Qingfeng Li

The effect of centrifugation on viability of fat grafts: an evaluation with the glucose transport test.

BACKGROUND An up-to-date, simple, but useful technique to evaluate the viability of fat grafts prior to transplant is lacking. The purpose of this study is to introduce the glucose transport test - a new method to evaluate the viability of fat grafts after they are subjected to different centrifugal forces in vitro. METHOD Fat grafts were harvested from healthy patients who underwent liposuction for body contouring. The glucose transport test was performed to evaluate the viability of fat grafts after centrifugation with different forces (1000-4000 rpm). An MTT assay was also performed with the same experimental protocol for comparison. Routine histological examination was done in all groups to examine possible structural destruction after centrifugation. RESULTS When compared with the group not subjected to centrifugation, the glucose transport test showed a significant decrease in viability of fat grafts in all of the other four groups (all p<0.001). There was a linear reduction of viability in fat grafts with the increase in centrifugal force (all p<0.03). MTT assay showed similar findings on the viability of fat grafts in all five groups and correlated well with the glucose transport test (r=0.9870). Histology showed significantly distorted and fractured adipocytes when the centrifugal force reached 4000 rpm. CONCLUSION Our study demonstrates the harmful effect on the viability of fat grafts with an increase in centrifugal force and, for the first time, that the glucose transport test may be an effective and potentially useful method to evaluate the viability of fat grafts in a clinical setting.

Bone regeneration of critical calvarial defect in goat model by PLGA/TCP/rhBMP-2 scaffolds prepared by low-temperature rapid-prototyping technology

Active artificial bone composed of poly lactide-co-glycolide (PLGA)/ tricalcium phosphate (TCP) was prefabricated using low-temperature rapid-prototyping technology so that the process of osteogenesis could be observed in it. PLGA and TCP were the primary materials, they were molded at low temperature, then recombinant human bone morphogenetic protein-2 (rhBMP-2) was added to form an active artificial bone. Goats with standard cranial defects were randomly divided into experimental (implants with rhBMP-2 added) and control (implants without rhBMP-2) groups, and osteogenesis was observed and evaluated by imaging and biomechanical and histological examinations. The PLGA-TCP artificial bone scaffold (90% porosity) had large and small pores of approximately 360microm and 3-5microm diameter. Preliminary and complete repair of the cranial defect in the goats occurred 12 and 24 weeks after surgery, respectively. The three-point bending strength of the repaired defects attained that of the normal cranium. In conclusion, low-temperature rapid-prototyping technology can preserve the biological activity of this scaffold material. The scaffold has a good three-dimensional structure and it becomes an active artificial bone after loading with rhBMP-2 with a modest degradation rate and excellent osteogenesis in the goat.

Correction of hemifacial atrophy with autologous fat transplantation.

Background:Autologous fat transplantation has frequently been used by many surgeons for facial recontouring in esthetic patients, with good long-term results. However, this technique has not been used primarily in treating patients with hemifacial atrophy, and its efficacy and long-term outcome remain unknown. Methods:In a 7-year period, 31 patients with hemifacial atrophy were treated with autologous fat transplantation in our institution. All patients had been in their stable phase of the disease for at least 1 year. Autologous fat grafts were harvested from the lower abdomen or thigh with our preferred low-pressure syringe technique and then spun at the lower speed. The fat grafts were injected into multiple areas in multiple tissue planes and tunnels to the diseased side of the face. The same procedure was repeated once or twice as necessary after each injection in at least 3 months. All patients were followed up to 5 years, and their outcomes were evaluated by the patients, plastic surgeons, and laypersons separately. Results:Obviously improved facial contour was evident in most patients after autologous fat transplantations. More than 65% of the patients in this series were assessed as satisfactory by all 3 groups. Between 10% and 30% of the patients were mostly satisfactory. Only less than 7% of the patients were unsatisfactory. No complications were seen in either donor sites or recipient sites in this series. Conclusions:Autologous fat transplantation can be a good treatment of choice for patients with hemifacial atrophy.

