Chitin was used as the stuffing material bonedefect in animal experiment. Radiological and his-tological examination showed that it had good bi-ologgical compatibility good strength, hemostaticeffect promoting tussue healing and no toxicity.Chitin could be degradated by enzyme and mightbe used as the bone supporting material for treament of bone defect.
Objective To review the osteoimmunomodulatory effects and related mechanisms of inorganic biomaterials in the process of bone repair. Methods A wide range of relevant domestic and foreign literature was reviewed, the characteristics of various inorganic biomaterials in the process of bone repair were summarized, and the osteoimmunomodulatory mechanism in the process of bone repair was discussed. Results Immune cells play a very important role in the dynamic balance of bone tissue. Inorganic biomaterials can directly regulate the immune cells in the body by changing their surface roughness, surface wettability, and other physical and chemical properties, constructing a suitable immune microenvironment, and then realizing dynamic regulation of bone repair. Conclusion Inorganic biomaterials are a class of biomaterials that are widely used in bone repair. Fully understanding the role of inorganic biomaterials in immunomodulation during bone repair will help to design novel bone immunomodulatory scaffolds for bone repair.
ObjectiveTo explore the feasibility of three-dimensional (3D) bioprinted adipose-derived stem cells (ADSCs) combined with gelatin methacryloyl (GelMA) to construct tissue engineered cartilage.MethodsAdipose tissue voluntarily donated by liposuction patients was collected to isolate and culture human ADSCs (hADSCs). The third generation cells were mixed with GelMA hydrogel and photoinitiator to make biological ink. The hADSCs-GelMA composite scaffold was prepared by 3D bioprinting technology, and it was observed in general, and observed by scanning electron microscope after cultured for 1 day and chondrogenic induction culture for 14 days. After cultured for 1, 4, and 7 days, the composite scaffolds were taken for live/dead cell staining to observe cell survival rate; and cell counting kit 8 (CCK-8) method was used to detect cell proliferation. The composite scaffold samples cultured in cartilage induction for 14 days were taken as the experimental group, and the composite scaffolds cultured in complete medium for 14 days were used as the control group. Real-time fluorescent quantitative PCR (qRT-PCR) was performed to detect cartilage formation. The relative expression levels of the mRNA of cartilage matrix gene [(aggrecan, ACAN)], chondrogenic regulatory factor (SOX9), cartilage-specific gene [collagen type Ⅱ A1 (COLⅡA1)], and cartilage hypertrophy marker gene [collagen type ⅩA1 (COLⅩA1)] were detected. The 3D bioprinted hADSCs-GelMA composite scaffold (experimental group) and the blank GelMA hydrogel scaffold without cells (control group) cultured for 14 days of chondrogenesis were implanted into the subcutaneous pockets of the back of nude mice respectively, and the materials were taken after 4 weeks, and gross observation, Safranin O staining, Alcian blue staining, and collagen type Ⅱ immunohistochemical staining were performed to observe the cartilage formation in the composite scaffold.ResultsMacroscope and scanning electron microscope observations showed that the hADSCs-GelMA composite scaffolds had a stable and regular structure. The cell viability could be maintained at 80%-90% at 1, 4, and 7 days after printing, and the differences between different time points were significant (P<0.05). The results of CCK-8 experiment showed that the cells in the scaffold showed continuous proliferation after printing. After 14 days of chondrogenic induction and culture on the composite scaffold, the expressions of ACAN, SOX9, and COLⅡA1 were significantly up-regulated (P<0.05), the expression of COLⅩA1 was significantly down-regulated (P<0.05). The scaffold was taken out at 4 weeks after implantation. The structure of the scaffold was complete and clear. Histological and immunohistochemical results showed that cartilage matrix and collagen type Ⅱ were deposited, and there was cartilage lacuna formation, which confirmed the formation of cartilage tissue.ConclusionThe 3D bioprinted hADSCs-GelMA composite scaffold has a stable 3D structure and high cell viability, and can be induced differentiation into cartilage tissue, which can be used to construct tissue engineered cartilage in vivo and in vitro.
