Michael S. Weingarten

Image analysis of chronic wounds for determining the surface area

Progress in wound healing is primarily quantified by the rate of change of the wounds surface area. The most recent guidelines of the Wound Healing Society suggest that a reduction in wound size of <40% within 4 weeks necessitates a reevaluation of the treatment. However, accurate measurement of wound size is challenging due to the complexity of a chronic wound, the variable lighting conditions of examination rooms, and the time constraints of a busy clinical practice. In this paper, we present our methodology to quantify a wound boundary and measure the enclosed wound area reproducibly. The method derives from a combination of color‐based image analysis algorithms, and our results are validated with wounds in animal models and human wounds of diverse patients. Images were taken by an inexpensive digital camera under variable lighting conditions. Approximately 100 patient images and 50 animal images were analyzed and a high overlap was achieved between the manual tracings and the calculated wound area by our method in both groups. The simplicity of our method combined with its robustness suggests that it can be a valuable tool in clinical wound evaluations. The basic challenge of our method is in deep wounds with very small surface areas where color‐based detection can lead to erroneous results and which could be overcome by texture‐based detection methods. The authors are willing to provide the developed MATLAB code for the work discussed in this paper.

Relative Expression of Proinflammatory and Antiinflammatory Genes Reveals Differences between Healing and Nonhealing Human Chronic Diabetic Foot Ulcers

driven neoplasms (Reifenberger et al., 2004; Palomba et al., 2012). Our identification of somatic RAS mutations in vascular tumors has clinical relevance. Current therapies against these lesions are limited to steroids and β-blockers, which achieve mixed results, often limited to tumor size reduction without resolution (Wine Lee et al., 2014). Some infantile vascular tumors, such as VASC101, are unresponsive to such interventions (Wine Lee et al., 2014). These cases may harbor RAS mutations, and might respond to farnesyl transferase inhibitors or Raf/Mek/Erk inhibitors, which block signaling upstream or downstream of RAS. The finding that RAS mutation drives vascular tumors provides potential opportunities to develop targeted therapies for current drug-resistant lesions.

Antimicrobial efficacy and wound-healing property of a topical ointment containing nitric-oxide-loaded zeolites.

Topical delivery of nitric oxide (NO) through a wound dressing has the potential to reduce wound infections and improve healing of acute and chronic wounds. This study characterized the antibacterial efficacy of an ointment containing NO-loaded, zinc-exchanged zeolite A that releases NO upon contact with water. The release rate of NO from the ointment was measured using a chemiluminescence detection system. Minimum bactericidal concentration assays were performed using five common wound pathogens, including Gram-negative bacteria (Escherichia coli and Acinetobacter baumannii), Gram-positive bacteria (Staphylococcus epidermidis and meticillin-resistant Staphylococcus aureus) and a fungus (Candida albicans). The time dependence of antimicrobial activity was characterized by performing log-reduction assays at four time points after 1-8 h ointment exposure. The cytotoxicity of the ointment after 24 h was assessed using cultured 3T3 fibroblast cells. Minimum microbicidal concentrations (MMCs) for bacterial organisms (5×10(7) c.f.u.) ranged from 50 to 100 mg ointment (ml media)(-1); the MMC for C. albicans (5×10(4) c.f.u.) was 50 mg ointment (ml media)(-1). Five to eight log reductions in bacterial viability and three log reductions in fungal viability were observed after 8 h exposure to NO-zeolite ointment compared with untreated organisms. Fibroblasts remained viable after 24 h exposure to the same concentration of NO-zeolite ointment as was used in antimicrobial tests. In parallel studies, full-thickness cutaneous wounds on Zucker obese rats healed faster than wounds treated with a control ointment. These data indicate that ointment containing NO-loaded zeolites could potentially be used as a broad-spectrum antimicrobial wound-healing dressing.

Correlation of near infrared absorption and diffuse reflectance spectroscopy scattering with tissue neovascularization and collagen concentration in a diabetic rat wound healing model

The objective of this paper was to correlate optical changes of tissue during wound healing measured by near infrared (NIR) and diffuse reflectance spectroscopy (DRS) with histologic changes in an animal model. Amplitude and phase of scattered light were obtained in a diabetic rat and control model and biopsies were taken for blood vessel ingrowth and collagen concentration. NIR absorption coefficient correlated with blood vessel ingrowth over time, in both the control and diabetic animals. DRS data correlated with collagen concentration. Previous publications by this group documented only the NIR changes during the wound healing process but this is the first reported correlation with histology data. The ability to correlate DRS scattering with collagen concentration during healing is another important and novel finding. This technology may play an important role clinically in assessing the efficacy of wound healing agents in diabetics.

Optical properties of wounds: diabetic versus healthy tissue

Diffuse photon density wave (DPDW) methodology at Near Infrared frequencies has been used to calculate absorption and scattering from wounds of healthy and diabetic rats. The diffusion equation for semi-infinite media is being used for calculating the absorption and scattering coefficients based on measurements of phase and amplitude with a frequency domain device. Differences observed during the course of healing in the two populations can be correlated to the delayed healing observed in diabetics. These results are encouraging and further work will focus on the implementation of this device to the clinical setting as a monitoring tool in chronic diabetic wounds.

