Assessing the impact of recovery housing on healthcare utilization in Portland, Oregon.

Introduction: Central City Concern (CCC) operates several recovery housing sites in the Portland, Oregon metropolitan region, including the Blackburn Center (Blackburn) and the Richard L. Harris Building (Harris). This retrospective, observational study was designed to assess recovery housing's impact on inpatient detoxification readmission rates and healthcare utilization patterns. Methods: Our study population consisted of individuals discharged from CCC's Hooper Detox Stabilization Center from June 2019 to September 2020. A total of 75 clients housed at Blackburn, 63 clients housed at Harris, and 57 clients discharged as unhoused were included in the study sample. Using logistic regression for each of the two recovery housing groups relative to the unhoused group, we examined differences in readmissions to inpatient detoxification after their qualifying discharge. We then used Difference-In-Difference model to compare the per member per year (PMPY) use of different domains of health care before and after their qualifying discharge. Results: Compared to clients discharged as unhoused, Blackburn and Harris residents had lower risk of readmissions to inpatient detoxification treatment at 90- and 180-days post-discharge. Additionally, while the mean number of PMPY emergency department visits increased for clients discharged as unhoused in the post period, the average number of emergency department visits decreased for clients who obtained recovery housing at Blackburn (DiD=-3.65 PMPY, p-value=0.02) and at Harris (DiD=-3.87 PMPY, p-value=0.01). Conclusion: Findings highlight the impact and importance of recovery housing for individuals managing a substance use disorder and the value of healthcare system and public sector investment housing like Blackburn and Harris.

Evaluation of an Integrated Intervention to Address Clinical Care and Social Needs Among Patients with Type 2 Diabetes.

BACKGROUND: The Providence Diabetes Collective Impact Initiative (DCII) was designed to address the clinical challenges of type 2 diabetes and the social determinants of health (SDoH) challenges that exacerbate disease impact. OBJECTIVE: We assessed the impact of the DCII, a multifaceted intervention approach to diabetes treatment that employed both clinical and SDoH strategies, on access to medical and social services. DESIGN: The evaluation employed a cohort design and used an adjusted difference-in-difference model to compare treatment and control groups. PARTICIPANTS: Our study population consisted of 1220 people (740 treatment, 480 control), aged 18-65 years old with a pre-existing type 2 diabetes diagnosis who visited one of the seven Providence clinics (three treatment and four control) in the tri-county area of Portland, Oregon, between August 2019 and November 2020. INTERVENTIONS: The DCII threaded together clinical approaches such as outreach, standardized protocols, and diabetes self-management education and SDoH strategies including social needs screening, referral to a community resource desk, and social needs support (e.g., transportation) to create a comprehensive, multi-sector intervention. MAIN MEASURES: Outcome measures included SDoH screens, diabetes education participation, HbA1c, blood pressure, and virtual and in-person primary care utilization, as well as inpatient and emergency department hospitalization. KEY RESULTS: Compared to patients at the control clinics, patients at DCII clinics saw an increase in diabetes education (15.5%, p<0.001), were modestly more likely to receive SDoH screening (4.4%, p<0.087), and had an increase in the average number of virtual primary care visits of 0.35 per member, per year (p<0.001). No differences in HbA1c, blood pressure, or hospitalization were observed. CONCLUSIONS: DCII participation was associated with improvements in diabetes education use, SDoH screening, and some measures of care utilization.

Patient experience and healthcare utilization for a COVID-19 telemedicine home monitoring program offered in English and Spanish.

