Exploring patient experiences with and attitudes towards hypertension at a private hospital in Uganda: a qualitative study.

BACKGROUND: Hypertension is the leading risk factor for mortality worldwide and is more common in sub-Saharan Africa than any other region. Work to date confirms that a lack of human and material resources for healthcare access contributes to this gap. The ways in which patients' knowledge and attitudes toward hypertension determine their engagement with and adherence to available care, however, remains unclear. METHODS: We conducted an exploratory, qualitative descriptive study to assess awareness, knowledge, and attitudes towards hypertension and its management at a large private hospital in Kampala. We interviewed 64 participants (29 with hypertension and 34 without, 1 excluded) in English. General thematic analysis using the Integrated Conceptual Health Literacy Model was used to iteratively generate themes and categories. RESULTS: We identified three main themes: Timing of Hypertension Diagnosis, Aiming for Health Literacy, and the Influence of Knowledge on Behavior. Most participants with hypertension learned of their condition incidentally, speaking to the lack of awareness of hypertension as an asymptomatic condition. Drove nearly all participants to desire more information. However, many struggled to translate knowledge into self-management behaviors due to incomplete information and conflicting desires of participants regarding lifestyle and treatment. CONCLUSIONS: Internal patient factors had a substantial impact on adherence, calling attention to the need for educational interventions. Systemic barriers such as cost still existed even for those with insurance and need to be recognized by treating providers.

Hydrogels with tunable stress relaxation regulate stem cell fate and activity.

Natural extracellular matrices (ECMs) are viscoelastic and exhibit stress relaxation. However, hydrogels used as synthetic ECMs for three-dimensional (3D) culture are typically elastic. Here, we report a materials approach to tune the rate of stress relaxation of hydrogels for 3D culture, independently of the hydrogel's initial elastic modulus, degradation, and cell-adhesion-ligand density. We find that cell spreading, proliferation, and osteogenic differentiation of mesenchymal stem cells (MSCs) are all enhanced in cells cultured in gels with faster relaxation. Strikingly, MSCs form a mineralized, collagen-1-rich matrix similar to bone in rapidly relaxing hydrogels with an initial elastic modulus of 17 kPa. We also show that the effects of stress relaxation are mediated by adhesion-ligand binding, actomyosin contractility and mechanical clustering of adhesion ligands. Our findings highlight stress relaxation as a key characteristic of cell-ECM interactions and as an important design parameter of biomaterials for cell culture.

Hypertension screening, prevalence, treatment, and control at a large private hospital in Kampala, Uganda: A retrospective analysis.

Adult hypertension prevalence in Uganda is 27%, but only 8% are aware of their diagnosis, accordingly treatment and control levels are limited. The private sector provides at least half of care nationwide, but little is known about its effectiveness in hypertension control. We analyzed clinical data from 39 235 outpatient visits among 17 777 adult patients from July 2017 to August 2018 at Uganda's largest private hospital. We calculated blood pressure screening rate at every visit, and hypertension prevalence, medication treatment, and control rates among the 5 090 patients with two or more blood pressure checks who received any medications from the hospital's pharmacy. We defined hypertension in this group as 1) an average of two blood pressure measurements at separate consecutive visits, higher than 140 mm Hg systolic or 90 mm Hg diastolic, 2) receipt of any antihypertensive medication, or 3) the use of a hypertension electronic medical record code. We deemed hypertension control as normotensive at the most recent check. 12 821 (72.1%) of patients received at least 1 blood pressure check. Among the 5 090 patients above, 2 121 (41.6%) had hypertension (33.4% age-standardized to a world population standard): 1 915 (37.6%) with elevated blood pressure, and 170 (3.3%) were normotensive but receiving medication. 838 (39.4%) of patients with hypertension received medication at least once. Overall, 18.3% of patients achieved control (27% of treated patients, and 15% of untreated patients). Hypertension is common and incompletely controlled in this Ugandan private-sector population, suggesting several avenues for novel interventions.

