The bone matrix plays an indispensable role in the human body,and its unique biomechanical and mechanobiological properties have received much attention.The bone matrix has unique mechanical anisotropy and exhibits both strong toughness and high strength.These mechanical properties are closely associated with human life activities and correspond to the function of bone in the human body.None of the mechanical properties exhibited by the bone matrix is independent of its composition and structure.Studies on the biomechanics of the bone matrix can provide a reference for the preparation of more applicable bone substitute implants,bone biomimetic materials and scaffolds for bone tissue repair in humans,as well as for biomimetic applications in other fields.In providing mechanical support to the human body,bone is constantly exposed to mechanical stimuli.Through the study of the mechanobiology of the bone matrix,the response mechanism of the bone matrix to its surrounding mechanical environment can be elucidated and used for the health maintenance of bone tissue and defect regeneration.This paper summarizes the biomechanical properties of the bone matrix and their biological significance,discusses the compositional and structural basis by which the bone matrix is capable of exhibiting these mechanical properties,and studies the effects of mechanical stimuli,especially fluid shear stress,on the components of the bone matrix,cells and their interactions.The problems that occur with regard to the biomechanics and mechanobiology of the bone matrix and the corresponding challenges that may need to be faced in the future are also described.
The development of small-diameter vascular grafts that can meet the long-term patency required for implementation in clinical practice presents a key challenge to the research field.Although techniques such as the braiding of scaffolds can offer a tunable platform for fabricating vascular grafts,the effects of braided silk fiber skeletons on the porosity,remodeling,and patency in vivo have not been thoroughly investigated.
Sensitive detection of SARS-CoV-2 is of great importance for inhibiting the current pandemic of COVID-19.Here,we report a simple yet efficient platform integrating a portable and low-cost custom-made detector and a novel microwell array biochip for rapid and accurate detection of SARS-CoV-2.The instrument exhibits expedited amplification speed that enables colorimetric read-out within 25 minutes.A polymeric chip with a laser-engraved microwell array was developed to process the reaction between the primers and the respiratory swab RNA extracts,based on reverse transcriptase loop-mediated isothermal amplification(RT-LAMP).To achieve clinically acceptable performance,we synthesized a group of six primers to identify the conserved regions of the ORF1ab gene of SARS-CoV-2.Clinical trials were conducted with 87 PCR-positive and 43 PCRnegative patient samples.The platform demonstrated both high sensitivity(95.40%)and high specificity(95.35%),showing potentials for rapid and user-friendly diagnosis of COVID-19 among many other infectious pathogens.
Biodegradable magnesium(Mg)has shown great potential advantages over current bone fixation devices and vascular scaffold technologies;however,there are few reports on the immunomodulation of corrosive Mg products,the micron-sized Mg particles(MgMPs).Human monocytic leukemia cell line THP-1 was set as the in vitro cell model to estimate the immunomodulation of MgMPs on cell proliferation,apoptosis,polarization and inflammatory reaction.Our results indicated highconcentration of Mg^2+ demoted the proliferation of the THP-1 cells and,especially,THP-1-derived macrophages,which was a potential factor that could affect cell function,but meanwhile,cell apoptosis was almost not affected by Mg^2+.In particular,the inflammation regulatory effects of MgMPs were investigated.Macrophages exposed to Mg^2+ exhibited down-regulated expressions of M1 subtype markers and secretions of pro-inflammatory cytokines,up-regulated expression of M2 subtype marker and secretion of anti-inflammatory cytokine.These results indicated Mg^2+ could convert macrophages from M0 to M2 phenotype,and the bioeffects of MgMPs on human inflammatory cells were most likely due to the Mg^2+-induced NF-jB activation reduction.Together,our results proved Mg^2+ could be used as a new anti-inflammatory agent to suppress inflammation in clinical applications,which may provide new ideas for studying the immunomodulation of Mg-based implants on human immune system.
