P16INK4a Upregulation Mediated by SIX6 Defines Retinal Ganglion Cell Pathogenesis in Glaucoma.

Glaucoma, a blinding neurodegenerative disease, whose risk factors include elevated intraocular pressure (IOP), age, and genetics, is characterized by accelerated and progressive retinal ganglion cell (RGC) death. Despite decades of research, the mechanism of RGC death in glaucoma is still unknown. Here, we demonstrate that the genetic effect of the SIX6 risk variant (rs33912345, His141Asn) is enhanced by another major POAG risk gene, p16INK4a (cyclin-dependent kinase inhibitor 2A, isoform INK4a). We further show that the upregulation of homozygous SIX6 risk alleles (CC) leads to an increase in p16INK4a expression, with subsequent cellular senescence, as evidenced in a mouse model of elevated IOP and in human POAG eyes. Our data indicate that SIX6 and/or IOP promotes POAG by directly increasing p16INK4a expression, leading to RGC senescence in adult human retinas. Our study provides important insights linking genetic susceptibility to the underlying mechanism of RGC death and provides a unified theory of glaucoma pathogenesis.

Lanosterol reverses protein aggregation in cataracts.

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Heparin-Tagged PLA-PEG Copolymer-Encapsulated Biochanin A-Loaded (Mg/Al) LDH Nanoparticles Recommended for Non-Thrombogenic and Anti-Proliferative Stent Coating.

Drug-eluting stents have been widely implanted to prevent neointimal hyperplasia associated with bare metal stents. Conventional polymers and anti-proliferative drugs suffer from stent thrombosis due to the non-selective nature of the drugs and hypersensitivity to polymer degradation products. Alternatively, various herbal anti-proliferative agents are sought, of which biochanin A (an isoflavone phytoestrogen) was known to have anti-proliferative and vasculoprotective action. PLA-PEG diblock copolymer was tagged with heparin, whose degradation releases heparin locally and prevents thrombosis. To get a controlled drug release, biochanin A was loaded in layered double hydroxide nanoparticles (LDH), which are further encapsulated in a heparin-tagged PLA-PEG copolymer. LDH nanoparticles are synthesized by a co-precipitation process; in situ as well as ex situ loading of biochanin A were done. PLA-PEG-heparin copolymer was synthesized by esterification reaction, and the drug-loaded nanoparticles are coated. The formulation was characterized by FTIR, XRD, DSC, DLS, and TEM. In vitro drug release studies, protein adhesion, wettability, hemocompatibility, and degradation studies were performed. The drug release was modeled by mathematical models to further emphasize the mechanism of drug release. The developed drug-eluting stent coating is non-thrombogenic, and it offers close to zero-order release for 40 days, with complete polymer degradation in 14 weeks.

Surface Engineering Strategies to Enhance the In Situ Performance of Medical Devices Including Atomic Scale Engineering.

Decades of intense scientific research investigations clearly suggest that only a subset of a large number of metals, ceramics, polymers, composites, and nanomaterials are suitable as biomaterials for a growing number of biomedical devices and biomedical uses. However, biomaterials are prone to microbial infection due to Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), hepatitis, tuberculosis, human immunodeficiency virus (HIV), and many more. Hence, a range of surface engineering strategies are devised in order to achieve desired biocompatibility and antimicrobial performance in situ. Surface engineering strategies are a group of techniques that alter or modify the surface properties of the material in order to obtain a product with desired functionalities. There are two categories of surface engineering methods: conventional surface engineering methods (such as coating, bioactive coating, plasma spray coating, hydrothermal, lithography, shot peening, and electrophoretic deposition) and emerging surface engineering methods (laser treatment, robot laser treatment, electrospinning, electrospray, additive manufacturing, and radio frequency magnetron sputtering technique). Atomic-scale engineering, such as chemical vapor deposition, atomic layer etching, plasma immersion ion deposition, and atomic layer deposition, is a subsection of emerging technology that has demonstrated improved control and flexibility at finer length scales than compared to the conventional methods. With the advancements in technologies and the demand for even better control of biomaterial surfaces, research efforts in recent years are aimed at the atomic scale and molecular scale while incorporating functional agents in order to elicit optimal in situ performance. The functional agents include synthetic materials (monolithic ZnO, quaternary ammonium salts, silver nano-clusters, titanium dioxide, and graphene) and natural materials (chitosan, totarol, botanical extracts, and nisin). This review highlights the various strategies of surface engineering of biomaterial including their functional mechanism, applications, and shortcomings. Additionally, this review article emphasizes atomic scale engineering of biomaterials for fabricating antimicrobial biomaterials and explores their challenges.

