Design,fabrication,and structural safety validation of 3D-printable biporous bone augments

The use of commercial products such as a cup and liner for total hip arthroplasty for patients with severe bone defects has a high probability of failure.In these patients the cup alone cannot cover the bone defect,and thus,an additional augment or cage is required.In this study,we designed three-dimensional(3D)printable bone augments as an alternative to surgeries using reinforcement cages.Thirty-five sharp-edged bone augments of various sizes were 3D printed.A biporous structure was designed to reduce the weight of the augment and to facilitate bone ingrowth.Two types of frames were used to prevent damage to the augment’s porous structure and maintain its stability during printing.Furthermore,two types of holes were provided for easy augment fixation at various angles.Fatigue tests were performed on a combination of worst-case sizes derived using finite element analysis.The test results confirmed the structural stability of the specimens at a load of 5340 N.Although the porosity of the specimens was measured to be 63.70%,it cannot be said that the porous nature was uniformly distributed because porosity tests were performed locally and randomly.In summary,3D-printable biporous bone augments capable of bonding from various angles and bidirectionally through angulation and bottom-plane screw holes are proposed.The mechanical results with bone augments indicate good structural safety in patients.However,further research is necessary to study the clinical applications of the proposed bone augment.

RGD peptide and graphene oxide co-functionalized PLGA nanofiber scaffolds for vascular tissue engineering

In recent years,much research has been suggested and examined for the development of tissue engineering scaffolds to promote cellular behaviors.In our study,RGD peptide and graphene oxide(GO)co-functionalized poly(lactide-co-glycolide,PLGA)(RGD-GO-PLGA)nanofiber mats were fabricated via electrospinning,and their physicochemical and thermal properties were characterized to explore their potential as biofunctional scaffolds for vascular tissue engineering.Scanning electron microscopy images revealed that the RGD-GO-PLGA nanofiber mats were readily fabricated and composed of randomoriented electrospun nanofibers with average diameter of 558nm.The successful co-functionalization of RGD peptide and GO into the PLGA nanofibers was confirmed by Fourier-transform infrared spectroscopic analysis.Moreover,the surface hydrophilicity of the nanofiber mats was markedly increased by co-functionalizing with RGD peptide and GO.It was found that the mats were thermally stable under the cell culture condition.Furthermore,the initial attachment and proliferation of primarily cultured vascular smoothmuscle cells(VSMCs)on the RGD-GO-PLGA nanofibermats were evaluated.It was revealed that the RGD-GO-PLGA nanofibermats can effectively promote the growth of VSMCs.In conclusion,our findings suggest that the RGD-GO-PLGA nanofiber mats can be promising candidates for tissue engineering scaffolds effective for the regeneration of vascular smooth muscle.

Preconditioning process for dermal tissue decellularization using electroporation with sonication

Decellularization to produce bioscaffolds composed of the extracellular matrix(ECM)uses enzymatic,chemical and physical methods to remove antigens and cellular components from tissues.Effective decellularization methods depend on the characteristics of tissues,and in particular,tissues with dense,complex structure and abundant lipid content are difficult to completely decellularize.Our study enables future research on the development of methods and treatments for fabricating bioscaffolds via decellularization of complex and rigid skin tissues,which are not commonly considered for decellularization to date as their structural and functional characteristics could not be preserved after severe decellularization.In this study,decellularization of human dermal tissue was done by a combination of both chemical(0.05%trypsin-EDTA,2%SDS and 1%Triton X-100)and physical methods(electroporation and sonication).After decellularization,the content of DNA remaining in the tissue was quantitatively confirmed,and the structural change of the tissue and the retention and distribution of ECM components were evaluated through histological and histochemical analysis,respectively.Conditions of the chemical pretreatment that increase the efficiency of physical stimulation as well as decellularization,and conditions for electroporation and sonication without the use of detergents,unlike the methods performed in previous studies,were established to enable the complete decellularization of the skin tissue.The combinatorial decellularization treatment formed micropores in the lipid bilayers of the skin tissues while removing all cell and cellular residues without affecting the ECM properties.Therefore,this procedure can be widely used to fabricate bioscaffolds by decellularizing biological tissues with dense and complex structures.

An effective method to generate controllable levels of ROS for the enhancement of HUVEC proliferation using a chlorin e6-immobilized PET film as a photo-functional biomaterial

Reactive oxygen species(ROS)are byproducts of cellular metabolism;they play a significant role as secondary messengers in cell signaling.In cells,high concentrations of ROS induce apoptosis,senescence,and contact inhibition,while low concentrations of ROS result in angiogenesis,proliferation,and cytoskeleton remodeling.Thus,controlling ROS generation is an important factor in cell biology.We designed a chlorin e6(Ce6)-immobilized polyethylene terephthalate(PET)film(Ce6-PET)to produce extracellular ROS under red-light irradiation.The application of Ce6-PET films can regulate the generation of ROS by altering the intensity of light-emitting diode sources.We confirmed that the Ce6-PET film could effectively promote cell growth under irradiation at 500 μW/cm^(2) for 30 min in human umbilical vein endothelial cells.We also found that the Ce6-PET film is more efficient in generating ROS than a Ce6-incorporated polyurethane film under the same conditions.Ce6-PET fabrication shows promise for improving the localized delivery of extracellular ROS and regulating ROS formation through the optimization of irradiation intensity.