Sumecton reinforced gelatin-based scaffolds for cell-free bone regeneration.

Bone tissue engineering has risen to tackle the challenges of the current clinical need concerning bone fractures that is already considered a healthcare system problem. Scaffold systems for the repair of this tissue have yielded different combinations including biomaterials with nanotechnology or biological agents. Herein, three-dimensional porous hydrogels were engineered based on gelatin as a natural biomaterial and reinforced with synthetic saponite nanoclays. Scaffolds were biocompatible and shown to enhance the inherent properties of pristine ones, in particular, proved to withstand pressures similar to load-bearing tissues. Studies with murine mesenchymal stem cells found that scaffolds had the potential to proliferate and promote cell differentiation. In vivo experiments were conducted to gain insight about the ability of these cell-free scaffolds to regenerate bone, as well as to determine the role that these nanoparticles in the scaffold could play as a drug delivery system. SDF-1 loaded scaffolds showed the highest percentage of bone formation, which was corroborated by osteogenic markers and new blood vessels. Albeit a first attempt in the field of synthetic nanosilicates, these results suggest that the designed constructs may serve as delivery platforms for biomimetic agents to mend bony defects, circumventing high doses of therapeutics and cell-loading systems.

Modulating osteoclasts with nanoparticles: A path for osteoporosis management?

Osteoclasts are the cells responsible for the bone resorption process during bone remodeling. In a healthy situation, this process results from an equilibrium between new matrix formation by osteoblast and matrix resorption by osteoclast. Osteoporosis (OP) is a systemic bone disease characterized by a decreased bone mass density and alterations in bone microarchitecture, increasing fracture predisposition. Despite the variety of available therapies for OP management there is a growing gap in its treatment associated to the low patients' adherence owing to concerns related with long-term efficacy or safety. This makes the development of new and safe treatments necessary. Among the newly developed strategies, the use of synthetic and natural nanoparticles to modulate osteoclasts differentiation, activity, apoptosis or crosstalk with osteoblasts have arisen. Synthetic nanoparticles exert their therapeutic effect either by loading antiresorptive drugs or including molecules for osteoclasts gene regulation. Moreover, this control over osteoclasts can be improved by their targeting to bone extracellular matrix or osteoclast membranes. Furthermore, natural nanoparticles, also known as extracellular vesicles, have been identified to play a key role in bone homeostasis. Consequently, these systems have been widely studied to control osteoblasts and osteoclasts under variable environments. Additionally, the ability to bioengineer extracellular vesicles has allowed to obtain biomimetic systems with desirable characteristics as drug carriers for osteoclasts. The analyzed information reveals the possibility of modulating osteoclasts by different mechanisms through nanoparticles decreasing bone resorption. These findings suggest that controlling osteoclast activity using nanoparticles has the potential to improve osteoporosis management. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Gold-catalyzed endo-selective cyclization of alkynylcyclobutanecarboxamides: synthesis of cyclobutane-fused dihydropyridones.

Cyclobutane-fused dihydropyridones can be efficiently synthesized by a completely endo-selective gold-catalyzed cyclization of alkynylcyclobutanes bearing an appended amide, which proceeds under mild conditions. The observed selectivity, which is reversed from that previously observed for the cyclization of related alcohols and acids, is supported by DFT calculations.

New local ganirelix sustained release therapy for uterine leiomyoma. Evaluation in a preclinical organ model.

Currently, there is a limited number of treatment options available for patients with symptomatic leiomyomas, and surgical removal is by far the most frequent procedure. Previous studies found that GnRH agonists and antagonists acting through GnRH receptors led to cell death and decreased extracellular synthesis in cultured leiomyoma cells. In this study, we encapsulated the GnRH antagonist ganirelix in PLGA microspheres contained in an alginate scaffold that also supports a leiomyoma ex vivo tissue explant. Microspheres maintained ganirelix concentration stably during six days of culture, inducing significant cell death in 50-55% of tumor cells. Although no changes were observed in the expression of extracellular matrix genes, a decreased expression of the Nuclear Factor of Activated T cells 5, a transcription factor involved in osmotic stress and tumor size. Interestingly, all tumors analyzed experienced apoptosis independently of the original driver mutation. These data indicate that local therapy of ganirelix would induce tumor reduction in a wide range of uterine leiomyomas.

Nanoparticle-mediated selective Sfrp-1 silencing enhances bone density in osteoporotic mice.