BACKGROUND: Telemedicine is a vital component of the healthcare system's response to COVID-19. In March of 2020, Providence health system rapidly implemented a telemedicine home monitoring program (HMP) for COVID-19 patients that included use of at-home pulse oximeters and thermometers and text-based surveys to monitor symptoms. By June 2020, Providence updated the HMP to be offered in Spanish. This program was implemented before COVID-19 testing was readily available and therefore was offered to all patients suspected of having COVID-19. This study examines engagement, experience, and utilization patterns for English and Spanish-speaking patients engaged in the COVID-19 HMP. METHODS: A retrospective review of program data was used to understand HMP patient engagement (responsiveness to three daily text to monitor symptoms), satisfaction with the program (likelihood to recommend the program) as well as comfort using home monitoring devices and comfort recovering from home. To understand impact on care for COVID-19 confirmed cases, we used electronic health records to measure patterns in healthcare use for COVID-19 positive HMP participants and non-HMP propensity weighted controls. All patients enrolled in the COVID-19 HMP from March-October 2020 were included in the study. Patients tested for COVID-19 during the time window and not enrolled in HMP were included in the propensity-weighted comparison group. Descriptive and regression analyses were performed overall and stratified by English and Spanish speakers. RESULTS: Of the 4,358 HMP participants, 75.5% identified as English speakers and 18.2% identified as Spanish speakers. There was high level of responsiveness to three daily text-based surveys monitoring symptoms engagement (>80%) and a high level of comfort using the home monitoring devices (thermometers and pulse oximeters) for English- and Spanish-speaking participants (97.3% and 99.6%, respectively). The majority of English (95.7%) and Spanish-speaking (100%) patients felt safe monitoring their condition from home and had high satisfaction with the HMP (76.5% and 83.6%, respectively). English and Spanish-speaking COVID-19 positive HMP participants had more outpatient and emergency departments (ED) encounters than non-participants 7 and 30 days after their positive test. CONCLUSION: This widely implemented HMP provided participants with a sense of safety and satisfaction and its use was associated with more outpatient care and ED encounters. These outcomes were comparable across English and Spanish-speakers, highlighting the importance and potential impact of language-concordant telemedicine.

Local Housing Choice Voucher Distribution Policies Impact Healthcare Utilization: a Randomized Natural Experiment.

While associations between obtaining affordable housing and improved health care are well documented, insufficient funding often forces housing authorities to prioritize limited housing vouchers to specific populations. We assessed the impact of obtaining housing on health care utilization at two urban housing authorities with different distribution policies: Housing Authority A prioritized seniors and people with disabilities, while Housing Authority B prioritized medically complex individuals and families with school-aged children. Both housing authorities used random selection to distribute vouchers, allowing us to conduct a randomized natural experiment of cases and waitlisted controls. No significant demographic differences were present between those receiving vouchers and waitlisted controls. Housing Authority A vouchers were associated with increased outpatient visits (OR = 1.19; P = 0.051). Housing Authority B vouchers decreased the likelihood of emergency department visits (OR = 0.61; P = 0.042). This study provides evidence that, while obtaining housing can result in better health care outcomes overall, local prioritization policies can influence that impact.

Health and Health Care Use Strongly Associated with Cumulative Burden of Social Determinants of Health.

Understanding health outcomes and patterns of health care utilization associated with patients' cumulative social determinant of health (SDOH) risk is essential to supporting better health care. This study compared mental and physical health outcomes and health care utilization by increasing number of social needs among a clinical adult population. Surveys were sent to 6000 patients with recent visits to 7 primary care clinics in Portland, Oregon in 2018. The final study sample included respondents who matched to medical claims data, N = 1748. The authors used a modified logistic regression model to estimate risk ratios for the relationship between cumulative SDOH factors and self-reported chronic conditions, and a 2-part model to estimate the effects of cumulative SDOH risk on health care utilization. Increased SDOH need was associated with increasing likelihood of worse self-reported health outcomes, especially mental health. Compared with those with no SDOH need, having 1-2 SDOH need(s) (adjusted risk ratio [aRR] 1.25; 95% confidence interval [CI]: 1.06-1.46) and 3 or more SDOH needs (aRR 1.45; 95% CI: 1.22-1.73) had a greater risk of reporting any behavioral health condition. However, the number of SDOH had a graded but inverse impact on use of mental health care services where fewer visits were observed among those using care. Having SDOH was associated with increased likelihood of having an emergency department visit and increased number of primary care visits. This study demonstrates the compounding impact of SDOH on health and health care use. This highlights the importance of collecting SDOH, including the total number of SDOH needs, when considering a patient's health and health care.

Effect of a Health System-Sponsored Mobile App on Perinatal Health Behaviors: Retrospective Cohort Study.

