Zijing Du

Transplantation of adipose stromal cells promotes neovascularization of random skin flaps.

The delivery of bone marrow-derived mononulear cells (BM-MNCs) has been proved to be effective at promoting neovascularization of ischemic skin flaps. However, the limited source of BM-MNCs restricts their clinical application. Stromal vascular fraction (SVF) contains a group of heterogeneous cells in the adipose tissue, including adipose tissue-derived stem cells, and it has abundant reserve in human body. In this study, we evaluated the therapeutic potential of SVF to promote neovascularization of random skin flaps. Female Wistar rats were randomly devided into three groups with 8 in each group and received allogeneic SVF, BM-MNCs and phosphate-buffered saline (PBS), respectively, before surgery. Two days after cell administration, a 10 × 3 cm random skin flap was elevated. Flap survival, blood flow perfusion and capillary density were examined 7 days after surgery, and the relevant mechanism was also explored. Results showed that SVF group and BM-MNCs group had higher survival percentage (72.2 ± 2.0% and 76.4 ± 3.1%, respectively) as compared with the control group (56.8 ± 4.6%, P < 0.05). Blood flow perfusion and capillary density of flap tissues in SVF and BM-MNCs groups were both improved. The expression levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were increased in flap tissues of SVF and BM-MNCs groups detected by ELISA. These results indicate that SVF could promote vascularization and increase flap survival probably by secreting VEGF and bFGF. The effect of transplantation of SVF on therapeutic angiogenesis of skin flaps is equivalent to that of BM-MNCs.

Reconstruction of the face and neck with different types of pre-expanded anterior chest flaps: a comprehensive strategy for multiple techniques.

BACKGROUND For large defects or deformities of the face and neck, the anterior chest area appears to be an excellent donor site that provides well-matched skin colour and texture. Many flap techniques based on the anterior chest area have been reported; however, there are few reports that focus on a treatment strategy for these different flap techniques. METHODS A retrospective study was performed to propose a treatment algorithm. A total of 69 cases were reviewed from May 2005 to July 2011, in which different types of anterior chest flaps were performed for face and neck reconstruction. The reconstructive procedures, the defect characteristics and the complications were collected and analysed. RESULTS Thirty-three pedicled thoracic branch of the supraclavicular artery flaps (the pedicled TBSA flap), 11 pedicled internal mammary artery perforator flaps (the pedicled IMAP flap), 8 free internal mammary artery perforator flaps (the free IMAP flap), 4 supercharged TBSA flaps, 17 prefabricated flaps and 3 supercharged prefabricated flaps were performed. The applications of six types of pre-expanded anterior chest flaps were described in an algorithmic approach. CONCLUSIONS A treatment strategy for face and neck reconstruction using six anterior chest flap techniques is proposed. It recommended a personalised flap planning according to the characteristics of deformities/defects and the regionally dominant vessels of the anterior chest area.

A study of blood flow dynamics in flap delay using the full-field laser perfusion imager.

It is crucial to monitor spatio-temporal changes in the microcirculation of flaps. A laser speckle imaging technique based on speckle contrast analysis compensates for disadvantages and can assess regional blood flow distribution at high resolution. In this paper, temporal changes in circulation were investigated with full-field laser perfusion imaging (FLPI) in rat dorsal delay random flaps. Twenty Sprague-Dawley rats were randomized into two groups (delay procedures and controls) with a standardized dorsal random pattern flap (caudally based, 3 × 10 cm). Blood flow dynamics in both groups were studied with FLPI at different timepoints, and the size of the surviving and necrotic areas of the flaps, vessel distribution, microvessel density and vessel diameters were appraised. The results showed that blood flow after secondary elevation of the flap did not rapidly decrease in the delay group compared to the control group. Viability of the skin flaps, vessel diameter, and micro-vessel density was significantly improved in the delay group. Delay procedure work by diminishing the resistance to blood flow of the flap with FLPI real-time detection, and laser speckle imaging could be a better method for studying microcirculation and judging flap vascularity.

