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Localized cutaneous infantile hemangioma acts like a tissue expander. This rapidly growing tumor can destroy elastic fibers or cause ulceration resulting in telangiectases, cutaneous laxity, scarring, and fibrofatty residuum. Although surgeons may dispute indications and timing, most would agree that the scar of resection should be minimized. For this reason, circular excision and purse-string closure is particularly applicable for hemangioma at any stage of its evolution. The purposes of this study were to: (1) analyze the results of circular excision/purse-string closure in all three phases of the life cycle of hemangioma; (2) quantify dimensional changes after resection; and (3) compare the scars after theoretical single-stage lenticular excision with those after staged circular excision/purse-string closure. The authors retrospectively analyzed their experience in 25 children with localized hemangioma who underwent circular excision/purse-string closure from 1997 to 2000. Each hemangioma was measured preoperatively and the scars were measured at most recent follow-up (minimum, 6 months). Preoperative and postoperative dimensions were analyzed using SPSS statistical software. The study included 22 girls and three boys, with an average time to follow-up evaluation of 13.1 months. Twenty-one lesions were in the face and scalp, and five were in the extremity. Five tumors were resected in the proliferative phase (either because of ulceration, bleeding, or visual complications) and 21 were excised in the involuting or involuted phase. Six patients had a second-stage procedure: three had another circular excision and three had later lenticular excision. After single circular excision/purse-string closure, the mean long-axial diameter (length) decreased by 45 percent, the mean short-axial width (width) decreased by 73 percent, and the mean scar area was only 15 percent of the original area. All these differences were statistically significant (p = 0.001). The average width/length ratio decreased by 50 percent, indicating a tendency for scars to linearize. There was no difference in linearization for the three phases of hemangioma (p > 0.05); extremity scars became more linear that those on the face (p = 0.01). The authors devised a formula for scar length after lenticular excision/linear closure, assuming a conventional excisional ratio of 3:1 for a circular lesion. Using this equation, the authors predicted that mean scar length after circular excision, followed by lenticular excision, would be 72 percent shorter than the calculated scar that would result from conventional lenticular excision. In three patients who underwent this two-stage approach, the resultant scar was 69 percent shorter. Circular excision of hemangioma and purse-string closure reduces both the longitudinal and transverse dimensions and converts a large circular lesion into a small ellipsoid scar. If subsequent revision to a linear scar is desirable, its length will be the same or slightly less than the diameter of the original lesion. No other e...

Skeletal muscle is responsible for the control of voluntary movement and the maintenance of structural contours of the body. Muscle loss or deficiency is encountered in various pathological states, and attempts to correct them have been employed with limited success. The aim of the present study was to tissue engineer three-dimensional vascularized skeletal muscle using isolated myoblasts attached to synthetic biodegradable polymer for tissue replacement in the enhancement of muscle regeneration. Myoblasts derived from neonatal rats (3-5-day-old), Fisher CDF-F344, were seeded onto polyglycolic acid meshes and implanted into the omentum of syngeneic adult Fisher CDF-F344 rats. Rats were sacrificed on day 30 and day 45 after the transplantation, and the cell-polymer constructs were harvested for morphological analysis. Histological analysis of the constructs were performed by hematoxylin and eosin, and immunohistochemical staining was positive for alpha sarcomeric actin and desmin skeletal muscle marker. Viable myoblasts organized between strands of degrading polymer mesh formed the new tissue, and vascularization of the entire construct was observed. Organization of neomuscle strands surrounded by vascularized tissue composed of degrading polymer and fusing myoblasts demonstrated the ability of myoblast constructs to survive, reorganize and regenerate tissue-like structures. Since myoblast transplantation to date has been limited to the cellular level of replacement, myoblast-polyglycolic acid constructs may be useful in defining the application of tissue engineering for future skeletal muscle transplantations.

