Parag Butala

Fat grafting accelerates revascularisation and decreases fibrosis following thermal injury

BACKGROUND Fat grafting has been shown clinically to improve the quality of burn scars. To date, no study has explored the mechanism of this effect. We aimed to do so by combining our murine model of fat grafting with a previously described murine model of thermal injury. METHODS Wild-type FVB mice (n=20) were anaesthetised, shaved and depilitated. Brass rods were heated to 100°C in a hot water bath before being applied to the dorsum of the mice for 10s, yielding a full-thickness injury. Following a 2-week recovery period, the mice underwent Doppler scanning before being fat/sham grafted with 1.5cc of human fat/saline. Half were sacrificed 4 weeks following grafting, and half were sacrificed 8 weeks following grafting. Both groups underwent repeat Doppler scanning immediately prior to sacrifice. Burn scar samples were taken following sacrifice at both time points for protein quantification, CD31 staining and Picrosirius red staining. RESULTS Doppler scanning demonstrated significantly greater flux in fat-grafted animals than saline-grafted animals at 4 weeks (fat=305±15.77mV, saline=242±15.83mV; p=0.026). Enzyme-linked immunosorbent assay (ELISA) analysis in fat-grafted animals demonstrated significant increase in vasculogenic proteins at 4 weeks (vascular endothelial growth factor (VEGF): fat=74.3±4.39ngml(-1), saline=34.3±5.23ngml(-1); p=0.004) (stromal cell-derived factor-1 (SDF-1): fat=51.8±1.23ngml(-1), saline grafted=10.2±3.22ngml(-1); p<0.001) and significant decreases in fibrotic markers at 8 weeks (transforming growth factor-ß1(TGF-ß): saline=9.30±0.93, fat=4.63±0.38ngml(-1); p=0.002) (matrix metallopeptidase 9 (MMP9): saline=13.05±1.21ngml(-1), fat=6.83±1.39ngml(-1); p=0.010). CD31 staining demonstrated significantly up-regulated vascularity at 4 weeks in fat-grafted animals (fat=30.8±3.39 vessels per high power field (hpf), saline=20.0±0.91 vessels per high power field (hpf); p=0.029). Sirius red staining demonstrated significantly reduced scar index in fat-grafted animals at 8 weeks (fat=0.69±0.10, saline=2.03±0.53; p=0.046). CONCLUSIONS Fat grafting resulted in more rapid revascularisation at the burn site as measured by laser Doppler flow, CD31 staining and chemical markers of angiogenesis. In turn, this resulted in decreased fibrosis as measured by Sirius red staining and chemical markers.

Endogenous stem cell therapy enhances fat graft survival.

Background: Lipoaspirate centrifugation creates graded density of adipose tissue. High-density fat contains more vasculogenic cytokines and progenitor cells and has greater graft survival than low-density fat. The authors hypothesize that accelerating the bone marrow–derived progenitor cell response to injected low-density fat will improve its graft survival. Methods: Male 8-week-old FVB mice (n = 60) were grafted with either high-density (n = 20) or low-density (n = 40) human lipoaspirate. Half of the mice receiving low-density fat (n = 20) were treated with a stem cell mobilizer for 14 days. Grafted fat was harvested at 2 and 10 weeks for analysis. Results: Low-density fat, low-density fat plus daily AMD3100, and high-density fat had 26 ± 3.0, 61.2 ± 7.5, and 49.6 ± 3.5 percent graft survival, respectively, at 2 weeks (low-density fat versus low-density fat plus daily AMD3100 and low-density fat versus high-density fat, both p < 0.01). Similar results were observed 10 weeks after grafting. Mice receiving low-density fat plus daily AMD3100 had significantly more vasculogenic progenitor cells per cubic centimeter of peripheral blood (p < 0.01) and more new blood vessels (p < 0.01). Both low-density fat plus daily AMD3100 and high-density fat contained more stromal-derived factor-1&agr; and vascular endothelial growth factor mRNA/protein. Conclusion: Endogenous progenitor cell mobilization enhances low-density fat neovascularization, increases vasculogenic cytokine expression, and improves graft survival to a level equal to that of high-density fat grafts.

The imaging of maxillofacial trauma and its pertinence to surgical intervention.

