Chimeric Protein Template-Induced Shape Control of Bone Mineral Nanoparticles and Its Impact on Mesenchymal Stem Cell Fate.

Protein-mediated molecular self-assembly has become a powerful strategy to fabricate biomimetic biomaterials with controlled shapes. Here we designed a novel chimeric molecular template made of two proteins, silk fibroin (SF) and albumin (ALB), which serve as a promoter and an inhibitor for hydroxyapatite (HA) formation, respectively, to synthesize HA nanoparticles with controlled shapes. HA nanospheres were produced by the chimeric ALB-SF template, whereas HA nanorods were generated by the SF template alone. The success in controlling the shape of HA nanoparticles allowed us to further study the effect of the shape of HA nanoparticles on the fate of rat mesenchymal stem cells (MSCs). We found that the nanoparticle shape had a crucial impact on the cellular uptake and HA nanospheres were internalized in MSCs at a faster rate. Both HA nanospheres and nanorods showed no significant influence on cell proliferation and migration. However, HA nanospheres significantly promoted the osteoblastic differentiation of MSCs in comparison to HA nanorods. Our work suggests that a chimeric combination of promoter and inhibitor proteins is a promising approach to tuning the shape of nanoparticles. It also sheds new light into the role of the shape of the HA nanoparticles in directing stem cell fate.

PCL nanofibrous incorporating unique matrix fusion protein adsorbed mesoporous bioactive glass for bone tissue engineering.

Mesoporous bioactive glass (MBG) is a potential biomedical material in bone defect repairment because of its bioactivity, biocompatibility, and osteoinduction properties. Here we report that Mg-doped MBG scaffold with 3:1 Ca/Mg ratio (MBG-Ca/Mg-3) is good for MC3T3-E1 osteoblast differentiation and mineralization. Mimicking bone extracellular matrix structure by electrospinning, we used MBG-Ca/Mg-3 adsorbed with Osteocalcin-Osteopontin-Biglycan (OOB), a new unique matrix fusion protein, to form OOB@MBG-Ca/Mg-3 scaffold, which has multifunctional ability in calvarial bone defect repairment in vivo. Intriguingly, we found that OOB@MBG-Ca/Mg-3 scaffold increases the expression of osteoblastic marker genes, including bone morphogenetic protein (Bmp2), osteopontin (Opn), Osterix, Runx2 through activation of ERK1/2. We concluded that OOB@MBG-Ca/Mg-3 scaffold promotes osteoblast differentiation and mineralization through ERK1/2 pathway and it can also enhance bone formation in vivo, which provides a new biomaterial in bone tissue engineering.

Air pollution as a determinant of food delivery and related plastic waste.

Plastic waste is a growing environmental concern. The food delivery industry is criticized for its environmental impact, especially its current use of plastic packaging. At the same time, the environment impacts the industry. We show that air pollution is a behavioural driver of food delivery consumption in the urban developing world. Our hypothesis is that individuals are more likely to order delivery when their personal cost of exposure to the outdoor environment rises. We surveyed office workers in three Chinese cities and found that an increase of 100 µg m-3 in particulate matter pollution (PM2.5) raised the propensity to order food delivery by two-fifths of the sample mean. We used photographic evidence to quantify disposable plastic in meal delivery. Data from an online delivery platform with a broad customer base indicate a smaller, but still substantial, causal link between air quality and food delivery. Overall, air pollution control brings plastic waste co-benefits.

Bioenergetic-active materials enhance tissue regeneration by modulating cellular metabolic state.

Cellular bioenergetics (CBE) plays a critical role in tissue regeneration. Physiologically, an enhanced metabolic state facilitates anabolic biosynthesis and mitosis to accelerate regeneration. However, the development of approaches to reprogram CBE, toward the treatment of substantial tissue injuries, has been limited thus far. Here, we show that induced repair in a rabbit model of weight-bearing bone defects is greatly enhanced using a bioenergetic-active material (BAM) scaffold compared to commercialized poly(lactic acid) and calcium phosphate ceramic scaffolds. This material was composed of energy-active units that can be released in a sustained degradation-mediated fashion once implanted. By establishing an intramitochondrial metabolic bypass, the internalized energy-active units significantly elevate mitochondrial membrane potential (ΔΨm) to supply increased bioenergetic levels and accelerate bone formation. The ready-to-use material developed here represents a highly efficient and easy-to-implement therapeutic approach toward tissue regeneration, with promise for bench-to-bedside translation.

