SNaP Wound Care System: Ultraportable Mechanically Powered Negative Pressure Wound Therapy.

Problem: Negative pressure wound therapy (NPWT) is a well-accepted modality for treatment of difficult wounds, but has traditionally required a bulky electrically powered pump that was difficult to procure and use for both caregivers and patients. Often times, treatment of refractory smaller-sized wounds was impractical even though they may benefit from NPWT.

Solution: Spiracur (Sunnyvale, CA) has developed a simple, easy-to-use, single-use, off-the-shelf, mechanically powered NPWT device that weighs <3 ounces.

Evaluation of chronic wound treatment with the SNaP wound care system versus modern dressing protocols.

Background: Traditional negative-pressure wound therapy systems use an electrically powered pump to generate negative pressure at the wound bed. The SNaP Wound Care System is a novel, ultraportable device that delivers negative-pressure wound therapy without the use of an electrically powered pump.

Methods: At an outpatient wound care clinic, 21 subjects with difficult-to-treat lower extremity ulcers received treatment with the SNaP System and were evaluated for wound healing for up to 4 months.

Initial clinical experience using a novel ultraportable negative pressure wound therapy device.

Unlabelled:  Background. Traditional negative pressure wound therapy (NPWT) devices, such as the electrically powered V.A.

The SNaP Wound Care System: a case series using a novel ultraportable negative pressure wound therapy device for the treatment of diabetic lower extremity wounds.

Although there is significant evidence supporting the use of negative pressure wound therapy (NPWT) for the treatment of lower extremity diabetic ulcers, currently available electrically powered NPWT systems are not ideally suited for treating smaller diabetic foot ulcers. The Smart Negative Pressure (SNaP) Wound Care System is a novel, ultraportable device that delivers NPWT without the use of an electrically powered pump. It was specifically designed to meet the wound care needs of patients with diabetes.

The SNaP system: biomechanical and animal model testing of a novel ultraportable negative-pressure wound therapy system.

Background: Negative-pressure wound therapy is traditionally achieved by attaching an electrically powered pump to a sealed wound bed and applying subatmospheric pressure by means of gauze or foam. The Smart Negative Pressure (SNaP) System (Spiracur, Inc., Sunnyvale, Calif.

Unique modulation of cadherin expression pattern during posterior frontal cranial suture development and closure.

Cranial suture development involves coordinated expression of multiple genes and tissue contribution from neural crest cells and paraxial mesoderm for timely sutural morphogenesis. Transcription factors, growth factors, and neural crest determinant genes play critical roles in calvarial growth ensuring normal development of the underlying brain. In vitro studies have implicated cell-cell adhesion molecules as a driving force behind suture closure.

Fluid shear stress magnitude, duration, and total applied load regulate gene expression and nitric oxide production in primary calvarial osteoblast cultures.

Background: Successful bone engineering requires an understanding of the effects of mechanical stress on osteoblast differentiation. Therefore, we examined the effects of varying magnitude and duration of fluid shear stress on factors associated with osteoblastic differentiation.

Methods: Using a cone viscometer, primary neonatal rat calvarial osteoblasts were exposed to continuous fluid shear stress at varying doses: 0.

Guided tissue regeneration enhances bone formation in a rat model of failed osteogenesis.

Background: Guided tissue regeneration is a technique that uses barrier materials to enhance tissue regeneration. Although previously demonstrated to be an effective way of enhancing craniofacial osteogenesis in several animal models, the ability of guided tissue regeneration to augment bone formation in the context of distraction osteogenesis is unknown. In the current study, the authors applied the principle of guided tissue regeneration to their rat mandibular distraction osteogenesis model in an attempt to enhance bone regeneration.

Microarray analysis of mechanical shear effects on flexor tendon cells.

Background: Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. The authors hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing.

Expression and possible mechanisms of regulation of BMP3 in rat cranial sutures.

Background: Clinical genetics data and investigative studies have contributed greatly to our understanding of the role of numerous genes in craniosynostosis. Recent studies have introduced antagonists of osteogenesis as potential key regulators of suture fusion and patency. The authors investigated the expression pattern of the bone morphogenetic protein antagonist BMP3 in rat cranial sutures and the factors regulating its expression in vitro.

Increased transcriptional response to mechanical strain in keloid fibroblasts due to increased focal adhesion complex formation.

Clinicians have observed that keloids preferentially form in body areas subject to increased skin tension. We hypothesized a difference exists in the transcriptional response of keloid fibroblasts to mechanical strain compared with normal fibroblasts. Normal and keloid fibroblasts were seeded in a device calibrated to deliver a known level of equibiaxial strain.

Gene profiling of cells expressing different FGF-2 forms.

Fibroblast Growth Factor-2 (FGF-2) induces cell proliferation, cell migration, embryonic development, cell differentiation, angiogenesis and malignant transformation. The four forms of FGF-2 (Low Molecular Weight) and (High Molecular Weights) are alternative translation products, and have a different subcellular localization: the high molecular weight (HMWFGF-2) forms are nuclear while the low molecular weight form, (LMWFGF-2) is mainly cytoplasmic. Our previous work demonstrated NIH 3T3 cells expressing different FGF-2 forms, displayed a different phenotype, suggesting that nuclear and cytoplasmic forms of FGF-2 may have different functions.

Differential transcriptional expression profiles of juvenile and adult calvarial bone.

Background: It has widely been observed that young children are capable of reossifying large calvarial defects, while adults lack this endogenous tissue-engineering capacity. The ability of juvenile animals to regenerate calvarial defects has been investigated in multiple animal models, including mice. In this study, the authors used cDNA microarrays to investigate the expression of osteogenesis-associated genes upstream and downstream of Runx2 in juvenile and adult mouse calvaria.