Tissue engineering, a field that combines polymer scaffolds with isolated cell populations to create new tissue, may be applied to soft-tissue augmentation-an area in which polymers and cell populations have been injected independently. We have developed an inbred rat model in which the subcutaneous injection of a hydrogel, a form of polymer, under vacuum permits direct comparison of different materials in terms of both histologic behavior and their ability to maintain the specific shape and volume of a construct. Using this model, we compared three forms of calcium alginate, a synthetic hydrogel, over an 8-week period-standard alginate that was gelled following injection into animals (alginate post-gel), standard alginate that was gelled before injection into animals (alginate pre-gel) and alginate-RGD, to which the cell adhesion tripeptide RGD was linked covalently (RGD post-gel). Parallel groups that included cultured syngeneic fibroblasts suspended within each of these three gels were also evaluated (alginate post-gel plus cells, alginate pre-gel plus cells, and RGD post-gel plus cells). The study used 54 inbred Lewis rats (n = 9 for each of the six groups). Construct geometry was optimally maintained in the alginate post-gel group in which 58 percent of the original volume was preserved at 8 weeks and increased to 88 percent at 8 weeks when syngeneic fibroblasts were included within the gel. Volume was not as well preserved in the RGD post-gel group (25 percent of original volume at 8 weeks), but again increased when syngeneic fibroblasts were included (41 percent of original volume at 8 weeks). Maintenance of volume was poorest in the alginate pre-gel group (31 percent of original volume at 8 weeks) and failed to be augmented by the addition of fibroblasts (19 percent of original volume at 8 weeks). Histologically, the gel remained a uniform sheet surrounded by a fibrous capsule in the alginate post-gel groups. In the alginate pre-gel and RGD post-gel groups, there was significant ingrowth of a fibrovascular stroma into the gel with fragmentation of the construct. In constructs in which syngeneic fibroblasts were included, cells were visualized throughout the gel but did not extend processes or appear to contribute to new tissue formation. Material compression testing indicated that the alginate and RGD post-gel constructs became stiffer over a 12-week period, particularly in the cell-containing groups. Our results suggest that calcium alginate could be a suitable agent for soft-tissue augmentation when gelled subcutaneously following injection. The addition of syngeneic fibroblasts enhanced the ability of the gel to maintain the volume of a construct; this seems to be mediated by increased gel stiffness rather than by de novo tissue formation. Our animal model, in combination with material testing data, permits rigorous comparison of different materials used for soft-tissue augmentation.

Objective. Matrix metalloproteinases (MMPs) and the angiogenic proteins basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have been implicated in mechanisms of human cancer and metastasis. Assays were conducted on the urine of patients with vascular anomalies (tumors and malformations), relatively common and occasionally life-threatening disorders for which few therapies exist. We sought to determine whether these angiogenesis modulators are present in the urine and whether their expression is associated with the extent and clinical course of the vascular lesion.Methods. A total of 217 patients with vascular anomalies and 74 age-matched control subjects participated. Urinary MMP expression was determined by substrate gel electrophoresis. Urinary bFGF and VEGF levels were measured by enzyme-linked immunosorbent assay. Each patient was assigned to 1 of 2 categories (tumor or malformation) and 1 of 9 specific groups. Extent of the vascular lesion and activity were scored by a blinded clinician.Results. Urinary high molecular weight (hMW) MMPs and bFGF were significantly increased in patients with vascular tumors (53%) and vascular malformations (41%), compared with control subjects (22%). These percentages increased as a function of extent of the lesion and disease activity. hMW MMPs were increased in 4 groups: infantile hemangioma, other vascular neoplasms, lymphatic malformation and capillary-lymphaticovenous malformations, and extensive and unremitting capillary malformation and arteriovenous malformation. No significant differences among the groups were detected for low molecular weight MMPs or VEGF.Conclusions. Expression patterns of hMW MMPs and bFGF in the urine of patients with tumors and malformations are consistent with their different clinical behavior. These data represent the first evidence that MMPs are elevated in the urine of children with vascular anomalies. These data also suggest that the increased expression of urinary MMPs parallels the extent and activity of vascular anomalies in children. In addition to tumors, vascular malformations are angiogenesis dependent, suggesting that progression of a vascular malformation might be suppressed by angiogenic inhibitors, which would target bFGF and MMPs. Pediatrics 2005;116:38-45; vascular anomalies, matrix metalloproteinases, urinalysis.

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In children, interruption of cardiac atrioventricular (AV) electrical conduction can result from congenital defects, surgical interventions, and maternal autoimmune diseases during pregnancy. Complete AV conduction block is typically treated by implanting an electronic pacemaker device, although long-term pacing therapy in pediatric patients has significant complications. As a first step toward developing a substitute treatment, we implanted engineered tissue constructs in rat hearts to create an alternative AV conduction pathway. We found that skeletal muscle-