treatment of keloids. collagen; fibroblasts; follistatin; keloid scar; keratinocytes; -smooth muscle actin; transforming growth factor-     

Dermal substitution in acute burns and reconstructive surgery: a subjective and objective long-term follow-up.

Tissue engineering and dermal substitution are currently prominent topics of wound-healing research. However, no extensive clinical trials with objective evaluation criteria have been published so far that support the clinical effectiveness of dermal equivalents in the long term. The dermal substitute that is discussed here is derived from bovine collagen and elastin-hydrolysate and has been shown to improve skin elasticity during a short-term clinical follow-up of scar reconstructions. In this study we will present the long-term outcome by means of objective and subjective scar assessment tools for dermal substitution in acute burn wounds and scar reconstructions.In a clinical trial, an intraindividual comparison was performed between the conventional split-thickness autograft and a combination of the collagen/elastin substitute with an autograft. After 1 year, scars were evaluated by the Cutometer SEM 474 for objective elasticity measurements and by planimetry to establish scar contraction. An independent observer subjected scars to a generally accepted clinical scar assessment tool: the Vancouver Scar Scale. In addition, patients gave their impression of the outcome. Forty-two paired burn wounds and 44 paired scar reconstructions were included and evaluated 1 year after surgery.Although substituted scar reconstructions demonstrated an elasticity improvement of approximately 20 percent compared with control wounds, no statistically significant differences were found for skin elasticity, scar contraction, Vancouver Scar Scale, and patient's impression in both categories after 1 year. An extensive long-term follow-up shows that the dermal substitute, which was proven effective in a clinical trial on a short-term basis, did not yield statistical evidence for a long-term clinical effectiveness of dermal substitution.     

PI3-K/AkT信号转导通路与瘢痕形成研究进展

临床上组织损伤2—3天后即可出现肉芽组织,进而由于成纤维细胞和血管内皮细胞的增殖逐渐形成纤维性瘢痕。瘢痕的形成与血管再生和细胞增殖及凋亡密切相关。常见的病理性瘢痕主要是增生性瘢痕和瘢痕疙瘩,他们不仅影响患者关键伤口的活动,而且在美观上给患者带来莫大的痛苦。但是由于对瘢痕的形成原因及发病机制仍不甚清楚,至今临床上实行地以手术为主的对瘢痕的治疗方法仍未取得较满意效果。磷脂酰肌醇3激酶（P13K,phosphoinositide3．Kinase）／Akt（P13．K／Akt）通路广泛存在于人体的多个生理功能中,其在细胞因子作用下介导细胞生存已被证实,目前研究表明,P13-k／Akt信号通路在瘢痕形成中也发挥了重要作用,这可能会为瘢痕的治疗带来新的前景。本文将就近年来关于P13-k／Akt通路在中发挥的作用机制作一综述,并对未来利用此通路彻底治疗瘢痕的可能方式做一展望。     

Therapeutic effects of liposome-enveloped Ligusticum chuanxiong essential oil on hypertrophic scars in the rabbit ear model

Hypertrophic scarring, a common proliferative disorder of dermal fibroblasts, results from an overproduction of fibroblasts and excessive deposition of collagen. Although treatment with surgical excision or steroid hormones can modify the symptoms, numerous treatment-related complications have been described. In view of this, we investigated the therapeutic effects of essential oil (EO) from rhizomes of Ligusticum chuanxiong Hort. (Umbelliferae) on formed hypertrophic scars in a rabbit ear model. EO was prepared as a liposomal formulation (liposome-enveloped essential oil, LEO) and a rabbit ear model with hypertrophic scars was established. LEO (2.5, 5, and 10%) was applied once daily to the scars for 28 days. On postoperative day 56, the scar tissue was excised for masson's trichrome staining, detection of fibroblast apoptosis, assays of the levels of collagens I and III, and analysis of the mRNA expression of matrix metalloproteinase-1 (MMP-1), caspase-3 and -9, and transforming growth factor beta 1 (TGF-β(1)). In addition, the scar elevation index (SEI) was also determined. As a result, LEO treatment significantly alleviated formed hypertrophic scars on rabbit ears. The levels of TGF-β(1), MMP-1, collagen I, and collagen III were evidently decreased, and caspase -3 and -9 levels and apoptosis cells were markedly increased in the scar tissue. SEI was also significantly reduced. Histological findings exhibited significant amelioration of the collagen tissue. These results suggest that LEO possesses the favorable therapeutic effects on formed hypertrophic scars in the rabbit ear model and may be an effective cure for human hypertrophic scars.     

