Using the pan-genomic framework for the discovery of genomic islands in the haloarchaeon Halorubrum ezzemoulense.

In this study, we use pan-genomics to characterize the genomic variability of the widely dispersed halophilic archaeal species Halorubrum ezzemoulense (Hez). We include a multi-regional sampling of newly sequenced, high-quality draft genomes. The pan-genome graph of the species reveals 50 genomic islands that represent rare accessory genetic capabilities available to members. Most notably, we observe rearrangements that have led to the insertion/recombination/replacement of mutually exclusive genomic islands in equivalent genome positions ("homeocassettes"). These conflicting islands encode for similar functions, but homologs from islands located between the same core genes exhibit high divergence on the amino acid level, while the neighboring core genes are nearly identical. Both islands of a homeocassette often coexist in the same geographic location, suggesting that either island may be beyond the reach of selective sweeps and that these loci of divergence between Hez members are maintained and persist long term. This implies that subsections of the population have different niche preferences and rare metabolic capabilities. After an evaluation of the gene content in the homeocassettes, we speculate that these islands may play a role in the speciation, niche adaptability, and group selection dynamics in Hez. Though homeocassettes are first described in this study, similar replacements and divergence of genes on genomic islands have been previously reported in other Haloarchaea and distantly related Archaea, suggesting that homeocassettes may be a feature in a wide range of organisms outside of Hez.IMPORTANCEThis study catalogs the rare genes discovered in strains of the species Halorubrum ezzemoulense (Hez), an obligate halophilic archaeon, through the perspective of its pan-genome. These rare genes are often found to be arranged on islands that confer metabolic and transport functions and contain genes that have eluded previous studies. The discovery of divergent, but homologous islands occupying equivalent genome positions ("homeocassettes") in different genomes, reveals significant new information on genome evolution in Hez. Homeocassette pairs encode for similar functions, but their dissimilarity and distribution imply high rates of recombination, different specializations, and niche preferences in Hez. The coexistence of both islands of a homeocassette pair in multiple environments demonstrates that both islands are beyond the reach of selective sweeps and that these genome content differences between strains persist long term. The switch between islands through recombination under different environmental conditions may lead to a greater range of niche adaptability in Hez.

The Evolutionary History of a DNA Methylase Reveals Frequent Horizontal Transfer and Within-Gene Recombination.

Inteins, often referred to as protein introns, are highly mobile genetic elements that invade conserved genes throughout the tree of life. Inteins have been found to invade a wide variety of key genes within actinophages. While in the process of conducting a survey of these inteins in actinophages, we discovered that one protein family of methylases contained a putative intein, and two other unique insertion elements. These methylases are known to occur commonly in phages as orphan methylases (possibly as a form of resistance to restriction-modification systems). We found that the methylase family is not conserved within phage clusters and has a disparate distribution across divergent phage groups. We determined that two of the three insertion elements have a patchy distribution within the methylase protein family. Additionally, we found that the third insertion element is likely a second homing endonuclease, and that all three elements (the intein, the homing endonuclease, and what we refer to as the ShiLan domain) have different insertion sites that are conserved in the methylase gene family. Furthermore, we find strong evidence that both the intein and ShiLan domain are partaking in long-distance horizontal gene transfer events between divergent methylases in disparate phage hosts within the already dispersed methylase distribution. The reticulate evolutionary history of methylases and their insertion elements reveals high rates of gene transfer and within-gene recombination in actinophages.

Neighboring inteins interfere with one another's homing capacity.