Objective To investigate bone regeneration of the cell-biomaterial complex using strategies of tissue engineering based on cells.Methods Hydroxyapatite/collagen (HAC) sandwich composite was produced to mimic the natural extracellular matrix of bone, with type Ⅰ collagen servingas a template for apatite formation. A three-dimensional ploy-porous scaffoldwas developed by mixing HAC with poly(L-lactic acid) (PLA) using a thermally induced phase separation technique (TIPS). The rabbit periosteal cells were treated with 500 ng/ml of recombinant human bone morphogenetic protein 2(rhBMP-2), followed by seeded into pre-wet HAC-PLA scaffolds. Eighteen 3-month nude mice were implanted subcutaneously cell suspension (groupA, n=6), simple HAC-PLA scaffold (group B, n=6) and cell-biomaterial complex(group C, n=6) respectively.Results Using type Icollagen to template mineralization of calcium and phosphate in solution, we get HAC sandwich composite, mimicking the natural bone both in compositionand microstructure. The three dimensional HAC-PLA scaffold synthesized by TIPShad high porosity up to 90%, with pore size ranging from 50 μm to 300 μm. SEMexamination proved that the scaffold supported the adhesion and proliferation of the periosteal cells. Histology results showed new bone formation 8 weeks after implantation in group C. The surface of group A was smooth without neoplasma. Fibrous tissueinvasion occured in group B and no bone and cartilage formations were observed.Conclusion The constructed tissue engineering bone has emerged as another promising alternative for bone repair.
ObjectiveTo review the research progress of natural biomaterial polyhydroxyalkanoate (PHA) in orthopedics. Methods The literature concerning PHA devices for bone defects, bone repair, and bone neoplasms, respectively, in recent years was extensively consulted. The three aspects of the advantages of PHA in bone repair, the preparation of PHA medical devices for bone repair and their application in orthopedics were discussed. ResultsDue to excellent biodegradability, biocompatibility, and potential osteoinduction, PHA is a kind of good bone repair material. In addition to the traditional PHA medical implants, the use of electrostatic spinning and three-dimensional printing can be designed to various functional PHA medical devices, in order to meet the orthopedic clinical demands, including the bone regeneration, minimally invasive bone tissue repair by injection, antibacterial bone repair, auxiliary establishment of three-dimensional bone tumor model, directed osteogenic differentiation of stem cells, etc. ConclusionAt present, PHA is a hotspot of biomaterials for translational medicine in orthopedics. Although they have not completely applied in the clinic, the advantages of repair in bone defects have been gradually reflected in tissue engineering, showing an application prospect in orthopedics.
ObjectiveTo summarize the developments of oxygen-generating materials as biomaterials and its applications in tissue engineering. MethodsThe recent literature on oxygen-generating materials as biomaterials was extensively reviewed, illustrating the properties and applications of oxygen-generating materials in tissue engineering. ResultsOxygen-generating materials as biomaterials have good biocompatibility and degradability. It supports the cell adhesion differentiation and growth. It is used for repairing liver, pancreas, myocardium, and so on. After modification, oxygen-generating materials can be extensively used in tissue engineering. ConclusionOxygen-generating materials is a good biomaterial, which has a great potential applications in tissue engineering.
Objective To observe the biocompatibil ity of self-assembled FGL peptide nano-fibers scaffold with neural stem cells (NSCs). Methods FGL peptide-amphiphile (FGL-PA) was synthesized by sol id-phase peptide synthesistechnique and thereafter It was analyzed and determined by high-performance l iquid chromatography (HPLC) and massspectrometry (MS). The diluted hydrochloric acid was added into FGL-PA solution to reduce the pH value and accordinglyinduce self-assembly. The morphological features of the assembled material were studied by transmission electron microscope (TEM). NSCs were cultured and different concentrations of FGL-PA assembled material were added with the terminal concentrations of 0, 50, 100, 200, 400 mg/L, respectively. CCK-8 kit was used to test the effect of FGL assembled material on prol iferation of NSCs. NSCs were added into differentiation mediums (control group: DMEM/F12 medium containing 2% B27 supplement and 10% FBS; experimental group: DMEM/F12 medium containing 2% B27 supplement, 10% FBS and 100 mg/L FGL-PA, respectively). Immunofluorescence was appl ied to test the effect of FGL-PA assembled material on differentiation of NSCs. Results FGL-PA could be self-assembled to form a gel. TEM showed the self-assembled gel was nano-fibers with diameter of 10-20 nm and length of hundreds nanometers. After NSCs were incubated for 48 hours with different concentrations of FGL-PA assembled material, the result of CCK-8 assay showed that FGL-PA with concentrations of 50, 100 or 200 mg/L could promote the prol iferation of NSCs and absorbance of them was increased (P lt; 0.05). Immunofluorescence analysis notified that the differentiation ratio of neurons from NSCs in control group and experimental group were 46.35% ± 1.27% and 72.85% ± 1.35%, respectively, when NSCs were induced to differentiation for 14 days, showing significant difference between 2 groups (P lt; 0.05). Conclusion FGL-PA can self-assemble to nano-fiber gel, which has good biocompatibil ity and neural bioactivity.