Nanocarriers, Progenitor Cells, Combinational Approaches, and New Insights on the Retinal Therapy.

Progenitor cells derived from the retinal pigment epithelium (RPECs) have shown promise as therapeutic approaches to degenerative retinal disorders including diabetic retinopathy, age-related macular degeneration and Stargardt disease. However, the degeneration of Bruch's membrane (BM), the natural substrate for the RPE, has been identified as one of the major limitations for utilizing RPECs. This degeneration leads to decreased support, survival and integration of the transplanted RPECs. It has been proposed that the generation of organized structures of nanofibers, in an attempt to mimic the natural retinal extracellular matrix (ECM) and its unique characteristics, could be utilized to overcome these limitations. Furthermore, nanoparticles could be incorporated to provide a platform for improved drug delivery and sustained release of molecules over several months to years. In addition, the incorporation of tissue-specific genes and stem cells into the nanostructures increased the stability and enhanced transfection efficiency of gene/drug to the posterior segment of the eye. This review discusses available drug delivery systems and combination therapies together with challenges associated with each approach. As the last step, we discuss the application of nanofibrous scaffolds for the implantation of RPE progenitor cells with the aim to enhance cell adhesion and support a functionally polarized RPE monolayer.

pHEMA: An Overview for Biomedical Applications.

Poly(2-hydroxyethyl methacrylate) (pHEMA) as a biomaterial with excellent biocompatibility and cytocompatibility elicits a minimal immunological response from host tissue making it desirable for different biomedical applications. This article seeks to provide an in-depth overview of the properties and biomedical applications of pHEMA for bone tissue regeneration, wound healing, cancer therapy (stimuli and non-stimuli responsive systems), and ophthalmic applications (contact lenses and ocular drug delivery). As this polymer has been widely applied in ophthalmic applications, a specific consideration has been devoted to this field. Pure pHEMA does not possess antimicrobial properties and the site where the biomedical device is employed may be susceptible to microbial infections. Therefore, antimicrobial strategies such as the use of silver nanoparticles, antibiotics, and antimicrobial agents can be utilized to protect against infections. Therefore, the antimicrobial strategies besides the drug delivery applications of pHEMA were covered. With continuous research and advancement in science and technology, the outlook of pHEMA is promising as it will most certainly be utilized in more biomedical applications in the near future. The aim of this review was to bring together state-of-the-art research on pHEMA and their applications.

Advanced Hydrogels as Exosome Delivery Systems for Osteogenic Differentiation of MSCs: Application in Bone Regeneration.

Hydrogels are known as water-swollen networks formed from naturally derived or synthetic polymers. They have a high potential for medical applications and play a crucial role in tissue repair and remodeling. MSC-derived exosomes are considered to be new entities for cell-free treatment in different human diseases. Recent progress in cell-free bone tissue engineering via combining exosomes obtained from human mesenchymal stem cells (MSCs) with hydrogel scaffolds has resulted in improvement of the methodologies in bone tissue engineering. Our research has been actively focused on application of biotechnological methods for improving osteogenesis and bone healing. The following text presents a concise review of the methodologies of fabrication and preparation of hydrogels that includes the exosome loading properties of hydrogels for bone regenerative applications.

Tunable Fast Relaxation in Imine-Based Nanofibrillar Hydrogels Stimulates Cell Response through TRPV4 Activation.

