Topical Anti-TNF-α Antibody Enhances Wound Healing in Diabetic Mice

Chronic wounds such as venous leg ulcers and diabetic foot ulcers represent a significant health problem for which current treatment options are limited and not highly effective. These wounds have major impacts on the quality of life for affected individuals, frequently lead to amputation, and cost many thousands of dollars per year to treat. Assessment of wound fluid from such wounds indicates greatly elevated and persistently high levels of inflammatory cytokines, in particular Tumor Necrosis Factor-alpha (TNF-α). As such, these wounds are not in a physiologic state conducive to healing. Our study in diabetic mice (db/db) suggests that topical application of antibodies capable of neutralizing TNF-α can enhance cutaneous wound healing.Full-thickness wounds 8 mm in diameter were created on the backs of db/db diabetic mice and wild type mice. After 24 hours, the wounds were treated topically with vehicle alone, vehicle + control antibody or vehicle + anti-TNF-α antibody. Wound healing was followed for up to 21 days with reapplication of the appropriate treatments every 2-3 days. Compared to wild type mice, untreated db/db mice exhibited an approximate 4 day delay in wound healing. When wounds on diabetic mice were treated topically with a TNF-α neutralizing antibody, this delay was shortened by about 1 day or 25%. The improvement in healing was confirmed by histologic analysis of the wound areas after euthanasia of the mice.This data suggests that topical treatment of diabetic wounds with antibodies that neutralize TNF-α may be a viable approach to promote healing of these difficult to heal wounds

Biodegradable Wound Dressing for Skin Regeneration

Using the delayed healing model of diabetic (db/db) mice, we evaluated the ability of a novel silk based dressing to facilitate healing of full-thickness excisional wounds. Silk protein from Bombyx mori was used to create wound dressings via a proprietary electrospinning technique. The resulting dressing is vapor and air transmissible. Eight millimeter diameter full-thickness wounds were created on the backs of diabetic mice and covered with either a standard (n=12) telfa-gauze or the silk (n=12) dressing. At 2 day intervals, the telfa dressings were removed, the wounds photographed, measured and fresh dressings placed. For mice receiving the silk dressing, it was allowed to remain in place unless it became dislodged. In that case, a fresh dressing was placed into the wound bed. Wound healing was followed for 21 days at which time the mice were sacrificed, the wound areas excised and subjected to H & E and Trichrome staining. Wounds covered with the silk dressings developed an eschar encompassing the silk whereas wounds dressed with gauze remained moist and without eschar throughout the study period. Upon histologic examination, 1 of the gauze dressed wounds developed a complete epithelial layer across the wound. The remaining 11 wounds had large areas remaining without an epithelial cover. In contrast, 5 of 12 mice receiving the silk dressing developed complete epithelial layers, 2 additional mice had very small areas remaining without a complete epithelium. The remaining 5 had modest areas without an epithelial covering. The ability of silk dressings to permit the formation of an eschar versus gauze in which the wounds remained wet may contribute significantly to the healing response observed. These results suggest that the breathable, vapor transmissible nature of the silk dressing may be an effective dressing for difficult to heal wounds such as diabetic foot ulcers

The skinny on CCN2

The CCN family of matricellular proteins directly or indirectly affects development and differentiation. A recent report written by Tan and colleagues (Am J Physiol Cell Physiol 295: C740–C751 2008) shows that CCN2 inhibits adipocyte differentiation. This commentary summarizes these observations

Hyperspectral Imaging for Burn Depth Assessment in an Animal Model

Differentiating between superficial and deep-dermal (DD) burns remains challenging. Superficial-dermal burns heal with conservative treatment; DD burns often require excision and skin grafting. Decision of surgical treatment is often delayed until burn depth is definitively identified. This study\u27s aim is to assess the ability of hyperspectral imaging (HSI) to differentiate burn depth. METHODS: Thermal injury of graded severity was generated on the dorsum of hairless mice with a heated brass rod. Perfusion and oxygenation parameters of injured skin were measured with HSI, a noninvasive method of diffuse reflectance spectroscopy, at 2 minutes, 1, 24, 48 and 72 hours after wounding. Burn depth was measured histologically in 12 mice from each burn group (n = 72) at 72 hours. RESULTS: Three levels of burn depth were verified histologically: intermediate-dermal (ID), DD, and full-thickness. At 24 hours post injury, total hemoglobin (tHb) increased by 67% and 16% in ID and DD burns, respectively. In contrast, tHb decreased to 36% of its original levels in full-thickness burns. Differences in deoxygenated and tHb among all groups were significant (P \u3c 0.001) at 24 hours post injury. CONCLUSIONS: HSI was able to differentiate among 3 discrete levels of burn injury. This is likely because of its correlation with skin perfusion: superficial burn injury causes an inflammatory response and increased perfusion to the burn site, whereas deeper burns destroy the dermal microvasculature and a decrease in perfusion follows. This study supports further investigation of HSI in early burn depth assessment