Enhanced endothelial progenitor cell mobilization and function through direct manipulation of hypoxia inducible factor‐1α

Endothelial progenitor cells (EPCs) play a significant role in physiological and pathological hypoxia resistance and neovascularization processes. The ability to mobilize EPCs from bone marrow usually indicates a prognostic endpoint of several vascular diseases. Thus, it is of great value to study possible approaches for activating functional EPCs. The mobilization/homing of EPCs from bone marrow is signalled by stromal‐derived factor‐1 (SDF‐1), which is regulated by the hypoxia‐inducible factor‐1α (HIF‐1α). This study investigated the effects of directly manipulating HIF‐1α on human EPCs in vitro. EPCs were isolated from human umbilical cord blood. Lentiviral vectors carrying HIF‐1α and shRNA targeting HIF‐1α were constructed for gene modification of the EPCs. Results demonstrated that after overexpression of HIF‐1α by lentiviral transfection, the proliferative capacity of EPCs was elevated while the apoptosis was inhibited and vice versa. On the other hand, the expression of angiogenic‐related cytokines including SDF‐1 was upregulated on both gene and protein levels when EPCs were transfected with HIF‐1α. These results indicate that direct HIF‐1α manipulation over human EPCs is an effective method to promote EPC function and mobilization, thus suggest that drugs or reagents that elevate HIF‐1α expression are capable of treating ischemic diseases. Copyright

Strategies for customized neck reconstruction based on the pre-expanded superficial cervical artery flap.

BACKGROUND It is still highly challenging to restore the esthetic neck contour for postburn deformities. In many patients with burns, the back skin remains intact, which is a useful donor site for extensive contracture release. As the main technique, the refinement of the pre-expanded superficial cervical artery (SCA) flaps may improve its application in diverse neck contractures. METHODS This study reviewed the cases of three types of neck contractures that were reconstructed with pre-expanded SCA flaps: (1) for unilateral neck contractures, the flaps were harvested as pedicled perforator flaps including a small amount of muscle; (2) for lateral and anterior neck contractures, vascular augmentation with circumflex scapular vessels was used to increase the flap size; (3) for contractures of the entire neck, maximal flap release with pedicle dissection toward the origin of the superficial cervical vessels allowed for reaching contralateral defects. RESULTS From March 2010 to September 2012, pre-expanded SCA flaps were recommended in 15 patients with severe neck contracture. Tip necrosis occurred in one patient. The donor sites were closed primarily in all cases. One patient had donor-site wound dehiscence that healed within 2 weeks by conservative management. All patients had restored neck extension to a near-normal position without the sense of restricted neck flexion or rotation. CONCLUSIONS Pre-expanded SCA flaps are practical and flexible for the reconstruction of diverse scar contractures ranging from unilateral to total neck lesions. Considering the reconstructive efficiency and the reduced donor-site morbidity, this flap may be an ideal option for the reconstruction of severe neck scar contractures.

Surgical treatment of facial soft-tissue deformities in postburn patients: a proposed classification based on a retrospective study.

BACKGROUND Postburn soft-tissue defects or scars can cause disfigurement and functional impairment and constitute a major therapeutic challenge. In the past 30 years, developments in reconstructive techniques have improved the treatment outcomes. However, these techniques are selected mainly according to the surgeons preference. There is no classification for postburn facial deformities that might contribute to high-level evidence and optimize management. METHODS The authors reviewed the clinical cases of preexpanded local flaps, perforator flaps, and prefabricated flaps between January of 2005 and September of 2012 in their unit. Deformities were categorized according to their size and location, in accordance with the concept of facial aesthetic units, to show the relationship between different deformities and the indicated surgical techniques. The findings were assessed to develop a classification system. RESULTS The study included 174 patients with facial deformities ranging from partial unit to total face defects. The authors classified postburn facial skin and soft-tissue deformities as follows: type I, single partial unit defect; type II, total unit defect or deformities that partially involved two adjacent units; type III, multiunit defects; and type IV, total/subtotal defects. The authors recommended reconstructive techniques for each deformity and developed a system to score postoperative aesthetic and functional improvements. CONCLUSIONS The authors have proposed a classification and scoring system for postburn facial deformities that will aid in the selection of reconstructive techniques. The proposed systems may facilitate multicenter studies with high-level evidence and improve the outcomes of postburn patients. CLINICAL QUESTION/LEVEL OF EVIDENCE Therapeutic, IV.