Substrate stiffening promotes endothelial monolayer disruption through enhanced physical forces.

A hallmark of many, sometimes life-threatening, inflammatory diseases and disorders is vascular leakage. The extent and severity of vascular leakage is broadly mediated by the integrity of the endothelial cell (EC) monolayer, which is in turn governed by three major interactions: cell-cell and cell-substrate contacts, soluble mediators, and biomechanical forces. A potentially critical but essentially uninvestigated component mediating these interactions is the stiffness of the substrate to which the endothelial monolayer is adherent. Accordingly, we investigated the extent to which substrate stiffening influences endothelial monolayer disruption and the role of cell-cell and cell-substrate contacts, soluble mediators, and physical forces in that process. Traction force microscopy showed that forces between cell and cell and between cell and substrate were greater on stiffer substrates. On stiffer substrates, these forces were substantially enhanced by a hyperpermeability stimulus (thrombin, 1 U/ml), and gaps formed between cells. On softer substrates, by contrast, these forces were increased far less by thrombin, and gaps did not form between cells. This stiffness-dependent force enhancement was associated with increased Rho kinase activity, whereas inhibition of Rho kinase attenuated baseline forces and lessened thrombin-induced inter-EC gap formation. Our findings demonstrate a central role of physical forces in EC gap formation and highlight a novel physiological mechanism. Integrity of the endothelial monolayer is governed by its physical microenvironment, which in normal circumstances is compliant but during pathology becomes stiffer.

Assessing Providers' Approach to Hypertension Management at a Large, Private Hospital in Kampala, Uganda.

Background: Hypertension is increasingly prevalent in Uganda and its clinical management remains suboptimal across the country. Prior research has elucidated some of the factors contributing to poor control, but little is known about providers' approaches to hypertension management and perceptions of barriers to care. This is particularly true in private health care settings - despite the fact that the private sector provides a substantial and growing portion of health care in Uganda. Objective: Our exploratory, pragmatic qualitative study aimed to examine the factors affecting the quality of hypertension care from the perspective of providers working in an urban, private hospital in Uganda. We focused on the organizational and system-level factors influencing providers' approaches to management in the outpatient setting. Methods: We conducted interviews with 19 health care providers working in the outpatient setting of a 110-bed, private urban hospital in Kampala, Uganda. We then coded the interviews for thematic analysis, using an inductive approach to generate the study's findings. Findings: Several themes emerged around perceived barriers and facilitators to care. Providers cited patient beliefs and behaviors, driven in part by cultural norms, as a key challenge to hypertension control; however, most felt their own approach to hypertension treatment aligned with international guidelines. Providers struggled to collaborate with colleagues in coordinating the joint management of patients. Furthermore, they cited the high cost and limited availability of medication as barriers. Conclusions: These findings offer important strategic direction for intervention development specific to this Ugandan context: for example, regarding culturally-adapted patient education initiatives, or programs to improve access to essential medications. Other settings facing similar challenges scaling up management of hypertension may find the results useful for informing intervention development as well.

Collagen type V modulates fibroblast behavior dependent on substrate stiffness.

Collagen type V is highly expressed during tissue development and wound repair, but its exact function remains unclear. Cell binding to collagen V affects various basic cell functions and increased collagen V levels alter the structural organization and the stiffness of the ECM. We studied the combined effects of collagen V and substrate stiffness on the morphology, focal adhesion formation, and actin organization of fibroblasts. We found that a hybrid collagen I/V coating impairs fibroblast spreading on soft substrates (<10 kPa), but not on stiffer substrates (68 kPa or glass). In sharp contrast, a pure collagen I coating does not impair cell spreading on soft substrates. The impairment of cell spreading by collagen V is accompanied by diffuse actin staining patterns and small focal adhesions. These observations suggest that collagen V plays an essential role in modifying cell behavior during development and remodeling, when very soft tissues are present.

