Journal of biomedical materials research. Part A最新文献

RNA-based therapeutics have gained traction for the prevention and treatment of a variety of diseases. However, their fragility and immunogenicity necessitate a drug carrier. Lipid nanoparticles (LNPs) have emerged as the predominant delivery vehicle for RNA therapeutics. An important component of LNPs is the ionizable lipid (IL), which is protonated in the acidic environment of the endosome, prompting cargo release into the cytosol. Currently, there is growing evidence that the structure of IL lipid tails significantly impacts the efficacy of LNP-mediated mRNA translation. Here, we optimized IL tail length for LNP-mediated delivery of three different mRNA cargos. Using C12-200, a gold standard IL, as a model, we designed a library of ILs with varying tail lengths and evaluated their potency in vivo. We demonstrated that small changes in lipophilicity can drastically increase or decrease mRNA translation. We identified that LNPs formulated with firefly luciferase mRNA (1929 base pairs) and C10-200, an IL with shorter tail lengths than C12-200, enhance liver transfection by over 10-fold. Furthermore, different IL tail lengths were found to be ideal for transfection of LNPs encapsulating mRNA cargos of varying sizes. LNPs formulated with erythropoietin (EPO), responsible for stimulating red blood cell production, mRNA (858 base pairs), and the C13-200 IL led to EPO translation at levels similar to the C12-200 LNP. The LNPs formulated with Cas9 mRNA (4521 base pairs) and the C9-200 IL induced over three times the quantity of indels compared with the C12-200 LNP. Our findings suggest that shorter IL tails may lead to higher transfection of LNPs encapsulating larger mRNAs, and that longer IL tails may be more efficacious for delivering smaller mRNA cargos. We envision that the results of this project can be utilized as future design criteria for the next generation of LNP delivery systems for RNA therapeutics.

Mesenchymal stem cell-derived secretome represents an emerging acellular therapeutic which possess significant opportunity for clinical applications due to its anti-inflammatory, immunomodulatory, and wound healing properties. However, maintaining therapeutic efficacy and ensuring stability of cell-based products is challenging, requiring a robust delivery method. Therefore, we designed a hydrogel-based scaffold loaded with CK Cell Technologies' proprietary Mesenchymal stem cell-secretome for controlled release treatment of acute and chronic wounds. We incorporated both conditioned media (CM) and extracellular vesicles (EVs) into gelatin methacryloyl (GelMA) hydrogels and demonstrated how we can tune the diffusive release of the EVs from them. To demonstrate viability of the approach, we developed a wound healing scratch assay where we see in situ release of CM and EVs promote enhanced migration of human dermal fibroblasts (hDFs). We see the colocalization of these EVs in the fibroblasts using fluorescent microscopy. Finally, as a surrogate for in vivo neovascularization, we conducted an in vitro tube formation assay for the MSC-secretome using matrigel-embedded human microvascular endothelial cells. By adding CM and EVs, we observe an increase in tubulogenesis. Collectively, our data demonstrates by tuning the GelMA properties, we can influence the controlled release of the MSC-secretome for a wound dressing and bandage application for chronic and acute wounds.

Critical-sized bone defects pose a significant challenge in advanced healthcare due to limited bone tissue regenerative capacity. The complex interplay of numerous overlapping variables hinders the development of multifunctional biocomposites. Phytochemicals show promise in promoting bone growth, but their dose-dependent nature and physicochemical properties halt clinical use. To develop a comprehensive solution, a 3D-printed (3DP) extrusion-based tricalcium phosphate-polycaprolactone (TCP-PCL) scaffold is augmented with quercetin and potassium chloride (KCl). This composite material demonstrates a compressive strength of 30 MPa showing promising stability for low load-bearing applications. Quercetin release from the scaffold follows a biphasic pattern that persists for up to 28 days, driven via diffusion-mediated kinetics. The incorporation of KCl allows for tunable degradation rates of scaffolds and prevents the initial rapid release. Functionalization of scaffolds facilitates the attachment and proliferation of human fetal osteoblasts (hfOB), resulting in a 2.1-fold increase in cell viability. Treated scaffolds exhibit a 3-fold reduction in osteosarcoma (MG-63) cell viability as compared to untreated substrates. Ruptured cell morphology and decreased mitochondrial membrane potential indicate the antitumorigenic potential. Scaffolds loaded with quercetin and quercetin-KCl (Q-KCl) demonstrate 76% and 89% reduction in bacterial colonies of Staphylococcus aureus, respectively. This study provides valuable insights as a promising strategy for bone tissue engineering (BTE) in orthopedic repair.

