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Eye organoid refers to a structure that possesses resembling cell types and functions to intraocular tissues, which is induced by stem cells in vitro. Transplanting it into the body for eye repair and regeneration is one of the key research directions in regenerative medicine, which also provides a novel direction and strategy for the treatment of major blinding diseases. As a carrier of biological tissue or cell growth, tissue engineering scaffold could support in vivo transplantation of eye organoids and promote their maturation. Organic combination of eye organoids and tissue engineering is a critical approach to realize in vivo integration of eye organoids and reconstruct corresponding structures and functions. In this review, the latest research status of eye organoids and in vivo transplantation were summarized, and relevant studies of tissue engineering scaffold-assisted eye organoid transplantation were highlighted, aiming to provide ideas and reference for subsequent inter-disciplinary research of eye organoids and tissue engineering.
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Tricalcium phosphate (TCP) is one of the most widely used bioceramics for constructing bone tissue engineering scaffold. The three-dimensional (3D) printed TCP scaffold has precise and controllable pore structure, while with the limitation of insufficient mechanical properties. In this study, we investigated the effect of sintering temperature on the mechanical properties of 3D-printed TCP scaffolds in detail, due to the important role of the sintering process on the mechanical properties of bioceramic scaffolds. The morphology, mass and volume shrinkage, porosity, mechanical properties and degradation property of the scaffold was studied. The results showed that the scaffold sintered at 1 150℃ had the maximum volume shrinkage, the minimum porosity and optimal mechanical strength, with the compressive strength of (6.52 ± 0.84) MPa and the compressive modulus of (100.08 ± 18.6) MPa, which could meet the requirements of human cancellous bone. In addition, the 1 150℃ sintered scaffold degraded most slowly in the acidic environment compared to the scaffolds sintered at the other temperatures, demonstrating its optimal mechanical stability over long-term implantation. The scaffold can support bone mesenchymal stem cells (BMSCs) adherence and rapid proliferation and has good biocompatibility. In summary, this paper optimizes the sintering process of 3D printed TCP scaffold and improves its mechanical properties, which lays a foundation for its application as a load-bearing bone.
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Objective To analyze the mechanical properties of bone tissue engineering scaffolds with different pore structure and porosity, and improve the mechanical properties of scaffolds by changing pore structure. Methods Square pore, spherical pore and cylindrical pore with different porosities from 55% to 75% were established by SolidWorks software, and the surface-volume ratio of different structures was calculated. The stress distribution and equivalent compression modulus of different scaffolds were obtained by ANSYS Workbench software. According to the stress distribution results, the scaffold with rectangular pore structure and cuboid element structure was improved instead of square pores. Results With the increase of porosity, the surface-volume ratio of the three structures increased. For the same porosity, the surface-volume ratio of square pores and spherical pores was larger, while that of cylindrical pores was the smallest. The modulus and porosity of the three structures were approximately linear. The modulus of the square pore and the cylindrical pore were similar. The stress analysis on the square pore and two improved structures with 60% porosity showed that for the two improve structures, the wall stress on 4 edges parallel to the direction of applied stresses could be reduced by 15%. Conclusions The surface-volume ratio and mechanical property of square pores were more advantageous than spherical pores and cylindrical pores with the same porosity, and the two improved structures could improve the mechanical properties of square pores. The two improved pores enriched the structure of tissue engineering scaffolds. The research findings provide the mechanical references for their clinical application.
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Objective When bacterial cellulose (BC) is used as a scaffold material in tissue engineering,the nano-structure of BC may not provide enough space for animal cell growth and differentiation which would not achieve a perfect application in tissue engineering.In order to solve this problem,a novel green approach is developed in this research to produce bacterial nanocellulose materials with micropores ranging 50-800 μm.Methods Several ratios of hydrogen peroxide to sodium chlorite were used to react instantly to produce a large number of bubbles in BC hydrogels,which formed micropores with diameters ranging 50-800 μm.Optical microscopy and scanning electron microscope were used to evaluate microporous BC hydrogels and verify the existence of micropores.Results The size of pores could be regulated along with the changes in the amount of reactants used in the experiment.Fourier transform infrared spectroscopy verified that no cellulose was oxidized.Water content of the microporous BC hydrogels was similar to that of the original BC hydrogels.The Young's modulus of microporous BC hydrogels was 26.1 kPa,which was lower than that of the original BC hydrogels (69.9 kPa).Thiazoyl blue tetrazolium bromide (MTT) test displayed a higher viability on the microporous BC hydrogels compared to the growth on the unmodified BC substrates.Conclusions This study provides a convenient and promising way to prepare microporous materials,which may not be limited to only BC material,but could be used in other hydrogels.The proposed approach is suitable for extensive industrialization.
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Objective The nano-zirconia scaffolds we previously prepared had a good 3-dimensional ( 3D ) connectivity but did not achieve the ideal sintering rate and compressive strength .The objective of this study was to explore the enhancing effect of polyvinyl butyral ( PVB) as a dispersant on the compressive strength of 3D nano-zirconia porous scaffolds for bone tissue engineering . Methods We prepared the slurry containing different concentrations of PVB and ana-lyzed the improving effect of PVB on the mechanical properties of the scaffolds by sediment experiment , compressive strength test and scan-ning electron microscopy . Results The sediment experiment showed no significant stratification in the slurry with 0.2wt%PVB, white suspension in the upper layer and white precipitate in the lower layer , with a significantly higher compressive strength of the scaffold ([0.324 ±0.030] MPa) than that of the scaffold prepared by adding other concentrations of PVB to the slurry (P <0.01).And the compressive strength of the scaffold constructed by adding no dispersant ([0.109 ±0.021] MPa) was remarkably lower than that of the scaffold constructed by adding PVB to the slurry (P<0.05).Scanning electron microscopy demonstrated that the scaffold prepared by adding 0.2wt%PVB to the slurry had a complete porous structure with the fewest and most sparsely distributed surface cracks as compared with other PVB concentration groups . Conclusion PVB can signifi-cantly improve the stability of zirconia slurry , enhance the compressive strength of the nano-zirconia porous scaffold , and make the scaf-fold more applicable to bone tissue engineering .
