The combined application of stem cells and three-dimensional bioprinting scaffolds for the repair of spinal cord injury

Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system.Following surgery,the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality.Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord.Consequently,there is a critical need to develop new treatments to promote functional repair after spinal cord injury.Over recent years,there have been seve ral developments in the use of stem cell therapy for the treatment of spinal cord injury.Alongside significant developments in the field of tissue engineering,three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures.This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization.These three-dimensional bioprinting scaffolds co uld repair damaged neural circuits and had the potential to repair the damaged spinal cord.In this review,we discuss the mechanisms underlying simple stem cell therapy,the application of different types of stem cells for the treatment of spinal cord injury,and the different manufa cturing methods for three-dimensional bioprinting scaffolds.In particular,we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.

Application of Digital Technology in Road and Bridge Design

With the development and progress of science and technology,road and bridge design has experienced rapid development,from the initial manual drawing design to the popularity of Computer-Aided Design(CAD),and then to today’s digital software design era.Early designers relied on hand-drawn paper design forms which was time-consuming and error-prone.Digital support for road and bridge design not only saves the design time but the design quality has also achieved a qualitative leap.This paper engages in the application of digital technology in road and bridge design,to provide technical reference for China’s road and bridge engineering design units,to promote the popularity of Civil3D and other advanced design software in the field of engineering design and development,ultimately contributing to the sustainable development of China’s road and bridge engineering.

Three-dimensional printing technology for patient-matched instrument in treatment of cubitus varus deformity:A case report

BACKGROUND Recently,medical three-dimensional printing technology(3DPT)has demonstrated potential benefits for the treatment of cubitus varus deformity(CVD)by improving accuracy of the osteotomy through the use of an osteotomy guide,with or without a patient-mated plate.Here,we present an interesting CVD case,involving a patient who was treated with corrective biplanar chevron osteotomy using an innovative customized osteotomy guide and a newly designed patient-matched monoblock crosslink plate created with 3DPT.CASE SUMMARY A 32-year-old female presented with a significant CVD from childhood injury.A computer simulation was processed using images from computerized tomography scans of both upper extremities.The biplanar chevron osteotomy was designed to create identical anatomy between the mirror image of the contralateral distal humerus and the osteotomized distal humerus.Next,the customized osteotomy guide and patient-matched monoblock crosslink plate were designed and printed.A simulation osteotomy was created for the real-sized bone model,and the operation was performed using the posterior paratricipital approach with k-wire positioning from the customized osteotomy guide as a predrilled hole for screw fixation to achieve immediate control of the reduction after osteotomy.Our method allowed for successful treatment of the CVD case,significantly improving the patient’s radiographic and clinical outcomes,with satisfactory result.CONCLUSION 3DPT-created patient-matched osteotomy guide and instrumentation provides accurate control during CVD correction.

Application and Analysis of Computer Virtual Simulation Technology in Three-dimensional Animation Production

With the continuous promotion of computer technology, the application system of virtual simulation technology has been further optimized and improved, and has been widely used in various fields of social development, such as urban construction, interior design, industrial simulation and tourism teaching. China's three-dimensional animation production started relatively late, but has achieved good results with the support of related advanced technology in the process of development. Computer virtual simulation technology is an important technical support in the production of three-dimensional animation. In this paper, firstly, the related content of computer virtual simulation technology was introduced. Then, the specific application of this technology in the production of three-dimensional animation was further elaborated, so as to provide some reference for the improvement of the production effect of three-dimensional animation in the future.

Application Status and Prospect of Three-Dimensional Printing Technology in the Field of Medical Devices

Three-dimensional(3D)printing technology belongs to a new manufacturing science and has been widely used in various fields of industry.This article will apply 3D printing technology as its main research topic,with emphasis on its application in the field of medical devices and prospects for contribution.

Application of Three-dimensional Laser Scanning Technology in the Teaching Practice of Surveying and Mapping of Ancient Buildings

Based on the study of the application of three-dimensional laser scanning technology in ancient building surveying and mapping,this paper briefly describes the working principle and flow of three-dimensional laser scanning technology.Based on the practical application,this paper puts forward the discussion of related problems and matters needing attention.This has a certain reference significance for the study of new technology in surveying and mapping of ancient buildings.