Sponge-like materials made from regenerated silk fibroin biopolymers are a tunable and advantageous platform for in vitro engineered tissue culture and in vivo tissue regeneration. Anisotropic, three-dimensional (3D) silk fibroin sponge-like scaffolds can mimic the architecture of contractile muscle. Herein, we use silk fibroin solution isolated from the cocoons of Bombyx mori silkworms to form aligned sponges via directional ice templating in a custom mold with a slurry of dry ice and ethanol. Hydrated tensile mechanical properties of these aligned sponges were evaluated as a function of silk polymer concentration (3% or 5%), freezing time (50% or 100% ethanol), and post-lyophilization method for inducing crystallinity (autoclaving, water annealing). Hydrated static tensile tests were used to determine Young's modulus and ultimate tensile strength across sponge formulations at two strain rates to evaluate rate dependence in the calculated parameters. Results aligned with previous reports in the literature for isotropic silk fibroin sponge-like scaffolds, where the method by which beta-sheets were formed and level of beta-sheet content (crystallinity) had the greatest impact on static parameters, while polymer concentration and freezing rate did not significantly impact static mechanical properties. We estimated the crystalline organization using molecular dynamics simulations to show that larger crystalline regions may be responsible for strength at low strain amplitudes and brittleness at high strain amplitudes in the autoclaved sponges. Within the parameters evaluated, extensional Young's modulus is tunable in the range of 600–2800 kPa. Dynamic tensile testing revealed the linear viscoelastic region to be between 0% and 10% strain amplitude and 0.2–2 Hz frequencies. Long-term stability was evaluated by hysteresis and fatigue tests. Fatigue tests showed minimal change in the storage and loss modulus of 5% silk fibroin sponges for more than 6000 min of continuous mechanical stimulation in the linear regime at 10% strain amplitude and 1 Hz frequency. Furthermore, we confirmed that these mechanical properties hold when decellularized extracellular matrix is added to the sponges and when the mechanical property assessments were performed in cell culture media. We also used nano-computed tomography (nano-CT) and simulations to explore pore interconnectivity and tortuosity. Overall, these results highlight the potential of anisotropic, sponge-like silk fibroin scaffolds for long-term (>6 weeks) contractile muscle culture with an in vitro bioreactor system that provides routine mechanical stimulation.

The physicochemical properties of grafting materials affect the quality of the osteointegration, resorption rate, and the new bone (NB) formation. This study assessed the physicochemical properties and integration of a low temperature deproteinized bovine bone xenograft (BBX), referred to as optimized MoaBone® (OMB). This novel BBX was physiochemically characterized both pre and post chemical bleaching and sterilization by gamma irradiation. OMB was compared to two commercial BBX; Bio-Oss® (BO) and MoaBone® (MB) using a rabbit cranial model. Residual graft and NB were quantified using histology and micro-computed tomography. Results showed that chemical treatment and gamma irradiation had limited effect on the surface texture. A significant decrease in the collagen content was detected post chemical treatment and in the carbonate content post gamma irradiation. There was no evidence of inflammatory infiltrate, necrosis, or connective tissue encapsulation, and a significant increase of NB in all grafted sites as compared to untreated defects could be observed. However, there was no statistically significant difference between the grafted sites. We conclude that chemical treatment and terminal sterilization strongly impact the final graft's properties. OMB graft showed equivalence with BO for in vivo bone formation and potentially results in lower levels of graft retention.

Currently available focal knee resurfacing implants (FKRIs) are fully or partially composed of metals, which show a large disparity in elastic modulus relative to bone and cartilage tissue. Although titanium is known for its excellent osseointegration, the application in FKRIs can lead to potential stress-shielding and metal implants can cause degeneration of the opposing articulating cartilage due to the high resulting contact stresses. Furthermore, metal implants do not allow for follow-up using magnetic resonance imaging (MRI).To overcome the drawbacks of using metal based FKRIs, a biomimetic and MRI compatible bi-layered non-resorbable thermoplastic polycarbonate-urethane (PCU)-based FKRI was developed. The objective of this preclinical study was to evaluate the mechanical properties, biocompatibility and osteoconduction of a novel Bionate® 75D - zirconium oxide (B75D-ZrO₂) composite material in vitro and the osseointegration of a B75D-ZrO₂ composite stem PCU implant in a caprine animal model. The tensile strength and elastic modulus of the B75D-ZrO₂ composite were characterized through in vitro mechanical tests under ambient and physiological conditions. In vitro biocompatibility and osteoconductivity were evaluated by exposing human mesenchymal stem cells to the B75D-ZrO₂ composite and culturing the cells under osteogenic conditions. Cell activity and mineralization were assessed and compared to Bionate® 75D (B75D) and titanium disks. The in vivo osseointegration of implants containing a B75D-ZrO₂ stem was compared to implants with a B75D stem and titanium stem in a caprine large animal model. After a follow-up of 6 months, bone histomorphometry was performed to assess the bone-to-implant contact area (BIC). Mechanical testing showed that the B75D-ZrO₂ composite material possesses an elastic modulus in the range of the elastic modulus reported for trabecular bone. The B75D-ZrO₂ composite material facilitated cell mediated mineralization to a comparable extent as titanium. A significantly higher bone-to-implant contact (BIC) score was observed in the B75D-ZrO₂ implants compared to the B75D implants. The BIC of B75D-ZrO₂ implants was not significantly different compared to titanium implants. A biocompatible B75D-ZrO₂ composite approximating the elastic modulus of trabecular bone was developed by compounding B75D with zirconium oxide. In vivo evaluation showed an significant increase of osseointegration for B75D-ZrO₂ composite stem implants compared to B75D polymer stem PCU implants. The osseointegration of B75D-ZrO₂ composite stem PCU implants was not significantly different in comparison to analogous titanium stem metal implants.

