Leptin enhances endothelial cell differentiation and angiogenesis in murine embryonic stem cells.

The metabolic regulation of leptin and its angiogenic effects have been well characterized in adult mammals. However, the role of leptin in the differentiation of embryonic stem cells (ESCs) to endothelial cells (ECs) has not been characterized. We hypothesized that leptin enhances the generation of ECs derived from ESCs and, in this way, promotes angiogenesis in embryonic vessels. To address this hypothesis, we utilized an in vitro model consisting of murine ESCs-derived embryoid bodies (EBs). Vascular density, EC and angiogenesis markers as well as phosphorylation levels of signal transducer and activator of transcription 3 (pSTAT3) were investigated in leptin-treated EBs and in untreated EBs as controls. ESC-derived ECs were isolated by magnetic sorting based on the expression of platelet endothelial cell adhesion molecule (PECAM-1/CD31). Significant upregulation of EC and angiogenic markers as well as higher vessel density were found in leptin-treated EBs compared to controls. CD31 positive enriched cells derived from leptin-treated EBs had improved proliferation and survival rate and showed higher levels of pSTAT3. These results suggested that leptin promotes EC differentiation and angiogenesis in mouse EBs and that janus tyrosine kinase (JAK)/STAT pathway can play a role in this biological process. Leptin-mediated EC differentiation and angiogenesis in ESCs can be a useful application towards regenerative medicine and tissue engineering.

Basic data related to thrombolytic therapy for acute venous thrombosis.

BACKGROUND: Treatment guidelines for thrombolysis in iliofemoral deep venous thrombosis (DVT) are based on a limited number of observational and prospective studies. The acute venous thrombosis: thrombus removal with adjunctive catheter-directed thrombolysis (ATTRACT) trial will be the first large, multicenter randomized control trial to evaluate the relative advantages of several current treatment strategies. The objective of this study was to summarize the existing data that inform the use of catheter-directed thrombolysis (CDT) or pharmacomechanical thrombectomy in the management of acute iliofemoral DVT. METHODS: A search of the current literature was done using PubMed, Ovid, and Cochrane databases for all available articles published up to December 2013. RESULTS: Of those studies, which included at least 25 patients, 19 case series were identified from 1996 to 2012. Treatment groups included anticoagulation, surgical thrombectomy, pharmacomechanical thrombectomy, and CDT. Cases observed in each ranged from 26 to 101. Three studies were identified which derived data from national multicenter registries. Only 2 randomized control trials were identified from 2002 to 2012. Both support the use of CDT over anticoagulation alone for treatment of iliofemoral DVT. CONCLUSIONS: Present treatment guidelines for acute iliofemoral DVT have been in flux and are derived from a relatively small amount of clinical data. They are summarized here in anticipation of results from the ongoing ATTRACT trial.

Characterization of microvascular endothelial cells isolated from the dermis of adult mouse tails.

Dermal microvascular endothelial cells (DMECs) play an important role in physiological and pathophysiological processes such as wound healing, cell differentiation, antigen-presentation, inflammation, tumor metastasis, and diabetes. The study of these processes requires a suitable and accessible in vitro model, such as murine DMECs (mDMECs). However, since these cells are difficult to isolate and propagate, some of their properties are not fully characterized. We isolated these cells from C57BL/6J adult mouse tail skin and purified them using magnetic sorting. Then, we tested several culture conditions and oxygen concentrations for mDMEC growth and propagation. After obtaining optimal culture conditions, we characterized the expression of EC markers and compared such expression with an established murine microvascular EC line (EOMA). Our results indicate that mDMECs isolated from mouse tails expressed most of the characteristic EC markers such as von Willebrand Factor (vWF), CD31, Tie1, Tie2, ANGPT1, ANGPT2, FLK-1, FLT-1, and VEGF-A. Further characterization demonstrated that these cells also expressed proteins involved in organogenesis such as bone morphogenetic proteins-2, -4 (BMP-2/-4), and their receptor (BMPR1A). Surprisingly, higher expression of vWF, ANGPT1, and BMP-2 was observed in mDMECs compared to EOMA cells. For mDMEC in vitro propagation, we found a twofold increase in cell proliferation in cells that grew at 1% O(2) compared to those cells that grew at standard 20% O(2.) Therefore, the method described herein for mDMECs isolation and propagation allowed us to analyze in more detail their biological properties that can be relevant for the study of pathological processes using mouse models.