Inteins are mobile genetic elements that invade conserved genes across all domains of life and viruses. In some instances, a single gene will have several intein insertion sites. In Haloarchaea, the minichromosome maintenance (MCM) protein at the core of replicative DNA helicase contains four intein insertion sites within close proximity, where two of these sites (MCM-a and MCM-d) are more likely to be invaded. A haloarchaeon that harbors both MCM-a and MCM-d inteins, Haloferax mediterranei, was studied in vivo to determine intein invasion dynamics and the interactions between neighboring inteins. Additionally, invasion frequencies and the conservation of insertion site sequences in 129 Haloferacales mcm homologs were analyzed to assess intein distribution across the order. We show that the inteins at MCM-a and MCM-d recognize and cleave their respective target sites and, in the event that only one empty intein invasion site is present, readily initiate homing (i.e. single homing). However, when two inteins are present co-homing into an intein-free target sequence is much less effective. The two inteins are more effective when invading alleles that already contain an intein at one of the two sites. Our in vivo and computational studies also support that having a proline in place of a serine as the first C-terminal extein residue of the MCM-d insertion site prevents successful intein splicing, but does not stop recognition of the insertion site by the intein's homing endonuclease.

Acid sphingomyelinase involvement in tumor necrosis factor alpha-regulated vascular and steroid disruption during luteolysis in vivo.

TNF is well known for its role in inflammation, including direct effects on the vasculature. TNF also is implicated in the regulation of reproduction by its actions to affect ovarian steroidogenic cells and to induce apoptosis of corpus luteum (CL)-derived endothelial cells in vitro. We hypothesized that the disruption of TNF signaling would postpone the regression of the highly vascularized CL in vivo, and this effect could be replicated in mutant mouse models lacking TNF receptor (TNFRI(-/-)) and/or a critical enzyme of TNF signaling, acid sphingomyelinase (ASMase(-/-)). In the current study, the treatment of pseudopregnant mice with the luteolytic mediator prostaglandin F2-alpha (PGF) significantly increased TNF in the ovaries when compared with saline-treated controls. Treatment with PGF also reduced serum progesterone (P4) concentrations and caused involution of the CL. However, pretreatment of pseudopregnant mice with Etanercept (ETA), a TNF-neutralizing antibody, inhibited the PGF-induced decrease in P4 and delayed luteal regression. A similar outcome was evident in pseudopregnant TNFRI(-/-) animals. Treatment of luteal microvascular endothelial cells (MVECs) with TNF provoked a significant increase in ASMase activity when compared with the corresponding controls. Furthermore, TNF-induced MVEC death was inhibited in the ASMase(-/-) mice. The ASMase(-/-) mice displayed no obvious evidence of luteal regression 24 h after treatment with PGF and were resistant to the PGF-induced decrease in P4. Together these data provide evidence that TNF plays an active role in luteolysis. Further studies are required to determine the deleterious effects of anti-inflammatory agents on basic ovarian processes.

Impact of fish oil-based lipid emulsion on serum triglyceride, bilirubin, and albumin levels in children with parenteral nutrition-associated liver disease.

Parenteral nutrition is known to cause liver injury in babies. The aim of this study is to investigate the effects of different lipid emulsions on parenteral nutrition-associated cholestasis in infants. In addition, there may be a relationship between the lipid emulsion and triglyceride levels. Furthermore, triglyceride levels may correlate with direct bilirubin and albumin, as markers of liver impairment and nutritional status. Patients with parenteral nutrition-associated cholestasis who were treated with a fish oil-based lipid emulsion (n = 18) were prospectively followed for triglyceride, direct bilirubin, and albumin levels and compared with patients who were maintained on a soy-based lipid emulsion (n = 59). Triglyceride levels decreased in the fish oil cohort from a mean of 140 mg/dL at wk 0 to 40 mg/dL at wk 20 but remained unchanged at approximately 140 mg/dL in the soybean cohort. Triglyceride levels of patients treated with fish oil declined over time, while those receiving soybean oil did not. Also, changes in triglyceride levels over time were directly correlated with direct bilirubin and inversely related to albumin levels. These findings may indicate an added benefit of reduced triglyceride levels for patients treated with fish oil and this effect coincides with markers for improved liver function and nutritional status.

Ablation of leptin signaling disrupts the establishment, development, and maintenance of endometriosis-like lesions in a murine model.

