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Environmental stiffness is a crucial determinant of cell function. There is a long-standing quest for reproducible and (human matrix) bio-mimicking biomaterials with controllable mechanical properties to unravel the relationship between stiffness and cell behavior. Here, we evaluate methacrylated human recombinant collagen peptide (RCPhC1-MA) hydrogels as a matrix to control 3D microenvironmental stiffness and monitor cardiac cell response. We show that RCPhC1-MA can form hydrogels with reproducible stiffness in the range of human developmental and adult myocardium. Cardiomyocytes (hPSC-CMs) and cardiac fibroblasts (cFBs) remain viable for up to 14 days inside RCPhC1-MA hydrogels while the effect of hydrogel stiffness on extracellular matrix production and hPSC-CM contractility can be monitored in real-time. Interestingly, whereas the beating behavior of the hPSC-CM monocultures is affected by environmental stiffness, this effect ceases when cFBs are present. Together, we demonstrate RCPhC1-MA to be a promising candidate to mimic and control the 3D biomechanical environment of cardiac cells., Competing Interests: H.A. van Boxtel is an employee of Fujifilm Manufacturing Europe B.V. The results of this study were not influenced by him or any other employee of Fujifilm Manufacturing Europe B.V., (© 2023 The Author(s).)

The myocardium is a mechanically active tissue typified by anisotropy of the resident cells [cardiomyocytes (CMs) and cardiac fibroblasts (cFBs)] and the extracellular matrix (ECM). Upon ischemic injury, the anisotropic tissue is replaced by disorganized scar tissue, resulting in loss of coordinated contraction. Efforts to re-establish tissue anisotropy in the injured myocardium are hampered by a lack of understanding of how CM and/or cFB structural organization is affected by the two major physical cues inherent in the myocardium: ECM organization and cyclic mechanical strain. Herein, we investigate the singular and combined effect of ECM (dis)organization and cyclic strain in a two-dimensional human in vitro co-culture model of the myocardial microenvironment. We show that (an)isotropic ECM protein patterning can guide the orientation of CMs and cFBs, both in mono- and co-culture. Subsequent application of uniaxial cyclic strain-mimicking the local anisotropic deformation of beating myocardium-causes no effect when applied parallel to the anisotropic ECM. However, when cultured on isotropic substrates, cFBs, but not CMs, orient away from the direction of cyclic uniaxial strain (strain avoidance). In contrast, CMs show strain avoidance via active remodeling of their sarcomeres only when co-cultured with at least 30% cFBs. Paracrine signaling or N-cadherin-mediated communication between CMs and cFBs was no contributing factor. Our findings suggest that the mechanoresponsive cFBs provide structural guidance for CM orientation and elongation. Our study, therefore, highlights a synergistic mechanobiological interplay between CMs and cFBs in shaping tissue organization, which is of relevance for regenerating functionally organized myocardium., (© 2022 Author(s).)

Objective: Congenital heart disease (CHD) can affect the developing central nervous system, resulting in neurocognitive and behavioral deficits. Preoperative neurological abnormalities as well as sequelae of the open heart operations required to correct structural abnormalities of the heart contribute to these deficits. There are few studies examining the neurocognitive functioning of adults with CHD. This study sought to investigate multiple domains of neurocognitive functioning in adult survivors of CHD who had childhood cardiac surgery with either moderate or severe disease complexity., Design: A total of 48 adults (18-49 years of age) who had undergone cardiac surgery for CHD prior to five years of age participated in the study. CHD severity was classified as moderate or severe according to the 32nd Bethesda Guidelines. A computerized battery of standardized neurocognitive tests (CNS-Vital Signs), a validated rating scale of executive functioning, and demographic questionnaires were administered., Results: There were no significant differences between the moderate CHD group and normative data on any cognitive measure. In contrast, the severe CHD group differed from norms in multiple domains: psychomotor speed, processing speed, complex attention, reaction time, and on the overall neurocognitive index. Number of surgeries was strongly related to worse executive functioning. There was no association between age at first surgery or time since last surgery and neuropsychological functioning. Number of surgeries was also unrelated to neurocognitive test performance., Conclusions: Patients with severe CHD performed significantly worse on measures of processing speed, attention, and executive functioning. These findings may be useful in the long-term care of adults with congenital heart disease., (© 2016 Wiley Periodicals, Inc.)