Maxillofacial skeletal injuries account for a large proportion of emergency department visits and often result in surgical consultation. Although many of the principles of detection and repair are basic, the evolution of technology and therapeutic strategies has led to improved patient outcomes. This article aims to provide a review of the imaging aspects involved in maxillofacial trauma and to delineate its relevance to management.

Interval Cranioplasty: Comparison of Current Standards

Background: Although different cranioplasty storage methods are currently in use, no study has prospectively compared these methods. The authors compare freezing and subcutaneous storage methods in a rat model. Methods: Trephine defects (10 mm) were created in 45 Sprague-Dawley rats. The cranial bone grafts were stored in an autologous subcutaneous pocket (n = 15), frozen at –80°C (n = 15), immediately analyzed (n = 12), or immediately replanted into the defect (n = 3). After 10 days of storage, the subcutaneous or frozen grafts were either replanted (subcutaneous, n = 3; frozen, n = 3) or analyzed (subcutaneous, n = 12; frozen, n = 12). Grafts underwent histologic analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, alkaline phosphatase assay, mechanical testing, and micro–computed tomographic imaging. Results: After 10 days of storage, physiologic assays demonstrated a significant decrease in cellular functionality (e.g., alkaline phosphatase assay concentration: fresh, 18.8 ± 0.77 mM/mg; subcutaneous, 12.2 ± 0.63 mM/mg; frozen, 8.07 ± 1.1 mM/mg; p < 0.012 for all comparisons). Mechanical integrity (maximal load) of fresh grafts was greatest (fresh, 9.26 ± 0.29 N; subcutaneous, 6.27 ± 0.64 N; frozen, 4.65 ± 0.29 N; fresh compared with frozen, p < 0.001; fresh compared with subcutaneous, p = 0.006). Replantation of subcutaneously stored and frozen grafts resulted in limited bony union and considerable resorption after 12 weeks; in contrast, replanted fresh grafts demonstrated bony union and little resorption. Conclusions: Current preservation methods for interval cranioplasty do not maintain bone graft viability. Subcutaneous storage appears to provide a small advantage compared with freezing.

Evolving Trends in Autologous Breast Reconstruction: Is the Deep Inferior Epigastric Artery Perforator Flap Taking Over?

Background Enthusiasm for the deep inferior epigastric artery perforator (DIEP) flap for autologous breast reconstruction has grown in recent years. However, this flap is not performed at all centers or by all plastic surgeons for breast reconstruction, and it is unclear whether practice patterns have measurably changed. This study aimed to (1) evaluate changing trends in breast flap use in the United States in recent years and (2) identify how these trends have affected charges and costs associated with autologous breast reconstruction. Methods Patients undergoing autologous breast reconstruction [latissimus dorsi (LD), pedicled transverse rectus abdominus myocutaneous (pTRAM), free TRAM (fTRAM), and DIEP] were identified using the Healthcare Cost and Utilization Project Nationwide Inpatient Sample database (2009-2011). A total of 19,182 hospital discharges were reviewed. Patient demographics, hospital teaching center status, payer status, length of stay, total charges, and total costs per discharge were reviewed. Statistical analysis was performed using linear regression, t test, and analysis of variance models. Results Between 2009 and 2011, the total number of discharges did not change significantly. Patient age distribution was similar for all flap groups. For individual flaps, there was a significant increase in DIEP flaps (P = 0.03), with a decreasing trend for other abdominal-based flaps. The patients receiving DIEP flap breast reconstruction were covered by private insurance at a higher rate than all other flap procedures (P = 0.03), whereas other potential cost determinants did not differ significantly between the groups. The mean charge per flap was

Augmenting neovascularization accelerates distraction osteogenesis.

40,704 for LD,

Factors associated with transfer of hand injuries to a level 1 trauma center: a descriptive analysis of 1147 cases

51,933 for pTRAM,

Abstract 30: the economic implications of changing trends in breast flap reconstruction in the United States.

69,909 for fTRAM, and

Lacunocanalicular Fluid Flow Transduces Mechanical Tension Stress During Distraction Osteogenesis

82,320 for DIEP. The mean cost per flap was

1: LACUNOCANALICULAR FLOW AND DISTRACTION OSTEOGENESIS: THEORY AND THERAPEUTICS

12,017 for LD,