Impact of right ventricular function on outcome of severe aortic stenosis patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Right ventricular (RV) dysfunction was shown to be associated with adverse outcomes in a variety of cardiac patients and is considered a risk factor for adverse outcome according to the updated Valve Academic Research Consortium criteria. OBJECTIVE: Our goal was to assess the impact of RV function at baseline on 1-year mortality among patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR). METHODS: All patients with severe AS treated with TAVR from May 2007 to March 2015 at our center were included in the present study, and baseline and procedural characteristics were recorded for each patient. The patients were categorized according to RV function at baseline as assessed by current guidelines, and a comparison of mortality rates up to 1 year was performed. RESULTS: Among 650 patients, 606 had adequate echocardiogram quality and 146 (24%) had RV dysfunction. There were significant differences between the 2 groups, as patients with RV dysfunction were younger (81±9 vs 84±7 years, P=.01) and were more likely to be male (65% vs 42%, P<.001). In addition, patients with RV dysfunction had higher rates of prior myocardial infarction (26% vs 16%, P=.02) and atrial fibrillation (51% vs 39%, P=.02). Echocardiographic parameters demonstrated higher rates of left ventricular ejection fraction <40% (40% vs 18%, P<.001), tricuspid regurgitation above moderate (16% vs 9%, P=.04), and higher pulmonary artery systolic pressure (50±17 vs 44±16 mm Hg, P<.001) among patients with severe AS and RV dysfunction compared with patients with normal RV function. Despite the unfavorable cardiac function, patients with severe AS undergoing TAVR have similar functional class (P=.22) and mortality rates at 1year (27% vs 23%, log-rank P=.45). CONCLUSIONS: Patients with severe AS and RV dysfunction have similar 1-year mortality and functional class after TAVR to patients with normal RV function. The presence of RV dysfunction does not correlate with outcome in patients with severe AS.

Synergistic enhancement of ectopic bone formation by supplementation of freshly isolated marrow cells with purified MSC in collagen-chitosan hydrogel microbeads.

PURPOSE: Bone marrow-derived mesenchymal stem cells (MSC) can differentiate osteogenic lineages, but their tissue regeneration ability is inconsistent. The bone marrow mononuclear cell (BMMC) fraction of adult bone marrow contains a variety of progenitor cells that may potentiate tissue regeneration. This study examined the utility of BMMC, both alone and in combination with purified MSC, as a cell source for bone regeneration. METHODS: Fresh BMMC, culture-expanded MSC, and a combination of BMMC and MSC were encapsulated in collagen-chitosan hydrogel microbeads for pre-culture and minimally invasive delivery. Microbeads were cultured in growth medium for 3 days, and then in either growth or osteogenic medium for 17 days prior to subcutaneous injection in the rat dorsum. RESULTS: MSC remained viable in microbeads over 17 days in pre-culture, while some of the BMMC fraction were nonviable. After 5 weeks of implantation, microCT and histology showed that supplementation of BMMC with MSC produced a strong synergistic effect on the volume of ectopic bone formation, compared to either cell source alone. Microbeads containing only fresh BMMC or only cultured MSC maintained in osteogenic medium resulted in more bone formation than their counterparts cultured in growth medium. Histological staining showed evidence of residual microbead matrix in undifferentiated samples and indications of more advanced tissue remodeling in differentiated samples. CONCLUSIONS: These data suggest that components of the BMMC fraction can act synergistically with predifferentiated MSC to potentiate ectopic bone formation. The microbead system may have utility in delivering desired cell populations in bone regeneration applications.

Dissection of complex adult traits in a mouse synthetic population.