Endothelial cells in co-culture enhance embryonic stem cell differentiation to pancreatic progenitors and insulin-producing cells through BMP signaling.

Endothelial cells (ECs) represent the major component of the embryonic pancreatic niche and play a key role in the differentiation of insulin-producing ß cells in vivo. However, it is unknown if ECs promote such differentiation in vitro. We investigated whether interaction of ECs with mouse embryoid bodies (EBs) in culture promotes differentiation of pancreatic progenitors and insulin-producing cells and the mechanisms involved. We developed a co-culture system of mouse EBs and human microvascular ECs (HMECs). An increase in the expression of the pancreatic markers PDX-1, Ngn3, Nkx6.1, proinsulin, GLUT-2, and Ptf1a was observed at the interface between EBs and ECs (EB-EC). No expression of these markers was found at the periphery of EBs cultured without ECs or those co-cultured with mouse embryonic fibroblasts (MEFs). At EB-EC interface, proinsulin and Nkx6.1 positive cells co-expressed phospho-Smad1/5/8 (pSmad1/5/8). Therefore, EBs were treated with HMEC conditioned media (HMEC-CM) suspecting soluble factors involved in bone morphogenetic protein (BMP) pathway activation. Upregulation of PDX-1, Ngn3, Nkx6.1, insulin-1, insulin-2, amylin, SUR1, GKS, and amylase as well as down-regulation of SST were detected in treated EBs. In addition, higher expression of BMP-2/-4 and their receptor (BMPR1A) were also found in these EBs. Recombinant human BMP-2 (rhBMP-2) mimicked the effects of the HMEC-CM on EBs. Noggin (NOG), a BMP antagonist, partially inhibited these effects. These results indicate that the differentiation of EBs to pancreatic progenitors and insulin-producing cells can be enhanced by ECs in vitro and that BMP pathway activation is central to this process.

Variations in the utilization of endovascular aneurysm repair reflect population risk factors and disease prevalence.

OBJECTIVE: Highly variable utilization rates for a diverse group of surgical procedures are commonly ascribed to physician practice patterns rather than clinical considerations. A previous investigation by our group showed that variations in the rates of carotid endarterectomy (CEA) actually reflected regional risk factors for atherosclerosis, not physician density or other socio-economic drivers. In this study, we examine the use of endovascular abdominal aortic aneurysm repair (EVAR) over six years to test our hypothesis that the utilization of innovative vascular procedures by vascular surgeons more closely reflects disease prevalence and consistent clinical judgment than non-medical factors. METHODS: The Nationwide Inpatient Samples and State Inpatient Databases (2001-2006) were accessed to document the number and type of aneurysm repairs (EVAR versus open). Multiple metrics pertaining to clinical risk factors, socioeconomic status, access to care, provider distribution, and local healthcare capacity were quantitated for each state. We performed bivariate analysis, Pearson (PC) or Spearman (SC) correlations, and multiple regression modeling. RESULTS: The total number of aneurysms repaired has not changed significantly (from 45,828 in 2001 to 45,111 in 2006). Over the same interval, the number of open AAA repair nationwide decreased by 48% while the number of AAA repaired endovascularly increased by 105%. In 2005, the utilization rate of EVAR among 29 states ranged widely from 39.3% to 69.9%. Use of EVAR was highest in states with higher incidences of aneurysms (PC = 0.43, P < .05), greater number of deaths from heart disease (PC = 0.42, P < .05), greater number of diabetes discharges (PC = 0.48, P < .005), higher number of carotid stenosis discharges (PC = 0.40, P < .05), and higher number of chronic obstructive pulmonary disorder (COPD) discharges (SC = 0.43, P < .05). Regional malpractice pressure, specifically the number of paid claims and mean malpractice premium, both exhibited positive correlations with the EVAR rate. The number of physicians, vascular surgeons, hospital beds, teaching hospitals, or trauma centers did not predict high utilization of EVAR nor did the other socio-economic indices tested. CONCLUSION: While there was substantial regional variation in the use of EVAR, utilization of the less morbid procedure was well correlated with higher risk populations (number of diabetic patients and deaths secondary to heart disease). Contrary to other studies of regional discrepancies in the utilization of some surgical procedures, it appears that the utilization of EVAR was not associated with physician distribution, socioeconomics, or other non-medical factors.

