Developmental morphogens direct human induced pluripotent stem cells toward an annulus fibrosus-like cell phenotype

Introduction

Therapeutic interventions for intervertebral disc herniation remain scarce due to the inability of endogenous annulus fibrosus (AF) cells to respond to injury and drive tissue regeneration. Unlike other orthopedic tissues, such as cartilage, delivery of exogenous cells to the site of annular injury remains underdeveloped, largely due to a lack of an ideal cell source and the invasive nature of cell isolation. Human induced pluripotent stem cells (iPSCs) can be differentiated to specific cell fates using biochemical factors and are, therefore, an invaluable tool for cell therapy approaches. While differentiation protocols have been developed for cartilage and fibrous connective tissues (e.g., tendon), the signals that regulate the induction and differentiation of human iPSCs toward the AF fate remain unknown.

Methods

iPSC-derived sclerotome cells were treated with various combinations of developmental signals including transforming growth factor beta 3 (TGF-β3), connective tissue growth factor (CTGF), platelet derived growth factor BB (PDGF-BB), insulin-like growth factor 1 (IGF-1), or the Hedgehog pathway activator, Purmorphamine, and gene expression changes in major AF-associated ECM genes were assessed. The top performing combination treatments were further validated by using three distinct iPSC lines and by assessing the production of upregulated ECM proteins of interest. To conduct a broader analysis of the transcriptomic shifts elicited by each factor combination, and to compare genetic profiles of treated cells to mature human AF cells, a 96.96 Fluidigm gene expression array was applied, and principal component analysis was employed to identify the transcriptional signatures of each cell population and treatment group in comparison to native AF cells.

Results

TGF-β3, in combination with PDGF-BB, CTGF, or IGF-1, induced an upregulation of key AF ECM genes in iPSC-derived sclerotome cells. In particular, treatment with a combination of TGF-β3 with PDGF-BB for 14 days significantly increased gene expression of collagen II and aggrecan and increased protein deposition of collagen I and elastin compared to other treatment groups. Assessment of genes uniquely highly expressed by AF cells or SCL cells, respectively, revealed a shift toward the genetic profile of AF cells with the addition of TGF-β3 and PDGF-BB for 14 days.

Discussion

These findings represent an initial approach to guide human induced pluripotent stem cells toward an AF-like fate for cellular delivery strategies.

Major Depressive Disorder Impacts Peripheral Artery Disease Risk Through Intermediary Risk Factors

BACKGROUND

Major depressive disorder (MDD) has been identified as a causal risk factor for multiple forms of cardiovascular disease. Although observational evidence has linked MDD to peripheral artery disease (PAD), causal evidence of this relationship is lacking.

METHODS AND RESULTS

Inverse variance weighted 2-sample Mendelian randomization was used to test the association the between genetic liability for MDD and genetic liability for PAD. Genetic liability for MDD was associated with increased genetic liability for PAD (odds ratio [OR], 1.17 [95% CI, 1.06-1.29]; P=2.6×10-3). Genetic liability for MDD was also associated with increased genetically determined lifetime smoking (β=0.11 [95% CI, 0.078-0.14]; P=1.2×10-12), decreased alcohol intake (β=-0.078 [95% CI, -0.15 to 0]; P=0.043), and increased body mass index (β=0.10 [95% CI, 0.02-0.19]; P=1.8×10-2), which in turn were associated with genetic liability for PAD (smoking: OR, 2.81 [95% CI, 2.28-3.47], P=9.8×10-22; alcohol: OR, 0.77 [95% CI, 0.66-0.88]; P=1.8×10-4; body mass index: OR, 1.61 [95% CI, 1.52-1.7]; P=1.3×10-57). Controlling for lifetime smoking index, alcohol intake, and body mass index with multivariable Mendelian randomization completely attenuated the association between genetic liability for MDD with genetic liability for PAD.

CONCLUSIONS

This work provides evidence for a possible causal association between MDD and PAD that is dependent on intermediate risk factors, adding to the growing body of evidence suggesting that effective management and treatment of cardiovascular diseases may require a composite of physical and mental health interventions.