Mechanobiology of mandibular distraction osteogenesis: finite element analyses with a rat model.

Three-dimensional finite element (FE) analyses were performed to characterize the local mechanical environment created within the tissue regenerate during mandibular distraction osteogenesis (DO) in a rat model. Finite element models were created from three-dimensional computed tomography image data of rat hemi-mandibles at four different time points during an optimal distraction osteogenesis protocol (i.e.

FGF-2 acts through an ERK1/2 intracellular pathway to affect osteoblast differentiation.

An abundance of genetic and experimental data have suggested that fibroblast growth factor (FGF) signaling plays a central role in physiological and pathological cranial suture fusion. Although alterations in the differentiation and proliferation of sutural osteoblasts may be a key mediator of this process, the mechanisms by which FGF signaling regulates osteoblast differentiation remain incompletely understood. In the current study, the authors show that recombinant human FGF-2 alters osteoblastic expression of bone morphogenetic protein-2 and Msx-2 in vitro to favor cellular differentiation and osteoinduction.

Quantitative transcriptional analysis of fusing and nonfusing cranial suture complexes in mice.

Previous studies have documented the differences in expression of various genes associated with the process of osteogenesis in fusing and nonfusing cranial sutures, including growth factors, growth factor receptors, and extracellular matrix molecules. Most of these studies were performed in rats, and although the biology regulating cranial suture fusion in mice and rats is presumed to be similar, studies are needed to verify these expression patterns as mice become increasingly utilized for scientific inquiry into the molecular biology of suture fusion and patency. The purpose of this study was to determine the differences in expression of several genes known to be critical to osteoblast biology.

Applications of a mouse model of calvarial healing: differences in regenerative abilities of juveniles and adults.

Young children are capable of healing large calvarial defects, whereas adults lack this endogenous osseous tissue-engineering capacity. Despite the important clinical implications, little is known about the molecular and cell biology underlying this differential ability. Traditionally, guinea pig, rabbit, and rat models have been used to study the orchestration of calvarial healing.

Apoptosis in a rodent model of cranial suture fusion: in situ imaging and gene expression analysis.

Craniosynostosis, the premature fusion of cranial sutures, is one of the most common craniofacial anomalies, with a reported incidence of up to one in 2500 live births. Despite its prevalence, the cause of craniosynostosis remains unknown. Previously, apoptosis has been postulated to be a contributing factor in the pathogenesis of craniosynostosis, although the role of programmed cell death in cranial sutures is poorly understood.

Creation and characterization of a mouse model of mandibular distraction osteogenesis.

While the histological and ultrastructural changes associated with distraction osteogenesis have been extensively characterized using various animal models, the molecular mechanisms governing this technique remain poorly understood. In the current study, for the first time, we describe a mouse mandibular distraction osteogenesis model. Development of this model will allow assessment of factors involved in normal vs.

Mechanisms of murine cranial suture patency mediated by a dominant negative transforming growth factor-beta receptor adenovirus.

Using a physiologic model of mouse cranial suture fusion, the authors' laboratory has previously demonstrated that transforming growth factor (TGF)-betas appear to be more abundantly expressed in the suture complex of the fusing posterior frontal compared with the patent sagittal suture. Furthermore, the authors have shown that by blocking TGF-beta signaling with a replication-deficient adenovirus encoding a defective, dominant negative type II TGF-beta receptor (AdDN-TbetaRII), posterior frontal suture fusion was inhibited. In this study, the authors attempt to further elucidate the role of TGF-beta in cranial suture fusion by investigating possible mechanisms of AdDN-TbetaRII-mediated cranial suture patency using both an established organ culture model and a novel in vitro co-culture system that recapitulates the in vivo anatomic dura mater/cranial suture relationship.

In vitro murine posterior frontal suture fate is age-dependent: implications for cranial suture biology.

In CD-1 mice, the posterior frontal suture (analogous to the human metopic suture) fuses while all other cranial sutures remain patent. In an in vitro organ culture model, the authors previously demonstrated that posterior frontal sutures explanted immediately before the onset of suture fusion (at 25 days old) mimic in vivo physiologic fusion. In the first portion of this study, the authors defined how early in development the posterior frontal suture fuses in their tension-free, serum-free organ culture system by serially analyzing posterior frontal suture fusion from calvariae explanted at different stages of postnatal development.

Mechanobiology of mandibular distraction osteogenesis: experimental analyses with a rat model.

We analyzed mechanobiological influences on successful distraction osteogenesis (DO). Mandibular distraction surgeries were performed on 15 adult male Sprague-Dawley rats. Animals underwent gradual distraction (GD), progressive lengthening by small increments (5-day latency followed by 0.

Markers of osteoblast differentiation in fusing and nonfusing cranial sutures.

Accumulating clinical genetic data support the hypothesis that alterations in osteoblast differentiation are closely associated with craniosynostoses. Gain-of-function mutations in FGFR1, FGFR2, FGFR3, and Msx2 and loss-of-function mutations in Twist are examples of such alterations. Several studies have examined how these mutations alter the expression patterns for transcription factors such as Runx2 and noncollagenous extracellular matrix molecules such as osteopontin and osteocalcin.

Mechanical strain affects dura mater biological processes: implications for immature calvarial healing.

The human brain grows rapidly during the first 2 years of life. This growth generates tensile strain in the overlying dura mater and neurocranium. Interestingly, it is largely during this 2-year growth period that infants are able to reossify calvarial defects.