Leptin, a 16-kDa cytokine, has been implicated in several reproductive processes and disorders. Notably, elevated leptin levels in the peritoneal fluid of women with mild endometriosis has been demonstrated, suggesting a role for this cytokine in the early stages of disease establishment. To gain insight into the functional significance of leptin during the initial requisite proliferative and neovascularization events involved in endometriosis, we investigated the effect of disruption of in vivo leptin signaling on the establishment and/or maintenance of an endometriosis-like lesion in a syngeneic immunocompetent mouse model of endometriosis. Findings of this study show that the disruption of leptin signaling by ip injection of the pegylated leptin peptide receptor antagonist (LPrA) impairs the establishment of endometriosis-like lesions (derived from uteri of C57BL/6 female siblings) and results in a reduction of viable organized glandular epithelium, vascular endothelial growth factor-A expression, and mitotic activity. LPrA treatment resulted in a significant reduction of microvascular density in endometriosis-like lesions after continuous and acute courses. Endometriosis-like lesions (derived from tissue with functional leptin receptor) of Lepr(db) hosts (nonfunctional leptin receptor) were phenotypically similar to those of LPrA-treated mice. Our results confirm that leptin signaling is a necessary component in lesion proliferation, early vascular recruitment, and maintenance of neoangiogenesis in a murine model of endometriosis.

Fish oil prevents essential fatty acid deficiency and enhances growth: clinical and biochemical implications.

Fish oil, a rich source of omega-3 fatty acids, has never been used as the sole source of lipid in clinical practice for fear of development of essential fatty acid deficiency, as it lacks the believed requisite levels of linoleic acid, an omega-6 fatty acid. The objectives of this study were to establish biochemical standards for fish oil as the sole fat and to test the hypothesis that fish oil contains adequate amounts of omega-6 fatty acids to prevent essential fatty acid deficiency. Forty mice were divided into 2 groups that were either pair fed or allowed to eat ad libitum. In each group, 4 subgroups of 5 mice were fed 1%, 5%, and 10% fish oil diets by weight or a control soybean diet for 9 weeks. Blood was collected at 4 time points, and fatty acid analysis was performed. Food intake and weight status were monitored. All groups but the pair-fed 1% fish oil group gained weight, and the 5% fish oil group showed the highest caloric efficiency in both pair-fed and ad libitum groups. Fatty acid profiles for the 1% fish oil group displayed clear essential fatty acid deficiency, 5% fish oil appeared marginal, and 10% and soybean oil diets were found to prevent essential fatty acid deficiency. Fish oil enhances growth through higher caloric efficiency. We established a total omega-6 fatty acid requirement of between 0.30% and 0.56% of dietary energy, approximately half of the conventionally believed 1% as linoleic acid. This can presumably be attributed to the fact that fish oil contains not only a small amount of linoleic acid, but also arachidonic acid, which has greater efficiency to meet omega-6 fatty acid requirements.

Inhibition of intra-abdominal adhesion formation with the angiogenesis inhibitor sunitinib.

OBJECTIVE: To determine the effects of sunitinib, a vascular endothelial growth factor receptor 2 (VEGFR-2) antagonist, on intra-abdominal adhesions. BACKGROUND: In the United States, complications from adhesions cost $1 billion and account for 846,000 inpatient days annually. Endothelial mitogens, such as VEGF, are up-regulated during adhesion formation. Sunitinib, a tyrosine kinase inhibitor with antiangiogenic and antitumor properties, may prevent or reduce postoperative abdominal adhesions by VEGFR-2 inhibition. METHODS: The cecum of 37 mice were abraded to promote adhesion formation and a silicone patch was sutured to the abdominal wall. The mice were randomized into two groups: Group 1 was treated with sunitinib in methylcellulose by oral gavage daily and Group 2 (control) received methylcellulose alone. After 10 d the mice were sacrificed and intra-abdominal adhesions were scored. The experiment was then repeated and mice were sacrificed on postoperative day 30 to assess the long-term effects of sunitinib. RESULTS: All 19 control mice developed intra-abdominal adhesions. Six of the 18 (33.3%) mice in the treatment group were adhesion-free. Collectively, the sunitinib-treated mice had a lower adhesion score [2.0 (IQR 0.0-5.0; range 0-8.0)] than the control group [5.0 (IQR 3.0-8.0; range 2.0-10.0) (P = 0.002)]. Long-term results were consistent with this finding [sunitinib 0.0 (IQR 0.0-3.0; range 0-7) and control 6.0 (IQR 3.0-7.0; range 0-12) (P = 0.049)]. CONCLUSION: Adhesion formation is angiogenesis-dependent and is in part mediated through VEGFR-2. Sunitinib, a VEGFR-2 antagonist, significantly reduces adhesion formation in a murine model. Antiangiogenic therapy may be an efficacious strategy to prevent or treat adhesions after intra-abdominal procedures.