BACKGROUND: Pregnancy mobile apps are becoming increasingly popular, with parents-to-be seeking information related to their pregnancy and their baby through mobile technology. This increase raises the need for prenatal apps with evidence-based content that is personalized and reliable. Previous studies have looked at whether prenatal apps impact health and behavior outcomes among pregnant and postpartum individuals; however, research has been limited. OBJECTIVE: The primary objective of this study is to assess whether the use of a health system-sponsored mobile app-Circle by Providence-aimed at providing personalized and reliable health information on pregnancy, postpartum recovery, and infant care is associated with improved health outcomes and increased healthy behaviors and knowledge among users. METHODS: This observational study compared app users and app nonusers using a self-reported survey and electronic medical records. The study took place over 18 months and was conducted at Providence St. Joseph Health in Portland, Oregon. The sample included patients who received prenatal care at one of seven Providence clinics and had a live birth at a Providence hospital. Recruitment occurred on a rolling basis and only those who completed the survey were included. Survey respondents were separated into app users and app nonusers, and survey responses and clinical outcomes were compared across groups using univariate and adjusted multivariate logistic regression. RESULTS: A total of 567 participants were enrolled in the study-167 in the app user group and 400 in the nonuser group. We found statistically significant differences between the two groups for certain behavior outcomes: subjects who used the app had 75% greater odds of breastfeeding beyond 6 months postpartum (P=.012), were less likely to miss prenatal appointments (P=.046), and were 50% more likely to exercise 3 or more times a week during pregnancy (P=.04). There were no differences in nutritional measures, including whether they took prenatal vitamins, ate 5 fruits or vegetables a day, or drank caffeine. We found no differences in many of the infant care outcomes; however, there was an increase in awareness of "purple crying." Finally, there were no significant differences in measured clinical health outcomes, including cesarean births, length of hospital stays (in minutes), low birth weight infants, preterm births, small-for-gestational-age births, large-for-gestational-age births, and neonatal intensive care unit stays. CONCLUSIONS: The use of the Circle app, which provides access to personalized and evidence-based health information, was associated with an increase in certain healthy behaviors and health knowledge, although there was no impact on clinical health outcomes. More research is needed to determine the impact of mobile prenatal apps on healthy pregnancies, clinical health outcomes, and infant care.

Understanding the Socioeconomic and Health Challenges of the Medicaid Expansion Population in Oregon.

Following the Patient Protection and Affordable Care Act, Medicaid eligibility in the United States expanded to include low-income adults. One key challenge for organizations and providers serving the Medicaid population was predicting if and how this change would alter the composition of enrollees. This study characterized demographics, socioeconomic challenges, and health of the expansion and non-expansion Medicaid populations in a metropolitan area in Oregon using a survey and Medicaid claims. Results showed that the expansion population has more men and non-English speakers than the non-expansion population. They also have greater education and employment, but face similar socioeconomic challenges including struggling to meet basic needs and housing instability. This study also found comparable self-reported physical and mental health, but lower prevalence of physical or mental health diagnoses and several ambulatory care reactive conditions including hypertension, obesity, and type 2 diabetes. The authors concluded that expansion and non-expansion populations differ in sex, language, education, employment, and health, but they face similar socioeconomic challenges. This information is useful for organizations coordinating and providing care to Medicaid members so they can understand the needs of the population and set appropriate population health management strategies.

Identifying underlying constructs of childhood adversity in a low-income population.

BACKGROUND: Extensive research has documented the association between adverse childhood experiences (ACEs) and poor outcomes later in life, as well as the high prevalence of ACEs in the American population. Studies consistently find that over half of American adults have experienced at least one ACE. Despite this, research on the long-term impacts of ACEs is challenging due to the complex nature of adversity. OBJECTIVE: Our study aimed to define underlying constructs of adversity, and explore how they changed throughout childhood, in a low-income population. PARTICIPANTS AND SETTING: We fielded a survey to Medicaid-enrolled adults in the Portland, OR metropolitan area. METHODS: Our survey captured different experiences in childhood, including relationships and support, educational challenges, housing and employment stability, neighborhood environment, discrimination, abuse, neglect, and household dysfunction; questions were asked for 6-12 and 13-18 years of age. We then used factor analysis to identify underlying constructs of adversity in the two age ranges. RESULTS: We identified two factors - Inadequate Emotional Support and Instability - in each age range. Inadequate Emotional Support remained consistent in both time periods while the Instability factor changed, expanding from household-centric experiences in childhood to a wider variety of experiences in adolescence. Additionally, a number of variables did not load on either factor in either age range. CONCLUSIONS: These results underscore the importance of expanding how we think about instability specifically, and childhood adversity in general.