Osteoporosis (OP) is characterized by a loss in bone mass and mineral density. The stimulation of the canonical Wnt/ß-catenin pathway has been reported to promote bone formation, this pathway is controlled by several regulators as secreted frizzled-related protein-1 (Sfrp-1), antagonist of the pathway. Thus, Sfrp-1 silencing therapies could be suitable for enhancing bone growth. However, the systemic stimulation of Wnt/ß-catenin has been correlated with side effects. This work hypothesizes the administration of lipid-polymer NPs (LPNPs) functionalized with a MSC specific aptamer (Apt) and carrying a SFRP1 silencing GapmeR, could favor bone formation in OP with minimal undesired effects. Suitable SFRP1 GapmeR-loaded Apt-LPNPs (Apt-LPNPs-SFRP1) were administered in osteoporotic mice and their biodistribution, toxicity and bone induction capacity were evaluated. The aptamer functionalization of the NPs modified their biodistribution profile showing a four-fold increase in the bone accumulation and a ten-fold decrease in the hepatic accumulation compared to naked LPNPs. Moreover, the histological evaluation revealed evident changes in bone structure observing a more compact trabecular bone and a cortical bone thickness increase in the Apt-LPNPs-SFRP1 treated mice with no toxic effects. Therefore, these LPNPs showed suitable properties and biodistribution profiles leading to an enhancement on the bone density of osteoporotic mice.

Synthesis of BN-Polyarenes by a Mild Borylative Cyclization Cascade.

Reaction of BCl3 with suitably substituted o-alkynylanilines promotes a cascade reaction in which BN-polycyclic compounds are obtained via the formation of two new cycles and three new bonds in a single operational step. The reaction is highly efficient and takes place at room temperature, providing a very mild and straightforward strategy for the preparation of BN-aromatic compounds, which can be further transformed into a variety of BN-PAHs with different polycyclic cores and substituents.

Screening strategies for surface modification of lipid-polymer hybrid nanoparticles.

Lipid-polymer hybrid nanoparticles are promising platforms in the field of targeted drug delivery, integrating the positive features of polymeric and lipid nanocarriers. However, the use of bulk procedures in lipid-polymer hybrid nanoparticles formulation is hindering their large-scale manufacturing. Therefore, the aim of this study is to explore the suitability of alternative formulation methods, such as microfluidics, to obtain surface-tunable nanoparticles displaying suitable characteristics. Formulations were prepared by single-step nanoprecipitation or using a micromixer chip. The nanocarriers were then surface-modified with an aptamer and an antibody, two common nanoparticle vectorization strategies, developing an optimized functionalization protocol. Both naked and surface-modified nanoparticles were characterized in terms of size, polydispersity, zeta potential and morphology. Moreover, the aptamer/antibody association efficiency was also determined. Nano-sized monodisperse nanoparticles, exhibiting a spherical core-shell structure, were obtained through both procedures. Furthermore, all the nanocarriers were successfully functionalized, showing association efficiency values above 70%. Interestingly, microfluidic-based nanoparticles displayed a smaller size and a more positive zeta potential than those prepared by single-step nanoprecipitation. Outcomes suggest both techniques led to lipid-polymer hybrid nanoparticles displaying a similar functionalization efficiency. Conversely, the microfluidic approach provided an improved control over critical parameters, as particle size or charge, constituting an interesting alternative to traditional formulation procedures.

Nanoclay-reinforced HA/alginate scaffolds as cell carriers and SDF-1 delivery-platforms for bone tissue engineering.

Bone tissue engineering has come on the scene to overcome the difficulties of the current treatment strategies. By combining biomaterials, active agents and growth factors, cells and nanomaterials, tissue engineering makes it possible to create new structures that enhance bone regeneration. Herein, hyaluronic acid and alginate were used to create biologically active hydrogels, and montmorillonite nanoclay was used to reinforce and stabilize them. The developed scaffolds were found to be biocompatible and osteogenic with mMSCs in vitro, especially those reinforced with the nanoclay, and allowed mineralization even in the absence of differentiation media. Moreover, an in vivo investigation was performed to establish the potential of the hydrogels to mend bone and act as cell-carriers and delivery platforms for SDF-1. Scaffolds embedded with SDF-1 exhibited the highest percentages of bone regeneration as well as of angiogenesis, which confirms the suitability of the scaffolds for bone. Although there are a number of obstacles to triumph over, these bioengineered structures showed potential as future bone regeneration treatments.