Effect of Mederma on hypertrophic scarring in the rabbit ear model

Currently accepted conservative treatments of hypertrophic scars are limited to steroid injections, radiation therapy, and silicone occlusive therapy. However, the use of Mederma for these problematic lesions has become quite prevalent in the clinical setting. Little scientific evidence exists to support the efficacy of this product in reducing hypertrophic scars. The aim of this study was to study the effects of Mederma on hypertrophic scars in the rabbit hypertrophic scar model, allowing the histologic quantification of scar elevation, dermal collagen organization, vascularity, and inflammation and the gross examination of scar erythema. Full-thickness wounds down to cartilage, four per ear, were created in four New Zealand White rabbits, for a total of 32 scars. Twenty-eight days after the initial wounding, the hypertrophic scars were photographed, and treatment of half of the scars on each ear was begun with Mederma three times per day for a total of 4 weeks. The untreated scars served as control scars and were left exposed to air. After 4 weeks of treatment, the scars were once again photographed. The rabbits were then killed, and the scars were analyzed histologically. The pretreatment and posttreatment photographs were compared by using computer quantification of magenta, yellow, and cyan expression within the scars.Histologic analysis demonstrated no significant reduction in scar hypertrophy or scar elevation index. However, a significant improvement in dermal collagen organization was noted on comparing Mederma-treated scars with untreated control scars (p < 0.05). No significant difference in dermal vascularity or inflammation was noted. Computer analysis of the scar photographs demonstrated no significant reduction in scar erythema with Mederma treatment. The active product in Mederma, allium cepa, has as its derivative quercetin, a bioflavonoid noted for its antiproliferative effects on both normal and malignant cells, and its antihistamine release effects. These properties could theoretically prove beneficial in reversing the inflammatory and proliferative responses noted in hypertrophic scars. Despite the authors' inability to demonstrate a reduction in scar hypertrophy, the improvement in collagen organization noted in the Mederma-treated scars suggests it may have an effect on the pathophysiology of hypertrophic scar formation.     

Secretory leukocyte protease inhibitor is a novel inhibitor of fibroblast-mediated collagen gel contraction

Cultured epithelial cells, including those from the oral epithelium, have been successfully applied in the promotion of scarless wound healing. Factors released from the epithelial cells are thought to contribute significantly to the beneficial effects. In the conditioned medium of human oral epithelial cells, we found a factor that inhibited fibroblast-mediated collagen gel contraction, an in vitro model of wound healing and scar formation. Biochemical analysis identified the factor to be human secretory leukocyte protease inhibitor (SLPI). Fibroblasts transfected with SLPI cDNA showed reduced gel-contracting activity. SLPI purified from the conditioned medium inhibited gel contraction in a dose-dependent manner, and anti-SLPI antibody counteracted this activity. Upon SLPI treatment, human skin fibroblasts in collagen gel became shorter in length and were inhibited in pseudopodia extension. Furthermore, after SLPI treatment, alpha(1)-integrin immunoreactivity decreased, and cyclic AMP levels increased. Excessive gel contraction was observed when fibroblasts treated with TGF-beta1 and fibroblasts from hypertrophic and from keloid scar tissue were cultured in collagen gel. SLPI was also effective in inhibiting gel contraction in the above three models of scar formation. These results suggest that SLPI may be useful in promoting scarless wound healing.     