Finding the causative genetic variations that underlie complex adult traits is a significant experimental challenge. The unbiased search strategy of genome-wide association (GWAS) has been used extensively in recent human population studies. These efforts, however, typically find only a minor fraction of the genetic loci that are predicted to affect variation. As an experimental model for the analysis of adult polygenic traits, we measured a mouse population for multiple phenotypes and conducted a genome-wide search for effector loci. Complex adult phenotypes, related to body size and bone structure, were measured as component phenotypes, and each subphenotype was associated with a genomic spectrum of candidate effector loci. The strategy successfully detected several loci for the phenotypes, at genome-wide significance, using a single, modest-sized population (N = 505). The effector loci each explain 2%-10% of the measured trait variation and, taken together, the loci can account for over 25% of a trait's total population variation. A replicate population (N = 378) was used to confirm initially observed loci for one trait (femur length), and, when the two groups were merged, the combined population demonstrated increased power to detect loci. In contrast to human population studies, our mouse genome-wide searches find loci that individually explain a larger fraction of the observed variation. Also, the additive effects of our detected mouse loci more closely match the predicted genetic component of variation. The genetic loci discovered are logical candidates for components of the genetic networks having evolutionary conservation with human biology.

Aged male rats regenerate cortical bone with reduced osteocyte density and reduced secretion of nitric oxide after mechanical stimulation.

Mechanical loading is integral to the repair of bone damage. Osteocytes are mechanosensors in bone and participate in signaling through gap junction channels, which are primarily comprised of connexin 43 (Cx43). Nitric oxide (NO) and prostaglandin E2 (PGE2) have anabolic and catabolic effects on bone, and the secretion of these molecules occurs after mechanical stimulation. The effect of age on the repair of bone tissue after damage and on the ability of regenerated bone to transduce mechanical stimulation into a cellular response is unexplored. The goal of this study was to examine (1) osteocytes and their mineralized matrix within regenerated bone from aged and mature animals and (2) the ability of regenerated bone explants from aged and mature animals to transduce cyclic mechanical loading into a cellular response through NO and PGE2 secretion. Bilateral cortical defects were created in the diaphysis of aged (21-month-old) or mature (6-month-old) male rats, and new bone tissue was allowed to grow into a custom implant of controlled geometry. Mineralization and mineral-to-matrix ratio were significantly higher in regenerated bone from aged animals, while lacunar and osteocyte density and phosphorylated (pCx43) and total Cx43 protein were significantly lower, relative to mature animals. Regenerated bone from mature rats had increased pCx43 protein and PGE2 secretion with loading and greater NO secretion relative to aged animals. Reduced osteocyte density and Cx43 in regenerated bone in aged animals could limit the establishment of gap junctions as well as NO and PGE2 secretion after loading, thereby altering bone formation and resorption in vivo.

Hypercholesterolemia promotes an osteoporotic phenotype.

A role for hypercholesterolemia in the development of osteoporosis has been suggested in published reports. However, few studies contain direct evidence of a role for maintenance of cholesterol homeostasis in bone health. Using isocaloric high-fat/high-cholesterol and low-fat/no-cholesterol diets in a 4-month feeding study combined with micro computed tomography analysis, we demonstrated in two different mouse strains that mice with hypercholesterolemia lose cortical and trabecular bone in the femurs and vertebrae (bone mineral density was decreased on average by ≈90 mg/mL in the cortical vertebrae in one strain) and cortical bone in the calvariae (bone mineral density was decreased on average by ≈60 mg/mL in one strain). Mechanical testing of the femurs demonstrated that loss of bone in the mice with hypercholesterolemia caused changes in the mechanical properties of the bone including loss of failure load (failure load was decreased by ≈10 N in one strain) and energy to failure. Serologic and histomorphologic analyses suggested that hypercholesterolemia promotes osteoclastogenesis. These studies support a role for hypercholesterolemia in the development of osteoporosis and provide a model with which to test intervention strategies to reduce the effects of hypercholesterolemia on bone health.

Preclinical evaluation of a novel implant for treatment of a full-thickness distal femoral focal cartilage defect.

A novel, nonresorbable, monolithic composite structure ceramic, developed using a partially stabilized zirconia ceramic common to implantable devices, was used in a cementless weight-bearing articular implant to test the feasibility of replacing a region of degenerated or damaged articular cartilage in the knee as part of a preclinical study using male mongrel dogs lasting up to 24 weeks. Gross/histological cartilage observations showed no differences among control, 12-week and 24-week groups, while pull-out tests showed an increase in maximum pull-out load over time relative to controls. Hence, the use of a novel ceramic implant as a replacement for a focal cartilage defect leads to effective implant fixation within 12 weeks and does not cause significant degradation in opposing articular cartilage in the time frame evaluated.