Background: Adults with congenital heart disease (CHD) are often cared for at pediatric hospitals. There are no data describing the incidence or type of medication prescribing errors in adult patients admitted to a pediatric cardiovascular intensive care unit (CVICU)., Methods: A review of patients >18 years of age admitted to the pediatric CVICU at our institution from 2009 to 2011 occurred. A comparator group <18 years of age but >70 kg (a typical adult weight) was identified. Medication prescribing errors were determined according to a commonly used adult drug reference. An independent panel consisting of a physician specializing in the care of adult CHD patients, a nurse, and a pharmacist evaluated all errors. Medication prescribing orders were classified as appropriate, underdose, overdose, or nonstandard (dosing per weight instead of standard adult dosing), and severity of error was classified., Results: Eighty-five adult (74 patients) and 33 pediatric admissions (32 patients) met study criteria (mean age 27.5 ± 9.4 years, 53% male vs. 14.9 ± 1.8 years, 63% male). A cardiothoracic surgical procedure occurred in 81.4% of admissions. Adult admissions weighed less than pediatric admissions (72.8 ± 22.4 kg vs. 85.6 ± 14.9 kg, P < .01) but hospital length of stay was similar. (Adult 6 days [range 1-216 days]; pediatric 5 days [Range 2-123 days], P = .52.) A total of 112 prescribing errors were identified and they occurred less often in adults (42.4% of admissions vs. 66.7% of admissions, P = .02). Adults had a lower mean number of errors (0.7 errors per adult admission vs. 1.7 errors per pediatric admission, P < .01). Prescribing errors occurred most commonly with antimicrobials (n = 27). Underdosing was the most common category of prescribing error. Most prescribing errors were determined to have not caused harm to the patient., Conclusions: Prescribing errors occur frequently in adult patients admitted to a pediatric CVICU but occur more often in pediatric patients of adult weight., (© 2013 Wiley Periodicals, Inc.)

Hydrogels that solidify in response to a dual, physical and chemical, mechanism upon temperature increase were fabricated and characterized. The hydrogels were based on N-isopropylacrylamide, which renders them thermoresponsive, and contained covalently cross-linkable moieties in the macromers. The effects of the macromer end group, acrylate or methacrylate, and the fabrication conditions on the degradative and swelling properties of the hydrogels were investigated. The hydrogels exhibited higher swelling below their lower critical solution temperature (LCST). When immersed in cell culture medium at physiological temperature, which was above their LCST, hydrogels showed constant swelling and no degradation over 8 weeks, with the methacrylated hydrogels showing greater swelling than their acrylated analogs. In addition, hydrogels immersed in cell culture medium under the same conditions showed lower swelling compared with phosphate-buffered saline. The interplay between chemical cross-linking and thermally induced phase separation affected the swelling characteristics of the hydrogels in different media. Mesenchymal stem cells encapsulated in the hydrogels in vitro were viable over 3 weeks and markers of osteogenic differentiation were detected when the cells were cultured with osteogenic supplements. Hydrogel mineralization in the absence of cells was observed in cell culture medium with the addition of fetal bovine serum and β-glycerol phosphate. The results suggest that these hydrogels may be suitable as carriers for cell delivery in tissue engineering., (Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The cytocompatibility of amphiphilic, thermoresponsive and chemically crosslinkable macromers was examined in vitro. Macromers synthesized from pentaerythritol diacrylate monostearate, N-isopropylacrylamide, acrylamide and hydroxyethyl acrylate in different molar ratios and with varying molecular weights and lower critical solution temperatures were evaluated for cytocompatibility with rat fibroblasts. Cell viabilities of over 60% for all and over 80% for most formulations were observed after 24-h incubation with macromers with molecular weights in the range of approximately 1500-3000 Da. The chemical modification of the macromers with a (meth)acrylate group was shown to have a time- and dose-dependent effect on cell viability. Uncrosslinked macromers with lower degrees of (meth)acrylation allowed for cell viability of over 60% for up to 6 h. (Meth)acrylated macromers with lower critical solution temperature (LCST) closer to physiological temperature allowed for higher cell viabilities as opposed to those with lower LCST. The data suggest that when the (meth)acrylated macromers are assembled into a physical gel, their cytotoxicity is diminished. After gel phase separation, cytotoxicity increased. This study gives information on the parameters that enable viable cell encapsulation for in situ forming hydrogel systems.

The selection of an appropriate scaffold represents one major key to success in tissue engineering. In cardiovascular applications, where a load-bearing structure is required, scaffolds need to demonstrate sufficient mechanical properties and importantly, reliable retention of these properties during the developmental phase of the tissue engineered construct. The effect of in vitro culture conditions, time and mechanical loading on the retention of mechanical properties of two scaffold types was investigated. First candidate tested was a poly-glycolic acid non-woven fiber mesh, coated with poly-4-hydroxybutyrate (PGA/P4HB), the standard scaffold used successfully in cardiovascular tissue engineering applications. As an alternative, an electrospun poly-epsilon-caprolactone (PCL) scaffold was used. A 15-day dynamic loading protocol was applied to the scaffolds. Additionally, control scaffolds were incubated statically. All studies were performed in a simulated physiological environment (phosphate-buffered saline solution, T=37 degrees C). PGA/P4HB scaffolds showed a dramatic decrease in mechanical properties as a function of incubation time and straining. Mechanical loading had a significant effect on PCL scaffold properties. Degradation as well as fiber fatigue caused by loading promote loss of mechanical properties in PGA/P4HB scaffolds. For PCL, fiber reorganization due to straining seems to be the main reason behind the brittle behavior that was pronounced in these scaffolds. It is suggested that those changes in scaffolds' mechanical properties must be considered at the application of in vitro tissue engineering protocols and should ideally be taken over by tissue formation to maintain mechanically stable tissue constructs.