Diaphragm impairment in patients admitted for severe COVID-19.

Among patients affected by the virus COVID-19, physicians have observed ventilation disorders. It is relevant to assess neurological involvement, including the role of diaphragmatic function. Its possible impairment could be related to the systemic inflammatory response and disease progression that both typify COVID-19 infection. We distinguished two groups (severe group (SG) and mild group (MG)) according to the severity of respiratory symptomatology. We performed neurophysiological and sonography studies to evaluate the diaphragmatic function. Regarding the sonography variables, we identified statistically significant differences in the right mean diaphragmatic thickness along with the expiration, showing 1.56 mm (SEM: 0.11) in the SG vs 1.92 mm (SEM: 0.19) in the MG (p = 0.042). The contractibility of both hemidiaphragms was 15% lower in the severe group, though this difference is not statistically significant. In our examination of the neurophysiological variables, in the amplitude responses, we observed a greater difference between responses from both phrenic nerves as follows: the raw differences in amplitude were 0.40 µV (SEM: 0.14) in the SG vs 0.35 µV (SEM: 0.19) in the MG and the percentage difference was 25.92% (SEM: 7.22) in the SG vs 16.28% (SEM: 4.38%) in the MG. Although diaphragmatic dysfunction is difficult to detect, our combined functional and morphological approach with phrenic electroneurograms and chest ultrasounds could improve diagnostic sensitivity. We suggest that diaphragmatic dysfunction could play a relevant role in respiratory disturbance in hospitalised patients with severe COVID-19.

Metal-Free Temperature-Controlled Regiodivergent Borylative Cyclizations of Enynes: BCl3 -Promoted Skeletal Rearrangement.

Metal-free borylative cyclization of biphenyl-embedded 1,3,5-trien-7-ynes in the presence of simple and inexpensive BCl3 provided synthetically useful borylated building blocks. The outcome of the process depends on the reaction temperature, with borylated phenanthrenes obtained at 60 °C and phenanthrene-fused borylated cyclobutanes formed at 0 °C. Based on DFT calculations, a mechanism for these novel transformations has been proposed, which involves an uncommon skeletal rearrangement, including migration of a methyl group and alkyne fragmentation, unprecedented in BCl3 -promoted cyclization reactions.

Osteoprotective effect of the marine alkaloid norzoanthamine on an osteoporosis model in ovariectomized rat.

Norzoanthamine (NZ), an alkaloid that has been isolated from the marine cnidiaria Zoanthus sp., has been shown an interesting anti-osteoporotic activity. Although its mechanism of action is not yet clear, it seems that it is different from those of currently used drugs making it particularly interesting. Previous studies have been carried out mostly in vitro. Herein, we present an in vivo study that allows to check the real potential of NZ as a protector substance by direct application into ovariectomized rat bone using a sustained delivery system. Histological and histomorphometric results in ovariectomized rats showed higher bone quality as a result of greater number of trabeculae and osteogenic activity in the group implanted with NZ, compared to controls. In contrast with the untreated controls, NZ-treated groups showed a balanced osteoblast/osteoclast number ratio, similar to that found in the normal bone. These results suggest that NZ could be useful as adjunct to other osteoporosis treatments, but probably its main therapeutic role would be as preventive therapy against bone deterioration.

1,10a-Dihydro-1-aza-10a-boraphenanthrene and 6a,7-Dihydro-7-aza-6a-boratetraphene: Two New Fluorescent BN-PAHs.

Previously unknown 1,10a-dihydro-1-aza-10a-boraphenanthrene and 6a,7-dihydro-7-aza-6a-boratetraphene have been efficiently synthesized. Bromination of these BN-PAHs proceeds with complete regioselectivity, resulting in the formation of different substituted derivatives via cross-coupling reactions. These compounds exhibit rather high fluorescence quantum yields (up to ϕF = 0.80).

Effective Osteogenic Priming of Mesenchymal Stem Cells through LNA-ASOs-Mediated Sfrp1 Gene Silencing.