Structural and biomechanical responses of osseous healing: a novel murine nonunion model.

BACKGROUND: Understanding the biological mechanisms of why certain fractures are at risk for delayed healing or nonunion requires translational animal models that take advantage of transgenic and other genetic manipulation technologies. Reliable murine nonunion models can be an important tool to understand the biology of nonunion. In this study, we report the results of a recently established model for creating critical defects that lead to atrophic nonunions based on a unique fracture fixation technique. MATERIALS AND METHODS: Subcritical (0.6 mm long) and critical (1.6 mm long) defects were created in femurs of 10-week-old double transgenic (Col1/Col2) mice and stabilized using a custom-designed plate and four screws. Four groups were used: normal, sham, subcritical, and critical. Histology (n = 3 for each group) was analyzed at 2 and 5 weeks, and micro-computed tomography (µCT) and torsional biomechanics (n = 12 for each group) were analyzed at 5 weeks. RESULTS: Subcritical defects showed healing at 2 weeks and were completely healed by 5 weeks, with biomechanical properties not significantly different from normal controls. However, critical defects showed no healing by histology or µCT. These nonunion fractures also displayed no torsional stiffness or strength in 10 of 12 cases. CONCLUSIONS: Our murine fracture model creates reproducible and reliable nonunions and can serve as an ideal platform for studying molecular pathways to contrast healing versus nonhealing events and for evaluating innovative therapeutic approaches to promote healing of a challenging osseous injury.

SUMOylation of NaV1.2 channels regulates the velocity of backpropagating action potentials in cortical pyramidal neurons.

Voltage-gated sodium channels located in axon initial segments (AIS) trigger action potentials (AP) and play pivotal roles in the excitability of cortical pyramidal neurons. The differential electrophysiological properties and distributions of NaV1.2 and NaV1.6 channels lead to distinct contributions to AP initiation and propagation. While NaV1.6 at the distal AIS promotes AP initiation and forward propagation, NaV1.2 at the proximal AIS promotes the backpropagation of APs to the soma. Here, we show the small ubiquitin-like modifier (SUMO) pathway modulates Na+ channels at the AIS to increase neuronal gain and the speed of backpropagation. Since SUMO does not affect NaV1.6, these effects were attributed to SUMOylation of NaV1.2. Moreover, SUMO effects were absent in a mouse engineered to express NaV1.2-Lys38Gln channels that lack the site for SUMO linkage. Thus, SUMOylation of NaV1.2 exclusively controls INaP generation and AP backpropagation, thereby playing a prominent role in synaptic integration and plasticity.

Two molecular weight species of thrombospondin-2 are present in bone and differentially modulated in fractured and nonfractured tibiae in a murine model of bone healing.

We report two immuoreactive species of thrombospondin-2 (TSP2), sized approximately 200 and 125 kDa, in the long bones of growing, but not skeletally mature, mice. In vitro osteoblasts secrete a 200-kDa species into the culture medium as early as day 3, and it appears in the cell-matrix layer by day 7. A 125-kDa species appears in the cell-matrix layer in parallel with mineralization; it is not detected in cell-conditioned medium. Unilateral tibial fracture induced a time-dependent upregulation of the 200-kDa species at the site of trauma. By contrast, relative levels of the 125-kDa species at the fracture site were lower than in bones from naive control animals. In the contralateral untouched control tibia, the 200-kDa species was rapidly and substantially reduced compared to bone harvested from naive control mice. Levels of the 125-kDa species in the untouched tibia declined gradually with time postfracture. TSP2 gene expression in uninjured control bone decreased modestly by 21 days postfracture. On the day of fracture, the osteoblast differentiation potential of MSCs harvested from uninjured bones decreased compared to those harvested from naive control animals. The presence of two isoforms suggests that TSP2 may undergo posttranscriptional or posttranslational processing in skeletal tissue. Our data also suggest that, in the context of trauma, the two TSP2 isforms are differentially modulated at injured and noninjured skeletal sites in an animal undergoing fracture healing.

Bone marrow stromal cells from aged male rats have delayed mineralization and reduced response to mechanical stimulation through nitric oxide and ERK1/2 signaling during osteogenic differentiation.