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@#Biological scaffolds imitate the structure and function of extracellular matrix,and so good biocompatibility is essential for it.The materials in neural tissue engineering mainly include natural biomaterial and artificial biodegradable materials presently.This article has reviewed the biological function of materials mostly used in neural tissue engineering.
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[Objective]Using a procedure of chemical agent to remove the cells and myethin in spinal cord of rat and to prepare the scaffold of extracellular matrix,so as to obtain an ideal natural spinal cord scaffold to bridge the nerve gap.[Method]Rat spinal cord was cut and treated using the method of freeze thawing and chemical extraction(3%sodiumdeoxycholate and 1KU/ml DNaseI,RNaseA).Histology was exploited to evaluate the degree of acellular and the structure of the spinal cord scaffold.[Result]In cross section,network of the extracellular matrix was presented in the scaffold.The cells,myethin and axons disappeared after the spinal cord was treated with sodium deoxycholate and DNaseI,RNaseA.Typical network of empty tubes were viewed in longitudinal sections.[Conclusion]An ideal spinal cord scaffold can be produced with the method designed in authors experiment.This scaffold has similar three dimensional structure with normal spinal cord,which can be used as a graft to bridge the nerve gap directly or as a scaffold to implant the seeding cells in spinal cord tissue engineering.The experiment indicates that cells and myethin can be removed and the three dimensional structure be reserved by chemical extraction with 3% sodium deoxycholate and 1KU/ml DNaseI,RNaseA.Chemical extraction is an ideal method to prepare tissue engineer scaffold of spinal cord.
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Objective To prepare the acellular scaffold of spinal cord and analyze its component.Methods The acellular scaffold was prepared with the freeze thawing and chemical extraction,its structure was observed by HE and SEM,its component was analyzed by immunohistochemistry.Results The cells,myelin sheath and axon of nerve fibers in the rat spinal cord were eliminated,but three-dimensional supports of extracellular matrix were reserved.The analytical results showed the component of the acellular spinal cord contain laminin,fibronectin and type Ⅳ collagen—the necessary components to facilitate and induce the regeneration of the injured nerves and enhance the adhesion and proliferation of cells.Conclusion The acellular spinal cord has three dimensional structure and contains several proteins related to the regeneration of the injured nerves and promotion of the survival and proliferation of cells.
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While calcium phosphate ceramics meet some of the needs for bone replacement, they have some limitation of unresorbability and fibrous encapsulation without direct bone apposition during bone remodelling. To address these problem, we developed a new ceramic, calcium metaphosphate(CMP), and report herein the biologic response to CMP in subcutaneous tissue, muscle and bone. Porous CMP blocks were prepared by condensation of anhydrous Ca(H2PO4)2 to form non-crystalline Ca(PO3)2. Macroporous scaffolds were made using a polyurethane sponge method. CMP block possesses a macroporous structure with approximate pore size range of 0.3-1mm. CMP blocks were implanted in 8 mm sized calvarial defect, subcutaneous tissue and muscle of 6 Newzealand White rabbits and histologic observation were performed at 4 and 6 weeks later. CMP blocks in subcutaneous tissue and muscle were well adapted without any adverse tissue reaction and resorbed slowly and spontaneously. Histologic observation of calvarial defect at 4 and 6 weeks revealed that CMP matrix were mingled with and directly apposed to new bone without any intervention of fibrous connective tissue. CMP blocks didn't show any adverse tissue reaction and resorbed spontaneously also in calvarial defect. This result revealed that CMP had a high affinity for bone and was very biocompatible. From this preliminary result, it was suggested that CMP was a promising ceramic as a bone substitute and tissue engineering scaffold for bone formation.
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Rabbits , AnimalsABSTRACT
Objective To compare the effect of 2 decellularizing methods,sodium deoxycholate plus Triton X-100 or plus DNase and Rnase,in the preparation of acelluar allograft spinal cord scaffold in order to provide an ideal natural spinal cord scaffold to bridge the nerve gap.Methods Spinal cord was removed from health rats,and then decellularized by the method of freeze thawing(immersing in 3% sodium deoxycholate followed by the mixture of 1?103 U/ml DNase and RNase),or by chemical extraction(immersing in 1% Triton X-100 and then 1% sodium deoxycholate).HE staining,myelin staining and scanning electron microscopy(SEM) were employed to evaluate the spinal cord scaffold after the 2 methods of decellularization.Results Both cells and myelin were completely decellularized with the 2 methods.In cross section,network of the extracellular matrix was presented without axon,sheath and cells nucleus being seen in the scaffold.Typical network of empty tubes were viewed in longitudinal sections.Conclusion An ideal spinal cord scaffold can be produced with these 2 decellularizing methods in tissue engineering.The scaffold made by the 2 methods have similar three dimensional structure with normal spinal cord,so can be used as a graft to bridge the nerve gap directly or as a scaffold to implant the seeding cells in spinal cord tissue engineering.