CD44 alternative splicing in gastric cancer cells is regulated by culture dimensionality and matrix stiffness.

Two-dimensional (2D) cultures often fail to mimic key architectural and physical features of the tumor microenvironment. Advances in biomaterial engineering allow the design of three-dimensional (3D) cultures within hydrogels that mimic important tumor-like features, unraveling cancer cell behaviors that would not have been observed in traditional 2D plastic surfaces. This study determined how 3D cultures impact CD44 alternative splicing in gastric cancer (GC) cells. In 3D cultures, GC cells lost expression of the standard CD44 isoform (CD44s), while gaining CD44 variant 6 (CD44v6) expression. This splicing switch was reversible, accelerated by nutrient shortage and delayed at lower initial cell densities, suggesting an environmental stress-induced response. It was further shown to be dependent on the hydrogel matrix mechanical properties and accompanied by the upregulation of genes involved in epithelial-mesenchymal transition (EMT), metabolism and angiogenesis. The 3D cultures reported here revealed the same CD44 alternative splicing pattern previously observed in human premalignant and malignant gastric lesions. These findings indicate that fundamental features of 3D cultures - such as soluble factors diffusion and mechanical cues - influence CD44 expression in GC cells. Moreover, this study provides a new model system to study CD44 dysfunction, whose role in cancer has been in the spotlight for decades.

From Skeletal Development to Tissue Engineering: Lessons from the Micromass Assay.

Damage and degeneration of the skeletal elements due to disease, trauma, and aging lead to a significant health and economical burden. To reduce this burden, skeletal tissue engineering strategies aim to regenerate functional bone and cartilage in the adult body. However, challenges still exist. Such challenges involve the identification of the external cues that determine differentiation, how to control chondrocyte hypertrophy, and how to achieve specific tissue patterns and boundaries. To address these issues, it could be insightful to look at skeletal development, a robust morphogenetic process that takes place during embryonic development and is commonly modeled in vitro by the micromass assay. In this review, we investigate what the tissue engineering field can learn from this assay. By comparing embryonic skeletal precursor cells from different anatomic locations and developmental stages in micromass, the external cues that guide lineage commitment can be identified. The signaling pathways regulating chondrocyte hypertrophy, and the cues required for tissue patterning, can be elucidated by combining the micromass assay with genetic, molecular, and engineering tools. The lessons from the micromass assay are limited by two major differences between developmental and regenerative skeletogenesis: cell type and scale. We highlight an important difference between embryonic and adult skeletal progenitor cells, in that adult progenitors are not able to form mesenchymal condensations spontaneously. Also, the mechanisms of tissue patterning need to be adjusted to the larger tissue engineering constructs. In conclusion, mechanistic insights of skeletal tissue generation gained from the micromass model could lead to improved tissue engineering strategies and constructs.

The effect of growth-mimicking continuous strain on the early stages of skeletal development in micromass culture.

Embryonic skeletogenesis involves proliferation, condensation and subsequent chondrogenic differentiation of mesenchymal precursor cells, and the strains and stresses inherent to these processes have been hypothesized to influence skeletal development. The aim of this study was to determine the effect of growth-mimicking strain on the process of early skeletal development in vitro. To this end, we applied continuous uniaxial strain to embryonic skeletal precursor cells in micromass culture. Strain was applied at different times of culture to specifically address the effect of mechanical loading on the sequential stages of cellular proliferation, condensation and differentiation. We found that growth-mimicking strain at all three times did not affect proliferation or chondrogenic differentiation under the tested conditions. However, the timing of the applied strain did play a role in the density of mesenchymal condensations. This finding suggests that a mechanically dynamic environment, and specifically strain, can influence skeletal patterning. The growth-mimicking micromass model presented here may be a useful tool for further studies into the role of mechanical loading in early skeletal development.

Substrate stress relaxation regulates cell spreading.