LPS-Stimulated Inflammatory Environment Inhibits BMP-2-Induced Osteoblastic Differentiation Through Crosstalk Between TLR4/MyD88/NF-κB and BMP/Smad Signaling

Bone morphogenetic protein-2 (BMP-2) is a novel differentiation factor that is capable of inducing osteoblast differentiation and bone formation, making it an attractive option in treatment of bone defects, fractures, and spine fusions. Inflammation, which was a common situation during bone healing, is recognized to inhibit osteogenic differentiation and bone formation. However, the effect of inflammation on BMP-2-induced osteoblastic differentiation remains ambiguous. In this study, we showed that an inflammatory environment triggered by lipopolysaccharide (LPS) in vitro would suppress BMP-2-induced osteogenic differentiation of bone marrow mesenchymal stem cells, which represented by decreased alkaline phosphatase (ALPase) activity and down-regulated osteogenic genes. In addition, LPS activated nuclear factor-κB (NF-κB) via a TLR4/MyD88-dependent manner and inhibited BMP-2-induced phosphorylation and nuclear translocation of Smad1/5/8. The blocking of NF-κB signaling by pretreatment with specific inhibitors such as BAY-11-7082, TPCK and PDTC, or by transfection with plasmids encoding p65 siRNA or IκBα siRNA could significantly reverse the inhibitory effect of LPS on BMP-2-induced BMP/Smad signaling and osteogenic differentiation. By contrast, even without stimulation of LPS, overexpression of p65 gene showed obvious inhibitory effects on BMP-2-induced BMP/Smad signaling and ALPase activity. These data indicate that the LPS-mediated inflammatory environment inhibits BMP-2-induced osteogenic differentiation, and that the crosstalk between TLR4/MyD88/NF-κB and BMP/Smad signaling negatively modulates the osteoinductive capacity of BMP-2.

Improvement of the skin flap survival with the bone marrow-derived mononuclear cells transplantation in a rat model.

Partial necrosis of skin flaps remains a significant problem in plastic and reconstructive surgery. In this study we attempted to evaluate the effect of bone marrow‐derived mononuclear cells (BM‐MNCs) transplantation on improvement of skin flap survival in a rat random pattern skin flap model. Thirty Wistar rats were divided into three groups with each consisting of 10 rats. BM‐MNCs and the adipose‐derived stem cells (ADSCs) were transplanted into the subcutaneous tissue in the area where the flap would be dissected. The flaps were then raised two days after cells transplantation. The animals receiving the preoperative Dulbeccos Modified Eagle Medium (DMEM) treatment were used as the controls. On the 7th postoperative day, the survival areas of flaps were measured and tissues were collected for examinations. The results showed that the mean survival areas were 46.33 ± 13.46% in the ADSCs group and 50.06 ± 13.82% in the BM‐MNCs group as the percentages of the total skin flaps, which were significantly higher than that in the control group (26.33 ± 7.14%) (P < 0.05). Histological analysis showed increased neovascularization in the flap treated with BM‐MNCs when compared with ADSCs transplantation. Survival BM‐MNCs and ADSCs were detected in the flap tissues. Higher levels of the basic fibroblast growth factor (bFGF) and vascular endothelium growth factor (VEGF) were found in the BM‐MNCs transplantation group (P < 0.05). The findings from this study demonstrated that preoperative treatment with BM‐MNCs transplantation could promote neovascularization and improve flap survival. These effects of BM‐MNCs on flap survival were comparable with ADSCs transplantation, but without necessity of in vitro cells expansion.

Complement C5a exacerbates acute lung injury induced through autophagy-mediated alveolar macrophage apoptosis

Intestinal ischemia has a high mortality and often causes acute lung injury (ALI), which is a serious complication, and is accompanied by high mortality up to 40%. An intense local and systemic inflammation occurs during intestinal ischemia/reperfusion (IR)-induced lung injury resulting from activation of immune responses. It has been reported that one component of complement, C5a, is indispensable for the full development of IR-induced lung injury, whereas the detailed molecular mechanism remains to be elucidated. In this study, we found that intestinal IR induced ALI-like symptoms, and C5a receptor (C5aR) expression was upregulated in alveolar macrophages, which are resident macrophages in lung tissue and are important in pulmonary homeostasis. C5a produced during lung injury binds to C5aR in alveolar macrophages, initiates downstream signaling that promotes autophagy, leading to apoptosis of alveolar macrophages. Using Mφ-ATG5−/− mice, in which the atg5 is deficient specifically in macrophages and autophagy is inhibited, we confirmed that in vivo C5a interacting with C5aR induced autophagy in alveolar macrophages, which promoted alveolar macrophage apoptosis. Further study indicated that autophagy was induced through C5aR-mediated degradation of bcl-2. Taken together, our results demonstrated that C5aR-mediated autophagy induced apoptosis in alveolar macrophages, disrupting pulmonary homeostasis and contributing to the development of ALI. This novel mechanism suggests new therapeutic potential of autophagy regulation in ALI.