Perfusion Changes by Hyperspectral Imaging in a Burn Model

BACKGROUND: Early excision and skin grafting of full-thickness and deep-dermal burns is therapeutically advantageous. However, while full-thickness burns are clinically evident, differentiating between superficial versus deep partial-thickness burns presents a diagnostic challenge, with only 50-75% accuracy. Superficial-dermal burns heal, while deep-dermal burns often require excision and skin grafting. Decision of surgical treatment is often delayed until burn depth is definitively identified. This study’s aim is to establish a thermal burn model in mice in order to assess the ability of Hyperspectral Imaging (HSI) in differentiating burn depth. METHODS: Burns of graded severity were generated on the dorsum of seventy-six hairless mice with a brass rod heated to 50, 60, 70, 80, or 90°C. Perfusion and oxygenation parameters of the injured skin were measured with HSI, a non-invasive method of wide-field, diffuse reflectance spectroscopy at 2 minutes, 1 hour, 24 hours, 48 hours, and 72 hours after wounding. Burn depth was measured histologically (n=44) at 72 hours post injury using Masson’s trichrome staining. RESULTS: Three discrete levels of burn depth were verified histologically, as follows in order of increasing depth: intermediate-dermal, deep-dermal, and full-thickness injury. At 24 hours post injury, total hemoglobin increased by 67% and 18% in intermediate and deep dermal burns, respectively. In contrast, total hemoglobin decreased by 64% in full-thickness burns. Differences in deoxygenated hemoglobin, total hemoglobin, and oxygen saturation for all group comparisons were statistically significant (p CONCLUSION: HSI was able to differentiate among three discrete levels of burn injury. This is likely due to its correlation with skin perfusion: superficial burn injury causes an inflammatory response and increased perfusion to the burn site, while deeper burns destroy the dermal microvasculature and a decrease in perfusion follows. This study supports further investigation in the use of HSI in early burn depth assessment

Detection of Diabetic Foot Ulcers Using SVM Based Classification

Diabetic foot ulcers represent a significant health issue, for both patients’ quality of life and healthcare system costs. Currently, wound care is mainly based on visual assessment of wound size, which suffers from lack of accuracy and consistency. Hence, a more quantitative and computer-based method is needed. Supervised machine learning based object recognition is an attractive option, using training sample images with boundaries labeled by experienced clinicians. We use forty sample images collected from the UMASS Wound Clinic by tracking 8 subjects over 6 months with a smartphone camera. To maintain a consistent imaging environment and facilitate the capture process for patients with limited mobility, an image capture box was designed with two right angled front surface mirrors and LED lighting. We developed a novel foot ulcer recognition system using these sample images as our test data. Instead of operating at the pixel level, we use super-pixels, resulting from the quick shift algorithm, as the basic processing units. Then a support vector machine (SVM) based classifier is trained on the Bag-of-Words histogram representation of local Scale-Invariant Feature Transform (SIFT) features found in each super-pixel. As this classifier is very specific and the resulting histogram is very sparse, we merge the histograms from super-pixels in a size-specified neighborhood into one instance. Finally, to recover more precise boundaries of the foot ulcers, we apply conditional random field techniques to introduce new constraints that allow us to reduce misclassifications that occur near the edges of objects. Experimental results show that our method provides promising recognition results, outperforming the regular SVM-based classification as well as the sliding window based object recognition method when evaluated using the Matthew correlation coefficient (MCC). We are integrating these algorithms into the wound assessment module of our Android phone-based diabetic self-management app

Hyperspectral imaging for early detection of oxygenation and perfusion changes in irradiated skin

Studies examining acute oxygenation and perfusion changes in irradiated skin are limited. Hyperspectral imaging (HSI), a method of wide-field, diffuse reflectance spectroscopy, provides noninvasive, quantified measurements of cutaneous oxygenation and perfusion. This study examines whether HSI can assess acute changes in oxygenation and perfusion following irradiation. Skin on both flanks of nude mice (n=20) was exposed to 50 Gy of beta radiation from a strontium-90 source. Hyperspectral images were obtained before irradiation and on selected days for three weeks. Skin reaction assessment was performed concurrently with HSI. Desquamative injury formed in all irradiated areas. Skin reactions were first seen on day 7, with peak formation on day 14, and resolution beginning by day 21. HSI demonstrated increased tissue oxygenation on day 1 before cutaneous changes were observed (

Translational Model for External Volume Expansion in Irradiated Skin

Introduction: External Volume Expansion (EVE) treatment has gained popularity in breast reconstruction, enriching recipient sites for fat grafting. For patients receiving radiotherapy (XRT), results of EVE use vary, partly because the effects of EVE on irradiated tissue are not well understood. Based on our previous work with EVE and XRT, we developed a new translational model to investigate the effects of EVE in the setting of chronic radiation skin injury. Methods: Twenty-Eight SKH1-E mice received 50Gy of beta-radiation to each flank. Animals were monitored until chronic radiation fibrosis developed (8 weeks). EVE was then applied to one side for 6hrs on 5 consecutive days. The opposite side served as control. Hyperspectral Imaging (HSI) was used to assess perfusion changes before and after EVE. Mice were sacrificed at 5 days (n=14) and 15 days (n=14) after last application for histological analysis. Tissue samples were stained for vascularity (CD31) and collagen composition (Picro-Sirius red). Results: All animals developed skin fibrosis 8 weeks post-radiation, and changes in perfusion verified skin damage. EVE application induced edema on treated sides. Five days post-application, both sides were hypo-perfused as seen by HSI; with the EVE side 13% more ischemic than the untreated side (p\u3c0.001). Perfusion returned to control side levels by day 15. Blood vessels increased 20% by day 5 in EVE versus control. Collagen composition showed no difference in scar index analysis. Conclusion: EVE temporarily augments radiation-induced hypo-perfusion, likely due to transient edema. Fibrosis remained unchanged after EVE, possibly accounting for the limited expansion seen in patients. It appears that EVE induces angiogenic effect but does not affect dermal collagen composition. Future efforts should focus on reducing fibrosis post radiation to allow EVE to achieve its full potential, to benefit irradiated patients

Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor beta 1

Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1