Bone marrow stromal cells (MSCs) are a source of osteoblast precursors that can be recruited during bone remodeling or injury, both important processes in aging populations. With advancing age, alterations in bone structure and mineralization are often associated with an increase in osteoporosis and fracture risk. Changes in the number of osteoprogenitor cells and their osteogenic potential may occur with advancing age; however few studies have considered the influence of mechanical conditions. Here, we investigated the ability of bone MSCs from mature and aged rats to differentiate into osteoblasts and to respond to short and long periods of mechanical stimulation through signaling by ERK1/2, nitric oxide (NO), and prostaglandin E(2) (PGE(2)) during differentiation. Mineralization was delayed and reduced, but extracellular matrix production appeared less affected by increased age. Differentiating MSCs from aged animals had a decreased response to short and long periods of mechanical stimulation through ERK1/2 signaling, and to long periods of mechanical loading through NO signaling early and late during differentiation. Increases in relative PGE(2) signaling were higher in MSCs from aged animals, which could compensate for reduced ERK1/2 and NO signaling. The decreased mineralization may decrease the ability of cells from aged animals to respond to mechanical stimulation through ERK1/2 and NO signaling, with increased impairment over differentiation time. Decreasing the delay in mineralization of MSCs from aging animals might improve their ability to respond to mechanical stimulation during bone remodeling and injury, suggesting therapies for bone fragility diseases and tissue engineering treatments in elderly populations.

Force-induced craniosynostosis via paracrine signaling in the murine sagittal suture.

INTRODUCTION: The role of genetic phenomena has been given central importance in the development of craniosynostosis. Proponents have dismissed the role of force as a key etiologic factor. Nonetheless, compressive forces on the developing calvarium have been shown to result in premature suture fusion. The purpose of this study was to determine whether cyclical loading of the murine calvarium could induce suture fusion in cocultured calvarial specimens. MATERIALS AND METHODS: Calvarial coupons from postnatal day 21, B6CBA wild-type mice (n = 24) were harvested and cultured. A custom appliance capable of delivering compressive loads was applied perpendicular to the sagittal suture in vitro. Six coupons were subjected to 0.3 g of force for 30 minutes each day for a total of 14 days. Six additional coupons were cocultured within the same medium. Control groups were devised. Histologic analysis of suture phenotype was performed. RESULTS: Sagittal sutures cocultured with unloaded specimens remained patent. In contradistinction, 4 of 6 specimens cocultured with loaded coupons demonstrated craniosynostosis (P = 0.03). Increased osteoid, alkaline phosphatase staining, and bone sialoprotein expression were observed when compared with matched controls. DISCUSSION: An in vitro model of force-induced craniosynostosis via paracrine effects has been devised. Premature fusion of the murine sagittal suture was induced in unloaded specimens cocultured with cyclically loaded calvarial coupons. These results implicate that abnormal forces may act through soluble factors to cause premature suture fusion in vitro. The findings support our global hypothesis that epigenetic phenomena play a crucial role in the pathogenesis of nonsyndromic craniosynostosis.

Correlates and causes of death in patients with severe symptomatic aortic stenosis who are not eligible to participate in a clinical trial of transcatheter aortic valve implantation.

BACKGROUND: Transcatheter aortic valve implantation is currently being evaluated in patients with severe aortic stenosis who are considered high-risk surgical candidates. This study aimed to detect incidences, causes, and correlates of mortality in patients ineligible to participate in transcatheter aortic valve implantation studies. METHODS AND RESULTS: From April 2007 to July 2009, a cohort of 362 patients with severe aortic stenosis were screened and did not meet the inclusion/exclusion criteria necessary to participate in a transcatheter aortic valve implantation trial. These patients were classified into 2 groups: group 1 (medical): 274 (75.7%): 97 (35.4%) treated medically and 177 (64.6%) treated with balloon aortic valvuloplasty; and group 2 (surgical): 88 (24.3%). The medical/balloon aortic valvuloplasty group had significantly higher clinical risk compared with the surgical group, with significantly higher Society of Thoracic Surgeons score (12.8±7.0 versus 8.5±5.1; P<0.001) and logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) (42.4±22.8 versus 24.4±18.1; P<0.001). The medical/balloon aortic valvuloplasty group had a higher New York Heart Association functional class, incidence of renal failure, and lower ejection fraction. During median follow-up of 377.5 days, mortality in the medical/balloon aortic valvuloplasty group was 102 (37.2%), and during median follow-up of 386 days, mortality in the surgical group was 19 (21.5%). Multivariable adjustment analysis identified renal failure (hazard ratio [HR]: 5.60), New York Heart Association class IV (HR: 5.88), and aortic systolic pressure (HR: 0.99) as independent correlates for mortality in the medical group, whereas renal failure (HR: 7.45), Society of Thoracic Surgeons score (STS; HR: 1.09) and logistic EuroSCORE (HR: 1.45) were correlates of mortality in the in the surgical group. CONCLUSIONS: Patients with severe symptomatic aortic stenosis not included in transcatheter aortic valve implantation trials do poorly and have extremely high mortality rates, especially in nonsurgical groups, and loss of quality of life in surgical groups.