Formerly Homeless People Had Lower Overall Health Care Expenditures After Moving Into Supportive Housing.

The provision of supportive housing is often recognized as important public policy, but it also plays a role in health care reform. Health care costs for the homeless reflect both their medical complexity and psychosocial risk factors. Supportive housing attempts to moderate both by providing stable places to live along with on-site integrated health services. In this pilot study we used a mixture of survey and administrative claims data to evaluate outcomes for formerly homeless people who were living in a supportive housing facility in Oregon between 2010 and 2014. Results from the claims analysis showed significantly lower overall health care expenditures for the people after they moved into supportive housing. Expenditure changes were driven primarily by reductions in emergency and inpatient care. Survey data suggest that the savings were not at the expense of quality: Respondents reported improved access to care, stronger primary care connections, and better subjective health outcomes. Together, these results indicate a potential association between supportive housing and reduced health care costs that warrants deeper consideration as part of ongoing health care reforms.

CpG preconditioning regulates miRNA expression that modulates genomic reprogramming associated with neuroprotection against ischemic injury.

Cytosine-phosphate-guanine (CpG) preconditioning reprograms the genomic response to stroke to protect the brain against ischemic injury. The mechanisms underlying genomic reprogramming are incompletely understood. MicroRNAs (miRNAs) regulate gene expression; however, their role in modulating gene responses produced by CpG preconditioning is unknown. We evaluated brain miRNA expression in response to CpG preconditioning before and after stroke using microarray. Importantly, we have data from previous gene microarrays under the same conditions, which allowed integration of miRNA and gene expression data to specifically identify regulated miRNA gene targets. CpG preconditioning did not significantly alter miRNA expression before stroke, indicating that miRNA regulation is not critical for the initiation of preconditioning-induced neuroprotection. However, after stroke, differentially regulated miRNAs between CpG- and saline-treated animals associated with the upregulation of several neuroprotective genes, implicating these miRNAs in genomic reprogramming that increases neuroprotection. Statistical analysis revealed that the miRNA targets were enriched in the gene population regulated in the setting of stroke, implying that miRNAs likely orchestrate this gene expression. These data suggest that miRNAs regulate endogenous responses to stroke and that manipulation of these miRNAs may have the potential to acutely activate novel neuroprotective processes that reduce damage.

Modeling dynamic regulatory processes in stroke.

The ability to examine the behavior of biological systems in silico has the potential to greatly accelerate the pace of discovery in diseases, such as stroke, where in vivo analysis is time intensive and costly. In this paper we describe an approach for in silico examination of responses of the blood transcriptome to neuroprotective agents and subsequent stroke through the development of dynamic models of the regulatory processes observed in the experimental gene expression data. First, we identified functional gene clusters from these data. Next, we derived ordinary differential equations (ODEs) from the data relating these functional clusters to each other in terms of their regulatory influence on one another. Dynamic models were developed by coupling these ODEs into a model that simulates the expression of regulated functional clusters. By changing the magnitude of gene expression in the initial input state it was possible to assess the behavior of the networks through time under varying conditions since the dynamic model only requires an initial starting state, and does not require measurement of regulatory influences at each time point in order to make accurate predictions. We discuss the implications of our models on neuroprotection in stroke, explore the limitations of the approach, and report that an optimized dynamic model can provide accurate predictions of overall system behavior under several different neuroprotective paradigms.

Poly-ICLC preconditioning protects the blood-brain barrier against ischemic injury in vitro through type I interferon signaling.