Current clinical applications of omega-6 and omega-3 fatty acids.

BACKGROUND: Recent years have brought a resurgence of research interest in fatty acids, with studied fields running the gamut of human disease. This movement has run in parallel with an increased interest in using nutrition modalities as therapeutic measures, as opposed to their conventional role as energy sources. The aim of this manuscript is to provide a basic review of current clinical applications of omega-6 and omega-3 fatty acids, with a particular focus on the latter. METHODS: A selective review of the voluminous literature, including randomized controlled trials, meta-analyses, population studies, and case reports, was used to compile data and identify trends in pertinent clinical applications of fatty acid therapy. CONCLUSIONS: There are a myriad of disorders and maladies that seem to benefit from fatty acid supplementation, specifically omega-3 fatty acids. It has clearly been shown that omega-3 fatty acid supplementation provides a protective benefit in heart disease, and in particular sudden cardiac death. Rheumatoid arthritis (RA) is another disease entity that has been proven to benefit from this nutrition intervention, with improvement in symptoms and diminished nonsteroidal antiinflammatory drug (NSAID) usage. In addition, many psychiatric disorders, particularly schizophrenia and major depressive disorder (MDD), have shown positive results when supplementation has been used as an adjunct to standard pharmacotherapy. The remainder of clinical applications for omega-3 fatty acids requires further investigation. Specifically, according to preliminary clinical evidence, parenteral administration of fatty acids warrants further study.

Cholestasis and growth in neonates with gastroschisis.

PURPOSE: The aim of this study was to determine the incidence of cholestasis and the correlation between cholestasis and weight-for-age z scores in parenteral nutrition-dependent neonates with gastroschisis. METHODS: A single-center retrospective review of 59 infants born with gastroschisis from January 2000 to June 2007 was conducted. Demographic and clinical data were collected and analyzed. Subjects were divided into cholestatic and noncholestatic groups. Statistical analyses included the Student t test, Wilcoxon rank sum test, Fisher exact test, and a general linear model. RESULTS: Fifty-nine neonates with gastroschisis were identified, and 16 (28%) of 58 patients developed cholestasis. Younger gestational age and cholestasis were found to be independently associated with weight-for-age z score in 30 of 58 patients with available long-term follow-up data. CONCLUSIONS: Parenteral nutrition-dependent neonates with gastroschisis remain at considerable risk for the development of cholestasis. Both gestational age and cholestasis were found to be independent risk factors, predisposing these neonates to poor postnatal growth.

Surgical intervention in the setting of parenteral nutrition-associated cholestasis may exacerbate liver injury.

PURPOSE: This study compares postoperative markers of liver injury in patients receiving intravenous fish oil (IFO) with parenteral nutrition (PN)-associated cholestasis (PNAC) to patients with resolved PNAC. METHODS: A retrospective review of all cholestatic-IFO patients undergoing abdominal laparotomy between March 1, 2007, and July 1, 2009, led to inclusion of 23 patients who collectively underwent 27 abdominal operations (13 pre-PNAC resolution and 14 post-PNAC resolution). Direct bilirubin (DB), total bilirubin, and alanine aminotransferase levels were examined over time in relation to operations. The time to resume presurgical trend of decreasing DB was calculated. RESULTS: Sixty-nine percent (9/13) of pre-PNAC resolution procedures were associated with postoperative increase in DB compared with 7% (1/14) of post-PNAC resolution procedures associated with a recurrence of cholestasis (P = .02; odds ratio, 29.3; 95% confidence interval, 2.79-306.8). The median time to return to the preoperative downward trend of DB was 21 days. CONCLUSIONS: Operations before PNAC resolution may be associated with an increased postoperative DB, possibly reflecting an exacerbation of liver injury. Operations post-PNAC resolution on IFO had a comparatively low incidence of postoperative cholestasis recurrence. Excepting clinical indication otherwise, it may be advisable to delay surgical intervention in the setting of PNAC in certain cases.

