Early detection of complete venous occlusion in a rodent and swine pedicle flap model using modulated imaging, a new novel multispectral imaging technique

treated ischemic limbs. Similar findings were noted at 4 weeks postisch-emia.Furthermore,IRI-inducedapoptosiswassignificantlydecreasedinHS-treatedischemiclimbs(58%–90%)versusischemiccontrols. CONCLUSIONS: Our results demonstrate that HS- completely prevents muscle cell injury in both in vitro and in vivo models of IRI. These data validate use of this molecule as a cytoprotectant with significant therapeutic potential in FTT and other conditions asso-ciated with IRI. continuous and sinusoidal waveform treatment induced the highest cellular proliferation rates, angiogenesis, and granulation tissue depth compared with controls. Decreasing square waveform frequency had a trend toward increased cell proliferation, angiogenesis, and granulation tissue depth. CONCLUSIONS: Waveform modulation appears to have a minor effect on granulation tissue formation, angiogenesis, and proliferation in our diabetic mouse model. impaired wound healing in nondiabetic is due to METHODS: Peripheral blood was obtained from nondiabetic obese patients (BMI (cid:6) 30, n (cid:7) 10), and nonobese controls (BMI (cid:3) 30, n (cid:7) 10). EPCs were isolated, and in vitro adhesion, migration, and proliferation assays were performed. In vivo, we created 6-mm stented wounds on nondiabetic, obese mice (TallyHo/JngJ, n (cid:7) 5) and nonobese controls (C57Bl/6, n (cid:7) 5). Wound healing was assessed photometrically on days 0, 7, 10, and 14. Time to closure was defined as the time to complete re-epithelialization of the wound bed. Wound area was calculated as a percentage of the original wound. RESULTS: EPCs from obese humans (EPC-ob) had impaired ad-hesion to collagen-coated slides compared with nonobese human EPCs (EPC-n) (92 (cid:2) 20 cells per LPF vs 137 (cid:2) 65 cells per LPF; p (cid:7) 0.05). EPC-ob had impaired migration compared with EPC-n (117 (cid:2) 21 cells per LPF vs 393 (cid:2) 6 cells per LPF; p (cid:7) 0.02). EPC-ob had impaired proliferation compared with EPC-n (179 (cid:2) 15 RFU vs 305 (cid:2) 63 RFU; p (cid:7) .0001). Obese mice wound healing was delayed by 42%. Wounds of obese mice demonstrated decreased new blood vessel formation (3 (cid:2) 2 per HPF vs 9 (cid:2) 2 per HPF). CONCLUSIONS: Our data implicate EPC dysfunction as a possible mechanism behind impaired wound healing in obesity. Ongoing experiments are exploring therapeutic strategies for wound healing in obesity. prior to venous occlusion. All 4 measured parameters in both the rodent and swine models became statically different between the control and experimental flaps over the time course of the experiment (p (cid:3) 0.05). CONCLUSIONS: Modulated imaging can be used to quantify and detect the expected physiological changes that occur after venous occlusion in tissue transfer flaps. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative patients. Further studies are needed to evaluate the predictive potential of this technique.

INTRODUCTION: Using a murine model, we have demonstrated that the Vacuum Assisted Closure device (VAC, Kinetics Concepts Inc) transduces micromechanical forces to a wound bed via a sponge under continuous suction causing wound proliferation and angiogenesis. Although widely used in a variety of wounds, including complex diabetic wounds, the VAC is largely used to deliver continuous suction without variation or pattern to the applied force. In this study, we evaluated whether modulating the waveform changes granulation tissue formation, cellular proliferation, or angiogenesis.
METHODS: Full-thickness wounds were made in male diabetic mice (C57BL/KsJ-Lepr db) and treated with the VAC device with 6 different modalities: square waveforms of 125 mm Hg suction for 2 minutes alternating with 50 mm Hg suction for 2 minutes, 5 minutes, or 10 minutes; sinusoidal waveform with 3.5 minutes at 125 mm Hg followed by 3.5 minutes of 50 mm Hg suction; continuous suction at 125 mm Hg or non-treated with an occlusive dressing alone. Eight mice per group were wounded and following 7 days of treatment wounds were evaluated by quantifying the depth of granulation tissue, new cell proliferation using the nuclear marker ki67, and angiogenesis using the endothelial cell marker CD31.