Preconditioning with a low dose of harmful stimulus prior to injury induces tolerance to a subsequent ischemic challenge resulting in neuroprotection against stroke. Experimental models of preconditioning primarily focus on neurons as the cellular target of cerebral protection, while less attention has been paid to the cerebrovascular compartment, whose role in the pathogenesis of ischemic brain injury is crucial. We have shown that preconditioning with polyinosinic polycytidylic acid (poly-ICLC) protects against cerebral ischemic damage. To delineate the mechanism of poly-ICLC protection, we investigated whether poly-ICLC preconditioning preserves the function of the blood-brain barrier (BBB) in response to ischemic injury. Using an in vitro BBB model, we found that poly-ICLC treatment prior to exposure to oxygen-glucose deprivation maintained the paracellular and transcellular transport across the endothelium and attenuated the drop in transendothelial electric resistance. We found that poly-ICLC treatment induced interferon (IFN) ß mRNA expression in astrocytes and microglia and that type I IFN signaling in brain microvascular endothelial cells was required for protection. Importantly, this implicates a potential mechanism underlying neuroprotection in our in vivo experimental stroke model, where type I IFN signaling is required for poly-ICLC-induced neuroprotection against ischemic injury. In conclusion, we are the first to show that preconditioning with poly-ICLC attenuates ischemia-induced BBB dysfunction. This mechanism is likely an important feature of poly-ICLC-mediated neuroprotection and highlights the therapeutic potential of targeting BBB signaling pathways to protect the brain against stroke.

TLR9 bone marrow chimeric mice define a role for cerebral TNF in neuroprotection induced by CpG preconditioning.

Systemic preconditioning with the TLR9 ligand CpG induces neuroprotection against brain ischemic injury through a tumor necrosis factor (TNF)-dependent mechanism. It is unclear how systemic administration of CpG engages the brain to induce the protective phenotype. To address this, we created TLR9-deficient reciprocal bone marrow chimeric mice lacking TLR9 on either hematopoietic cells or radiation-resistant cells of nonhematopoietic origin. We report that wild-type mice reconstituted with TLR9-deficient hematopoietic cells failed to show neuroprotection after systemic CpG preconditioning. Further, while hematopoietic expression of TLR9 is required for CpG-induced neuroprotection it is not sufficient to restore protection to TLR9-deficient mice that are reconstituted with hematopoietic cells bearing TLR9. To determine whether the absence of protection was associated with TNF, we examined TNF levels in the systemic circulation and the brain. We found that although TNF is required for CpG preconditioning, systemic TNF levels did not correlate with the protective phenotype. However, induction of cerebral TNF mRNA required expression of TLR9 on both hematopoietic and nonhematopoietic cells and correlated with neuroprotection. In accordance with these results, we show the therapeutic potential of intranasal CpG preconditioning, which induces brain TNF mRNA and robust neuroprotection with no concomitant increase in systemic levels of TNF.

Identification and validation of Ifit1 as an important innate immune bottleneck.

The innate immune system plays important roles in a number of disparate processes. Foremost, innate immunity is a first responder to invasion by pathogens and triggers early defensive responses and recruits the adaptive immune system. The innate immune system also responds to endogenous damage signals that arise from tissue injury. Recently it has been found that innate immunity plays an important role in neuroprotection against ischemic stroke through the activation of the primary innate immune receptors, Toll-like receptors (TLRs). Using several large-scale transcriptomic data sets from mouse and mouse macrophage studies we identified targets predicted to be important in controlling innate immune processes initiated by TLR activation. Targets were identified as genes with high betweenness centrality, so-called bottlenecks, in networks inferred from statistical associations between gene expression patterns. A small set of putative bottlenecks were identified in each of the data sets investigated including interferon-stimulated genes (Ifit1, Ifi47, Tgtp and Oasl2) as well as genes uncharacterized in immune responses (Axud1 and Ppp1r15a). We further validated one of these targets, Ifit1, in mouse macrophages by showing that silencing it suppresses induction of predicted downstream genes by lipopolysaccharide (LPS)-mediated TLR4 activation through an unknown direct or indirect mechanism. Our study demonstrates the utility of network analysis for identification of interesting targets related to innate immune function, and highlights that Ifit1 can exert a positive regulatory effect on downstream genes.

