The study of sophisticated biomaterials and their cellular targets requires visualization methods with exquisite spatial and temporal resolution to discern cell organelles and molecular events. ...Monitoring cell-material interactions at high resolution is key for the continued development and optimization of biomaterials, for monitoring cell uptake of cargo, and for understanding the cell response to extracellular cues. This review evaluates the advantages and disadvantages of different forms of electron microscopy and super-resolution microscopy in elucidating how biomaterial surface chemistry and topography can affect intracellular events at the nanoscale.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Matrix metalloproteinases (MMPs) contribute to the breakdown of tissue structures such as the basement membrane, promoting tissue fibrosis. Here we developed an electrospun membrane biofunctionalized ...with a fragment of the laminin β1-chain to modulate the expression of MMP2 in this context. We demonstrate that interfacing of the β1-fragment with the mesothelium of the peritoneal membrane via a biomaterial abrogates the release of active MMP2 in response to transforming growth factor β1 and rescues tissue integrity ex vivo and in vivo in a mouse model of peritoneal fibrosis. Importantly, our data demonstrate that the membrane inhibits MMP2 expression. Changes in the expression of epithelial-to-mesenchymal transition (EMT)-related molecules further point towards a contribution of the modulation of EMT. Biomaterial-based presentation of regulatory basement membrane signals directly addresses limitations of current therapeutic approaches by enabling a localized and specific method to counteract MMP2 release applicable to a broad range of therapeutic targets.
Inspired by biological systems, many biomimetic methods suggest fabrication of functional materials with unique physicochemical properties. Such methods frequently generate organic–inorganic ...composites that feature highly ordered hierarchical structures with intriguing properties, distinct from their individual components. A striking example is that of DNA–inorganic hybrid micro/nanostructures, fabricated by the rolling circle technique. Here, a novel concept for the encapsulation of bioactive proteins in DNA flowers (DNF) while maintaining the activity of protein payloads is reported. A wide range of proteins, including enzymes, can be simultaneously associated with the growing DNA strands and Mg2PPi crystals during the rolling circle process, ultimately leading to the direct immobilization of proteins into DNF. The unique porous structure of this construct, along with the abundance of Mg ions and DNA molecules present, provides many interaction sites for proteins, enabling high loading efficiency and enhanced stability. Further, as a proof of concept, it is demonstrated that the DNF can deliver payloads of cytotoxic protein (i.e., RNase A) to the cells without a loss in its biological function and structural integrity, resulting in highly increased cell death compared to the free protein.
Encapsulation of various bioactive proteins in DNA constructs is realized at physiological conditions by a biomimetic crystallization approach, based on the nucleation and growth of Mg2PPi crystals with organic additives such as proteins and DNA. This method offers highly simple and efficient protein loading while retaining the biological functionality of the payloads, opening up a new strategy for protein‐based therapeutics.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Polyurethane‐based hydrogels are relatively inexpensive and mechanically robust biomaterials with ideal properties for various applications, including drug delivery, prosthetics, implant coatings, ...soft robotics, and tissue engineering. In this report, a simple method is presented for synthesizing and casting biocompatible polyurethane‐poly(ethylene glycol) (PU‐PEG) hydrogels with tunable mechanical properties, nonfouling characteristics, and sustained tolerability as an implantable material or coating. The hydrogels are synthesized via a simple one‐pot method using commercially available precursors and low toxicity solvents and reagents, yielding a consistent and biocompatible gel platform primed for long‐term biomaterial applications. The mechanical and physical properties of the gels are easily controlled by varying the curing concentration, producing networks with complex shear moduli of 0.82–190 kPa, similar to a range of human soft tissues. When evaluated against a mechanically matched poly(dimethylsiloxane) (PDMS) formulation, the PU‐PEG hydrogels demonstrated favorable nonfouling characteristics, including comparable adsorption of plasma proteins (albumin and fibrinogen) and significantly reduced cellular adhesion. Moreover, preliminary murine implant studies reveal a mild foreign body response after 41 days. Due to the tunable mechanical properties, excellent biocompatibility, and sustained in vivo tolerability of these hydrogels, it is proposed that this method offers a simplified platform for fabricating soft PU‐based biomaterials for a variety of applications.
A simplified one‐pot method and inexpensive casting set‐up for fabricating and casting biocompatible polyurethane‐poly(ethylene glycol) (PU‐PEG) hydrogels from nontoxic commercially available reagents is presented. The resulting PU‐PEG materials have concentration‐modular mechanical properties, nonfouling characteristics, and sustained tolerability as an implantable material making them an attractive scaffold material for a variety of tissue‐engineering and drug delivery applications.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Biomaterial substrates can be engineered to present topographical signals to cells which, through interactions between the material and active components of the cell membrane, regulate key cellular ...processes and guide cell fate decisions. However, targeting mechanoresponsive elements that reside within the intracellular domain is a concept that has only recently emerged. Here, we show that mesoporous silicon nanoneedle arrays interact simultaneously with the cell membrane, cytoskeleton, and nucleus of primary human cells, generating distinct responses at each of these cellular compartments. Specifically, nanoneedles inhibit focal adhesion maturation at the membrane, reduce tension in the cytoskeleton, and lead to remodeling of the nuclear envelope at sites of impingement. The combined changes in actin cytoskeleton assembly, expression and segregation of the nuclear lamina, and localization of Yes-associated protein (YAP) correlate differently from what is canonically observed upon stimulation at the cell membrane, revealing that biophysical cues directed to the intracellular space can generate heretofore unobserved mechanosensory responses. These findings highlight the ability of nanoneedles to study and direct the phenotype of large cell populations simultaneously, through biophysical interactions with multiple mechanoresponsive components.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Postpartum haemorrhage (PPH) is the leading cause of maternal mortality worldwide and India accounts for approximately 19% of global maternal deaths, with PPH as the leading cause. In recent years, ...care bundles have been shown to increase adherence to clinical guidelines and improve patient outcomes. The objective of this study was to develop a PPH cost-effectiveness model to estimate the potential health impact and cost-effectiveness of a quality improvement programme for PPH management featuring a first response bundle and a set of refractory PPH interventions in health facilities in Uttar Pradesh, India.
