Accurately shaped tooth bud cell-derived mineralized tissue formation on silk scaffolds

Based on the successful use of silk scaffolds in bone tissue engineering, we examined their utility for mineralized dental tissue engineering. Four types of hexafluoroisopropanol (HFIP) silk scaffolds-(250 and 550 microm diameter pores, with or without arginine-glycine-aspartic acid (RGD) peptide) were seeded with cultured 4-day postnatal rat tooth bud cells and grown in the rat omentum for 20 weeks. Analyses of harvested implants revealed the formation of bioengineered mineralized tissue that was most robust in 550 microm pore RGD-containing scaffolds and least robust in 250 microm pore sized scaffolds without RGD. The size and shape of the silk scaffold pores appeared to guide mineralized tissue formation, as revealed using polarized light imaging of collagen fiber alignment along the scaffold surfaces. This study is the first to characterize bioengineered tissues generated from tooth bud cells seeded onto silk scaffolds and indicates that silk scaffolds may be useful in forming mineralized osteodentin of specified sizes and shapes.     

Cell proliferation and migration in silk fibroin 3D scaffolds

Pore architecture in 3D polymeric scaffolds is known to play a critical role in tissue engineering as it provides the vital framework for the seeded cells to organize into a functioning tissue. In this report, we investigated the effects of different freezing temperature regimes on silk fibroin protein 3D scaffold pore microstructure. The fabricated scaffolds using freeze-dry technique were used as a 3D model to monitor cell proliferation and migration. Pores of 200–250 μm diameter were formed by slow cooling at temperatures of ?20 and ?80 °C but were found to be limited in porosity and pore interconnectivity as observed through scanning electron microscopic images. In contrast, highly interconnected pores with 96% porosity were observed when silk solutions were rapidly frozen at ?196 °C. A detailed study was conducted to assess the affect of pore size, porosity and interconnectivity on human dermal fibroblast cell proliferation and migration on these 3D scaffolds using confocal microscopy. The cells were observed to migrate within the scaffold interconnectivities and were found to reach scaffold periphery within 28 days of culture. Confocal images further confirmed normal cell attachment and alignment of actin filaments within the porous scaffold matrix with well-developed nuclei. This study indicates rapid freeze-drying technique as an alternative method to fabricate highly interconnected porous scaffolds for developing functional 3D silk fibroin matrices for potential tissue engineering, biomedical and biotechnological applications.     

Influence of freezing rate on pore structure in freeze-dried collagen-GAG scaffolds

The cellular structure of collagen-glycosaminoglycan (CG) scaffolds used in tissue engineering must be designed to meet a number of constraints with respect to biocompatibility, degradability, pore size, pore structure, and specific surface area. The conventional freeze-drying process for fabricating CG scaffolds creates variable cooling rates throughout the scaffold during freezing, producing a heterogeneous matrix pore structure with a large variation in average pore diameter at different locations throughout the scaffold. In this study, the scaffold synthesis process was modified to produce more homogeneous freezing by controlling of the rate of freezing during fabrication and obtaining more uniform contact between the pan containing the CG suspension and the freezing shelf through the use of smaller, less warped pans. The modified fabrication technique has allowed production of CG scaffolds with a more homogeneous structure characterized by less variation in mean pore size throughout the scaffold (mean: 95.9 microm, CV: 0.128) compared to the original scaffold (mean: 132.4 microm, CV: 0.185). The pores produced using the new technique appear to be more equiaxed, compared with those in scaffolds produced using the original technique.     

基于有限元法的骨组织工程支架力学性能分析及改进设计

目的分析不同孔隙结构和孔隙率骨组织工程支架的力学性能,并对支架的孔隙结构进行改进设计使其性能提高。方法利用SolidWorks软件进行方形孔、球形孔和圆柱形孔3种结构55%～75%孔隙率的支架建模,计算得到各结构的表面积体积比;利用ANSYS Workbench软件进行结构受力的有限元计算,得到支架结构的应力分布和等效压缩模量;根据应力分布的特点,将方形孔的支架结构改进为长方形孔隙结构和长方体单元结构两种支架。结果随着孔隙率的增加,3种结构的表面积体积比均增大,对于相同的孔隙率,方形孔和球形孔的表面积体积比较大,圆柱形孔最小;3种结构的最大压应力总体趋势是随着孔隙率的增加而增大,对于同一孔隙率的3种结构,方形孔的最大压应力最小;3种结构的模量和孔隙率近似呈线性关系,方形孔和圆柱形孔的模量值相近;60%孔隙率的方形孔及两种改进结构应力分析表明,两种改进结构的平行于应力方向的4条棱侧壁应力可减小约15%。结论方形孔的表面积体积比和力学性能比相同孔隙率的球形孔和圆柱形孔结构要更有优势,而改进的两种结构又可以提高方形孔的力学性能,两种改进的孔隙丰富了组织工程支架的结构,研究结果为两种支架的临床应用提供力学依据。     