Mesenchymal stem cell (MSC) transplantation has emerged as a promising approach for bone regeneration. Importantly, the beneficial effects of MSCs can be improved by modulating the expression levels of specific genes to stimulate MSC osteogenic differentiation. We have previously shown that Smurf1 silencing by using Locked Nucleic Acid-Antisense Oligonucleotides, in combination with a scaffold that sustainably releases low doses of BMP-2, was able to increase the osteogenic potential of MSCs in the presence of BMP-2 doses significantly smaller than those currently used in the clinic. This would potentially allow an important reduction in this protein in MSs-based treatments, and thus of the side effects linked to its administration. We have further improved this system by specifically targeting the Wnt pathway modulator Sfrp1. This approach not only increases MSC bone regeneration efficiency, but is also able to induce osteogenic differentiation in osteoporotic human MSCs, bypassing the need for BMP-2 induction, underscoring the regenerative potential of this system. Achieving successful osteogenesis with the sole use of LNA-ASOs, without the need of administering pro-osteogenic factors such as BMP-2, would not only reduce the cost of treatments, but would also open the possibility of targeting these LNA-ASOs specifically to MSCs in the bone marrow, allowing us to treat systemic bone loss such as that associated with osteoporosis.

The Bone Regeneration Capacity of BMP-2 + MMP-10 Loaded Scaffolds Depends on the Tissue Status.

Biomaterials-mediated bone formation in osteoporosis (OP) is challenging as it requires tissue growth promotion and adequate mineralization. Based on our previous findings, the development of scaffolds combining bone morphogenetic protein 2 (BMP-2) and matrix metalloproteinase 10 (MMP-10) shows promise for OP management. To test our hypothesis, scaffolds containing BMP-2 + MMP-10 at variable ratios or BMP-2 + Alendronate (ALD) were prepared. Systems were characterized and tested in vitro on healthy and OP mesenchymal stem cells and in vivo bone formation was studied on healthy and OP animals. Therapeutic molecules were efficiently encapsulated into PLGA microspheres and embedded into chitosan foams. The use of PLGA (poly(lactic-co-glycolic acid)) microspheres as therapeutic molecule reservoirs allowed them to achieve an in vitro and in vivo controlled release. A beneficial effect on the alkaline phosphatase activity of non-OP cells was observed for both combinations when compared with BMP-2 alone. This effect was not detected on OP cells where all treatments promoted a similar increase in ALP activity compared with control. The in vivo results indicated a positive effect of the BMP-2 + MMP-10 combination at both of the doses tested on tissue repair for OP mice while it had the opposite effect on non-OP animals. This fact can be explained by the scaffold's slow-release rate and degradation that could be beneficial for delayed bone regeneration conditions but had the reverse effect on healthy animals. Therefore, the development of adequate scaffolds for bone regeneration requires consideration of the tissue catabolic/anabolic balance to obtain biomaterials with degradation/release behaviors suited for the existing tissue status.

Tailor-made oligonucleotide-loaded lipid-polymer nanosystems designed for bone gene therapy.

Gene therapy has emerged as a tool for the treatment of systemic metabolic disorders as osteoporosis (OP). However, the design of a suitable vehicle able to efficiently load and release the genetic material on the target cells is still a challenge. Moreover, the internalization pathway of nanosystems has been described to be dependent on their surface characteristics and the cell type evaluated. In this study, we aim at obtaining PEGylated lipid-PLGA nanoparticles (NPs) with variable surface charge able to incorporate GapmeRs (single-strand antisense oligonucleotides) for OP treatment. Nanoparticles showing negative, positive, and neutral surface charge were obtained by modulating the lipid composition. All formulations showed a remarkably low polydispersity index with adequate size. NPs were loaded with GapmeRs showing a high encapsulation efficiency and a surface charge-independent oligonucleotide loading. All the formulations were adequately internalized by MSCs. Future experiments will be devoted to use the developed formulations to clarify if the intracellular distribution of hybrid NPs on mesenchymal stem cells (MSCs) is dependent on surface charge. This portfolio of NPs will serve as a tool to analyze the effect of NP surface charge on gene therapy efficiency.

Selective Synthesis of Phenanthrenes and Dihydrophenanthrenes via Gold-Catalyzed Cycloisomerization of Biphenyl Embedded Trienynes.

Readily available o'-alkenyl-o-alkynylbiaryls, a particular type of 1,7-enynes, undergo a selective cycloisomerization reaction in the presence of a gold(I) catalyst to give interesting phenanthrene and dihydrophenanthrene derivatives in high yields. The solvent used provokes a switch in the evolution of the gold intermediate and plays a key role in the reaction outcome.