As a key mechanical signal of natural extracellular matrix (ECM), stress relaxation plays an essential role in cell fate decision. However, the biomimetic matrix with fast stress relaxation and its cellular response mechanism have received little attention. Meanwhile, the nanofibrillar architecture which is conductive to mechanical transduction has invariably been ignored in the previous viscoelastic matrix design. Herein, by introducing a dynamic covalent imine bond into a physically cross-linked collagen hydrogel, we prepared bionic fast-relaxing nanofibrillar hydrogels with relaxation time less than 10 s. Through a single control of imine bond content, we realized fine-tuning of the relaxation rate while maintaining a constant initial modulus and fiber density. Using MC3T3-E1 cells as a model, we then proved that the nanofibrillar matrix with fast relaxation mechanics can effectively promote cell spreading and differentiation. In particular, TRPV4 as a molecular sensor of matrix viscoelasticity was demonstrated to regulate cell fate on the nanofibrillar hydrogels by mediating calcium influx. It is expected that the material design principle combining both nanofibrillar structure and tunable fast-relaxation can provide a more broadly adaptable materials platform for simulating natural ECM mechanical cues, and the investigation of the TRPV4 ion channel mediated cellular response will facilitate discovery of more fundamental mechanisms in tissue growth and development.

Noninvasive prenatal diagnosis of common aneuploidies by semiconductor sequencing.

Massively parallel sequencing (MPS) of cell-free fetal DNA from maternal plasma has revolutionized our ability to perform noninvasive prenatal diagnosis. This approach avoids the risk of fetal loss associated with more invasive diagnostic procedures. The present study developed an effective method for noninvasive prenatal diagnosis of common chromosomal aneuploidies using a benchtop semiconductor sequencing platform (SSP), which relies on the MPS platform but offers advantages over existing noninvasive screening techniques. A total of 2,275 pregnant subjects was included in the study; of these, 515 subjects who had full karyotyping results were used in a retrospective analysis, and 1,760 subjects without karyotyping were analyzed in a prospective study. In the retrospective study, all 55 fetal trisomy 21 cases were identified using the SSP with a sensitivity and specificity of 99.94% and 99.46%, respectively. The SSP also detected 16 trisomy 18 cases with 100% sensitivity and 99.24% specificity and 3 trisomy 13 cases with 100% sensitivity and 100% specificity. Furthermore, 15 fetuses with sex chromosome aneuploidies (10 45,X, 2 47,XYY, 2 47,XXX, and 1 47,XXY) were detected. In the prospective study, nine fetuses with trisomy 21, three with trisomy 18, three with trisomy 13, and one with 45,X were detected. To our knowledge, this is the first large-scale clinical study to systematically identify chromosomal aneuploidies based on cell-free fetal DNA using the SSP and provides an effective strategy for large-scale noninvasive screening for chromosomal aneuploidies in a clinical setting.

In vivo immunological properties research on mesenchymal stem cells based engineering cartilage by a dialyzer pocket model.

As the seed cells, the immune properties of the mesenchymal stem cells are important for the tissue engineering restoring effect. But the in vivo research model is lacking. In the study, based on a dialyzer pocket model, changes in immunological properties and the differentiation of seeded mesenchymal stem cells (MSCs) in collagen hydrogel were studied in muscle and articular cavity implantation, respectively. The results showed that collagen hydrogel can induce MSCs to form cartilage tissue, followed by alteration of immunological properties. In muscle implantation, relatively low expression of major histocompatibility complex (MHC) molecules and low level of one-way mixed lymphocyte reactions (MLR) on the seeded MSCs were observed, but only a little cartilage tissue formed. In articular cavity implantation, more cartilage tissue formed, but higher MHC expressions and MLR level were found. Results indicated that the immunomodulation and the cartilage formation of the seeded MSCs will be impacted by the scaffold and the environment of the in vivo implanted site. The dialyzer pocket model can be used for the in vivo research for the MSC-based strategy of the tissue engineering, especially for the optimization of the immunomodulation.

Human retinal progenitor cell transplantation preserves vision.