Targeting the IL-17 Receptor Using Liposomal Spherical Nucleic Acids as Topical Therapy for Psoriasis.

The activation of T helper 17 signaling plays a critical role in psoriasis pathogenesis, and systemically-administered IL-17 inhibitors are highly effective therapy for moderate-to-severe disease. We generated topically-delivered gene-regulating nanoconstructs, comprised of spherically-arrayed antisense DNA (liposomal spherical nucleic acids [L-SNAs]), which are able to penetrate human skin to knock down cutaneous gene targets. Topically-applied L-SNAs targeting the gene encoding the mouse IL-17A receptor (Il17ra) reversed the development of psoriasis clinically, histologically, and transcriptionally in imiquimod-treated psoriasis-like mouse skin. Il17ra L-SNAs reduced the modified PASI by 74% versus controls and decreased epidermal thickness by 56%. Il17ra L-SNA reduced Il17ra protein expression by 75% and significantly decreased the mRNA expression of psoriasis markers, including Defb4, Il17c, S100a7, Pi3, Krt16, and Tnfa versus scrambled spherical nucleic acid (Scr SNA) controls. A human IL17RA L-SNA penetrates 3-dimensional cultures and normal human explants to knock down IL17RA mRNA by 63% and 66%, respectively. After topical application to psoriatic 3-dimensional rafts, anti-human IL17RA L-SNAs reduced the expression of IL17RA (by 72%) and the IL-17-induced genes IL17C (by 85%), DEFB4 (by 83%), TNFA (by 77%), and PI3 (by 65%) versus scrambled L-SNA and vehicle controls (all P < 0.001). Taken together, these data suggest that targeted suppression of IL17RA is a promising new topical treatment strategy for psoriasis.

Ångstrom-scale silver particle-embedded carbomer gel promotes wound healing by inhibiting bacterial colonization and inflammation.

Poor wound healing after diabetes or extensive burn remains a challenging problem. Recently, we presented a physical approach to fabricate ultrasmall silver particles from Ångstrom scale to nanoscale and determined the antitumor efficacy of Ångstrom-scale silver particles (AgÅPs) in the smallest size range. Here we used the medium-sized AgÅPs (65.9 ± 31.6 Å) to prepare carbomer gel incorporated with these larger AgÅPs (L-AgÅPs-gel) and demonstrated the potent broad-spectrum antibacterial activity of L-AgÅPs-gel without obvious toxicity on wound healing-related cells. Induction of reactive oxygen species contributed to L-AgÅPs-gel-induced bacterial death. Topical application of L-AgÅPs-gel to mouse skin triggered much stronger effects than the commercial silver nanoparticles (AgNPs)-gel to prevent bacterial colonization, reduce inflammation, and accelerate diabetic and burn wound healing. L-AgÅPs were distributed locally in skin without inducing systemic toxicities. This study suggests that L-AgÅPs-gel represents an effective and safe antibacterial and anti-inflammatory material for wound therapy.

A high-strength biodegradable thermoset polymer for internal fixation bone screws: Preparation, in vitro and in vivo evaluation.

Thermoset polymers synthesized from the polycondensation of glycerol with biocompatible diacids represent a promising class of absorbable materials for biomedical applications. However, the utility of these polymers for bone fixation devices is hampered due to the lack of mechanical strength. Herein we synthesized a high-strength thermoset polymer, poly(glycerol-succinate) (PGS), via a catalyst-free and solvent-free reaction. The bending strength of PGS reaches 122.01 ±â€¯8.82 MPa, signifying its great potential for fixation devices. The degradation property of the polymer can be tuned by adjusting the monomer ratio and reaction time. Bone screws based on the PGS polymer were successfully manufactured using a lathe. In vitro evaluation showed the PGS polymer was able to well support cell adhesion and proliferation. In vivo evaluation using a rat subcutaneous implantation model showed that the inflammatory response to the polymer was mild. After the PGS screws were implanted in the rabbit femoral condyle for 12 weeks, micro-computed tomography (micro-CT) and histological analysis revealed that the screws achieved good osseointegration. Consequently, the polymer developed in current study can serve as internal fixation devices due to the proper mechanical strength, excellent biocompatibility, and feasibility of manufacturing screws.