Parenteral fish-oil-based lipid emulsion improves fatty acid profiles and lipids in parenteral nutrition-dependent children.

BACKGROUND: Total parenteral nutrition (PN), including fat administered as a soybean oil-based lipid emulsion (SOLE), is a life-saving therapy but may be complicated by PN-induced cholestasis and dyslipidemia. A fish-oil-based lipid emulsion (FOLE) as a component of PN can reverse PN-cholestasis and has been shown to improve lipid profiles. OBJECTIVE: The objective was to describe changes in the fatty acid and lipid profiles of children with PN-cholestasis who were treated with a FOLE. DESIGN: Lipid and fatty acid profiles of 79 pediatric patients who developed PN-cholestasis while receiving standard PN with a SOLE were examined before and after the switch to a FOLE. All patients received PN with the FOLE at a dose of 1 g · kg(-1) · d(-1) for ≥1 mo. RESULTS: The median (interquartile range) age at the start of the FOLE treatment was 91 (56-188) d. After a median (interquartile range) of 18.3 (9.4-41.4) wk of receiving the FOLE, the subjects' median total and direct bilirubin improved from 7.9 and 5.4 mg/dL to 0.5 and 0.2 mg/dL, respectively (P < 0.0001). Serum triglyceride, total cholesterol, LDL, and VLDL concentrations significantly decreased by 51.7%, 17.4%, 23.7%, and 47.9%, respectively. CONCLUSIONS: The switch from a SOLE to a FOLE in PN-dependent children with cholestasis and dyslipidemia was associated with a dramatic improvement in serum triglyceride and VLDL concentrations, a significant increase in serum omega-3 (n-3) fatty acids (EPA and DHA), and a decrease in serum omega-6 fatty acids (arachidonic acid). A FOLE may be the preferred lipid emulsion in patients with PN-cholestasis, dyslipidemia, or both. This trial is registered at clinicaltrials.gov as NCT00910104.

Pediatric rib lesions: a 13-year experience.

BACKGROUND: Rib lesions in the pediatric population are rare but significant processes and are often neoplastic. METHODS: All patients with primary rib lesions evaluated by the Department of Surgery at Children's Hospital Boston from 1992 to 2005 were studied. The patient's diagnosis, sex, symptoms and their duration, radiologic evaluation, biopsy status, surgical procedure, and follow-up were assessed. RESULTS: Thirty-three patients, ages 3 to 23 years (median, 12.7 years), were evaluated. Sixteen patients (48%) had benign and 17 (52%) had malignant lesions. Within the benign cohort of 16 patients, there were 6 osteochondromas, 4 aneurysmal bone cysts, and 2 fibrous dysplasias as well as 1 of each of the following: enchondroma, periosteal chondroma, eosinophilic granuloma, and chondrophyte. Within the malignant cohort of 17 patients, 13 were diagnosed with Ewing's sarcoma, 3 with osteogenic sarcoma, and 1 with chondrosarcoma. The sex distribution for the malignant group was 11 (65%) females and 6 (35%) males. CONCLUSIONS: Rib tumors are rare entities in the pediatric population. However, a significant number of rib lesions are malignant. Therefore, proper diagnosis and expeditious treatment are critical.

A critical role for matrix metalloproteinases in liver regeneration.

