Hypoxia plays an important role in vascular development through hypoxia-inducible factor-1alpha (HIF-1alpha) accumulation and downstream pathway activation. We sought to explore the in vitro response of cultures of human embryonic stem cells (hESCs), induced pluripotent stem cells (iPSCs), human endothelial progenitor cells (hEPCs), and human umbilical cord vein endothelial cells (HUVECs) to normoxic and hypoxic oxygen tensions. We first measured dissolved oxygen (DO) in the media of adherent cultures in atmospheric (21% O(2)), physiological (5% O(2)), and hypoxic oxygen conditions (1% O(2)). In cultures of both hEPCs and HUVECs, lower oxygen consumption was observed when cultured in 1% O(2). At each oxygen tension, feeder-free cultured hESCs and iPSCs were found to consume comparable amounts of oxygen. Transport analysis revealed that the oxygen uptake rate (OUR) of hESCs and iPSCs decreased distinctly as DO availability decreased, whereas the OUR of all cell types was found to be low when cultured in 1% O(2), demonstrating cell adaptation to lower oxygen tensions by limiting oxygen consumption. Next, we examined HIF-1alpha accumulation and the expression of target genes, including VEGF and angiopoietins (ANGPT; angiogenic response), GLUT-1 (glucose transport), BNIP3, and BNIP3L (autophagy and apoptosis). Accumulations of HIF-1alpha were detected in all four cell lines cultured in 1% O(2). Corresponding upregulation of VEGF, ANGPT2, and GLUT-1 was observed in response to HIF-1alpha accumulation, whereas upregulation of ANGPT1 was detected only in hESCs and iPSCs. Upregulation of BNIP3 and BNIP3L was detected in all cells after 24-h culture in hypoxic conditions, whereas apoptosis was not detectable using flow cytometry analysis, suggesting that BNIP3 and BNIP3L can lead to cell autophagy rather than apoptosis. These results demonstrate adaptation of all cell types to hypoxia but different cellular responses, suggesting that continuous measurements and control over oxygen environments will enable us to guide cellular responses.

The generation of functional vascular networks has the potential to improve treatment for vascular diseases and to facilitate successful organ transplantation. Endothelial colony-forming cells (ECFCs) have robust proliferative potential and can form vascular networks in vivo. ECFCs are recruited from a bone marrow niche to the site of vascularization, where cues from the extracellular matrix instigate vascular morphogenesis. Although this process has been elucidated using natural matrix, little is known about vascular morphogenesis by ECFCs in synthetic matrix, a xeno-free scaffold that can provide a more controllable and clinically relevant alternative for regenerative medicine. We sought to study hyaluronic acid (HA) hydrogels as three-dimensional scaffolds for capillary-like structure formation from ECFCs, and to determine the crucial parameters needed to design such synthetic scaffolds. We found that ECFCs express HA-specific receptors and that vascular endothelial growth factor stimulates hyaluronidase expression in ECFCs. Using a well-defined and controllable three-dimensional HA culture system, we were able to decouple the effect of matrix viscoelasticity from changes in adhesion peptide density. We determined that decreasing matrix viscoelasticity, which corresponds to a loose ultrastructure, significantly increases ECFC vascular tube length and area, and that the effect of local delivery of vascular endothelial growth factor within the hydrogel depends on the makeup of the synthetic environment. Collectively, these results set forth initial design criteria that need to be considered in developing vascularized tissue constructs.