RESULTS:
The continuous and sinusoidal waveform treatment induced the highest cellular proliferation rates, angiogenesis, and granulation tissue depth compared with controls. Decreasing square waveform frequency had a trend toward increased cell proliferation, angiogenesis, and granulation tissue depth.
CONCLUSIONS: Waveform modulation appears to have a minor effect on granulation tissue formation, angiogenesis, and proliferation in our diabetic mouse model. of new blood vessel formation in healing wounds, we hypothesize that impaired wound healing in nondiabetic obesity is due to EPC dysfunction.

METHODS:
Peripheral blood was obtained from nondiabetic obese patients (BMI Ͼ 30, n ϭ 10), and nonobese controls (BMI Ͻ 30, n ϭ 10). EPCs were isolated, and in vitro adhesion, migration, and proliferation assays were performed. In vivo, we created 6-mm stented wounds on nondiabetic, obese mice (TallyHo/JngJ, n ϭ 5) and nonobese controls (C57Bl/6, n ϭ 5). Wound healing was assessed photometrically on days 0, 7, 10, and 14. Time to closure was defined as the time to complete re-epithelialization of the wound bed. Wound area was calculated as a percentage of the original wound.

METHODS:
In this study, bilateral pedicle groin flaps based on the inferior epigastric vessels were prepared in Wistar Rats (400-500 g), and Yorkshire Pigs (25-30 kg). The flaps were imaged at baseline for 10 minutes, followed by selective complete venous occlusion in the experimental flap and imaging for 55 minutes. The contralateral flap served as a control. The results were analyzed using a Wilcoxon signed rank t test, as well as a 2-way ANOVA with Bonferroni posttest to analyze the differences between the control and experimental flaps over the entire time course.
prior to venous occlusion. All 4 measured parameters in both the rodent and swine models became statically different between the control and experimental flaps over the time course of the experiment (p Ͻ 0.05).
CONCLUSIONS: Modulated imaging can be used to quantify and detect the expected physiological changes that occur after venous occlusion in tissue transfer flaps. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative patients. Further studies are needed to evaluate the predictive potential of this technique. INTRODUCTION: Acellular dermal matrices are an ideal scaffold for dermal substitution due to an intact native extracellular matrix. Current approaches utilizing engineered biomaterials fail to completely recapitulate dermal architecture. Pullulan, a biocompatible and biodegradable polysaccharide, provides a modifiable environment for cellular incorporation. Here we investigated a pullulan-collagen hydrogel scaffold, micropatterned with fibronectin, as a functional dermal substitute.

METHODS:
Pullulan hydrogel and collagen were fabricated by crosslinking with trisodium trimetaphosphate, and scaffold porosity was induced by in-gel crystallization of potassium chloride followed by dissolution. Pore size and ultrastructure were assessed with scanning electron microscopy. Bioscaffolds microprinted with fibronectin were seeded with mesenchymal stem cells in vitro, and cellular invasion was evaluated by microscopy. Scaffolds were then placed intradermally using a novel full-thickness incisional murine model and assessed for cellular incorporation, degradation rate, and replication of native dermal architecture.
RESULTS: Pullulan-collagen hydrogel scaffolds displayed excellent mechanical properties and consistent porosity and pore size. Potassium chloride crystallization promoted reticular domain formation within the hydrogel. In vitro, mesenchymal stem cells were sustained within the constructs, particularly in the presence of fibronectin. In vivo, bioscaffolds implanted into full-thickness incisions replicated the dermal architecture of unwounded skin and contained viable cellular elements on microscopic examination.

CONCLUSIONS:
Pullulan-collagen hydrogels successfully replicate dermal architecture in vivo and support the incorporation of stem cells and wound repair elements. This highly modifiable bioscaffold is a promising dermal substitute for tissue engineering and reconstruction of human skin.