Insomnia and Early Incident Atrial Fibrillation: A 16-Year Cohort Study of Younger Men and Women Veterans

Background There is growing consideration of sleep disturbances and disorders in early cardiovascular risk, including atrial fibrillation (AF). Obstructive sleep apnea confers risk for AF but is highly comorbid with insomnia, another common sleep disorder. We sought to first determine the association of insomnia and early incident AF risk, and second, to determine if AF onset is earlier among those with insomnia. Methods and Results This retrospective analysis used electronic health records from a cohort study of US veterans who were discharged from military service since October 1, 2001 (ie, post-9/11) and received Veterans Health Administration care, 2001 to 2017. Time-varying, multivariate Cox proportional hazard models were used to examine the independent contribution of insomnia diagnosis to AF incidence while serially adjusting for demographics, lifestyle factors, clinical comorbidities including obstructive sleep apnea and psychiatric disorders, and health care utilization. Overall, 1 063 723 post-9/11 veterans (Mean age=28.2 years, 14% women) were followed for 10 years on average. There were 4168 cases of AF (0.42/1000 person-years). Insomnia was associated with a 32% greater adjusted risk of AF (95% CI, 1.21-1.43), and veterans with insomnia showed AF onset up to 2 years earlier. Insomnia-AF associations were similar after accounting for health care utilization (adjusted hazard ratio [aHR], 1.27 [95% CI, 1.17-1.39]), excluding veterans with obstructive sleep apnea (aHR, 1.38 [95% CI, 1.24-1.53]), and among those with a sleep study (aHR, 1.26 [95% CI, 1.07-1.50]). Conclusions In younger adults, insomnia was independently associated with incident AF. Additional studies should determine if this association differs by sex and if behavioral or pharmacological treatment for insomnia attenuates AF risk.

Applying cognitive task analysis to health services research

OBJECTIVE

Designing practical decision support tools and other health care technology in health services research relies on a clear understanding of the cognitive processes that underlie the use of these tools. Unfortunately, methods to explore cognitive processes are rarely used in health services research. Thus, the objective of this manuscript is to introduce cognitive task analysis (CTA), a family of methods to study cognitive processes involved in completing a task, to a health services research audience. This methods article describes CTA procedures, proposes a framework for their use in health services research studies, and provides an example of its application in a pilot study.

DATA SOURCES AND STUDY SETTING

Observations and interviews of health care providers involved in discharge planning at six hospitals in the Veterans Health Administration.

STUDY DESIGN

Qualitative study of discharge planning using CTA.

DATA COLLECTION/EXTRACTION METHODS

Data were collected from structured observations and semi-structured interviews using the Critical Decision Method and analyzed using thematic analysis.

PRINCIPAL FINDINGS

We developed an adaptation of CTA that could be used in a clinical environment to describe clinical decision-making and other cognitive processes. The adapted CTA framework guides the user through four steps: (1) Planning, (2) Environmental Analysis, (3) Knowledge Elicitation, and (4) Analyses and Results. This adapted CTA framework provides an iterative and systematic approach to identifying and describing the knowledge, expertise, thought processes, procedures, actors, goals, and mental strategies that underlie completing a clinical task.

CONCLUSIONS

A better understanding of the cognitive processes that underly clinical tasks is key to developing health care technology and decision-support tools that will have a meaningful impact on processes of care and patient outcomes. Our adapted framework offers a more rigorous and detailed method for identifying task-related cognitive processes in implementation studies and quality improvement. Our adaptation of this underutilized qualitative research method may be helpful to other researchers and inform future research in health services research.

Physical function and fatigue recovery at 6 months after hospitalization for COVID-19

INTRODUCTION

There are an increasing number of individuals with long-term symptoms of coronavirus-19 disease (COVID-19); however, the prognosis for recovery of physical function and fatigue after COVID-19 is uncertain.

OBJECTIVE

To report the changes in functional recovery between 1 and 6 months after hospitalization of adults hospitalized for COVID-19 and explore the baseline factors associated with physical function recovery.

DESIGN

A prospective cohort study.

SETTING

Tertiary care hospital.

PARTICIPANTS

U.S. adult COVID-19 survivors.

INTERVENTION

N/A.

MAIN OUTCOME MEASURES

Telephone interviews assessed three outcome domains: basic and instrumental activities of daily living (ADLs) performance, fatigue, and general physical function (Health Assessment Questionnaire [HAQ]).