Digital measurement of bone tumor volume by CT three-dimensional reconstruction technology

Objective To discuss the measurement of bone tumor volume on the basis of three dimensional images segmentation technology. Methods Twenty patients with lacunar bone tumor from Tianjin Hospital and Tongji Hospital were included in the

A review on cell damage,viability,and functionality during 3D bioprinting

Three-dimensional(3D)bioprinting fabricates 3D functional tissues/organs by accurately depositing the bioink composed of the biological materials and living cells.Even though 3D bioprinting techniques have experienced significant advancement over the past decades,it remains challenging for 3D bioprinting to artificially fabricate functional tissues/organs with high post-printing cell viability and functionality since cells endure various types of stress during the bioprinting process.Generally,cell viability which is affected by several factors including the stress and the environmental factors,such as pH and temperature,is mainly determined by the magnitude and duration of the stress imposed on the cells with poorer cell viability under a higher stress and a longer duration condition.The maintenance of high cell viability especially for those vulnerable cells,such as stem cells which are more sensitive to multiple stresses,is a key initial step to ensure the functionality of the artificial tissues/organs.In addition,maintaining the pluripotency of the cells such as proliferation and differentiation abilities is also essential for the 3D-bioprinted tissues/organs to be similar to native tissues/organs.This review discusses various pathways triggering cell damage and the major factors affecting cell viability during different bioprinting processes,summarizes the studies on cell viabilities and functionalities in different bioprinting processes,and presents several potential approaches to protect cells from injuries to ensure high cell viability and functionality.

Prospects for the use of olfactory mucosa cells in bioprinting for the treatment of spinal cord injuries

The review focuses on the most important areas of cell therapy for spinal cord injuries.Olfactory mucosa cells are promising for transplantation.Obtaining these cells is safe for patients.The use of olfactory mucosa cells is effective in restoring motor function due to the remyelination and regeneration of axons after spinal cord injuries.These cells express neurotrophic factors that play an important role in the functional recovery of nerve tissue after spinal cord injuries.In addition,it is possible to increase the content of neurotrophic factors,at the site of injury,exogenously by the direct injection of neurotrophic factors or their delivery using gene therapy.The advantages of olfactory mucosa cells,in combination with neurotrophic factors,open up wide possibilities for their application in threedimensional and four-dimensional bioprinting technology treating spinal cord injuries.

3D Bioprinting:A Novel Avenue for Manufacturing Tissues and Organs

Three-dimensional(3D)bioprinting is a rapidly growing technology that has been widely used in tissue engineering,disease studies,and drug screening.It provides the unprecedented capacity of depositing various types of biomaterials,cells,and biomolecules in a layer-by-layer fashion,with precisely controlled spatial distribution.This technology is expected to address the organ-shortage issue in the future.In this review,we first introduce three categories of 3D bioprinting strategies:inkjet-based printing(IBP),extrusion-based printing(EBP),and light-based printing(LBP).Biomaterials and cells,which are normally referred to as“bioinks,”are then discussed.We also systematically describe the recent advancements of 3D bioprinting in fabricating cell-laden artificial tissues and organs with solid or hollow structures,including cartilage,bone,skin,muscle,vascular network,and so on.The development of organs-onchips utilizing 3D bioprinting technology for drug discovery and toxicity testing is reviewed as well.Finally,the main challenges in current studies and an outlook of the future research of 3D bioprinting are discussed.

Prospects for 3D bioprinting of organoids

Three-dimensional(3D)organoids derived from pluripotent or adult tissue stem cells seem to possess excellent potential for studying development and disease mechanisms alongside having a myriad of applications in regenerative therapies.However,lack of precise architectures and large-scale tissue sizes are some of the key limitations of current organoid technologies.3D bioprinting of organoids has recently emerged to address some of these impediments.In this review,we discuss 3D bioprinting with respect to the use of bioinks and bioprinting methods and highlight recent studies that have shown success in bioprinting of stem cells and organoids.We also summarize the use of several vascularization strategies for the bioprinted organoids,that are critical for a complex tissue organization.To fully realize the translational applications of organoids in disease modeling and regenerative medicine,these areas in 3D bioprinting need to be appropriately harnessed and channelized.

Microfluidic three-dimensional cell culture of stem cells for high-throughput analysis

Although the recent advances in stem cell engineering have gained a great deal of attention due to their high potential in clinical research,the applicability of stem cells for preclinical screening in the drug discovery process is still challenging due to difficulties in controlling the stem cell microenvironment and the limited availability of high-throughput systems.Recently,researchers have been actively developing and evaluating three-dimensional(3D)cell culture-based platforms using microfluidic technologies,such as organ-on-a-chip and organoid-on-a-chip platforms,and they have achieved promising breakthroughs in stem cell engineering.In this review,we start with a comprehensive discussion on the importance of microfluidic 3D cell culture techniques in stem cell research and their technical strategies in the field of drug discovery.In a subsequent section,we discuss microfluidic 3D cell culture techniques for high-throughput analysis for use in stem cell research.In addition,some potential and practical applications of organ-on-a-chip or organoid-on-a-chip platforms using stem cells as drug screening and disease models are highlighted.