Thermally triggered injectable chitosan/silk fibroin/bioactive glass nanoparticle hydrogels for in-situ bone formation in rat calvarial bone defects.

Copper-containing bioactive glass nanoparticles (Cu-BG NPs) with designed compositions and sizes were synthesized and incorporated into chitosan (CH)/silk fibroin (SF)/glycerophosphate (GP) composites to prepare injectable hydrogels for cell-free bone repair. The resulting Cu-BG/CH/SF/GP gels were found to exhibit well-defined injectability and to undergo rapid gelation at physiological temperature and pH. They were highly porous and showed the ability to administer Si, Ca and Cu ions at their respective safe doses in a sustained and controlled manner. In vitro studies revealed that the gels supported the growth of seeded MC3T3-E1 and human umbilical vein endothelial cells, and effectively induced them toward osteogenesis and angiogenesis, respectively. In vivo bone repair based on a critical-size rat calvarial bone defect model demonstrated that the optimal Cu-BG/CH/SF/GP gel was able to fully restore the bone defect with formation of vascularized bone tissue and mineralized collagen deposition during a treatment period of 8 weeks without utilization of any cells and/or growth factors. The results suggest that the presently developed Cu-BG/CH/SF/GP composite hydrogels have great potential and translation ability for bone regeneration owing to their thermo-sensitive properties, cell-free bioactivity, and cost-effectiveness. STATEMENT OF SIGNIFICANCE: Hydrogels loaded with cells and/or growth factors exhibit potential in bone repair. However, they have been facing obstacles related to the clinic translation. Here, a novel type of hydrogel system consisting of copper-containing bioactive glass nanoparticles and chitosan/silk fibroin composite was developed. These gels showed injectability and thermally triggered in situ gelation properties and were able to administer the release of ions at safe but effective doses in a controlled manner while inducing the seeded cells toward osteogenesis and angiogenesis. The optimal gel showed the ability to fully repair critical-size rat calvarial bone defects without involving time consuming cell processing and/or the use of expensive growth factors, confirming that this novel hydrogel system has great potential for translation to the clinic.

Selective laser sintering scaffold with hierarchical architecture and gradient composition for osteochondral repair in rabbits.

Osteochondral defects cannot be adequately self-repaired due to the presence of the sophisticated hierarchical structure and the lack of blood supply in cartilage. Thus, one of the major challenges remaining in this field is the structural design of a biomimetic scaffold that satisfies the specific requirements for osteochondral repair. To address this hurdle, a bio-inspired multilayer osteochondral scaffold that consisted of the poly(ε-caprolactone) (PCL) and the hydroxyapatite (HA)/PCL microspheres, was constructed via selective laser sintering (SLS) technique. The SLS-derived scaffolds exhibited an excellent biocompatibility to support cell adhesion and proliferation in vitro. The repair effect was evaluated by implanting the acellular multilayer scaffolds into osteochondral defects of a rabbit model. Our findings demonstrated that the multilayer scaffolds were able to induce articular cartilage formation by accelerating the early subchondral bone regeneration, and the newly formed tissues could well integrate with the native tissues. Consequently, the current study not only achieves osteochondral repair, but also suggests a promising strategy for the fabrication of bio-inspired multilayer scaffolds with well-designed architecture and gradient composition via SLS technique.

Microsphere-based selective laser sintering for building macroporous bone scaffolds with controlled microstructure and excellent biocompatibility.