The clinical impact of tissue engineering depends upon our ability to direct cells to form tissues with characteristic structural and mechanical properties from the molecular level up to organized tissue. Induction and creation of functional vascular networks has been one of the main goals of tissue engineering either in vitro, for the transplantation of prevascularized constructs, or in vivo, for cellular organization within the implantation site. In most cases, tissue engineering attempts to recapitulate certain aspects of normal development in order to stimulate cell differentiation and functional tissue assembly. The induction of tissue growth generally involves the use of biodegradable and bioactive materials designed, ideally, to provide a mechanical, physical, and biochemical template for tissue regeneration. Human embryonic stem cells (hESCs), derived from the inner cell mass of a developing blastocyst, are capable of differentiating into all cell types of the body. Specifically, hESCs have the capability to differentiate and form blood vessels de novo in a process called vasculogenesis. Human ESC-derived endothelial progenitor cells (EPCs) and endothelial cells have substantial potential for microvessel formation, in vitro and in vivo. Human adult EPCs are being isolated to understand the fundamental biology of how these cells are regulated as a population and to explore whether these cells can be differentiated and reimplanted as a cellular therapy in order to arrest or even reverse damaged vasculature. This chapter focuses on advances made toward the generation and engineering of functional vascular tissue, focusing on both the scaffolds - the synthetic and biopolymer materials - and the cell sources - hESCs and hEPCs.

Severe thyrotoxicosis is an acute and life-threatening state of hyperthyroidism. While it is a rare presentation of hyperthyroidism, it is clinically significant because of its high mortality and necessitates early identification and treatment to reduce the incidence of poor outcomes. The most common causes of this hypermetabolic state are Graves' disease, toxic thyroid adenoma or multinodular goiter, thyroiditis, iodine-induced hyperthyroidism, and excessive intake of levothyroxine. The less common causes include trauma, medications (i.e., amiodarone), discontinuation of anti-thyroid medications, and interactions with sympathomimetic medications such as ketamine that may be administered during general anesthesia. Regardless of etiology, thyrotoxicosis management should be coordinated using an interdisciplinary team-based approach to optimize outcomes.We discuss a molar pregnancy requiring emergency surgery as an uncommon cause of thyrotoxicosis and highlight appropriate management steps. The patient's symptoms resolved post-operatively, and her postoperative laboratory results (thyroid function and beta-human chorionic gonadotropin {β-hCG}) were followed until they normalized. The patient's preoperative presentation and preparation with a multidisciplinary team discussion, intraoperative anesthetic considerations and course, and post-operative management and follow-up are described.

Purpose: Within the HIV population, the incidence of lung cancer is estimated to be 2-4 times that of the general population. Of the non AIDS associated malignancies, lung cancer is the leading cause of death among HIV patients who develop malignancy because of its advanced stage of presentation. The National Lung Cancer Screening Trial recently reported a 20% reduction in mortality for patients undergoing low dose computed tomography (CT) screening, but individuals with HIV diagnosis were excluded. To report the results of an observational pilot study of lung cancer CT screening in a cohort of HIV heavy smokers. Materials and Methods: A prospective cohort study was performed with 185 asymptomatic individuals with confirmed HIV diagnosis who had smoked 20 pack-years or more. All participants had baseline (prevalence) chest CT scanning and 107 patients (58.2%) also received at least one subsequent annual (incidence) examination of the chest and upper abdomen. All patients underwent hand held spirometry testing, cytologic analysis of sputa, and detailed health status questioning. Results: Of the 185 individuals, there were 31.4% females, 68.6% males, 90.3% African-Americans, 8.7% Caucasian, and 1.1% Hispanic. The median age at enrolment was 48 years, and the median number of smoking pack-years was 34. Non-calcified nodules were detected in 4 participants (2.1%) by low-dose prevalent CT compared to no nodules on incident CT scans. Only one patient with malignancy was detected (0.54%) on prevalent scanning and none on incident scanning. Stage of malignancy was advanced. No biopsies were undertaken for benign disease. CT evidence of COPD and coronary artery disease were present in 24% and 27% of patients, respectively. Additional CT findings of clinical importance were noted in the chest in 132 (71.7%) patients and extrathoracically in 30 (16.3%) of patients, respectively. Conclusion: The prevalence results of this pilot study are in line with other observational studies of greater sample size for HIV indeterminate patients. Although the sample size is small, it suggests no elevated incidence of lung cancer in HIV heavy smokers. Although the rate of incident scanning is low, CT screening of HIV patients is feasible. This justifies accruing a larger sample of HIV patients perhaps from an already well defined, large, prospective cohort of HIV heavy smokers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3679. doi:10.1158/1538-7445.AM2011-3679