Studies of cellular mechanotransduction have converged upon the idea that cells sense extracellular matrix (ECM) elasticity by gauging resistance to the traction forces they exert on the ECM. However, these studies typically utilize purely elastic materials as substrates, whereas physiological ECMs are viscoelastic, and exhibit stress relaxation, so that cellular traction forces exerted by cells remodel the ECM. Here we investigate the influence of ECM stress relaxation on cell behaviour through computational modelling and cellular experiments. Surprisingly, both our computational model and experiments find that spreading for cells cultured on soft substrates that exhibit stress relaxation is greater than cells spreading on elastic substrates of the same modulus, but similar to that of cells spreading on stiffer elastic substrates. These findings challenge the current view of how cells sense and respond to the ECM.

Linear patterning of mesenchymal condensations is modulated by geometric constraints.

The development of the vertebral column starts with the formation of a linear array of mesenchymal condensations, forming the blueprint for the eventual alternating pattern of bone and cartilage. Despite growing insight into the molecular mechanisms of morphogenesis, the impact of the physical aspects of the environment is not well understood. We hypothesized that geometric boundary conditions may play a pivotal role in the linear patterning of condensations, as neighbouring tissues provide physical constraints to the cell population. To study the process of condensation and the patterning thereof under tightly controlled geometric constraints, we developed a novel in vitro model that combines micropatterning with the established micromass assay. The spacing and alignment of condensations changed with the width of the cell adhesive patterns, a phenomenon that could not be explained by cell availability alone. Moreover, the extent of chondrogenic commitment was increased on substrates with tighter geometric constraints. When the in vivo pattern of condensations was investigated in the developing vertebral column of chicken embryos, the measurements closely fit into the quantitative relation between geometric constraints and inter-condensation distance found in vitro. Together, these findings suggest a potential role of geometric constraints in skeletal patterning in a cellular process of self-organization.

Influence of the stiffness of three-dimensional alginate/collagen-I interpenetrating networks on fibroblast biology.

Wound dressing biomaterials are increasingly being designed to incorporate bioactive molecules to promote healing, but the impact of matrix mechanical properties on the biology of resident cells orchestrating skin repair and regeneration remains to be fully understood. This study investigated whether tuning the stiffness of a model wound dressing biomaterial could control the behavior of dermal fibroblasts. Fully interpenetrating networks (IPNs) of collagen-I and alginate were fabricated to enable gel stiffness to be tuned independently of gel architecture, polymer concentration or adhesion ligand density. Three-dimensional cultures of dermal fibroblasts encapsulated within matrices of different stiffness were shown to promote dramatically different cell morphologies, and enhanced stiffness resulted in upregulation of key-mediators of inflammation such as IL-10 and COX-2. These findings suggest that simply modulating the matrix mechanical properties of a given wound dressing biomaterial deposited at the wound site could regulate the progression of wound healing.

Cell mediated contraction in 3D cell-matrix constructs leads to spatially regulated osteogenic differentiation.

During embryonic development, morphogenetic processes give rise to a variety of shapes and patterns that lead to functional tissues and organs. While the impact of chemical signals on these processes is widely studied, the role of physical cues is less understood. The aim of this study was to test the hypothesis that the interplay of cell mediated contraction and mechanical boundary conditions alone can result in spatially regulated differentiation in simple 3D constructs. An experimental model consisting of a 3D cell-gel construct and a finite element (FE) model were used to study the effect of cellular traction exerted by mesenchymal stem cells (MSCs) on an initially homogeneous matrix under inhomogeneous boundary conditions. A robust shape change is observed due to contraction under time-varying mechanical boundary conditions, which is explained by the finite element model. Furthermore, distinct local differences in osteogenic differentiation are observed, with a spatial pattern independent of osteogenic factors in the culture medium. Regions that are predicted to have experienced relatively high shear stress at any time during contraction correlate with the regions of distinct osteogenesis. Taken together, these results support the underlying hypothesis that cellular contractility and mechanical boundary conditions alone can result in spatially regulated differentiation. These results will have important implications for tissue engineering and regeneration.