ObjectiveTo review the current research status of in situ three-dimensional (3-D) printing technique and future trends. MethodsRecent related literature about in situ 3-D printing technique was summarized, reviewed, and analyzed. ResultsBased on the cl inical need for surgical repair, in situ 3-D printing technique is in the preliminary study, mainly focuses on in situ dermal repair and bone and cartilage repair, and succeeds in experiments, but there are still a lot of problems for cl inical application. ConclusionWith the development of in situ 3-D printing technique, it will provide patients with real-time and in situ digital design and 3-D printing treatment with a timely and minimally invasive surgical repair process. It will be widely used in the future.
ObjectiveTo construct large block of engineered liver tissue by co-culture of fibroblasts and hepatocytes on collagen hydrogels in vitro and do in vivo implantation research. MethodsSilastic mould was prepared using three-dimensional printing technology. The collagen hydrogel scaffold was prepared by collagen hydrogel gel in the silicone mould and was removed. Sprague Dawley rat lung fibroblasts were co-cultured with primary hepatocytes at a ratio of 0.4:1 on the collagen hydrogel scaffold to construct large block of engineered liver tissue in vitro (group B), and primary hepatocytes cultured on the collagen hydrogel scaffold served as control group (group A). The cell morphology was observed, and the liver function was tested at 1, 3, 7, 14, and 21 days after culture. The rat model (n=24) of hepatic cirrhosis was made by subcutaneous injection of carbon tetrachloride. And in vivo implantation study was carried in cirrhosis rat model. The phenotypic characteristics and functional expression of hepatocytes were evaluated at 3, 7, 14, 21, and 28 days after implantation. ResultsIn vitro results indicated that hepatocytes in group B exhibited compact polyhedral cells with round nuclei and high expression of liver function. Moreover, cells aggregated to the most at 7 days. Album production and urea synthesis incresed significantly when compared with group A (P<0.05). In vivo results showed hepatocytes in group B survived for 28 days, and albumin production and urea synthesis were significantly increased. In addition, hepatocytes showed an aggregated distribution and cord-like structures, which was similar to normal liver tissue. ConclusionThe large block of engineered liver tissue constructed by co-cultured cells can form tissue similar to normal liver tissue in vivo, and survive for a long time, laying foundations for building more complete engineered liver tissue in the future.
ObjectiveTo solve the fixation problem between ligament grafts and host bones in ligament reconstruction surgery by using ligament-bone composite scaffolds to repair the ligaments, to explore the fabrication method for ligament-bone composite scaffolds based on three-dimensional (3-D) printing technique, and to investigate their mechanical and biological properties in animal experiments. MethodsThe model of bone scaffolds was designed using CAD software, and the corresponding negative mould was created by boolean operation. 3-D printing techinique was employed to fabricate resin mold. Ceramic bone scaffolds were obtained by casting the ceramic slurry in the resin mould and sintering the dried ceramics-resin composites. Ligament scaffolds were obtained by weaving degummed silk fibers, and then assembled with bone scaffolds and bone anchors. The resultant ligament-bone composite scaffolds were implanted into 10 porcine left anterior cruciate ligament rupture models at the age of 4 months. Mechanical testing and histological examination were performed at 3 months postoperatively, and natural anterior cruciate ligaments of the right sides served as control. ResultsBiomechanical testing showed that the natural anterior cruciate ligament of control group can withstand maximum tensile force of (1 384±181) N and dynamic creep of (0.74±0.21) mm, while the regenerated ligament-bone scaffolds of experimental group can withstand maximum tensile force of (370±103) N and dynamic creep of (1.48±0.49) mm, showing significant differences (t=11.617,P=0.000; t=-2.991,P=0.020). In experimental group, histological examination showed that new bone formed in bone scaffolds. A hierarchical transition structure regenerated between ligament-bone scaffolds and the host bones, which was similar to the structural organizations of natural ligament-bone interface. ConclusionLigament-bone composite scaffolds based on 3-D printing technique facilitates the regeneration of biomimetic ligament-bone interface. It is expected to achieve physical fixation between ligament grafts and host bone.