Diabetic wounds environment is over-oxidized, over-inflammatory, leading to difficulties in regenerating blood vessels, and retardation of healing in diabetic wounds. Therefore, diabetic wounds can be treated from the perspective of scavenging oxidative free radicals and reducing the level of inflammation. Herein, we report a bioactive poly(salicylic acid)-poly(citric acid) (FPSa-PCG) hydrogel for diabetic wound repair. The FPSa-PCG hydrogel shows abilities of antioxidation, anti-inflammation, and regulation of macrophage phenotype. The FPSa-PCG hydrogel showed good biocompatibility, and obtain the abilities of promotion of macrophages migration, reduction of ROS generation, suppression of the M1-type macrophage polarization. FPSa and PCG could synergistically enhance the angiogenesis through upregulating the mRNA expression of HIF1Α, VEGF, and CD31 in endothelial cells and reduce the ROS level of macrophages through upregulating the mRNA expression of Nrf2. The in vivo diabetic wound model confirmed the promoting effect of FPSa-PCG hydrogel on wound closure in diabetes. The further studies found that FPSa-PCG hydrogel could induce the CD31 protein expression in the subcutaneous tissue and inhibit the TNF-a protein expression. This work shows that the simple composition FPSa-PCG hydrogel has a promising therapeutic potential in the treatment of diabetic wounds.

Dental enamel is a mineralized extracellular matrix, and enamel defect is a common oral disease. However, the self-repair capacity of enamel is limited due to the absence of cellular components and organic matter. Efficacy of biomimetic enamel mineralization using calcium phosphate ion clusters (CPICs), is an effective method to compensate for the limited self-healing ability of fully developed enamel. Preparing and stabilizing CPICs presents a significant challenge, as the addition of certain stabilizers can diminish the mechanical properties or biosafety of mineralized enamel. To efficiently and safely repair enamel damage, this study quickly prepared CPICs without stabilizers using the atomization method. The formed CPICs were evenly distributed on the enamel surface, prompting directional growth and transformation of hydroxyapatite (HA) crystals. The study revealed that the mended enamel displayed comparable morphology, chemical composition, hardness, and mechanical properties to those of the original enamel. The approach of repairing dental enamel by utilizing ultrasonic nebulization of CPICs is highly efficient and safe, therefore indicating great promise.

Induced Tregs (iTregs) have great promise in adoptive immunotherapy for treatment of autoimmune diseases. This report investigates the impacts of substrate stiffness on human Treg induction, providing a powerful yet simple approach to improving production of these cells. Conventional CD4⁺ human T cells were activated on materials of different elastic modulus and cultured under suppressive conditions. Enhanced Treg induction was observed on softer materials as early as 3 days following activation and persisted for multiple weeks. Substrate stiffness also affected epigenetic modification of Treg specific genes and Treg suppressive capacity. Tregs induced on substrates of an optimal stiffness balance quantity and suppressive quality.

Maurizio Sabbatini, Valentina Piffanelli, Francesca Boccafoschi, Silvia Gatti, Filippo Renò, Michela Bosetti, Massimiliano Leigheb, Alessandro Massè, Cannas Mario, Different apoptosis modalities in periprosthetic membranes, Biomed. Mater. Res., 92A: 175–184. DOI: 10.1002/jbm.a.32349.

The journal publishes this Expression of Concern to notify the readers regarding irregularities identified in Figure 1A and 1B of the above article, published online on 22 January 2009, in Wiley Online Library (wileyonlinelibrary.com). High similarities of histological images presented in Figure 1A and 1B were confirmed by professional image analysis after concerns were raised by a third party. These similarities affect the integrity of the presented micrographs representing two different membranes. Raw data provided by the authors could not explain the identified issues. The investigation performed by the journal team could not exclude that these concerns affect the overall conclusions of the article.