Cellular signaling by tyrosine phosphorylation in keloid and normal human dermal fibroblasts

Keloids represent a dysregulated response to cutaneous wounding that results in disfiguring scars. Unique to humans, keloids are characterized by an accumulation of extracellular matrix components. The underlying molecular mechanisms of keloid pathogenesis, however, remain largely uncharacterized. Similarly, cellular signaling mechanisms, which may indicate inherent differences in the way keloid fibroblasts and normal human dermal fibroblasts interact with extracellular matrix or other cells, have not been investigated. As part of a fundamental assessment of cellular response to injury in keloid fibroblasts, phosphorylation studies were performed using three different keloid (n = 3) and normal human dermal (n = 3) fibroblast cell lines. These studies were undertaken to elucidate whether keloid and normal human dermal fibroblasts exhibit different tyrosine kinase activity. Initially, distinct tyrosine phosphorylation patterns of keloid and normal human dermal fibroblasts were demonstrated. Next, the phosphorylation patterns were correlated with known molecules that may be important to keloid pathogenesis. On the basis of molecular weight, it was hypothesized that the highly phosphorylated bands seen in keloid fibroblasts represented epidermal growth factor receptor (EGFR); discoidin domain receptor 1 (DDR1); and Shc, an adaptor protein known to bind many tyrosine kinases, including EGFR and DDR1. Individual immunoblotting using EGFR, DDR1, and Shc antibodies revealed greater expression in keloid fibroblasts compared with normal human dermal fibroblasts. These data substantiate for the first time the finding of greater phosphorylation by the above-mentioned molecules, which may be important in keloid pathogenesis.     

病理性瘢痕的发病机制及临床治疗方法的进展

增生性瘢痕和瘢痕疙瘩是临床上常见的病理性瘢痕。本文阐述了局部和全身因素对其形成的影响机制,并对其临床治疗方法的现状和将来的可能性治疗作一概述。     

咪喹莫特调节Th1、Th2细胞相关趋化因子表达抑制兔耳瘢痕增生

目的:免疫因素在增生性瘢痕的发生中起重要作用,本实验研究免疫抑制剂咪喹莫特对兔耳增生性瘢痕组织中辅助性T淋巴(Th)细胞亚群Th1、Th2细胞相关趋化因子CXCL10、CXCL12、CCL2、CCL3、CCL5、CCL7、CCL13表达的影响,探讨咪喹莫特抑制兔耳瘢痕增生的作用机制。方法:选取16只新西兰大耳白兔,雌雄不限。建立兔耳增生性瘢痕模型,每只兔耳腹侧做四个直径为1 cm的圆形创面,每个相距1.5 cm,双侧对称,右耳为咪喹莫特组涂抹5%咪喹莫特软膏,左耳为空白对照组涂抹等量凡士林软膏,待术后14天上皮化均完全后开始涂抹,一日一次,持续一个月。分别于术后第21、28、35、42、49、56、63天同一时间空气栓塞法随机处死2只兔子,收集所有瘢痕标本。另外处死2只健康兔并采集兔耳正常皮肤组织。所有标本行HE染色及Masson三色法染色,观察形态学差异;测量并计算瘢痕增生指数(Scar elevation index,SEI);行Real-time PCR检测CXCL10、CXCL12、CCL2、CCL3、CCL5、CCL7、CCL13的表达。结果:HE及Masson染色可见咪喹莫特组胶原沉积较空白对照组明显减少,SEI显示空白对照组于术后第28天增生程度达到高峰,其增生程度明显高于咪喹莫特组(P0.05);Real-time PCR结果可见咪喹莫特组Th2细胞相关趋化因子CCL2、CCL3、CCL5、CCL7及CCL13表达在各时间点较空白对照组明显降低,Th1细胞相关趋化因子CXCL10、CXCL12的表达在各时间点较空白对照组明显增高(P0.05)。结论:咪喹莫特可通过调节Th1、Th2细胞相关趋化因子的表达来发挥抑制兔耳瘢痕增生的作用。     

595nm 激光对兔耳瘢痕成纤维细胞增殖活性的影响

目的：探讨兔耳增生性瘢痕动物模型形成过程中成纤维细胞增殖活性的动态变化及595nm Vbeam激光照射的影响。方法：利用兔耳腹侧面建立增生性瘢痕模型,按不同时间段取材,采用免疫组织化学方法观察瘢痕形成不同时期增殖细胞核抗原（PCNA）蛋白的表达,对比研究在兔耳增生性瘢痕形成过程中595nm Vbeam激光照射对成纤维细胞增殖活性的影响。结果：上皮化后增殖细胞核抗原阳性细胞反应率随时间推移逐渐增高,至上皮化后4周达高峰。从上皮化后1周开始即可见到595nm Vbeam激光照射后增殖细胞核抗原蛋白表达较对照组明显减弱,成纤维细胞增殖活性受到明显抑制,两组差异具有极显著性（P〈0．01）。结论：595nm Vbeam激光照射可明显抑制兔耳增生性瘢痕成纤维细胞的增殖活性,对兔耳腹侧面增生性瘢痕有明显的防治作用。     