Biodegradable polymer scaffolds with well-defined interconnected spherical pore network

Scaffolding plays pivotal role in tissue engineering. In this work, a novel processing technique has been developed to create three-dimensional biodegradable polymer scaffolds with well-controlled interconnected spherical pores. Paraffin spheres were fabricated with a dispersion method, and were bonded together through a heat treatment to form a three-dimensional assembly in a mold. Biodegradable polymers such as PLLA and PLGA were dissolved in a solvent and cast onto the paraffin sphere assembly. After dissolving the paraffin, a porous polymer scaffold was formed. The fabrication parameters were studied in relation to the pore shape, interpore connectivity, pore wall morphology, and mechanical properties of the polymer scaffolds. The compressive modulus of the scaffolds decreased with increasing porosity. Longer heat treatment time of the paraffin spheres resulted in larger openings between the pores of the scaffolds. Foams of smaller pore size (100-200 microm) resulted in significantly lower compressive modulus than that of larger pore sizes (250-350 or 420-500 microm). The PLLA foams had a skeletal structure consisting of small platelets, whereas PLGA foams had homogeneous skeletal structure. The new processing technique can tailor the polymer scaffolds for a variety of potential tissue engineering applications because of the well-controlled architecture, interpore connectivity, and mechanical properties.     

Fabrication and mechanical and tissue ingrowth properties of unidirectionally porous hydroxyapatite/collagen composite

This study investigated the effects of the three-dimensional (3-D) pore structure of a porous hydroxyapatite/collagen (HAp/Col) composite on their mechanical properties and in vivo tissue ingrowth. The unique 3-D pore structure, comprising unidirectionally interconnected pores, was fabricated by the unidirectional growth of ice crystals by using a cooling stage and a subsequent freeze-drying process. The unidirectional pores had a spindle-shaped cross section, and their size gradually increased from the bottom to the upper face. The porous composite showed an elastic property and anisotropic compressive strength for the pore directions. While the strength and modulus parallel to the pore axis were 1.3- and twofold higher than those of the porous composite with spherical pores formed randomly, the strength and modulus perpendicular to the pore axis showed the lowest values. The subcutaneous implantations revealed that when compared with the random pores, the unidirectional pores promote the ingrowth of the surrounding tissues into the pores.     

Direct deposited porous scaffolds of calcium phosphate cement with alginate for drug delivery and bone tissue engineering

This study reports the preparation of novel porous scaffolds of calcium phosphate cement (CPC) combined with alginate, and their potential usefulness as a three-dimensional (3-D) matrix for drug delivery and tissue engineering of bone. An α-tricalcium phosphate-based powder was mixed with sodium alginate solution and then directly injected into a fibrous structure in a Ca-containing bath. A rapid hardening reaction of the alginate with Ca(2+) helps to shape the composite into a fibrous form with diameters of hundreds of micrometers, and subsequent pressing in a mold allows the formation of 3-D porous scaffolds with different porosity levels. After transformation of the CPC into a calcium-deficient hydroxyapatite phase in simulated biological fluid the scaffold was shown to retain its mechanical stability. During the process biological proteins, such as bovine serum albumin and lysozyme, used as model proteins, were observed to be effectively loaded onto and released from the scaffolds for up to more than a month, proving the efficacy of the scaffolds as a drug delivering matrix. Mesenchymal stem cells (MSCs) were isolated from rat bone marrow and then cultured on the CPC-alginate porous scaffolds to investigate the ability to support proliferation of cells and their subsequent differentiation along the osteogenic lineage. It was shown that MSCs increasingly actively populated and also permeated into the porous network with time of culture. In particular, cells cultured within a scaffold with a relatively high porosity level showed favorable proliferation and osteogenic differentiation. An in vivo pilot study of the CPC-alginate porous scaffolds after implantation into the rat calvarium for 6 weeks revealed the formation of new bone tissue within the scaffold, closing the defect almost completely. Based on these results, the newly developed CPC-alginate porous scaffolds could be potentially useful as a 3-D matrix for drug delivery and tissue engineering of bone.     