Role of three-dimensional printing and artificial intelligence in the management of hepatocellular carcinoma:Challenges and opportunities

Hepatocellular carcinoma(HCC)constitutes the fifth most frequent malignancy worldwide and the third most frequent cause of cancer-related deaths.Currently,treatment selection is based on the stage of the disease.Emerging fields such as three-dimensional(3D)printing,3D bioprinting,artificial intelligence(AI),and machine learning(ML)could lead to evidence-based,individualized management of HCC.In this review,we comprehensively report the current applications of 3D printing,3D bioprinting,and AI/ML-based models in HCC management;we outline the significant challenges to the broad use of these novel technologies in the clinical setting with the goal of identifying means to overcome them,and finally,we discuss the opportunities that arise from these applications.Notably,regarding 3D printing and bioprinting-related challenges,we elaborate on cost and cost-effectiveness,cell sourcing,cell viability,safety,accessibility,regulation,and legal and ethical concerns.Similarly,regarding AI/ML-related challenges,we elaborate on intellectual property,liability,intrinsic biases,data protection,cybersecurity,ethical challenges,and transparency.Our findings show that AI and 3D printing applications in HCC management and healthcare,in general,are steadily expanding;thus,these technologies will be integrated into the clinical setting sooner or later.Therefore,we believe that physicians need to become familiar with these technologies and prepare to engage with them constructively.

Three-dimensional printed talar prosthesis with biological function for giant cell tumor of the talus:A case report and review of the literature

BACKGROUND Giant cell tumors(GCT)are most commonly seen in the distal femur.These tumors are uncommon in the small bones of the hand and feet,and a very few cases have been reported.A giant cell tumor of the talus is rarely seen clinically and could be a challenge to physicians.CASE SUMMARY We report a rare case of GCT of the talus in one patient who underwent a new reconstructive surgery technique using a three-dimensional(3D)printing talar prosthesis.The prosthesis shape was designed by tomographic image processing and segmentation using technology to match the intact side by mirror symmetry with 3D post-processing technologies.The patient recovered nearly full range of motion of the ankle after 6 mo.The visual analogue scale and American Orthopaedic Foot and Ankle Society scores were 1 and 89 points,respectively.CONCLUSION We demonstrated that 3D printing of a talar prosthesis is a beneficial option for GCT of the talus.

Experimental investigation on the invert stability of operating railway tunnels with different drainage systems using 3D printing technology

In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in China and its optimized drainage system(ODS) with bottom drainage function. Six test groups with a total of 110 test conditions were designed to consider the design factors and environmental factors in engineering practice,including layout of the drainage system, blockage of the drainage system and groundwater level fluctuation. It was found that there are significant differences in the water discharge, EWP and invert stability for the tunnels with the two drainage systems. Even with a dense arrangement of the external blind tubes, TDS was still difficult to eliminate the excessive EWP below the invert, which is the main cause for the invert instability. Blockage of drainage system further increased the invert uplift and aggravated the track irregularity, especially when the blockage degree is more than 50%. However, ODS can prevent these invert anomalies by reasonably controlling the EWP at tunnel bottom. Even when the groundwater level reached 60 m and the blind tubes were fully blocked, the invert stability can still be maintained and the railway track experienced a settlement of only 1.8 mm. Meanwhile, the on-site monitoring under several rainstorms further showed that the average EWP of the invert was controlled within 84 k Pa, while the maximum settlement of the track slab was only 0.92 mm, which also was in good agreement with the results of model test.

Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak,cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laserscanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%e90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

Application of digital technology in nasal reconstruction

Nasal defects are facial defects caused by trauma,tumors,or congenital diseases that seriously damage a patient’s physical and mental health.Nasal defects,from skin defects to total nasal defects,require surgical repair and reconstruction to restore the appearance and function of the nose,which have always been challenges for rhinoplasty.The development of digital technology has increased the possibility of nasal reconstruction.Digital technology is involved in the preoperative,intraoperative,and postoperative stages of nasal construction and is of great significance in improving the effect of this surgery.This article reviews the application of major digital technologies,including three-dimensional(3D)imaging technology,computer-assisted surgical navigation,and 3D printing,in nasal reconstruction and discusses the shortcomings of the current application of digital technology.

Revolutionizing preclinical research for pancreatic cancer:the potential of 3D bioprinting technology for personalized therapy

Pancreatic cancer(PC)is a prevalent digestive malignancy worldwide and ranks as the fourth leading cause of cancer-related deaths globally.The incidence and mortality rates have been increasing annually,and due to its insidious onset and high malignancy,most patients are diagnosed at an advanced stage,with a 5-year survival rate of less than 8%(1).PC can be classified into endocrine and exocrine tumors,with over 95% of pancreatic malignant tumors originating from the exocrine portion of the pancreas.