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.

Face resurfacing using a cervicothoracic skin flap prefabricated by lateral thigh fascial flap and tissue expander.

Background: Resurfacing of facial massive soft tissue defect is a formidable challenge because of the unique character of the region and the limitation of well‐matched donor site. In this report, we introduce a technique for using the prefabricated cervicothoracic skin flap for facial resurfacing, in an attempt to meet the principle of flap selection in face reconstructive surgery for matching the color and texture, large dimension, and thinner thickness (MLT) of the recipient. Materials: Eleven patients with massive facial scars underwent resurfacing procedures with prefabricated cervicothoracic flaps. The vasculature of the lateral thigh fascial flap, including the descending branch of the lateral femoral circumflex vessels and the surrounding muscle fascia, was used as the vascular carrier, and the pedicles of the fascial flap were anastomosed to either the superior thyroid or facial vessels in flap prefabrication. A tissue expander was placed beneath the fascial flap to enlarge the size and reduce the thickness of the flap. Results: The average size of the harvested fascia flap was 6.5 × 11.7 cm. After a mean interval of 21.5 weeks, the expanders were filled to a mean volume of 1,685 ml. The sizes of the prefabricated skin flaps ranged from 12 × 15 cm to 15 × 32 cm. The prefabricated skin flaps were then transferred to the recipient site as pedicled flaps for facial resurfacing. All facial soft tissue defects were successfully covered by the flaps. The donor sites were primarily closed and healed without complications. Although varied degrees of venous congestion were developed after flap transfers, the marginal necrosis only occurred in two cases. The results in follow‐up showed most resurfaced faces restored natural contour and regained emotional expression. Conclusion: MLT is the principle for flap selection in resurfacing of the massive facial soft tissue defect. Our experience in this series of patients demonstrated that the prefabricated cervicothoracic skin flap could be a reliable alternative tool for resurfacing of massive facial soft tissue defects.

Laser therapy for prevention and treatment of pathologic excessive scars.

Background: The management of hypertrophic scars and keloids remains a therapeutic challenge. Treatment regimens are currently based on clinical experience rather than substantiated evidence. Laser therapy is an emerging minimally invasive treatment that has recently gained attention. Methods: A meta-analysis was conducted to evaluate the effectiveness of various laser therapies. The pooled response rate, pooled standardized mean difference of Vancouver Scar Scale scores, scar height, erythema, and pliability were reported. Results: Twenty-eight well-designed clinical trials with 919 patients were included in the meta-analysis. The overall response rate for laser therapy was 71 percent for scar prevention, 68 percent for hypertrophic scar treatment, and 72 percent for keloid treatment. The 585/595-nm pulsed-dye laser and 532-nm laser subgroups yielded the best responses among all laser systems. The pooled estimates of hypertrophic scar studies also showed that laser therapy reduced total Vancouver Scar Scale scores, scar height, and scar erythema of hypertrophic scars. Regression analyses of pulsed-dye laser therapy suggested that the optimal treatment interval is 5 to 6 weeks. In addition, the therapeutic effect of pulsed-dye laser therapy is better on patients with lower Fitzpatrick skin type scores. Conclusions: This study presents the first meta-analysis to confirm the efficacy and safety of laser therapy in hypertrophic scar management. The level of evidence for laser therapy as a keloid treatment is low. Further research is required to determine the mechanism of action for different laser systems and to examine the efficacy in quantifiable parameters, such as scar erythema, scar texture, degrees of symptom relief, recurrence rates, and adverse effects.

Stem Cell Therapy for Lower Extremity Diabetic Ulcers: Where Do We Stand?

The impairment of wound healing in diabetic patients is an important clinical problem affecting millions of patients worldwide. Various clinical and basic science studies show that stem cell therapy, as a regenerative medical therapy, can be a good solution. In this paper, we begin with an introduction of the cellular mechanism of the diabetic ulcer. We will then discuss the advantages and limitations of various stem cell therapies that have been under extensive recent study.