In utero transplantation of adult bone marrow decreases perinatal lethality and rescues the bone phenotype in the knockin murine model for classical, dominant osteogenesis imperfecta.

Autosomal dominant osteogenesis imperfecta (OI) caused by glycine substitutions in type I collagen is a paradigmatic disorder for stem cell therapy. Bone marrow transplantation in OI children has produced a low engraftment rate, but surprisingly encouraging symptomatic improvements. In utero transplantation (IUT) may hold even more promise. However, systematic studies of both methods have so far been limited to a recessive mouse model. In this study, we evaluated intrauterine transplantation of adult bone marrow into heterozygous BrtlIV mice. Brtl is a knockin mouse with a classical glycine substitution in type I collagen [alpha1(I)-Gly349Cys], dominant trait transmission, and a phenotype resembling moderately severe and lethal OI. Adult bone marrow donor cells from enhanced green fluorescent protein (eGFP) transgenic mice engrafted in hematopoietic and nonhematopoietic tissues differentiated to trabecular and cortical bone cells and synthesized up to 20% of all type I collagen in the host bone. The transplantation eliminated the perinatal lethality of heterozygous BrtlIV mice. At 2 months of age, femora of treated Brtl mice had significant improvement in geometric parameters (P < .05) versus untreated Brtl mice, and their mechanical properties attained wild-type values. Our results suggest that the engrafted cells form bone with higher efficiency than the endogenous cells, supporting IUT as a promising approach for the treatment of genetic bone diseases.

Biomedical tissue phantoms with controlled geometric and optical properties for Raman spectroscopy and tomography.

To support the translation of Raman spectroscopy into clinical applications, synthetic models are needed to accurately test, optimize and validate prototype fiber optic instrumentation. Synthetic models (also called tissue phantoms) are widely used for developing and testing optical instrumentation for diffuse reflectance, fluorescence, and Raman spectroscopies. While existing tissue phantoms accurately model tissue optical scattering and absorption, they do not typically model the anatomic shapes and chemical composition of tissue. Because Raman spectroscopy is sensitive to molecular composition, Raman tissue phantoms should also approximate the bulk tissue composition. We describe the fabrication and characterization of tissue phantoms for Raman tomography and spectroscopy. These phantoms have controlled chemical and optical properties, and also multilayer morphologies which approximate the appropriate anatomic shapes. Tissue phantoms were fabricated to support on-going Raman studies by simulating the human wrist and rat leg. Surface meshes (triangle patch models) were generated from computed tomography (CT) images of a human arm and rat leg. Rapid prototyping was used to print mold templates with complex geometric patterns. Plastic casting techniques used for movie special effects were adapted to fabricate molds from the rapid prototypes, and finally to cast multilayer gelatin tissue phantoms. The gelatin base was enriched with additives to model the approximate chemistry and optical properties of individual tissue layers. Additional studies were performed to determine optimal casting conditions, phantom stability, layer delamination and chemical diffusion between layers. Recovery of diffuse reflectance and Raman spectra in tissue phantoms varied with probe placement. These phantoms enable optimization of probe placement for human or rat studies. These multilayer tissue phantoms with complex geometries are shown to be stable, with minimal layer delamination and chemical diffusion.