RESULTS

The age of participants (n = 92) ranged from 22 to 95 years (54.3 ± 17.2). Across outcome domains, a majority (63%-67%) of participants developed new ADL impairment, fatigue, or worsening HAQ severity by 1 month. Of those, 50%-79% partially or fully recovered by 6 months, but 21%-50% did not recover at least partially. Fifteen to 30% developed new impairment between 1 and 6 months. For those without any improvement in ADL impairments at 6 months, lower socioeconomic status was significantly more common (p = .01) and age ≥ 65 (p = .06), trending toward being more common.

CONCLUSION

In this cohort, a substantial proportion of the participants who developed new ADL impairment, worsening fatigue, or HAQ severity after hospitalization for COVID-19 did not recover at least partially by 6 months after discharge. Evaluating functional status 1 month after discharge may be important in understanding functional prognosis and recovery after hospitalization for COVID-19.

Differential Associations of Cystatin C Versus Creatinine-Based Kidney Function With Risks of Cardiovascular Event and Mortality Among South Asian Individuals in the UK Biobank

Background South Asian individuals have increased cardiovascular disease and mortality risks. Reliance on creatinine- rather than cystatin C-based estimated glomerular filtration rate (eGFRcys) may underestimate the cardiovascular disease risk associated with chronic kidney disease. Methods and Results Among 7738 South Asian UK BioBank participants without prevalent heart failure (HF) or atherosclerotic cardiovascular disease, we investigated associations of 4 eGFRcys and creatinine-based estimated glomerular filtration rate categories (<45, 45-59, 60-89, and ≥90 mL/min per 1.73 m2) with risks of all-cause mortality, incident HF, and incident atherosclerotic cardiovascular disease. The mean age was 53±8 years; 4085 (53%) were women. Compared with creatinine, cystatin C identified triple the number of participants with estimated glomerular filtration <45 (n=35 versus n=113) and 6 times the number with estimated glomerular filtration 45 to 59 (n=80 versus n=481). After multivariable adjustment, the eGFRcys 45 to 59 category was associated with higher risks of mortality (hazard ratio [HR], 2.38 [95% CI, 1.55-3.65]) and incident HF (sub-HR [sHR], 1.87 [95% CI, 1.09-3.22]) versus the eGFRcys ≥90 category; the creatinine-based estimated glomerular filtration rate 45 to 59 category had no significant associations with outcomes. Of the 7623 participants with creatinine-based estimated glomerular filtration rate ≥60, 498 (6.5%) were reclassified into eGFRcys <60 categories. Participants who were reclassified as having eGFRcys <45 had higher risks of mortality (HR, 4.88 [95% CI, 2.56-9.31]), incident HF (sHR, 4.96 [95% CI, 2.21-11.16]), and incident atherosclerotic cardiovascular disease (sHR, 2.29 [95% CI, 1.14-4.61]) versus those with eGFRcys ≥90; those reclassified as having eGFRcys 45 to 59 had double the mortality risk (HR, 2.25 [95% CI, 1.45-3.51]). Conclusions Among South Asian individuals, cystatin C identified a high-risk chronic kidney disease population that was not detected by creatinine and enhanced estimated glomerular filtration rate-based risk stratification for mortality, incident HF, and incident atherosclerotic cardiovascular disease.

Effectiveness of the VA-Geriatric Resources for Assessment and Care of Elders (VA-GRACE) program: An observational cohort study

BACKGROUND

As the Department of Veterans Affairs (VA) healthcare system seeks to expand access to comprehensive geriatric assessments, evidence-based models of care are needed to support community-dwelling older persons. We evaluated the VA Geriatric Resources for Assessment and Care of Elders (VA-GRACE) program's effect on mortality and readmissions, as well as patient, caregiver, and staff satisfaction.

METHODS

This retrospective cohort included patients admitted to the Richard L. Roudebush VA hospital (2010-2019) who received VA-GRACE services post-discharge and usual care controls who were potentially eligible for VA-GRACE but did not receive services. The VA-GRACE program provided home-based comprehensive, multi-disciplinary geriatrics assessment, and ongoing care. Primary outcomes included 90-day and 1-year all-cause readmissions and mortality, and patient, caregiver, and staff satisfaction. We used propensity score modeling with overlapping weighting to adjust for differences in characteristics between groups.

