High-precision 3D printing of multi-branch vascular scaffold with plasticized PLCL thermoplastic elastomer.

Three-dimensional (3D) printing has emerged as a transformative technology for tissue engineering, enabling the production of structures that closely emulate the intricate architecture and mechanical properties of native biological tissues. However, the fabrication of complex microstructures with high accuracy using biocompatible, degradable thermoplastic elastomers poses significant technical obstacles. This is primarily due to the inherent soft-matter nature of such materials, which complicates real-time control of micro-squeezing, resulting in low fidelity or even failure. In this study, we employ Poly (L-lactide-co-ϵ-caprolactone) (PLCL) as a model material and introduce a novel framework for high-precision 3D printing based on the material plasticization process. This approach significantly enhances the dynamic responsiveness of the start-stop transition during printing, thereby reducing harmful errors by up to 93%. Leveraging this enhanced material, we have efficiently fabricated arrays of multi-branched vascular scaffolds that exhibit exceptional morphological fidelity and possess elastic moduli that faithfully approximate the physiological modulus spectrum of native blood vessels, ranging from 2.5 to 45 MPa. The methodology we propose for the compatibilization and modification of elastomeric materials addresses the challenge of real-time precision control, representing a significant advancement in the domain of melt polymer 3D printing. This innovation holds considerable promise for the creation of detailed multi-branch vascular scaffolds and other sophisticated organotypic structures critical to advancing tissue engineering and regenerative medicine.

Computational investigation of a 3D-printed skin substitute with orthotropy in mechanical property.

As a promising treatment for third-degree burns, grafting with bioengineering skin substitutes shows a capability to overcome the deficiency of donor skin. Similar mechanical properties with human skin are required for employed skin substitutes to avoid secondary damage to patients. Given the representativeness of orthotropy in mechanical properties, there is a need for developing orthotropic skin substitutes. This paper presents computational investigation as well as structural design for the fabrication of orthotropic skin substitutes. A finite element method (FEM) based mechanics simulation model for analyzing the stress field in the skin substitute was developed, by which the stress distribution in mimetic structures of the epidermis and dermis can be acquired. Moreover, the equation of Young's modulus was deduced based on the simulation result, which expressed the mechanical property of designed skin substitutes. Furthermore, several structures of skin substitutes were proposed and their calculated Young's modulus ranged from 21.87 kPa to 213.32 kPa, which was similar to the human skin. Ultimately, uniaxial tensile tests were performed for three types of 3D-printed orthotropic skin substitutes, which validates the feasibility to regulate Young's modulus by regulating the structure of fabricated skin substitutes.

Case Report: Recurrent Placental Abruption During Pregnancy in a Patient With Pseudoexstrophy.

Background: Pseudoexstrophy is a rare variant of the exstrophy-epispadias complex, which comprises musculoskeletal defects associated with bladder exstrophy without any urinary tract defects. However, only a few pregnancy complications have been reported in patients with pseudoexstrophy. Case Presentation: This report presents the case of a woman with pseudoexstrophy, who survived recurrent placental abruption during the second trimester of her pregnancy. The patient presented with a bicornuate uterus and survived placental abruption twice, which may have resulted from the malformation of the uterus. Placental abruption occurred at 20 weeks during her first pregnancy, and because she was already in labor, uterine contraction was augmented until vaginal delivery was achieved. The second pregnancy, however, could not be terminated quickly enough; therefore, a cesarean section was performed to save the patient's life. Conclusions: Our study makes a significant contribution to the literature although pregnancy complications have been reported in patients with pseudoexstrophy. Our findings show that in female patients with pseudoexstrophy who are or wish to become pregnant, detailed imaging studies must be performed to identify any deformities of the pelvis or reproductive organs, in order to make a pregnancy-related risk assessment. Our experience also indicates that if surgery is inevitable, the obstetrician must be more careful when entering the abdominal cavity during the surgery to avoid secondary injury. Furthermore, the peritoneum and fascia layers must be sutured more firmly when closing the abdomen to avoid an abdominal wall hernia, because of the lack of abdominal muscle and fat tissue in such patients.

Hepatitis B virus infection and decreased risk of stroke: a meta-analysis.

Several studies have reported that hepatitis B virus (HBV) infection may decrease the risk of stroke. However, its association is controversial. Thus, we conducted a systematic review and meta-analysis to investigate the relationship between hepatitis B virus (HBV) infection and the risk of stroke. Relevant studies published before May 2017 were identified by searching PubMed, EMBASE, and ISI Web of Science. The relationships between HBV infection and the risk of stroke were assessed using odds ratio (OR)/risk ratio (RR) values and the corresponding 95% confidence intervals (CIs). We used the random effects model proposed by DerSimonian and Laird to quantify the relationship. Five articles, including 834,75 HBV-infected patients and 593,949 uninfected controls, were included in the meta-analysis. The risk of stroke was significantly lower in HBV-infected patients than in uninfected controls (summary OR = 0.78; 95% CI = 0.70-0.86; I2 = 0%). However, this inverse relationship was only observed in cohort studies (OR = 0.77; 95% CI = 0.69-0.86), rather than cross-sectional study (OR = 1.10; 95% CI = 0.55-2.19). In summary, HBV infection was associated with lower risk of developing stroke.

Magnetic Resonance Imaging of Postoperative Fracture Healing Process without Metal Artifact: A Preliminary Report of a Novel Animal Model.

Background. Early radiological diagnosis and continual monitoring are of ultimate importance for timely treatment of delayed union, nonunion, and infection after bone fracture surgery. Although magnetic resonance imaging (MRI) could provide superior detailed images compared with X-ray and computed tomography (CT) without ionizing radiation, metal implants used for fracture fixation lead to abundant artifacts on MRI and thus prohibit accurate interpretation. The authors develop a novel intramedullary fixation model of rat femoral fracture using polyetheretherketone (PEEK) threaded rods and investigate its feasibility for in vivo MRI monitoring of the fracture healing process without artifact. Methods. Femoral fractures of 3 adult male Sprague-Dawley rats were fixed with intramedullary PEEK threaded rods. X-ray and MRI examinations were performed at day 7 postoperatively. Radiological images were analyzed for the existence of artifact interruption and postoperative changes in bone and peripheral soft tissue. Results. Postoperative plain film revealed no loss of reduction. MRI images illustrated the whole length of femur and peripheral tissue without artifact interruption, and the cortical bone, implanted PEEK rod, and soft tissue were clearly illustrated. Conclusion. This preliminary study introduced a novel rat model for in vivo MRI monitoring of the fracture healing process without metal artifact, by using intramedullary fixation of femur with PEEK threaded rod.

A Novel Rat Model of Intramedullary Tibia Fracture Fixation Using Polyetheretherketone Threaded Rod.

BACKGROUND: The rat fracture fixation models have been widely adopted, but current implant designs suffer from operational difficulty, massive soft-tissue dissection, and radiological intervention. The authors developed a new tibia fracture-healing model using minor invasive intramedullary fixations with polyetheretherketone (PEEK) threaded rods, which have excellent x-ray translucency and no magnetic resonance artifact. METHODS: Tibia fractures of 6 adult male Sprague-Dawley rats were fixed with intramedullary PEEK threaded rods. X-ray examination was performed at 0, 4, and 8 weeks postoperatively. Histological analysis was conducted via hematoxylin-eosin staining of nondecalcified tissue sections. RESULTS: Radiological fracture healing was observed at 8 weeks postoperatively. Histology demonstrated fracture gap bridging and bone ingrowth adjacent to PEEK. CONCLUSION: This innovative model is simple and effective, providing a new selection in future biomedical research.