Subclinical brain embolization in left-sided infective endocarditis: results from the evaluation by MRI of the brains of patients with left-sided intracardiac solid masses (EMBOLISM) pilot study.

BACKGROUND: Acute brain embolization (ABE) in left-sided infective endocarditis has significant implications for clinical decision making. The true incidence of ABE, including subclinical brain embolization, is unknown. METHODS AND RESULTS: We prospectively studied 56 patients with definite left-sided infective endocarditis. Patients were examined by a study neurologist, and those without contraindication had magnetic resonance imaging of the brain. Patients without clinical evidence of acute stroke but with magnetic resonance imaging evidence of ABE were considered to have subclinical brain embolization. Clinical stroke was present in 14 of 56 patients (25%). Among 40 patients undergoing magnetic resonance imaging, the incidence rates of subclinical brain embolization and any ABE were 48% and 80%, respectively. ABE was present in 18 of 19 patients (95%) with Staphylococcus aureus infection. At 3 months, mortality was similar among patients with clinical stroke and subclinical brain embolization (62% versus 53%; P=NS) and was higher among patients with any ABE than among those without ABE (56% versus 12%; P=0.046). Valvular surgery was performed in 25 patients (45%), including 16 with ABE, at a median of 4 days. No patient suffered a postoperative neurological complication. Surgery was independently associated with a lower risk of mortality at 3 months (odds ratio, 0.1; 95% confidence interval, 0.03 to 0.6; P=0.008). CONCLUSIONS: Magnetic resonance imaging detected subclinical brain embolization in a substantial number of patients with left-sided infective endocarditis, suggesting that the incidence of ABE may be significantly higher than reports based on clinical and computed tomography findings have indicated. Brain magnetic resonance imaging may play a role in the complex decision about surgical intervention in infective endocarditis.

A mineral-rich extract from the red marine algae Lithothamnion calcareum preserves bone structure and function in female mice on a Western-style diet.

The purpose of this study was to determine whether a mineral-rich extract derived from the red marine algae Lithothamnion calcareum could be used as a dietary supplement for prevention of bone mineral loss. Sixty C57BL/6 mice were divided into three groups based on diet: the first group received a high-fat Western-style diet (HFWD), the second group was fed the same HFWD along with the mineral-rich extract included as a dietary supplement, and the third group was used as a control and was fed a low-fat rodent chow diet (AIN76A). Mice were maintained on the respective diets for 15 months. Then, long bones (femora and tibiae) from both males and females were analyzed by three-dimensional micro-computed tomography (micro-CT) and (bones from female mice) concomitantly assessed in bone strength studies. Tartrate-resistant acid phosphatase (TRAP), osteocalcin, and N-terminal peptide of type I procollagen (PINP) were assessed in plasma samples obtained from female mice at the time of sacrifice. To summarize, female mice on the HFWD had reduced bone mineralization and reduced bone strength relative to female mice on the low-fat chow diet. The bone defects in female mice on the HFWD were overcome in the presence of the mineral-rich supplement. In fact, female mice receiving the mineral-rich supplement in the HFWD had better bone structure/function than did female mice on the low-fat chow diet. Female mice on the mineral-supplemented HFWD had higher plasma levels of TRAP than mice of the other groups. There were no differences in the other two markers. Male mice showed little diet-specific differences by micro-CT.

Development of non-invasive Raman spectroscopy for in vivo evaluation of bone graft osseointegration in a rat model.

The use of bone structural allografts for reconstruction following tumor resection is widespread, although successful incorporation and regeneration remain uncertain. There are few non-invasive methods to fully assess the progress of graft incorporation. Computed tomography and MRI provide information on the morphology of the graft/host interface. Limited information is also available from DXA and ultrasound. Only few techniques can provide information on the metabolic status of the graft, such as the mineral and matrix composition of the regenerated tissue that may provide early indications of graft success or failure. To address this challenge, we discuss here the implementation of Raman spectroscopy for in vivo assessment of allograft implantation in a rat model. An array of optical fibers was developed to allow excitation and collection of Raman spectra through the skin of rat at various positions around the rat's tibia. The system is calibrated against locally constructed phantoms that mimic the morphology, optics and spectroscopy of the rat. The system was evaluated by carrying out transcutaneous Raman measurement on rat. Bone mineral and matrix Raman bands are successfully recovered. This new technology provides a non-invasive method for in vivo monitoring of bone graft osseointegration.