RESULTS

VA-GRACE patients (N = 683) were older than controls (N = 4313) (mean age 78.3 ± 8.2 standard deviation vs. 72.2 ± 6.9 years; p < 0.001) and had greater comorbidity (median Charlson Comorbidity Index 3 vs. 0; p < 0.001). VA-GRACE patients had higher 90-day readmissions (adjusted odds ratio [aOR] 1.55 [95%CI 1.01-2.38]) and higher 1-year readmissions (aOR 1.74 [95%CI 1.22-2.48]). However, VA-GRACE patients had lower 90-day mortality (aOR 0.31 [95%CI 0.11-0.92]), but no statistically significant difference in 1-year mortality was observed (aOR 0.88 [95%CI 0.55-1.41]). Patients and caregivers reported that VA-GRACE home visits reduced travel burden and the program linked Veterans and caregivers to needed resources. Primary care providers reported that the VA-GRACE team helped to reduce their workload, improved medication management for their patients, and provided a view into patients' daily living situation.

CONCLUSIONS

The VA-GRACE program provides comprehensive geriatric assessments and care to high-risk, community-dwelling older persons with high rates of satisfaction from patients, caregivers, and providers. Widespread deployment of programs like VA-GRACE will be required to support Veterans aging in place.

Epigenetic modulation of visceral nociception

Epigenetics is a process that alters gene activity or phenotype without any changes in the underlying DNA sequence or genotype. These biological changes may have deleterious effects and can lead to various human diseases. Ongoing research is continuing to illuminate the role of epigenetics in a variety of pathophysiologic processes. Several categories of epigenetic mechanisms have been studied including chromatin remodeling, DNA methylation, histone modification, and non-coding RNA mechanisms. These epigenetic changes can have a long-term effect on gene expression without any underlying changes in the DNA sequences. The underlying pathophysiology of disorders of brain-gut interaction and stress-induced visceral pain are not fully understood and the role of epigenetic mechanisms in these disorders are starting to be better understood. Current work is underway to determine how epigenetics plays a role in the neurobiology of patients with chronic visceral pain and heightened visceral nociception. More recently, both animal models and human studies have shown how epigenetic regulation modulates stress-induced visceral pain. While much more work is needed to fully delineate the mechanistic role of epigenetics in the neurobiology of chronic visceral nociception, the current study by Louwies et al., in Neurogastroenterology and Motility provides additional evidence supporting the involvement of epigenetic alterations in the central nucleus of the amygdala in stress-induced visceral hypersensitivity in rodents.

The effect of brain serotonin deficiency on breathing is magnified by age

Serotonin is an important mediator modulating behavior, metabolism, sleep, control of breathing, and upper airway function, but the role of aging in serotonin-mediated effects has not been previously defined. Our study aimed to examine the effect of brain serotonin deficiency on breathing during sleep and metabolism in younger and older mice. We measured breathing during sleep, hypercapnic ventilatory response (HCVR), CO2 production (VCO2 ), and O2 consumption (VO2 ) in 16-18-week old and 40-44-week old mice with deficiency of tryptophan hydroxylase 2 (Tph2), which regulates serotonin synthesis specifically in neurons, compared to Tph2+/+ mice. As expected, aging decreased VCO2 and VO2 . Tph2 knockout resulted in an increase in both metabolic indexes and no interaction between age and the genotype was observed. During wakefulness, neither age nor genotype had an effect on minute ventilation. The genotype did not affect hypercapnic sensitivity in younger mice. During sleep, Tph2-/- mice showed significant decreases in maximal inspiratory flow in NREM sleep, respiratory rate, and oxyhemoglobin saturation in REM sleep, compared to wildtype, regardless of age. Neither serotonin deficiency nor aging affected the frequency of flow limited breaths (a marker of upper airway closure) or apneas. Serotonin deficiency increased the amount and efficiency of sleep only in older animals. In conclusion, younger Tph2-/- mice were able to defend their ventilation and phenotypically did not differ from wildtype during wakefulness. In contrast, both young and old Tph2-/- mice showed sleep-related hypoventilation, which was manifested by hypoxemia during REM sleep.