Lei SunXiaoyu LiMenghan XuFenghe YangWei WangXufeng Niu
Retinal injury is the most common ocular impairment associated with shaken baby syndrome(SBS), which could lead to vision loss and blindness. However, a woodpecker does not develop retinal hemorrhages or detachment even at a high acceleration of 1,000×g during pecking. To understand the mechanism of retinal injury and its resistance strategy, we put insight into the special ability of the woodpecker to protect the retina against damage under acceleration–deceleration impact. In this study, the structural and mechanical differences on the eyes of the woodpecker and human were analyzed quantitatively based on anatomical observation. We developed finite element eye models of the woodpecker and human to evaluate the dynamic response of the retina to the shaking load obtained from experimental data. Moreover, several structural parameters and mechanical conditions were exchanged between the woodpecker and human to evaluate their effects on retinal injury in SBS. The simulation results indicated that scleral ossification, lack of vitreoretinal attachment, and rotational acceleration–deceleration impact loading in a woodpecker contribute to the resistance to retinal injuries during pecking. The above mentioned special physical structures and mechanical behavior can distribute the high strain in the posterior segment of the woodpecker’s retina, which decrease the risk of retinal injury to SBS.
This study aimed to explore the optimal invisible orthodontic force system during the en-mass distalization of two maxillary molars to minimize the side effect of anchorage loss by changing the direction of the application of the orthodontic force system.A high bio-fidelity 3D finite element model including maxilla,periodontal ligament,dentition,clear aligner,3D anchorage attachment and mini-implant was established.Different lengths of lateral hooks of 3D-printed anchorage attachments and mini-implant positions into the palatal alveolus were considered.A 200 g distal force was applied to the lateral hooks of different horizontal lengths(3.26 mm,6.52 mm and 9.78 mm)with the mini-implant as the application point.Using ABAQUS software,orthodontic tooth movements under 12 different clinical treatment designs were analyzed and calculated.The 3D anchorage attachment enhanced the anchorage of anterior teeth and alleviated the tipping/extrusion of premolars.In contrast to without clear aligners,length of the lateral hook had a negligible effect on both mesial tipping and buccal tipping with clear aligners,which could then be ignored.The change in mesial tipping was less and nearly remained constant despite of the different heights of the mini-implant.The 3D anchorage attachment assisted clear aligner can avoid the side effects of anterior tooth proclination caused by insufficient anchorage.The length of the lateral hook,and height of the mini-implant in this invisible orthodontic force system hardly affects the tooth movement of anchorage units.Clear aligners can effectively control the rotation and tipping of anchorage units caused by 3D anchorage attachment.
Lurong JiaChunjuan WangYao HeChao WangAntonio ApicellaJinlin SongYubo Fan
For the surgical treatment of cardiovascular disease(CVD),there is a clear and unmet need in developing small-diameter(diameter<6 mm)vascular grafts.In our previous work,sulfated silk fibroin(SF)was successfully fabricated as a potential candidate for preparing vascular grafts due to the great cytocompatibility and hemocompatibility.However,vascular graft with single layer is difficult to adapt to the complex internal environment.In this work,polycaprolactone(PCL)and sulfated SF were used to fabricate bilayer vascular graft(BLVG)to mimic the structure of natural blood vessels.To enhance the biological activity of BLVG,nicorandil(NIC),an FDA-approved drug with multi-bioactivity,was loaded in the BLVG to fabricate NIC-loaded BLVG.The morphology,chemical composition and mechanical properties of NIC-loaded BLVG were assessed.The results showed that the bilayer structure of NIC-loaded BLVG endowed the graft with a biphasic drug release behavior.The in vitro studies indicated that NIC-loaded BLVG could significantly increase the proliferation,migration and antioxidation capability of endothelial cells(ECs).Moreover,we found that the potential biological mechanism was the activation of PI3K/AKT/eNOS signaling pathway.Overall,the results effectively demonstrated that NIC-loaded BLVG had a promising in vitro performance as a functional small-diameter vascular graft.
Zheng XingChen ZhaoChunchen ZhangYubo FanHaifeng Liu