Three-Dimensional Volumetric Analysis of Venous Malformations for Assessing the Effectiveness of Percutaneous Sclerotherapy

BACKGROUND Percutaneous sclerotherapy can be used to successfully treat venous malformations(VMs)of the head,neck,and limbs.However,the standard curative effect of sclerotherapy has rarely been analyzed,and there is currently no accurate statistical method to measure the volume of VMs after sclerotherapy.Here,we propose a novel threedimensional(3D)reconstruction method to evaluate this effect.OBJECTIVE To test the feasibility of 3D software(MIMICS 19.0)to evaluate the treatment effect of sclerotherapy.METHODS This retrospective study included patients with VMs on the head,neck,and limbs who were treated with ethanol sclerotherapy or foam sclerotherapy every 8 weeks.MIMICS 19.0 was used to calculate the performance of the lesion after treatment and measure the VM volumes before and after the treatment.The effect of the clinical treatment dose on the lesion was evaluated,and the treatment effect of each patient was recorded.The relationship between the number of treatments and the reduced volume of VMs was analyzed.RESULTS Based on the MIMICS-calculated regions of interest(ROI),we found that 1 mL of ethanol reduced the lesion by 473 mm3 and that one dosage of foam(1 mL of polidocanol and 4 mL air content)reduced the lesion by 2138 mm3,demonstrating that the foam sclerosing agent exhibited greater efficacy in this study.CONCLUSIONS The MIMICS 3D volume reconstruction method can effectively and safely evaluate the efficacy of sclerotherapy and provide a preoperative evaluation.This method is simple,accurate,and feasible.

Three-dimensional digital technology-assisted precise tumor resection and reconstruction of the femoral trochanter and postoperative functional recovery:a retrospective study

Background The trochanter of the femur is a common site for bone tumors.However,locating the specificboundary of bone tumor infiltration and determining the surgical method can be challenging.The objective of thisstudy was to review the diagnosis,treatment,and surgical outcomes of patients with tumors or tumor-like changesin the femoral trochanter after computer-assisted precise tumor resection and hip-preserving reconstruction ofthe trochanter.Methods From January 2005 to September 2020,11 patients with trochanteric tumors(aged:18–53 years;sixmales and five females)were treated in Guangzhou First People’s Hospital.The cases included aneurysmal bonecyst(n=1),giant cell tumor of bone(n=2),fibrous histiocytoma of bone(n=1),endochondroma(n=1),andfibrous dysplasia of bone(n=6).For patients with trochanteric tumors,computed tomography and magnetic resonance imaging scanning were performed before operation to obtain two-dimensional image data of the lesion.Athree-dimensional digital model of bilateral lower limbs was reconstructed by computer technology,the boundary of tumor growth was determined by computer simulation,the process of tumor resection and reconstructionwas simulated,and the personalized guide template was designed.During the operation,the personalized guideplate guided the precise resection of the tumor,and the allogeneic bone was trimmed to match the shape of thebone defect.Results All 11 patients underwent accurate resection of the tumor or tumor-like lesion and reconstruction ofthe hip.In eight cases,the lesion was confined to the trochanter,which was fixed with large segment allogeneicbone,autologous iliac bone,and proximal femoral anatomic plate.In three cases,allogeneic bone,autologousiliac bone,and femoral reconstruction nail were used to fix the tumor under the trochanter.Postoperative Xray examination showed that the repair and reconstruction of the bone defect was effective,and callus bridgingbetween the allogenic bone and autogenous bone was observed 6 months after operation.All patients recoveredtheir walking function 3–6 months after operation.The duration of the follow-up period ranged from 6 monthsto 6 years.A patient experienced recurrence of endochondroma;pathological examination revealed chondrocyticsarcoma.The remaining 10 patients were treated with segmental resection and reconstruction.The operationtime ranged 2.5–4.5 h(average:3.2 h).Intraoperative blood loss ranged from 300 to 500 ml(average:368 ml).The local recurrence rate was 9.1%,and the overall survival rate was 100%.The average Musculoskeletal TumorSociety score was 27(excellent and good for eight and three patients,respectively).Conclusions Three-dimensional computer skeleton modeling and simulation-assisted resection and reconstruction of femoral trochanteric tumor is a new surgical technique,which might markedly improve the surgical effect,shorten the surgical time,increase the overall survival rate of patients with tumors,reduce the local recurrencerate,assist in the digitization and programming of femoral trochanteric tumor surgery,and improve surgicalaccuracy.