LPS preconditioning redirects TLR signaling following stroke: TRIF-IRF3 plays a seminal role in mediating tolerance to ischemic injury.

BACKGROUND: Toll-like receptor 4 (TLR4) is activated in response to cerebral ischemia leading to substantial brain damage. In contrast, mild activation of TLR4 by preconditioning with low dose exposure to lipopolysaccharide (LPS) prior to cerebral ischemia dramatically improves outcome by reprogramming the signaling response to injury. This suggests that TLR4 signaling can be altered to induce an endogenously neuroprotective phenotype. However, the TLR4 signaling events involved in this neuroprotective response are poorly understood. Here we define several molecular mediators of the primary signaling cascades induced by LPS preconditioning that give rise to the reprogrammed response to cerebral ischemia and confer the neuroprotective phenotype. METHODS: C57BL6 mice were preconditioned with low dose LPS prior to transient middle cerebral artery occlusion (MCAO). Cortical tissue and blood were collected following MCAO. Microarray and qtPCR were performed to analyze gene expression associated with TLR4 signaling. EMSA and DNA binding ELISA were used to evaluate NFκB and IRF3 activity. Protein expression was determined using Western blot or ELISA. MyD88-/- and TRIF-/- mice were utilized to evaluate signaling in LPS preconditioning-induced neuroprotection. RESULTS: Gene expression analyses revealed that LPS preconditioning resulted in a marked upregulation of anti-inflammatory/type I IFN-associated genes following ischemia while pro-inflammatory genes induced following ischemia were present but not differentially modulated by LPS. Interestingly, although expression of pro-inflammatory genes was observed, there was decreased activity of NFκB p65 and increased presence of NFκB inhibitors, including Ship1, Tollip, and p105, in LPS-preconditioned mice following stroke. In contrast, IRF3 activity was enhanced in LPS-preconditioned mice following stroke. TRIF and MyD88 deficient mice revealed that neuroprotection induced by LPS depends on TLR4 signaling via TRIF, which activates IRF3, but does not depend on MyD88 signaling. CONCLUSION: Our results characterize several critical mediators of the TLR4 signaling events associated with neuroprotection. LPS preconditioning redirects TLR4 signaling in response to stroke through suppression of NFκB activity, enhanced IRF3 activity, and increased anti-inflammatory/type I IFN gene expression. Interestingly, this protective phenotype does not require the suppression of pro-inflammatory mediators. Furthermore, our results highlight a critical role for TRIF-IRF3 signaling as the governing mechanism in the neuroprotective response to stroke.

Multiple preconditioning paradigms converge on interferon regulatory factor-dependent signaling to promote tolerance to ischemic brain injury.

Ischemic tolerance can be induced by numerous preconditioning stimuli, including various Toll-like receptor (TLR) ligands. We have shown previously that systemic administration of the TLR4 ligand LPS or the TLR9 ligand unmethylated CpG oligodeoxynucleotide before transient brain ischemia in mice confers substantial protection against ischemic damage. To elucidate the molecular mechanisms of preconditioning, we compared brain genomic profiles in response to preconditioning with these TLR ligands and with preconditioning via exposure to brief ischemia. We found that exposure to the TLR ligands and brief ischemia induced genomic changes in the brain characteristic of a TLR pathway-mediated response. Interestingly, all three preconditioning stimuli resulted in a reprogrammed response to stroke injury that converged on a shared subset of 13 genes not evident in the genomic profile from brains that were subjected to stroke without prior preconditioning. Analysis of the promoter region of these shared genes showed sequences required for interferon regulatory factor (IRF)-mediated transcription. The importance of this IRF gene network was tested using mice deficient in IRF3 or IRF7. Our data show that both transcription factors are required for TLR-mediated preconditioning and neuroprotection. These studies are the first to discover a convergent mechanism of neuroprotection induced by preconditioning--one that potentially results in reprogramming of the TLR-mediated response to stroke and requires the presence of IRF3 and IRF7.

Localized alteration of microtubule polymerization in response to guidance cues.