Continuous delivery of biomaterials to the skin-percutaneous device interface using a fluid pump.

We have developed an in vitro culture system composed of organotypic human skin explants interfaced with titanium rods attached to a fluid pump. This device was designed to mimic the process of natural mucosa delivery at the point where a rigid, permanent object penetrates living skin. Full thickness human breast skin explants discarded from surgeries were cultured at different time points at the air-liquid interface. The skin specimens were punctured to fit at the bottom of hollow cylindrical titanium rods. Sodium lauryl sulfate (SLS) was delivered continuously to the specimens through the rods by using an attached fluid pump. Histological analysis of the skin explants as well as no-pump controls was then performed. Our results show substantial differences between controls, where no material was pumped at the interface of rod-skin, and specimens treated with SLS, indicating that the technique of pumping the material is effective in producing observable epithelial changes. These results suggest that an adaptation of this type of device may be useful for the treatment of complications arising from the contact between tissues and percutaneous devices in vivo.

Evaluation of global gene expression in regenerate tissues during Masquelet treatment.

The Masquelet induced-membrane (IM) technique is indicated for large segmental bone defects. Attributes of the IM and local milieu that contribute to graft-to-bone union are unknown. Using a rat model, we compared global gene expression profiles in critically sized femoral osteotomies managed using a cement spacer as per Masquelet to those left empty. At the end of the experiment, IM and bone adjacent to the spacer were collected from the Masquelet side. Nonunion tissue in the defect and bone next to the empty defect were collected from the contralateral side. Tissues were subjected to RNA isolation, sequencing, and differential expression analysis. Cell type enrichment analysis suggested the IM and the bone next to the polymethylmethacrylate (PMMA) spacer were comparatively enriched for osteoblastic genes. The nonunion environment was comparatively enriched for innate and adaptive immune cell markers, but only macrophages were evident in the Masquelet context. iPathwayGuide was utilized to identify cell signaling pathways and protein interaction networks enriched in the Masquelet environment. For IM vs nonunion false-discovery rate correction of P values rendered overall pathway differences nonsignificant, and so only protein interaction networks are presented. For the bone comparison, substantial enrichment of pathways and networks known to contribute to osteogenic mechanisms was revealed. Our results suggest that the PMMA spacer affects the cut bone ends that are in contact with it and at the same time induces the foreign body reaction and formation of the IM. B cells in the empty defect suggest a chronic inflammatory response to a large segmental osteotomy.

Impact of Baseline Left Ventricular Diastolic Dysfunction in Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Implantation.

We sought to assess the impact of diastolic dysfunction (DD) grade, as per the 2016 American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines, on survival of patients with severe aortic stenosis (AS) who underwent transcatheter aortic valve implantation (TAVI). We included consecutive patients with severe AS who underwent TAVI in our institution. DD grading was determined retrospectively according to the 2016 ASE DD guidelines and categorized to grade I-III and indeterminate grade I-II DD. Comparison of 1-year survival according to DD grade was performed by Kaplan-Meier analysis, and evaluation of DD at 1 year was performed in a subset of patients. Among 606 TAVI patients, 394 (65%) had sufficient data for DD grading. Seventy-seven (20%) had grade I DD, 191 (48%) had grade II, 60 (15%) had grade III, and 66 (17%) had an indeterminate grade between I and II. Baseline characteristics indicate higher rates of atrial fibrillation, brain natriuretic peptide level, pulmonary artery systolic pressure, and indexed left ventricular mass as DD grade increases (all p ≤0.01). In conclusion, comparison of 1-year survival revealed a higher rate of mortality in patients with grade III DD that remained statistically significant following adjustment in a multivariate Cox proportional hazard model. DD grade after TAVI improved in patients with grades II and III. Severe AS patients with grade III DD have higher risk for 1-year mortality after TAVI compared with milder degrees of DD. Further research is warranted to explore a potential benefit for aortic valve therapy at an earlier stage of the disease process.