BACKGROUND: Matrix metalloproteinases (MMPs), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) are mediators of liver regeneration. To determine whether MMPs are required for normal hepatic regeneration, we performed 67% hepatectomies on mice treated with a broad-spectrum MMP-inhibitor, and assessed the effect on liver regeneration and urinary MMP activity. METHODS: Mice were subjected to sham operations, 67% hepatectomy, or 67% hepatectomy plus treatment with the broad-spectrum MMP inhibitor Marimastat. Urine collected preoperatively and for 8 d postoperatively was tested for MMP-2 and MMP-9 activity using zymography. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, TNF-alpha, IL-6, and hepatocyte growth factor levels were measured. Liver sections were analyzed by CD31 immunohistochemistry and microvessel density. Mitotic index and proliferating cell nuclear antigen labeling index were determined. RESULTS: The mean regenerating liver weight on postoperative day 8 was 0.72 +/- 0.01 grams for the hepatectomy Marimastat group, and 0.83 +/- 0.02 grams for the hepatectomy control group (P < 0.001). Urinary MMP-9 activity was elevated during hepatic regeneration, and decreased on postoperative day 8 when the liver returned to its preoperative mass. In contrast, urine from hepatectomy Marimastat mice, in which liver regeneration was successfully inhibited, showed consistently low levels of MMP-2 and MMP-9 activity. The hepatectomy Marimastat group also exhibited elevated serum IL-6 levels on post-operative day 8, while serum TNF-alpha soluble receptor II levels were unchanged. Hepatocyte growth factor levels were not significantly different between the control hepatectomy and hepatectomy Marimastat groups at days 2, 4, and 8. Liver microvessel density was reduced in the hepatectomy Marimastat group at day 4. Mitotic index and proliferating cell nuclear antigen index were significantly decreased in the Marimastat hepatectomy group at post-operative day 2. CONCLUSIONS: The broad-spectrum MMP-inhibitor Marimastat inhibits liver regeneration. Microvessel density is reduced at day 4. Furthermore, urinary MMP-9 is elevated during liver regeneration, and this effect is not observed when regeneration is inhibited by the broad-spectrum MMP-inhibitor Marimastat.

Safety and efficacy of a fish-oil-based fat emulsion in the treatment of parenteral nutrition-associated liver disease.

BACKGROUND: Parenteral nutrition-associated liver disease can be a progressive and fatal entity in children with short-bowel syndrome. Soybean-fat emulsions provided as part of standard parenteral nutrition may contribute to its pathophysiology. METHODS: We compared safety and efficacy outcomes of a fish-oil-based fat emulsion in 18 infants with short-bowel syndrome who developed cholestasis (serum direct bilirubin level of > 2 mg/dL) while receiving soybean emulsions with those from a historical cohort of 21 infants with short-bowel syndrome who also developed cholestasis while receiving soybean emulsions. The primary end point was time to reversal of cholestasis (3 consecutive measurements of serum direct bilirubin level of < or = 2 mg/dL). RESULTS: Among survivors, the median time to reversal of cholestasis was 9.4 and 44.1 weeks in the fish-oil and historical cohorts, respectively. Subjects who received fish-oil-based emulsion experienced reversal of cholestasis 4.8 times faster than those who received soybean emulsions and 6.8 times faster in analysis adjusted for baseline bilirubin concentration, gestational age, and the diagnosis of necrotizing enterocolitis. A total of 2 deaths and 0 liver transplantations were recorded in the fish-oil cohort and 7 deaths and 2 transplantations in the historical cohort. The provision of fish-oil-based fat emulsion was not associated with essential fatty acid deficiency, hypertriglyceridemia, coagulopathy, infections, or growth delay. CONCLUSIONS: Parenteral fish-oil-based fat emulsions are safe and may be effective in the treatment of parenteral nutrition-associated liver disease.

Vascular endothelial growth factor accelerates compensatory lung growth after unilateral pneumonectomy.