Cell transplantation is a potential therapeutic strategy for retinal degenerative diseases involving the loss of photoreceptors. However, it faces challenges to clinical translation due to safety concerns and a limited supply of cells. Human retinal progenitor cells (hRPCs) from fetal neural retina are expandable in vitro and maintain an undifferentiated state. This study aimed to investigate the therapeutic potential of hRPCs transplanted into a Royal College of Surgeons (RCS) rat model of retinal degeneration. At 12 weeks, optokinetic response showed that hRPC-grafted eyes had significantly superior visual acuity compared with vehicle-treated eyes. Histological evaluation of outer nuclear layer (ONL) characteristics such as ONL thickness, spread distance, and cell count demonstrated a significantly greater preservation of the ONL in hRPC-treated eyes compared with both vehicle-treated and control eyes. The transplanted hRPCs arrested visual decline over time in the RCS rat and rescued retinal morphology, demonstrating their potential as a therapy for retinal diseases. We suggest that the preservation of visual acuity was likely achieved through host photoreceptor rescue. We found that hRPC transplantation into the subretinal space of RCS rats was well tolerated, with no adverse effects such as tumor formation noted at 12 weeks after treatment.

Next generation sequencing-based molecular diagnosis of retinitis pigmentosa: identification of a novel genotype-phenotype correlation and clinical refinements.

Retinitis pigmentosa (RP) is a devastating form of retinal degeneration, with significant social and professional consequences. Molecular genetic information is invaluable for an accurate clinical diagnosis of RP due to its high genetic and clinical heterogeneity. Using a gene capture panel that covers 163 of the currently known retinal disease genes, including 48 RP genes, we performed a comprehensive molecular screening in a collection of 123 RP unsettled probands from a wide variety of ethnic backgrounds, including 113 unrelated simplex and 10 autosomal recessive RP (arRP) cases. As a result, 61 mutations were identified in 45 probands, including 38 novel pathogenic alleles. Interestingly, we observed that phenotype and genotype were not in full agreement in 21 probands. Among them, eight probands were clinically reassessed, resulting in refinement of clinical diagnoses for six of these patients. Finally, recessive mutations in CLN3 were identified in five retinal degeneration patients, including four RP probands and one cone-rod dystrophy patient, suggesting that CLN3 is a novel non-syndromic retinal disease gene. Collectively, our results underscore that, due to the high molecular and clinical heterogeneity of RP, comprehensive screening of all retinal disease genes is effective in identifying novel pathogenic mutations and provides an opportunity to discover new genotype-phenotype correlations. Information gained from this genetic screening will directly aid in patient diagnosis, prognosis, and treatment, as well as allowing appropriate family planning and counseling.

Effect of the Sr-Fe layered double hydroxide coating based on the microenvironment response on implant osseointegration in osteoporotic rats.

Osteoporosis is a disease that manifests itself as an abnormality of bone metabolism and is characterized by low bone mass and destruction of the bone microstructure. Since bone resorption occurs more rapidly than new bone formation, osteoporosis leads to reduced orthopedic implant stability. From a microenvironmental point of view, the rationale for this outcome is that osteoclasts are overactive in the bone tissue of patients with osteoporosis, and the large amount of H+ they produce leads to local chronic acidosis, which promotes bone mineral loss. Therefore, we designed a weakly alkaline layered double hydroxide (LDH) coating to modulate the pathologically acidic microenvironment and the osteogenic-osteoclastic coupling by releasing Sr2+. We prepared Sr-Fe LDH coatings on pure titanium implants using a hydrothermal method in this study and characterized the material using SEM, AFM, XRD, XPS, EDS, ICP, pH acidimeter, etc. We found that the coatings had good nanomorphology and were able to efficiently neutralize H+ as well as steadily release Sr2+ for up to 21 days. In vitro, the coating not only significantly promoted the adhesion, proliferation, and differentiation of osteoblasts, but also inhibited the differentiation of osteoclasts at the same time. In addition, in animal experiments, the coating significantly improved the mechanical stability of the implant in osteoporotic rats, increasing Sr-Fe LDH@Ti maximal push-out force by 72.2% compared to Ti. At the same time, the coating was effective in reversing the osteoporotic state, resulting in a 58.5% increase in BV/TV (%), and a 12.4% increase in Tb. N (1 mm-1), a 31.6% increase in Tb. Th (µm), and a 30.9% increase in BA (%). Our results suggest that this Sr-Fe LDH nanocoating material with acid-neutralizing, as well as long-term Sr2+-releasing capabilities, is a novel and effective orthopedic implant coating material under osteoporotic conditions.

