ObjectiveTo observe the long-term outcome and biocompatibility of the porcine collagen membrane (DermalGen) after xenotransplantation in vivo.MethodsTwenty Sprague Dawley rats were randomly divided into 2 groups (n=10). DermalGen were implanted subcutaneously into the dorsum of rats in experimental group, and the rats in control group were treated with sham-operation. At 3, 7, and 15 days and 1, 3, 6, and 12 months after operation, the samples of experimental group were harvested and gross observation, histological observation, CD31 immunohistochemical staining, and transmission electron microscope observation were taken to observe the inflammatory reaction, angiogenesis, and collagen arrangement. The skin tissues of the control group at 12 months were observed and compared.ResultsAll incisions healed in experimental group, without obvious swelling and inflammatory reaction. The DermalGen was closely contact with the surrounding tissue without obvious rejection, and it was still legible at 12 months. Histological observation of experimental group showed that the infiltration of fibroblasts and inflammatory cells were seen at 7 days. More capillaries and fibroblast cells were seen and the inflammatory response gradually faded at 15 days and 1 month. There were abundant vessels and cells in the DermalGen at 3 months. The angiogenesis and fibroblasts decreased gradually, and the collagen started to format and margin blended simultaneously at 6 and 12 months. The inflammatory cells in experimental group at 15 days and 1 month were significantly more than that in control group (P<0.05), and no significant difference was found at 12 months between experimental group and control group (P>0.05). Immunohistochemical staining of experimental group showed that the angiogenesis changed obviously with the time, and the density of vessels decreased significantly at 12 months. Compared with control group, the possitive expressions of CD31 in experimental group at 15 days and 12 months after operation were significantly decreased (P<0.05), and were significantly increased at 1 month (P<0.05). Transmision electron microscope observation showed that the arrangement of collagen in grafted DermalGen had no obvious changed when compared with the DermalGen, and vascular endothelial cell, capillarypericytes and fibroblast cells could be seen inside.ConclusionThe DermalGen structure is stable after long-term xenotransplantation and with good tolerogenic property in vivo.
Objective To explore theeffectiveness of free paraumbilical perforator flaps in repairing skin and soft tissue defects in children. Methods Between February 2018 and March 2024, 12 children with skin and soft tissue defects were treated with the free paraumbilical perforator flaps. There were 7 boys and 5 girls with an average age of 6.3 years (range, 2-12 years). The defects were located on the upper limbs in 6 cases, lower limbs in 5 cases, and neck in 1 case. The causes of wounds included 7 cases of electrical burns, 1 case of burn, 2 cases of scar release and excision due to scar contraction after burns, 1 case of scar excision due to scar ulcer at the amputation stump after severe burns, and 1 case of skin necrosis after a traffic accident injury. The size of defects after debridement ranged from 7.0 cm×4.0 cm to 18.0 cm×10.0 cm. According to the defect size, 11 cases were repaired with unilateral paraumbilical perforator flaps centered on the umbilicus, among which 3 cases with larger defects were designed as "L"-shaped flaps along the lateral and lower ends of the perforator; the donor sites were directly closed. One case with extensive defect after scar excision and release was repaired with bilateral expanded paraumbilical perforator flaps; the donor sites were repaired with autologous split-thickness skin grafts. The size of flaps ranged from 9.0 cm×4.0 cm to 20.0 cm×11.0 cm. Postoperatively, analgesia and sedation were provided, and the blood supply of the flaps was closely observed. Results All operations were successfully completed. 6he operation time was 4 to 7 hours, with an average of 5.0 hours. After postoperative analgesia and sedation, the visual analogue scale (VAS) score for pain in all children was ≤ 3, and there was no non-cooperation due to pain. All flaps and skin grafts survived completely, and the wounds healed by the first intention. Ten children underwent 0 to 4 times of flap de-fatting, finger separation, and trimming. All children were followed up 6-48 months (mean, 26 .6months). No obvious swelling of the flaps occurred, and the texture was soft. At last follow-up, among the 6 children with upper limb defects, 4 had upper limb function grade IV and 2 had upper limb function grade V according to the Carroll upper limb function assessment method. The 4 children with lower limb defects had no limitation of joint movement. The neck flexion and rotation in the 1 child with neck defect was significantly improved compared with that before operation. The 1 child with residual ulcer at the amputation stump could wear a prosthesis and move without limitation, and no new ulcers occurred. Linear scars were left at the donor sites, and no abdominal wall hernia was formed. ConclusionThe free umbilical perforator flap has abundant blood supply and can be harvested in large size. It can be used to repair skin and soft tissue defects in children and has the advantages of short operation time, minimal injury, high safety, and minimal impact on the growth and development of children.