Fabrication of bulk biomaterials with controlled structures and excellent properties is increasingly important in tissue engineering, but remains a major challenge in the current stage. Herein we used selective laser sintering (SLS) to construct a series of three-dimensional (3D) bone scaffolds with uniform multi-scaled porosity, moderate mechanical properties as well as good biocompatibility. As starting architectural units for SLS, the pure microspheres of polycaprolactone (PCL) and the composite microspheres of PCL and hydroxyapatite (HA) were firstly synthesized via a modified solvent evaporation method, respectively. Our findings showed that the as-prepared microspheres exhibited the uniform size and monodispersity. Moreover, the microsphere-based 3D scaffolds generated by SLS technique showed a multi-scaled porous structure, and adequate mechanical features. Both in vitro and in vivo evaluations further demonstrated that the resultant SLS-derived scaffolds can not only manipulate multiple stem cell behaviors including promoting cell adhesion, supporting cell proliferation and inducing cell differentiation in vitro, but also showed an excellent histocompatibility and induced the vascularization of newly formed tissue in vivo. Consequently, our current study suggests a feasible and effective protocol for fabricating new biomimetic bone biomaterials via SLS technique, also paves a new way for other bulk biomaterials.

Selenite-Releasing Bone Mineral Nanoparticles Retard Bone Tumor Growth and Improve Healthy Tissue Functions In Vivo.

Selenite-doped bone mineral nanoparticles can retard the growth of osteosarcoma in a nude mice model, through sustained release of selenite ions. The selenite ions released from the nanoparticles through a degradation-mediated fashion inhibit tumor metastasis. Blood routine analysis indicates that selenite ions can also improve the functions of liver, kidney, and heart.

Novel alternative therapy for spinal tuberculosis during surgery: reconstructing with anti-tuberculosis bioactivity implants.

Accompanied with the worsening of the pulmonary tuberculosis bacterium (TB) epidemic, the incidence of spinal TB has increased in recent years. Spinal reconstruction and stabilisation, and bone defect repair play a crucial role in the surgical treatment of spinal TB. Unfortunately, the existing materials have not completely met the requirements for spinal TB reconstruction due to their diverse deficiencies. Therefore, there is an urgent need to develop novel reconstructing implants. Poly-DL-lactide (PDLLA) and nano-hydroxyapatite (nHA) are two promising drug delivery systems (DDS) and materials for bone repair, which could help us to overcome the difficulties in spinal TB reconstruction in the future. In this article, we discuss the properties of PDLLA and nHA, two potential drug delivering and bone repair materials for spinal TB reconstruction. We also presented two alternatives for spinal TB in future. Two strategies have the potential for treating spinal TB in the future. One such strategy consists of mixing anti-TB drugs, PDLLA with nHA to fabricate a novel three-dimensional (3D) porous scaffold via 3D printing (3DP) technology. Another is preparing a novel titanium mesh implant coated with drugs/PDLLA/nHA composites by solvent evaporation and low-temperature drying technology. These two hypotheses have recently been tested in a laboratory setting by our team.

Preparation, characterization, and in vitro cytotoxicity evaluation of a novel anti-tuberculosis reconstruction implant.

BACKGROUND: Reconstruction materials currently used in clinical for osteoarticular tuberculosis (TB) are unsatisfactory due to a variety of reasons. Rifampicin (RFP) is a well-known and highly effective first-line anti-tuberculosis (anti-TB) drug. Poly-DL-lactide (PDLLA) and nano-hydroxyapatite (nHA) are two promising materials that have been used both for orthopedic reconstruction and as carriers for drug release. In this study we report the development of a novel anti-TB implant for osteoarticular TB reconstruction using a combination of RFP, PDLLA and nHA. METHODS: RFP, PDLLA and nHA were used as starting materials to produce a novel anti-TB activity implant by the solvent evaporation method. After manufacture, the implant was characterized and its biodegradation and drug release profile were tested. The in vitro cytotoxicity of the implant was also evaluated in pre-osteoblast MC3T3-E1 cells using multiple methodologies. RESULTS: A RFP/PDLLA/nHA composite was successfully synthesized using the solvent evaporation method. The composite has a loose and porous structure with evenly distributed pores. The production process was steady and no chemical reaction occurred as proved by Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). Meanwhile, the composite blocks degraded and released drug for at least 12 weeks. Evaluation of in vitro cytotoxicity in MC3T3-E1 cells verified that the synthesized composite blocks did not affect cell growth and proliferation. CONCLUSION: It is feasible to manufacture a novel bioactive anti-TB RFP/PDLLA/nHA composite by the solvent evaporation method. The composite blocks showed appropriate properties such as degradation, drug release and biosafety to MC3T3-E1 cells. In conclusion, the novel composite blocks may have great potential for clinical applications in repairing bone defects caused by osteoarticular TB.