Black Phosphorous Aptamer-based Platform for Biomarker Detection.

Black phosphorus nanostructures (nano-BPs) mainly include BP nanosheets (BP NSs), BP quantum dots (BPQDs), and other nano-BPs-based particles at nanoscale. Firstly discovered in 2014, nano-BPs are one of the most popular nanomaterials. Different synthesis methods are discussed in short to understand the basic concepts and developments in synthesis. Exfoliated nano-BPs, i.e. nano-BPs possess high surface area, high photothermal conversion efficacy, excellent biocompatibility, high charge carrier mobility (~1000 cm-2V-1s-1), thermal conductivity of 86 Wm-1K-1; and these properties make it a highly potential candidate for fabrication of biosensing platform. These properties enable nano-BPs to be promising photothermal/drug delivery agents as well as in electrochemical data storage devices and sensing devices; and in super capacitors, photodetectors, photovoltaics and solar cells, LEDs, super-conductors, etc. Early diagnosis is very critical in the health sector scenarios. This review attempts to highlight the attempts made towards attaining stable BP, BP-aptamer conjugates for successful biosensing applications. BP-aptamer- based platforms are reviewed to highlight the significance of BP in detecting biological and physiological markers of cardiovascular diseases and cancer; to be useful in disease diagnosis and management.

An upconversion nanoparticle-integrated fibrillar scaffold combined with a NIR-optogenetic strategy to regulate neural cell performance.

Optogenetics using light-sensitive proteins such as calcium transport channel rhodopsin (CatCh) opens up new possibilities for non-invasive remote manipulation of neural function. However, current optogenetic approaches for neurological disorder therapies rely on visible light excitation and are rarely applied to neurogenesis and nerve regeneration. Herein, we propose a new strategy for tissue engineering which combines optogenetic technology and biomimetic nerve scaffolds. Upconversion nanoparticles (UCNPs) were synthesized and integrated with oriented fibrillar PCL membranes with a collagen coating to establish neuro-matrix interfaces. Benefiting from the excellent bioactivity, oriented fibrillation and NIR-photoresponsivity, the CatCh-transfected PC12 cells on these interfaces exhibited enhanced cell elongation and neurite extension, as well as upregulated neurogenesis upon NIR excitation. Furthermore, a UCNP-integrated scaffold as an optogenetic actuator allowed NIR to penetrate dermal tissues to mediate neural activation, with an efficiency comparable to that of a 470 nm blue light. Compared with current visible light-excited optogenetics, our composite scaffold-mediated NIR stimulation addresses the problem of tissue penetration and will enable less-invasive neurofunctional manipulation, with the potential for remote therapy.

Defect-Modified nano-BaTiO3 as a Sonosensitizer for Rapid and High-Efficiency Sonodynamic Sterilization.