We hypothesize that compensatory lung growth after unilateral pneumonectomy in a murine model is, in part, angiogenesis dependent and can be altered using angiogenic agents, possibly through regulation of endothelial cell proliferation and apoptosis. Left pneumonectomy was performed in mice. Mice were then treated with proangiogenic factors [vascular endothelial growth factor (VEGF); basic fibroblast growth factor (bFGF)], VEGF receptor antibodies (MF-1, DC101), and VEGF receptor small molecule chemical inhibitors. Lung volume and mass were measured. The lungs were analyzed using immunohistochemistry by CD31 staining, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling, type II pneumocytes staining, and proliferating cell nuclear antigen. Compensatory lung growth was complete by postoperative day 10 and was associated with diffuse apoptosis of endothelial cells and pneumocytes. This process was accelerated by VEGF, such that growth was complete by postoperative day 4 with similar associated apoptosis. bFGF had no effect on lung growth. MF-1 and DC101 had no effect. The VEGF receptor small molecule chemical inhibitors also had no effect. VEGF, but not bFGF, accelerates growth. VEGF receptor inhibitors do not block growth, suggesting that other proangiogenic factors play a role or can compensate for VEGF receptor blockade. Diffuse apoptosis, endothelial cell and pneumocyte, occurs at cessation of both normal compensatory and VEGF-accelerated growth. Angiogenesis modulators may control growth via regulation of endothelial cell proliferation and apoptosis, although the exact relationship between endothelial cells and pneumocytes has yet to be determined. The fact that bFGF did not accelerate growth in our model when it did accelerate regeneration in the liver model suggests that angiogenesis during organ regeneration is regulated in an organ-specific manner.

Endothelial progenitor cells contribute to accelerated liver regeneration.

Two classes of circulating endothelial cells (CECs) have been identified and are distinguished by the expression of the stem cell markers CD117 or CD133 together with endothelial-specific antigens. Stem cell marker-positive CECs originate from bone marrow and have been designated as circulating endothelial progenitors (CEPs). We have demonstrated that exogenous vascular endothelial growth factor (VEGF) effectively mobilizes CEP cells. Furthermore, it has been demonstrated that VEGF regulates liver regeneration after partial hepatectomy. Although local endothelial cells can regulate tissue mass during liver regeneration, the contribution of CEPs to this process is unknown. We discovered loss of CD117 and CD133 from murine CEP cells and that both markers underestimated the number of bone marrow-derived CEP cells. We therefore used wild type and green fluorescent protein (GFP)-bone marrow transplanted into wild-type mice and performed 70% hepatectomies. Furthermore, we found that treatment with exogenous VEGF accelerated liver regeneration after 70% hepatectomy, whereas immunohistochemical analysis showed a 7-fold increase in the incorporation of CEP cells into liver vasculature. These results suggest that CEP cells play a role in regulating liver regeneration and that VEGF treatment can mobilize CEP cells to accelerate this process.

Microdeformational wound therapy: effects on angiogenesis and matrix metalloproteinases in chronic wounds of 3 debilitated patients.

The vacuum-assisted closure (VAC) device causes microdeformations of the wound surface in contact with the foam. Because angiogenesis and matrix metalloproteinase (MMP) activity are altered in chronic wounds, we hypothesized that microdeformations stimulate capillary formation and affect MMP activity. A VAC device was used to deliver microdeformational wound therapy (MDWT) to the chronic wounds of 3 debilitated patients. Debrided tissue was obtained from wound areas with and without foam contact. Microvessel density and MMP activity were determined by immunohistochemistry and zymography, respectively. Microvessel density of MDWT-treated wounds was 4.5% (+/-0.8) compared with areas not covered by foam [1.6% (+/-0.1)] (P = 0.05) during the first week of treatment and 2.7% (+/-0.3) compared with untreated tissue [1.3% (+/-0.1)] (P = 0.03) during the second treatment week. Wounds subjected to MDWT had greater microvessel density compared with the same wound prior to treatment [1.5% (+/-0.3)] (P = 0.02). MMP-9/NGAL (neutrophil gelatinase-associated lipocalin), MMP-9, latent MMP-2, and active MMP-2 were reduced by 15%-76% in MDWT-treated wounds. MDWT provides a favorable wound-healing environment by increasing angiogenesis and decreasing MMP activity in chronic wounds.