Noninvasive assessment of diabetic foot ulcers with diffuse photon density wave methodology: pilot human study

A pilot human study is conducted to evaluate the potential of using diffuse photon density wave (DPDW) methodology at near-infrared (NIR) wavelengths (685 to 830 nm) to monitor changes in tissue hemoglobin concentration in diabetic foot ulcers. Hemoglobin concentration is measured by DPDW in 12 human wounds for a period ranging from 10 to 61 weeks. In all wounds that healed completely, gradual decreases in optical absorption coefficient, oxygenated hemoglobin concentration, and total hemoglobin concentration are observed between the first and last measurements. In nonhealing wounds, the rates of change of these properties are nearly zero or slightly positive, and a statistically significant difference (p<0.05) is observed in the rates of change between healing and nonhealing wounds. Differences in the variability of DPDW measurements over time are observed between healing and nonhealing wounds, and this variance may also be a useful indicator of nonhealing wounds. Our results demonstrate that DPDW methodology with a frequency domain NIR device can differentiate healing from nonhealing diabetic foot ulcers, and indicate that it may have clinical utility in the evaluation of wound healing potential.

Prediction of wound healing in human diabetic foot ulcers by diffuse near‐infrared spectroscopy: A pilot study

A human study was conducted in which the efficacy of in vivo diffuse near‐infrared (NIR) spectroscopy was demonstrated in predicting wound healing in diabetic foot ulcers. Sixteen chronic diabetic wounds were followed and assessed for subsurface oxy‐hemoglobin concentration using the NIR device. Weekly measurements were conducted until there was wound closure, limb amputation, or 20 completed visits without healing. Digital photography measured wound size, and the degree of wound contraction was compared with the NIR results. In the 16 patients followed, seven wounds healed, six limbs were amputated, and three wounds remained opened after 20 visits. The initial values in subsurface hemoglobin concentration in all wounds were higher than the nonwound control sites. Healed wounds showed a consistent reduction of hemoglobin concentration several weeks before closure that approached control site values. In wounds that did not heal or resulted in amputation of the limb, the hemoglobin concentration remained elevated. In some cases, these nonhealing wounds appeared to be improving clinically. A negative slope for the rate of change of hemoglobin concentration was indicative of healing across all wounds. In conclusion, evaluation of wounds using NIR may provide an effective measurement of wound healing. NIR spectroscopy can determine wound healing earlier than that visibly assessed by current clinical approaches.

Changes in optical properties of tissue during acute wound healing in an animal model

Changes of optical properties of wound tissue in hairless rats were quantified by diffuse photon density wave methodology at near-infrared frequencies. The diffusion equation for semi-infinite media was used to calculate the absorption and scattering coefficients based on measurements of phase and amplitude with a frequency domain device. There was an increase in the absorption and scattering coefficients and a decrease in blood saturation of the wounds compared with the nonwounded sites. The changes correlated with the healing stage of the wound. The data obtained were supported by immunohistochemical analysis of wound tissue. These results verified now by two independent animal studies could suggest a noninvasive method to detect the progress of wound healing.

Response of human macrophages to wound matrices in vitro.

Chronic wounds remain a major burden to the global healthcare system. Myriad wound matrices are commercially available but their mechanisms of action are poorly understood. Recent studies have shown that macrophages are highly influenced by their microenvironment, but it is not known how different biomaterials affect this interaction. Here, it was hypothesized that human macrophages respond differently to changes in biomaterial properties in vitro with respect to phenotype, including pro‐inflammatory M1, anti‐inflammatory M2a, known for facilitating extracellular matrix deposition and proliferation, and M2c, which has recently been associated with tissue remodeling. Using multiple donors, it was found that collagen scaffolds cross‐linked with 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide and N‐hydroxysuccinimide (EDC/NHS) promoted the least inflammatory phenotype in primary human macrophages compared with scaffolds cross‐linked with formaldehyde or glutaraldehyde. Importantly, gene expression analysis trends were largely conserved between donors, especially TNFa (M1), CCL22 (M2a), and MRC1 (M2a). Then the response of primary and THP1 monocyte‐derived macrophages to four commercially available wound matrices were compared—Integra Dermal Regeneration Template (Integra), PriMatrix Dermal Repair Scaffold (PriMatrix), AlloMend Acellular Dermal Matrix (AlloMend), and Oasis Wound Matrix (Oasis). Gene expression trends were different between primary and THP1 monocyte‐derived macrophages for all six genes analyzed in this study. Finally, the behavior of primary macrophages cultured onto the wound matrices over time was analyzed. Integra and Oasis caused down‐regulation of M2a markers CCL22 and TIMP3. PriMatrix caused up‐regulation of TNFa (M1) and CD163 (M2c) and down‐regulation of CCL22 and TIMP3 (both M2a). AlloMend caused up‐regulation in CD163 (M2c). Lastly, Oasis promoted the largest increase in the combinatorial M1/M2 score, defined as the sum of M1 genes divided by the sum of M2 genes. This preliminary study suggested that biomaterials influenced the wound microenvironment to affect macrophage phenotype.

Low-frequency (<100 kHz), low-intensity (<100 mW/cm2) ultrasound to treat venous ulcers: A human study and in vitro experiments

The purpose of this study was to examine whether low frequency (<100 kHz), low intensity (<100 mW/cm(2), spatial peak temporal peak) ultrasound can be an effective treatment of venous stasis ulcers, which affect 500 000 patients annually costing over