A Tissue-Engineered Microvascular System to Evaluate Vascular Progenitor Cells for Angiogenic Therapies

The ability of tissue engineered constructs to replace diseased or damaged organs is limited without the incorporation of a functional vascular system. To design microvasculature that recapitulates the vascular niche functions for each tissue in the body, we investigated the following hypotheses: (1) cocultures of human umbilical cord blood-derived endothelial progenitor cells (hCB-EPCs) with mural cells can produce the microenvironmental cues necessary to support physiological microvessel formation in vitro; (2) poly(ethylene glycol) (PEG) hydrogel systems can support 3D microvessel formation by hCB-EPCs in coculture with mural cells; (3) mesenchymal cells, derived from either umbilical cord blood (MPCs) or bone marrow (MSCs), can serve as mural cells upon coculture with hCB-EPCs. Coculture ratios between 0.2 (16,000 cells/cm2) and 0.6 (48,000 cells/cm2) of hCB-EPCs plated upon 3.3 µg/ml of fibronectin-coated tissue culture plastic with (80,000 cells/cm2) of human aortic smooth muscle cells (SMCs), results in robust microvessel structures observable for several weeks in vitro. Endothelial basal media (EBM-2, Lonza) with 9% v/v fetal bovine serum (FBS) could support viability of both hCB-EPCs and SMCs. Coculture spatial arrangement of hCB-EPCs and SMCs significantly affected network formation with mixed systems showing greater connectivity and increased solution levels of angiogenic cytokines than lamellar systems. We extended this model into a 3D system by encapsulation of a 1 to 1 ratio of hCB-EPC and SMCs (30,000 cells/µl) within hydrogels of PEG-conjugated RGDS adhesive peptide (3.5 mM) and PEG-conjugated protease sensitive peptide (6 mM). Robust hCB-EPC microvessels formed within the gel with invasion up to 150 µm depths and parameters of total tubule length (12 mm/mm2), branch points (127/mm2), and average tubule thickness (27 µm). 3D hCB-EPC microvessels showed quiescence of hCB-EPCs (<1% proliferating cells), lumen formation, expression of EC proteins connexin 32 and VE-cadherin, eNOS, basement membrane formation by collagen IV and laminin, and perivascular investment of PDGFR-β+/α-SMA+ cells. MPCs present in <15% of isolations displayed >98% expression for mural markers PDGFR-β, α-SMA, NG2 and supported hCB-EPC by day 14 of coculture with total tubule lengths near 12 mm/mm2. hCB-EPCs cocultured with MSCs underwent cell loss by day 10 with a 4-fold reduction in CD31/PECAM+ cells, in comparison to controls of hCB-EPCs in SMC coculture. Changing the coculture media to endothelial growth media (EBM-2 + 2% v/v FBS + EGM-2 supplement containing VEGF, FGF-2, EGF, hydrocortisone, IGF-1, ascorbic acid, and heparin), promoted stable hCB-EPC network formation in MSC cocultures over 2 weeks in vitro, with total segment length per image area of 9 mm/mm2. Taken together, these findings demonstrate a tissue engineered system that can be utilized to evaluate vascular progenitor cells for angiogenic therapies.

Selecting renal replacement therapies: what do African American and non-African American patients and their families think others should know? A mixed methods study.

BACKGROUND: Little is known regarding the types of information African American and non-African American patients with chronic kidney disease (CKD) and their families need to inform renal replacement therapy (RRT) decisions. METHODS: In 20 structured group interviews, we elicited views of African American and non-African American patients with CKD and their families about factors that should be addressed in educational materials informing patients' RRT selection decisions. We asked participants to select factors from a list and obtained their open-ended feedback. RESULTS: Ten groups of patients (5 African American, 5 non-African American; total 68 individuals) and ten groups of family members (5 African American, 5 non-African American; total 62 individuals) participated. Patients and families had a range (none to extensive) of experiences with various RRTs. Patients identified morbidity or mortality, autonomy, treatment delivery, and symptoms as important factors to address. Family members identified similar factors but also cited the effects of RRT decisions on patients' psychological well-being and finances. Views of African American and non-African American participants were largely similar. CONCLUSIONS: Educational resources addressing the influence of RRT selection on patients' morbidity and mortality, autonomy, treatment delivery, and symptoms could help patients and their families select RRT options closely aligned with their values. Including information about the influence of RRT selection on patients' personal relationships and finances could enhance resources' cultural relevance for African Americans.

Baby on board: olfactory cues indicate pregnancy and fetal sex in a non-human primate.

Olfactory cues play an integral, albeit underappreciated, role in mediating vertebrate social and reproductive behaviour. These cues fluctuate with the signaller's hormonal condition, coincident with and informative about relevant aspects of its reproductive state, such as pubertal onset, change in season and, in females, timing of ovulation. Although pregnancy dramatically alters a female's endocrine profiles, which can be further influenced by fetal sex, the relationship between gestation and olfactory cues is poorly understood. We therefore examined the effects of pregnancy and fetal sex on volatile genital secretions in the ring-tailed lemur (Lemur catta), a strepsirrhine primate possessing complex olfactory mechanisms of reproductive signalling. While pregnant, dams altered and dampened their expression of volatile chemicals, with compound richness being particularly reduced in dams bearing sons. These changes were comparable in magnitude with other, published chemical differences among lemurs that are salient to conspecifics. Such olfactory 'signatures' of pregnancy may help guide social interactions, potentially promoting mother-infant recognition, reducing intragroup conflict or counteracting behavioural mechanisms of paternity confusion; cues that also advertise fetal sex may additionally facilitate differential sex allocation.

The impact of gestational age and fetal weight on the risk of failure of spinal anesthesia for cesarean delivery.

BACKGROUND: There are limited data about spinal dosing for cesarean delivery in preterm parturients. We investigated the hypothesis that preterm gestation is associated with an increased incidence of inadequate spinal anesthesia for cesarean delivery compared with term gestation. METHODS: We searched our perioperative database for women who underwent cesarean delivery under spinal or combined spinal-epidural anesthesia with hyperbaric bupivacaine ⩾10.5mg. The primary outcome was the incidence of inadequate surgical anesthesia needing conversion to general anesthesia or repetition or supplementation of the block. We divided patients into four categories: <28, 28 to <32, 32 to <37 and ⩾37weeks of gestation. The chi-square test was used to compare failure rates and a multivariable regression analysis was performed to investigate potential confounders of the relationship between gestational age and failure. RESULTS: A total of 5015 patients (3387 term and 1628 preterm) were included. There were 278 failures (5.5%). The incidence of failure was higher in preterm versus term patients (6.4% vs. 5.1%, P=0.02). Failure rates were 10.8%, 7.7%, 5.3% and 5% for <28, 28 to <32, 32 to <37 and ⩾37weeks of gestation, respectively. In the multivariable model, low birth weight (P<0.0001), gestational age (P=0.03), ethnicity (P=0.02) and use of combined spinal-epidural anesthesia (P<0.0001) were significantly associated with failure. CONCLUSIONS: At standard spinal doses of hyperbaric bupivacaine used in our practice (⩾10.5mg), there were higher odds of inadequate surgical anesthesia in preterm parturients. When adjusting for potential confounders, low birth weight was the main factor associated with failure.