Multidrug-resistant bacteria caused by the unlimited overuse of antibiotics pose a great challenge to global health. An antibacterial method based on reactive oxygen species (ROS) is one of the effective strategies without inducing bacterial resistance. Owing to the ability of generating ROS, piezocatalytic material-mediated sonodynamic therapy (SDT) has drawn much attention. However, its major challenge is the low ROS generation efficiency in the piezocatalytic process due to the poor charge carrier concentration of piezoelectric materials. Vacancy engineering can regulate the charge density and largely promote ROS generation under ultrasound (US) irradiation. Herein, a US-responsive self-doped barium titanate with controlled oxygen vacancy (Vo) concentrations was successfully synthesized through a facile thermal reduction treatment at different temperatures (i.e., 350, 400, and 450 °C), and the corresponding samples were named as BTO-350, BTO-400, and BTO-450, respectively. Then, the effect of Vo concentrations on ROS generation efficiency during the piezocatalytic process was systematically studied. And BTO-400 was found to possess the highest piezocatalytic activity and excellent sonodynamic antibacterial performance against Escherichia coli and Staphylococcus aureus. Furthermore, its antibacterial mechanism was confirmed that the ROS generated under US could damage bacterial cell membrane and cause considerable leakage of cytoplasmic components and irreversible death of bacteria. Notably, the in vivo results illustrated that the BTO-400 could serve as an effective antibacterial agent and accelerate skin healing via SDT therapy. In all, the Vo defect-modified nano-BaTiO3 has a noticeable potential to induce a rapid and efficient sterilization as well as skin tissue repair by SDT.

Selective effects of hydroxyapatite nanoparticles on osteosarcoma cells and osteoblasts.

The effects of hydroxyapatite nanoparticles (HA-NPs) on two kinds of cells, human MG63 cells and the normal osteoblasts were investigated. According to the MTT assay and fluorescent staining assay, it was proved that HA-NPs could inhibit the growth of MG63 cells but slightly support proliferation of the osteoblasts. Meanwhile, transmission electron microscopy (TEM) was employed to observe the ultrastructural alterations of both cells. The TEM results showed that HA-NPs had entered the two kinds of cells. Typical apoptosis was observed in the MG63 cells, especially in the group of 250 µg/mL with 5 days culture. While no apoptosis could be found in the normal osteoblasts at any concentration group of HA-NPs. Our results suggested that the HA-NPs had selective effects to different kinds of cells: supporting proliferation to the normal bone cells while causing apoptosis to the osteosarcoma cells.

Aldehyde-methacrylate-hyaluronan profited hydrogel system integrating aligned and viscoelastic cues for neurogenesis.

Either oriented architecture or viscoelasticity is pivotal to neurogenesis, thus, native neural extracellular matrix derived-hyaluronan hydrogels with nano-orientation and viscoelasticity recapitulated might be instructive for neurogenesis, however it is still unexploited. Herein, based on aldehyde-methacrylate difunctionalized hyaluronan, by integrating imine kinetic modulation and microfluidic biofabrication, we construct a hydrogel system with orthogonal viscoelasticity and nano-topography. We then find the positive synergy effects of matrix nano-orientation and viscoelasticity not only on neurites outgrowth and elongation of neural cells, but also on neuronal differentiation of stem cells. Moreover, by implanting viscoelastic and nano-aligned hydrogels into lesion sites, we demonstrate the enhanced repair of spinal cord injury, including ameliorated pathological microenvironment, facilitated endogenous neurogenesis and functional axons regeneration as well as motor function restoration. This work supplies universal platform for preparing neuronal inducing hyaluronan-based hydrogels which might serve as promising therapeutic strategies for nerve injury.

Antimicrobial Peptides and Their Applications in Biomedical Sector.

In a report by WHO (2014), it was stated that antimicrobial resistance is an arising challenge that needs to be resolved. This resistance is a critical issue in terms of disease or infection treatment and is usually caused due to mutation, gene transfer, long-term usage or inadequate use of antimicrobials, survival of microbes after consumption of antimicrobials, and the presence of antimicrobials in agricultural feeds. One of the solutions to this problem is antimicrobial peptides (AMPs), which are ubiquitously present in the environment. These peptides are of concern due to their special mode of action against a wide spectrum of infections and health-related problems. The biomedical field has the highest need of AMPs as it possesses prominent desirable activity against HIV-1, skin cancer, breast cancer, in Behcet's disease treatment, as well as in reducing the release of inflammatory cells such as TNFα, IL-8, and IL-1ß, enhancing the production of anti-inflammatory cytokines such as IL-10 and GM-CSF, and in wound healing properties. This review has highlighted all the major functions and applications of AMPs in the biomedical field and concludes the future potential of AMPs.