Pancreatic serous cystadenocarcinoma: a case report and review of the literature.

BACKGROUND: Serous cystic neoplasms of the pancreas are benign lesions with little chance for malignant degeneration. We report a case of malignant serous cystadenocarcinoma of the pancreas and review the literature. METHODS: Structured review of the literature was performed using PubMed and MEDLINE searches, and cases of serous cystadenocarcinoma of the pancreas were compiled. RESULTS: A 70-year-old man diagnosed with a serous cystadenoma was managed expectantly until he became symptomatic, and studies revealed an increase in the size of the lesion as well as duodenal invasion. The patient underwent a pancreaticoduodenectomy, and histopathological examination revealed a locally invasive cystadenocarcinoma without metastatic disease. Seven years later, the patient remains disease-free. Review of the literature identified 25 cases of serous cystadenocarcinoma published to date. The mean age at diagnosis is 68 +/- 2 years (range, 52 to 81), and women are affected more commonly (2:1). CONCLUSIONS: We conclude that there is a small but finite risk of malignancy for serous cystic neoplasms of the pancreas. The clinician should bear this in mind when faced with decisions regarding patient management. Prognosis is excellent with multiple reports of long-term survival even in the face of metastatic disease.

Enhancement of embryonic stem cell differentiation promoted by avian chorioallantoic membranes.

Avian chorioallantoic membrane (CAM) has been used as a model to explore angiogenesis and to study the microvasculature of transplanted tissues. Because CAM provides a vascular bed, cells can be implanted, and their development can be monitored and modified. We used the CAM model to study the differentiation process of embryoid bodies (EBs) derived from mouse embryonic stem cells (ESCs) influenced by the CAM vascular bed. After EBs were incubated in CAM for 5 days, they underwent further differentiation and became tissue masses (TMs) of different morphologies from those that grew outside CAM. Immunohistochemical analysis of TMs demonstrated tissue-specific markers such as neurofilament light, CD34, collagen IV, cardiac myosin heavy chain (MHC), and cardiotin. Differentiated mouse blood vessels stained with anti-CD31 were found within the TMs, as well as blood vessels stained positive for QH1 and QCPN, markers for quail endothelial cells and perinuclear quail antigen, respectively. Quail erythrocytes inside mouse blood vessels suggested a connection between existing quail vessels and blood vessels growing inside the TMs as a result of EB differentiation. Therefore, CAM could be a suitable model to trigger and study the differentiation of EBs in close interaction with surrogate quail blood vessels.

Meta-analysis in surgery: methods and limitations.

The growth of new knowledge continues to advance the surgical disciplines, and several types of literature reviews attempt to consolidate this expansion of information. Meta-analysis is one such method that integrates findings on the same subject from different studies. Within surgery, there is a wealth of literature on a given topic, which needs to be considered collectively. As such, meta-analyses have been performed to address issues like the use of bowel preparation for colorectal surgery and comparisons of outcomes for laparoscopic vs open surgical approaches. A basic understanding of the groundwork required for meta-analysis is fundamental toward interpreting and critiquing its results. This review provides an overview of the principles, application, and limitations of meta-analysis in the context of surgery.