Alginate-hydrogel versus alginate-solid system. Efficacy in bone regeneration in osteoporosis.

In the present study, two different PLGA-Alginate scaffolds, a hydrogel (HY) and a solid sponge (SS), were developed for ß-estradiol and BMP-2 sustained delivery for bone regeneration in osteoporosis. ß-Estradiol and BMP-2 were encapsulated in PLGA and PLGA-Alginate microspheres respectively. Scaffolds were characterized in vitro in terms of porosity, water uptake, release rate and HY rheological properties. BMP-2 release profiles were also analysed in vivo. The bone regeneration induced by both HY and SS was evaluated using a critical-sized bone defect in an osteoporotic (OP) rat model. Compared to HY, SS presented 30% higher porosity, more than double water absorption capacity and almost negligible mass loss compared to the 40% of HY. Both systems were flexible and fit well the defect shape, however, HY has the advantage of being injectable. Despite both delivery systems had similar composition and release profile, bone repair was around 30% higher with SS than with HY, possibly due to its longer residence time at the defect site. The incorporation of mesenchymal stem cells obtained from OP rats did not result in any improvement or synergistic effect on bone repair.

Expanding the BN-embedded PAH family: 4a-aza-12a-borachrysene.

Previously unknown 4a-aza-12a-borachrysene has been synthesized in only four steps. The reactions of this BN-embedded PAH with bromine and organolithium compounds proceed with complete regioselectivity, resulting in the formation of nine derivatives. One of these, a phenylalkynyl-substituted derivative, exhibits a remarkably high fluorescence quantum yield (ΦF = 0.68).

Synthesis and Photophysical Behavior of a Highly Fluorescent Family of Unsymmetrical Organoboron Complexes Containing 5-(Pyridin-2-ylmethylene)imidazolidine-2,4-dione Moieties.

A new and highly fluorescent family of unsymmetrical organoboron complexes containing 5-(pyridin-2-ylmethylene)imidazolidine-2,4-dione moieties has been synthesized in three steps. These compounds show strong absorptions covering a wide range of the UV-vis spectrum and are strongly emissive (ϕf of up to 0.92 in CH3CN). Moreover, two fluorophores that include an alkyne or an azide group at the end of the alkyl chain and with potential utility in bioorthogonal chemistry have been developed. One of these, in which the glycol substituent provides an enhanced water solubility without compromising the fluorescence (ϕf = 0.85 in water), may be of particular importance.

PLGA-BMP-2 and PLA-17ß-Estradiol Microspheres Reinforcing a Composite Hydrogel for Bone Regeneration in Osteoporosis.

The controlled release of active substances-bone morphogenetic protein 2 (BMP-2) and 17ß-estradiol-is one of the main aspects to be taken into account to successfully regenerate a tissue defect. In this study, BMP-2- and 17ß-estradiol-loaded microspheres were combined in a sandwich-like system formed by a hydrogel core composed of chitosan (CHT) collagen, 2-hidroxipropil γ-ciclodextrin (HP-γ-CD), nanoparticles of hydroxyapatite (nano-HAP), and an electrospun mesh shell prepared with two external electrospinning films for the regeneration of a critical bone defect in osteoporotic rats. Microspheres were made with poly-lactide-co-glycolide (PLGA) to encapsulate BMP-2, whereas the different formulations of 17ß-estradiol were prepared with poly-lactic acid (PLA) and PLGA. The in vitro and in vivo BMP-2 delivered from the system fitted a biphasic profile. Although the in vivo burst effect was higher than in vitro the second phases (lasted up to 6 weeks) were parallel, the release rate ranged between 55 and 70 ng/day. The in vitro release kinetics of the 17ß-estradiol dissolved in the polymeric matrix of the microspheres depended on the partition coefficient. The 17ß-estradiol was slowly released from the core system using an aqueous release medium (Deff = 5.58·10-16 ± 9.81·10-17m2s-1) and very fast in MeOH-water (50:50). The hydrogel core system was injectable, and approximately 83% of the loaded dose is uniformly discharged through a 20G needle. The system placed in the defect was easily adapted to the defect shape and after 12 weeks approximately 50% of the defect was refilled by new tissue. None differences were observed between the osteoporotic and non-osteoporotic groups. Despite the role of 17ß-estradiol on the bone remodeling process, the obtained results in this study suggest that the observed regeneration was only due to the controlled rate released of BMP-2 from the PLGA microspheres.