We used a decision tree model to compare the status quo delivery of PPH care in Uttar Pradesh with two scenarios in which recommended bundles for PPH management were optimally applied. Status quo PPH care includes intravenous fluids, uterotonics, and uterine massage delivered with a setting-specific probability that increases with the level of health facility. In the strengthened PPH care scenario, status quo interventions are combined with tranexamic acid in a first response bundle which is used in all PPH cases, plus manual placenta removal and suturing when indicated. In the enhanced PPH care scenario, PPH care is further enhanced through implementation of non-surgical interventions for managing refractory PPH (including uterine balloon tamponade, aortic compression, and non-pneumatic anti-shock garment). For each scenario, we conducted a Monte Carlo simulation of cohorts of 1 million women delivering at home, subcentres, primary-health clinics, community-health centres, and district hospitals. The results were scaled to represent the annual number of deliveries in Uttar Pradesh and their distribution across health facilities. The main outcomes were PPH cases, PPH deaths, and PPH surgical procedures.
Compared with status quo, perfect implementation of enhanced PPH care was predicted to reduce PPH-related maternal mortality in intervention facilities by 98%, from 10·7 to 0·3 per 100 000 deliveries, averting 450 deaths per year in Uttar Pradesh. Although enhanced PPH care would increase annual costs associated with the active management of the third stage of labour and non-surgical PPH management by US$190 000 and $300 000, respectively, service delivery costs were reduced by $1·42 million per year. Strengthened PPH care was predicted to prevent PPH deaths and reduce service delivery costs compared with status quo, but to have only 66% of the health impact and 63% of the cost-savings compared with enhanced PPH care. The upfront programme implementation costs and persistence of change in PPH management after implementation are uncertain. If enhanced PPH care were implemented with up to $2300 per facility, and the change in PPH management persisted for at least 2 years, the programme is estimated to be cost-effective (<0·5 GDP per capita per life year gained).
Implementation of an enhanced PPH care programme, including the first response bundle and non-surgical refractory PPH interventions, is likely to be cost-effective and life-saving in Uttar Pradesh, India. Moreover, enhanced PPH care is likely to generate more health impact and cost-savings compared with strengthened PPH care because of the greater reduction in number of surgeries needed.
Bill & Melinda Gates Foundation
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Automation is critical in delivering adaptable, robust and reproducible high-throughput screens.•Innovative design solutions have delivered increased flexibility.•Enhanced integration of hardware ...and software allows continuous improvement.•Future developments will embrace artificial intelligence to enhance the efficiency of high-throughput screening.
Challenged by ageing infrastructure and increasingly demanding screening cascades, AstraZeneca High Throughput Screening department has developed advanced automation systems that can support both current needs and future strategies in drug discovery. Through collaboration with HighRes Biosolutions and other third-party vendors, highly versatile automated modular platforms have been designed. Safety features such as collaborative robots allow enhanced system accessibility, and adaptive scheduling software has improved protocol design and system recovery. These innovations have led to significant improvements in system flexibility while maintaining screening productivity.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The mechanism by which cyclin-dependent kinase 4 (CDK4) regulates cell cycle progression is not entirely clear. Cyclin D/CDK4 appears to initiate phosphorylation of retinoblastoma protein (Rb) ...leading to inactivation of the S-phase-inhibitory action of Rb. However, cyclin D/CDK4 has been postulated to act in a noncatalytic manner to regulate the cyclin E/CDK2-inhibitory activity of p27(Kip1) by sequestration. In this study we investigated the roles of CDK4 in cell cycle regulation by targeted disruption of the mouse CDK4 gene. CDK4(-/-) mice survived embryogenesis and showed growth retardation and reproductive dysfunction associated with hypoplastic seminiferous tubules in the testis and perturbed corpus luteum formation in the ovary. These phenotypes appear to be opposite to those of p27-deficient mice such as gigantism and gonadal hyperplasia. A majority of CDK4(-/-) mice developed diabetes mellitus by 6 weeks, associated with degeneration of pancreatic islets. Fibroblasts from CDK4(-/-) mouse embryos proliferated similarly to wild-type embryonic fibroblasts under conditions that promote continuous growth. However, quiescent CDK4(-/-) fibroblasts exhibited a substantial ( approximately 6-h) delay in S-phase entry after serum stimulation. This cell cycle perturbation by CDK4 disruption was associated with increased binding of p27 to cyclin E/CDK2 and diminished activation of CDK2 accompanied by impaired Rb phosphorylation. Importantly, fibroblasts from CDK4(-/-) p27(-/-) embryos displayed partially restored kinetics of the G(0)-S transition, indicating the significance of the sequestration of p27 by CDK4. These results suggest that at least part of CDK4's participation in the rate-limiting mechanism for the G(0)-S transition consists of controlling p27 activity.
PDF