ObjectiveTo summarize the recent development of the magnetic compression anastomosis in surgery. MethodsThe abroad and domestic relevant literature about magnetic compression anastomosis was extensively reviewed, and comprehensive analyzed. ResultsMagnetic compression anastomosis in the reconstruction of the body lumen is a simple and effective way; laparoscopy combined with magnetic compression anastomosis has the advantages of small wound and quick recovery. Magnetic compression anastomosis has been increasingly used in cl inical practice. But its mechanism has not been fully revealed, and it is difficulty in expelling out of the magnet for the gastrointestinal and certain large-size lumen, so further research and optimization are still needed. ConclusionRelative to the traditional manual suture, magnetic anastomosis has great advantage, especially a combination of magnetic compression anastomosis and minimally invasive surgery has bright prospects for development.
ObjectiveTo investigate whether subchondral bone microstructural parameters are related to cartilage repair during large osteochondral defect repairing based on three-dimensional (3-D) printing technique. MethodsBiomimetic biphasic osteochondral composite scaffolds were fabricated by using 3-D printing technique. The right trochlea critical sized defects (4.8 mm in diameter, 7.5 mm in depth) were created in 40 New Zealand white rabbits (aged 6 months, weighing 2.5-3.5 kg). Biomimetic biphasic osteochondral composite scaffolds were implanted into the defects in the experimental group (n=35), and no composite scaffolds implantation served as control group (n=5); the left side had no defect as sham-operation group. Animals of experimental and sham-operation groups were euthanized at 1, 2, 4, 8, 16, 24, and 52 weeks after operation, while animals of control group were sampled at 24 weeks. Subchondral bone microstructural parameters and cartilage repair were quantitatively analyzed using Micro-CT and Wayne scoring system. Correlation analysis and regression analysis were applied to reveal the relationship between subchondral bone parameters and cartilage repair. The subchondral bone parameters included bone volume fraction (BV/TV), bone surface area fraction (BSA/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular spacing (Tb.Sp). ResultsIn the experimental group, articular cartilage repair was significantly improved at 52 weeks postoperatively, which was dominated by hyaline cartilage tissue, and tidal line formed. Wayne scores at 24 and 52 weeks were significantly higher than that at 16 weeks in the experimental group (P<0.05), but no significant difference was found between at 24 and 52 weeks (P>0.05); the scores of experimental group were significantly lower than those of sham-operation group at all time points (P<0.05). In the experimental group, new subchondral bone migrated from the surrounding defect to the centre, and subchondral bony plate formed at 24 and 52 weeks. The microstructural parameters of repaired subchondral bone followed a "twin peaks" like discipline to which BV/TV, BSA/BV, and Tb.N increased at 2 and 16 weeks, and then they returned to normal level. The Tb.Sp showed reversed discipline compared to the former 3 parameters, no significant change was found for Tb.Th during the repair process. Correlation analysis showed that BV/TV, BSA/BV, Tb.Th, Tb.N, and Tb.Sp were all related with gross appearance score and histology score of repaired cartilage. ConclusionSubchondral bone parameters are related with cartilage repair in critical size osteochondral repair in vivo. Microstructural parameters of repaired subchondral bone follow a "twin peaks" like discipline (osteoplasia-remodeling-osteoplasia-remodeling) to achieve reconstruction, 2nd week and 16th week are critical time points for subchondral bone functional restoration.
ObjectiveTo summarize the latest research development of the application of digital design and three-dimensional (3-D) printing technique on individualized medical treatment. MethodsRecent research data and clinical literature about the application of digital design and 3-D printing technique on individualized medical treatment in Xi'an Jiaotong University and its cooperation unit were summarized, reviewed, and analyzed. ResultsDigital design and 3-D printing technique can design and manufacture individualized implant based on the patient's specific disease conditions. And the implant can satisfy the needs of specific shape and function of the patient, reducing dependence on the level of experience required for the doctor. So 3-D printing technique get more and more recognition of the surgeon on the individualized repair of human tissue. Xi'an Jiaotong University is the first unit to develop the commercial 3-D printer and conduct depth research on the design and manufacture of individualized medical implant. And complete technological processes and quality standards of product have been developed. ConclusionThe individualized medical implant manufactured by 3-D printing technique can not only achieve personalized match but also meet the functional requirements and aesthetic requirements of patients. In addition, the individualized medical implant has the advantages of accurate positioning, stable connection, and high strength. So 3-D printing technique has broad prospects in the manufacture and application of individualized implant.