Circumferential variation in mechanical characteristics of porcine descending aorta

Arterial characterization of healthy descending thoracic aorta(DTA)is indispensable in determining stress distributions across wall thickness and different regions that may be responsible for aorta inhomogeneous dilation,rupture,and dissection when aneurysm occurs.Few studies have shown the inhomogeneity of DTA along the aorta tree considering changes in circumferential direction.The present study aims to clarify the circumferential regional characterization of DTA.Porcine DTA tissues were tested according to region and orientation using uniaxial tension.For axial test,results show that the difference in circumferential direction was mainly in collagen fiber modulus,where the anterior collagen fiber modulus was significantly lower than the posterior quadrant.For circumferential test,the difference in circumferential direction was mainly in the recruitment parameter,where the circumferential stiffness is significantly higher in the posterior region at physiological maximum stress.The proximal posterior quadrant and left quadrant showed significantly lower axial collagen fiber stiffness than the right and anterior quadrants,which may be a factor in aneurysm development.Furthermore,the constitutive parameters for similar detailed regions can be used by biomedical engineers to investigate improved therapies and thoroughly understand the initial stage of aneurysm development.The regional collagen fiber modulus can help improve our understanding of the mechanisms of arterial dilation and aortic dissection.

Biomimetic microchannel network with functional endothelium formed by sacrificial electrospun fibers inside 3D gelatin methacryloyl(GelMA)hydrogel models

Three-dimensional(3D)hydrogel models play a crucial role in tissue engineering for promoting tissue regeneration.A biomimetic microchannel network system in the 3D hydrogel model is necessary for optimal cellular function.This report describes the preparation of a biomimetic hydrogel scaffold with an internal microchannel network,using electrospinning techniques and the sacrificial template method for 3D cell culture.Microchannels and cavities were created within the gelatin methacryloyl(GelMA)hydrogel by sacrificing polyvinyl alcohol(PVA)electrospun fibers(>10µm),resulting in the creation of microvessel-like channels.Mechanical characterizations,swelling properties,and biodegradation analysis were conducted to investigate the feasibility of a biomimetic microchannel network hydrogel scaffold for 3D cell culture applications.Compared to pure GelMA hydrogel,the hydrogel with microchannels promoted cell proliferation,adhesion,and endothelial tube formation.Moreover,the results confirmed that the biomimetic microchannel network scaffold had a major impact on the distribution and arrangement of human umbilical vein endothelial cells(HUVECs)and can enable the formation of artificial microvasculature by the culture of HUVECs and cell media perfusion.

Erratum to Mechanical performance and cyocompatibility of PU/PLCL nanofibrous electrospun scaffolds for skin regeneration

The publisher regrets that ethical approval was not included in the published version.Upon request,the authors have provided the appropriate ethical approval statement,which states that the human skin fibroblasts used in this study were derived from normal skin tissues of patients after scar resection at Shanxi Bethune Hospital,and were obtained under ethical requirements.The experimental process strictly adhered to relevant ethical requirements and guidelines,and was granted approval by the ethics committee with protocol number SBQLL-2021-065 from Shanxi Bethune Hospital.

DETERMINATION OF QUADRICEPS FORCES IN SQUAT AND ITS APPLICATION IN CONTACT PRESSURE ANALYSIS OF KNEE JOINT

While the quadriceps muscles of human body are quite important to the daily ac-tivities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in vivo.Here,a novel approach is presented to obtain the forces in squat through the combination of motion photography,force transducers measuring,multi-rigid-body theory and finite element analysis.Firstly,the geometrical and angular data of human for squat process were obtained through the analysis of photographed pictures for human squat with cam-era.At the same time,force transducers were used to measure the reaction forces from feet and to determine the center of gravity for identical squat process.Next,based on the multi-rigid-body dynamics,a mathematical model for human right leg and foot was established in order to determine the quadriceps torques under different squat angles.Then,so as to determine the quadriceps forces along with varied squat angles,a simplified three-dimensional finite element model was built,including tibia,fibula,patella,patella ligament and quadriceps tendon.Finally,the contact pressure of knee joint was analyzed for the squat with the established model of knee joint involving the obtained quadriceps forces from finite element analysis.And it showed that in the 0-90 degree squat process,the peak value of contact pressure of articular cartilages and menisci is increased with the increased squat angle.This study can be referenced for further un-derstanding of the biomechanical behaviors of knee,contact pressure effects of daily activities on knee,and is significantly instructive for sports rehabilitation.

Mechanical performance and cyocompatibility of PU/PLCL nanofibrous electrospun scaffolds for skin regeneration

Skin tissue engineering with considerable skin regeneration capability is an urgent need for the wound site.The current challenge for researchers is to develop a bionic scaffold that imitates the extracellular matrix for the regeneration of the damaged regions.In our study,poly(L-lactide-co-caprolactone)(PLCL)was blended with polyurethane(PU)to obtain nanofibrous scaffolds via electrospinning.The electrospun fibers with 50%PLCL content had a certain number of intersections and jointing points,and exhibited significantly enhanced mechani-cal properties combined with suitable porosity.Moreover,cell activities demonstrated that PU/PLCL membranes had significantly biological advantages in enhanced growth of human skin fibroblasts with spreading morphology compared with PU membranes,indicating good cytocompatibility of composite scaffolds.These findings proved that PU/PLCL electrospun membranes have great potential in applications of skin tissue engineering.