Investigation of the influence of keloid-derived keratinocytes on fibroblast growth and proliferation in vitro

Keloids are disfiguring, proliferative scars that represent a pathological response to cutaneous injury. The overabundant extracellular matrix formation, largely from collagen deposition, is characteristic of these lesions and has led to investigations into the role of the fibroblast in its pathogenesis. Curiously, the role of the epidermis in extracellular matrix collagen deposition of normal skin has been established, but a similar hypothesis in keloids has not been investigated. The aim of this study was to investigate the influence of keloid epithelial keratinocytes on the growth and proliferation of normal fibroblasts in an in vitro serum-free co-culture system. A permeable membrane separated two chambers; the upper chamber contained a fully differentiated stratified epithelium derived from the skin of excised earlobe keloid specimens, whereas the lower chamber contained a monolayer of normal or keloid fibroblasts. Both cell types were nourished by serum-free medium from the lower chamber.Epithelial keratinocytes from five separate earlobe keloid specimens were investigated. Four sets of quadruplicates were performed for each specimen co-cultured with normal fibroblasts or keloid-derived fibroblasts. Controls consisted of (1) normal keratinocytes co-cultured with normal fibroblasts, and (2) fibroblasts grown in serum-free media in the absence of keratinocytes in the upper chamber. Fibroblasts were indirectly quantified by 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay, with results confirmed by DNA content measurement, at days 1 and 5 after the co- culture initiation.Significantly, increased proliferation was seen in fibroblasts co-cultured with keloid keratinocytes, as compared with the normal keratinocyte controls at day 5 (analysis of variance, p < 0.001). These results strongly suggest that the overlying epidermal keratinocytes of the keloid may have an important, previously unappreciated role in keloid pathogenesis using paracrine or epithelial-mesenchymal signaling.     

Matrix metalloproteinase‐2 and ‐9 activities in human keloids,hypertrophic and atrophic scars: a pilot study

Proteolytic degradation of extracellular matrix is one of the principal features of cutaneous wound healing but little is known about the activities of gelatinases; matrix metalloproteinase‐2 (MMP‐2) and matrix metalloproteinase‐9 (MMP‐9) on abnormal scar formation. The aim of this study is to determine collagen levels and the gelatinase activities in tissue from hypertrophic scars, atrophic scars, keloids and donor skin in 36 patients and 14 donors. Gelatinase levels (proenzyme + active enzyme) were determined by ELISA and their activities by gelatin zymography. MMP‐9 activity was undetectable in gelatin zymography analysis. Pro‐MMP‐2 levels (median) were highest in normal skin group 53.58 (36.40–75.11) OD µg^?1 protein, while active MMP‐2 levels were highest in keloid group 52.53 (42.47–61.51) OD µg^?1 protein. The active/pro ratio was the highest in keloid group 0.97 followed by hypertrophic scar, normal skin and atrophic scar groups 0.69 > 0.54 > 0.48, respectively. According to results of our study, the two‐phase theory of the duration of hypertrophic scar and keloid formation can be supported by the data of tissue collagen and gelatinase analysis. This study is the first to relate scar formation relationship in regard to gelatinase activation ratio in a keloid, hypertrophic and atrophic scar patient group which is chosen appropriate in age and sex. Copyright © 2009 John Wiley & Sons, Ltd.     