HOXA5 inhibits keratinocytes growth and epidermal formation in organotypic cultures in vitro and in vivo.

BACKGROUND Homeobox transcription factors play important roles in epidermal renewal. Among them HOXA5 emerges as a promising member. However, its direct effect on epidermal biology, either to promote or to inhibit growth, is still controversial. OBJECTIVE We proposed to unravel the role of HOXA5 in modulating keratinocytes growth and epidermal formation in organotypic cultures both in vitro and in vivo. METHODS We transfected HaCaT cells with lentivirual vectors which over-expressed either wild-type or mutant HOXA5 cDNAs with deleted homeodomain. Subsequently we propagated the cells in organotypic cultures (OTCs) and then transplanted them into nude mice. Cell proliferation and cell cycle progression were detected. Epidermal morphogenesis and stratification were investigated by immunohistochemistry and immunofluorescence staining of a series of epidermal markers. RESULTS HaCaT cells transfected with HOXA5 cDNAs displayed lower growth rate and delayed G1-S transition. HOXA5-transfected OTC exhibited an aberrantly organized epithelium with significantly increased TUNEL staining as well as decreased PCNA and K5 staining, while expression of differentiation markers as K10, involucrin and filaggrin were somewhat enhanced. However, under in vivo environment in nude mice which had great paracrine regulatory mechanisms, the aberrant phenotype was ameliorated as shown by a more regular tissue organization and normal expression of PCNA and K5. Inversely, cells transfected with the homeodomain-deleted protein exhibited accelerated growth and produced a more proliferative and better-orchestrated epidermis, as shown by well-expressed proliferation and differentiation markers. CONCLUSIONS HOXA5 can suppress keratinocytes growth and epidermal formation. It probably activated antagonist genes against growth factors release, which depends on its homeodomain.

Local Skin Warming Enhances Color Duplex Imaging of Cutaneous Perforators.

AbstractThe perforator flap is one of the most useful techniques in reconstructive surgery. The operative procedure for these flaps will be greatly simplified if accurate localization of the course of the perforator can be preoperatively confirmed. However, small vessels with diameters less than 0.5 mm cannot be readily traced with conventional imaging techniques. Local skin warming temporarily increases cutaneous blood flow and vasodilation. In this study, we established a local skin warming procedure, and performed this before color duplex imaging to improve preoperative perforator mapping and enable precise flap design.

DFO enhances the targeting of CD34-positive cells and improves neovascularization.

Desferoxamine (DFO), an iron chelator, mimicked hypoxia by inhibiting HIF-1α degradation and upregulated angiogenic factors. In this experiment, we elucidated the effect of DFO on CD34-positive cell migration and neovascularization. CD34-positive cells were cultured in media with DFO or an inhibitor and subjected to in vitro tubule formation and the expression of factors. Nude mice were randomly divided into five groups of 12: control, CD34, CD34-DFO, CD34-DFO-AMD (AMD3100, CXCR4 inhibitor), and CD34-DFO-LY (LY294002, the PI3K inhibitor) groups. Limb perfusion and in vivo imaging was evaluated by laser speckle imaging (LSI) and bioluminescence imaging (BLI). Capillary density was examined 14 days after surgery, and the relevant mechanism was also explored. In vitro, DFO significantly increased the tube formation and expression of angiogenic factors in CD34-positive cells, which were blocked by the PI3K inhibitor, LY294002. DFO enhanced blood flow, the function of the ischemic hindlimb, and the levels of VEGF. Further, p-eNOS and p-Akt increased in response to the ischemia. BLI showed that DFO increased the number of CD34-positive cells targeted to the ischemic sites. Immunohistofluorescence revealed that the capillary density in the ischemic hindlimb was significantly higher in the DFO treatment group compared with the other groups. However, all of these effects were diminished by LY294002. DFO treatment enhanced CD34-positive cell targeting and improved neovascularization via the PI3K/Akt signal transduction pathway in an ischemic hindlimb.