Inhibition of microtubule dynamic instability prevents growth cone turning in response to guidance cues, yet specific changes in microtubule polymerization as growth cones encounter boundaries have not been investigated. In this study, we examined the rate and direction of microtubule polymerization in response to soluble nerve growth factor (NGF) and immobilized chondroitin sulfate proteoglycans (CSPGs) by expressing enhanced GFP-EB3 in rat pheochromocytoma (PC12) cells. GFP-EB3 comets were monitored in live cells using time-lapse epifluorescent microscopy. With an automated tracking system, the rate of microtubule polymerization was calculated as the frame-to-frame displacement of EB3 comets. Our results demonstrate that the rate of microtubule polymerization is increased following NGF treatment, whereas contact with CSPGs decreases microtubule polymerization rates. This reduction in microtubule polymerization rates was specifically localized to neurites in direct contact with CSPGs and not at noncontacting neurites. Additionally, we found an increase in the percentage of microtubules polymerizing in the retrograde direction in neurites at CSPG boundaries, with a concomitant decrease in the rate of retrograde microtubule polymerization. These results implicate localized changes in microtubule dynamics as an important component of the growth cone response to guidance cues.

Cytoskeletal structure regulates endothelial cell immunogenicity independent of fluid shear stress.

The cardiovascular disease atherosclerosis is directly linked to the functions of endothelial cells (ECs), which are affected by fluid shear stress (FSS). High, unidirectional FSS causes EC elongation with aligned cytoskeletal components and nonimmunogenic EC functions that protect against atherosclerosis. In contrast, low, oscillatory FSS is associated with cobblestone-shaped ECs with randomly oriented cytoskeletons and proinflammatory EC functions that promote atherosclerosis. Whether EC shape plays a role in EC immunogenic functions, independent of FSS, has not been previously determined. The goal of this study was to determine the effect of EC elongation and cytoskeletal alignment on the expression of inflammatory genes and functions. With the use of micropatterned lanes, EC elongation and cytoskeletal alignment were achieved in the absence of FSS. EC gene expression of key inflammation markers determined that the elongation and cytoskeletal alignment of micropattern-elongated ECs (MPECs) alone significantly downregulated VCAM-1 while having no effect on E-selectin and ICAM-1. The positive control of FSS-elongated ECs promoted E-selectin and VCAM-1 downregulation and upregulation of ICAM-1. Functionally, monocytic U937 cells formed weaker interactions on the surface of MPECs compared with cobblestone ECs. Interestingly, MPEC expression of the known FSS-dependent transcription factor krüppel-like factor 2 (KLF2), which promotes a nonimmunogenic EC phenotype, was significantly upregulated in MPECs compared with cobblestone ECs. Cytoskeletal regulation of KLF2 expression was shown to be dependent on microtubules. Therefore, the cellular elongation and cytoskeletal alignment of MPECs regulated immunogenic gene expression and functions and may act synergistically with FSS to create an EC surface with reduced inflammatory capability.

Distinct extracellular matrix microenvironments of progenitor and carotid endothelial cells.

Endothelial cells (ECs) produce and maintain the local extracellular matrix (ECM), a critical function that contributes to EC and blood vessel health. This function is also crucial to vascular tissue engineering, where endothelialization of vascular constructs require a cell source that readily produces and maintains ECM. In this study, baboon endothelial progenitor cell (EPC) deposition of ECM (laminin, collagen IV, and fibronectin) was characterized and compared to mature carotid ECs, evaluated in both elongated and cobblestone morphologies typically found in vivo. Microfluidic micropatterning was used to create 15-microm wide adhesive lanes with 45-microm spacing to reproduce the elongated EC morphology without the influence of external forces. Both EPCs and ECs elongated on micropatterned lanes had aligned actin cytoskeleton and readily deposited ECM. EPCs deposited and remodeled the ECM to a greater extent than ECs. Since a readily produced ECM can improve graft patency, EPCs are an advantageous cell source for endothelializing vascular constructs. Furthermore, EC deposition of ECM was dependent on cell morphology, where elongated ECs deposited more collagen IV and less fibronectin compared to matched cobblestone controls. Thus micropatterned surfaces controlled EC shape and ECM deposition, which ultimately has implications for the design of tissue-engineered vascular constructs.