ObjectiveTo review the research progress and challenges of poly (L-lactic acid) (PLLA) membrane in preventing tendon adhesion. MethodsThe relevant literature at home and abroad in recent years was extensively searched, covering the mechanism of tendon adhesion formation, the adaptation challenge and balancing strategy of PLLA, the physicochemical modification of PLLA anti-adhesion membrane and its application in tendon anti-adhesion. In this paper, the research progress and modification strategies of PLLA membranes were systematically reviewed from the three dimensions of tissue adaptation, mechanical adaptation, and degradation adaptation. ResultsThe three-dimensional adaptation of PLLA membrane is optimized by combining materials (such as hydroxyapatite, polycaprolactone), structural design (multilayer/gradient membrane), and drug loading (anti-inflammatory drug). The balance between anti-adhesion and pro-healing is achieved, the mechanical adaptation significantly improve, and degradation is achieved (targeting the degradation cycle to 2-4 weeks to cover the tendon repair period). ConclusionIn the future, it is necessary to identify the optimal balance point of three-dimensional fitness, unify the evaluation criteria and solve the degradation side effects through the co-design of physicochemical modification and drug loading system to break through the bottleneck of clinical translation.
Objective To study the clinical effects of the artificial vertebral body of the biomimetic nanohydroxyapatite/polyamide 66 (nHA/PA66) compositefor the structural reconstruction and the height restoring of the vertebral body in the thoracolumbar fractures by the anterior surgical procedures. Methods From December 2003 to January 2006, 42 patients with thoracolumbar fractures received the anterior surgical procedures to decompress and reconstruct the spinal vertebral structure with the artificial vertebral body of the nHA/PA66 composite. Among the patients, there were 28 males and 14 females, aged 1767 years, averaged 43.6 years. The thoracolumbar fractures developed at T12 in 5 patients, at L1 in 17, at L2 in 14, and at L3 in 6. The height of the anterior border of thevertebral body amounted to 29%-47% of the vertebral body height, averaged 40.6%.The Cobb angle on the sagittal plane was 2138° averaged 27.6°. According tothe Frankel grading scale, the injuries to the nerves were as the following: Grade A in 7 patients, Grade B in 19, Grade C in 8, Grade D in 6, and Grade E in 2. Results All the 42 patients were followed up for 625 months. Among the patients, 36 were reconstructed almost based on the normal anatomic structure, and 6 were well reconstructed. The mean height of the anterior border of the vertebralbody was 40.6% of the vertebral body height before operation but 91.7% after operation. And the reconstructed height of the vertebra was maintained. The mean Cobb angle on the sagittal plane was 27.6°before operation but 13.4° after operation. All the patients had a recovery of the neurological function that had a 1grade or 2grade improvement except 7 patients who were still in Grade A and 2 patients who were in Grade D. The implant was fused 35 months after operation. No infection, nail break, bar/plate break or loosening of the internal fixation occurred. Conclusion The artificial vertebral body of the biomimetic nHA/PA66 composite can effectively restore the height and the structure of the vertebra, can be fused with the vertebral body to reconstruct the spinal structural stability effectively, and can be extensively used in the clinical practice.
Objective To evaluate the biocompatibility of a new bone matrix material (NBM) composed of both organic and inorganic materials for bone tissue engineering. Methods Osteoblasts combined with NBM in vitro were cultured. The morphological characteristics was observed; cell proliferation, protein content and basic alkaline phosphatase(ALP) activity were measured. NBM combined with osteoblasts were implanted into the skeletal muscles of rabbits and the osteogenic potential of NBM was evaluated through contraat microscope, scanning electromicroscope and histological examination. In vitro osteoblasts could attach and proliferate well in the NBM, secreting lots of extracellular matrix; NBM did not cause the inhibition of proliferation and ALP activity of osteoblasts. While in vivo experiment of the NBM with osteoblasts showed that a large number of lymphacytes and phagocytes invading into the inner of the material in the rabbit skeletalmuscle were seen after 4 weeks of implantation and that no new bone formation was observed after 8 weeks. Conclusion This biocompat ibility difference between in vitro and in vivo may be due to the immunogenity of NBM which causes cellular immuno reaction so as to destroy the osteogenic environment. The immunoreaction between the host and the organic-inorganic composite materials in tissue engineering should be paid more attention to.