Methylation of secreted frizzled-related protein 1 (SFRP1) promoter downregulates Wnt/β-catenin activity in keloids

Keloid, a benign skin disorder, forms during wound healing in genetically susceptible individuals. To better control keloid and understand the molecular mechanisms, this study screened gene hypermethylations of GEO database microarray data on keloids and identified the hypermethylation of the secreted frizzled related protein-1 (SFRP1) promoter. Subsequently, hypermethylation and mRNA and protein levels were assessed in 57 cases of keloid vs. normal skin tissues. Fibroblasts from tissues were isolated for the assessment of gene regulation in vitro. The methods used were bioinformatic analysis, lentiviral infection carrying SFRP1 cDNA, qRT-PCR, western blot, immunohistochemistry, luciferase reporter assay, methylation-specific PCR and methylated DNA immunoprecipitation-qPCR, ELISA, and/or 5-Aza-2′-deoxycytidine treatment. The data revealed that the SFRP1 promoter was hypermethylated in keloid tissues, compared with that in normal skin tissues. The SFRP1 promoter methylation contributed to the downregulation of SFRP1 mRNA and protein in keloid tissues and keloid fibroblasts. The 5-Aza treatment significantly upregulated SFRP1 mRNA and protein level in keloid fibroblasts. Furthermore, the knockdown of DNMT1 expression, and not the expression of DNMT3a or DMNT3b, was responsible for the hypermethylation of the SFRP1 promoter and upregulation of SFRP1 mRNA and protein in keloid fibroblasts. In addition, the infection of lentivirus carrying SFRP1 cDNA significantly inhibited the signaling activity of Wnt/β-catenin and the mRNA and protein expression of β-catenin and α-SMA in keloid fibroblasts. In summary, the lost SFRP1 expression-induced Wnt/β-catenin signaling due to the hypermethylation of the SFRP1 promoter could associate with keloid development, suggesting that SFRP1 might be a therapeutic target for keloid treatment.     

Mast cells: an unexpected finding in the modulation of cutaneous wound repair by charged beads

Increased numbers of mast cells are affiliated with a broad spectrum of pathologic skin conditions, including ulcers, atopic dermatitis, neurofibromatosis, hemangiomas, keloids, and hypertrophic scars. It has been proposed that mast cells play a primary pathophysiologic role in these disorders and that their presence represents not merely a secondary event. While investigating their recent hypothesis that positively charged cross-linked diethylaminoethyl dextran (CLDD) beads potentiate cutaneous wound healing, the authors serendipitously observed increased numbers of mast cells in the deep dermis of wounds treated with CLDD beads. The authors propose that mast cells may play an important role in the modulation of healing seen with CLDD beads. Incisional wounds were studied in 30 Sprague-Dawley rats partitioned into two groups that were killed 7 or 14 days after wounding. The wounds were treated with positively, negatively, or neutrally charged CLDD beads. Physiologic saline served as a control. At the designated times after incisional wounding, biopsy specimens were tested for wound breaking strength or processed for histologic testing, fixed in 4% paraformaldehyde, and stained with Giemsa and Goldner-Masson trichrome. Mast cells were counted under light microscopy in a blinded fashion and were expressed as the number of cells per millimeter squared. Significant increases in the number of mast cells were observed in the deep dermis of incisional wounds after implantation with positively or negatively charged CLDD beads. In contrast, neutrally charged beads had no effect on mast cell numbers. At 7 days, the incisions treated with positively charged beads averaged 2.1 times more mast cells compared with those treated with physiologic saline or neutrally charged beads, whereas the incisions treated with negatively charged beads displayed 3.2 times more mast cells. By day 14, the incisions treated with positively charged beads averaged 2.5 times more mast cells than those wounds treated with saline or neutrally charged beads; the incisions treated with negatively charged CLDD beads had 3.4 times more mast cells. The 7-day tensiometric data indicated that wounds treated with negatively charged CLDD beads had increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.8 and 1.7 times, respectively; p = 0.01 and p = 0.02). Wounds treated with positively charged beads also showed increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.5 and 1.4 times greater); however, this did not reach statistical significance. There was no apparent difference in breaking strength when neutrally charged beads were compared with those treated with saline. At 14 days, there was no statistically significant difference in wound breaking strength between different treatments. These findings are clinically germane to the assessment of proposed therapeutic applications of CLDD beads for a variety of impaired wound-healing states. Furthermore, if increased mast cell populations are intimately linked to hypertrophic scar and keloid formation, the results of the authors' study suggest that CLDD bead therapy of cutaneous wounds may lead to pathologic wound healing in humans.