An innovative method to obtain porous PLLA scaffolds with highly spherical and interconnected pores

Scaffolding is an essential issue in tissue engineering and scaffolds should answer certain essential criteria: biocompatibility, high porosity, and important pore interconnectivity to facilitate cell migration and fluid diffusion. In this work, a modified solvent casting-particulate leaching out method is presented to produce scaffolds with spherical and interconnected pores. Sugar particles (200-300 microm and 300-500 microm) were poured through a horizontal Meker burner flame and collected below the flame. While crossing the high temperature zone, the particles melted and adopted a spherical shape. Spherical particles were compressed in plastic mold. Then, poly-L-lactic acid solution was cast in the sugar assembly. After solvent evaporation, the sugar was removed by immersing the structure into distilled water for 3 days. The obtained scaffolds presented highly spherical interconnected pores, with interconnection pathways from 10 to 100 mum. Pore interconnection was obtained without any additional step. Compression tests were carried out to evaluate the scaffold mechanical performances. Moreover, rabbit bone marrow mesenchymal stem cells were found to adhere and to proliferate in vitro in the scaffold over 21 days. This technique produced scaffold with highly spherical and interconnected pores without the use of additional organic solvents to leach out the porogen.     

Porous carriers for biomedical applications based on alginate hydrogels

Macroporous scaffolds are typically utilized in tissue engineering applications to allow for the migration of cells throughout the scaffold and integration of the engineered tissue with the surrounding host tissue. A method to form macroporous beads with an interconnected pore structure from alginate has been developed by incorporating gas pockets within alginate beads, stabilizing the gas bubbles with surfactants, and subsequently removing the gas. Macroporous scaffolds could be formed from alginate with different average molecular weights (5-200 kDa) and various surfactants. The gross morphology, amount of interconnected pores, and total void volume was investigated both qualitatively and quantitatively. Importantly, macroporous alginate beads supported cell invasion in vitro and in vivo.     

Novel porous gelatin scaffolds by overrun/particle leaching process for tissue engineering applications

Porous gelatin scaffolds were prepared using a modified overrun process, which is a novel method for preparing a porous matrix by injecting air and mixing polymer solution at low temperature. The pores in the scaffolds formed by the overrun process exhibited a dual-pore structure due to the injection of air bubbles and ice recrystallization. However, the morphology of the overrun-processed gelatin scaffolds had closed pore structures. The closed pore structure was reformed into a uniformly distributed and interconnected open structure by the combination of the overrun process and a particle-leaching technique (NaCl and sucrose). The mechanical strength and biodegradation rate of gelatin scaffolds were controlled by the matrix porosity and concentration of gelatin solution. Despite higher porosity, overrun processed gelatin scaffolds showed similar mechanical strength to freeze-dried scaffolds. After 1 week of in vitro culturing, the fibroblasts in overrun-processed scaffolds were widely distributed on the surface of the scaffold pores, whereas cells seeded in freeze-dried scaffolds were mainly placed on the top and bottom of the scaffolds. Therefore, the overrun process combined with a particle-leaching technique can be applied to fabricate porous scaffolds with a desirable cellular structure for tissue engineering applications.     

Application of microstereolithography in the development of three-dimensional cartilage regeneration scaffolds

Conventional methods for fabricating three-dimensional (3-D) tissue engineering scaffolds have substantial limitations. In this paper, we present a method for applying microstereolithography in the construction of 3-D cartilage scaffolds. The system provides the ability to fabricate scaffolds having a pre-designed internal structure, such as pore size and porosity, by stacking photopolymerized materials. To control scaffold structure, CAD/CAM technology was used to generate a scaffold pattern algorithm. Since tissue scaffolds must be constructed using a biocompatible, biodegradable material, scaffolds were synthesized using liquid photocurable TMC/TMP, followed by acrylation at the terminal ends, and photocured under UV light irradiation. The solidification properties of the TMC/TMP polymer were also assessed. To assess scaffold functionality, chondrocytes were seeded on two types of 3-D scaffold and characterized for cell adhesion. Results indicate that scaffold geometry plays a critical role in chondrocyte adhesion, ultimately affecting the tissue regeneration utility of the scaffolds. These 3-D scaffolds could eventually lead to optimally designed constructs for the regeneration of various tissues, such as cartilage and bone.     

Nano-fibrous poly(L-lactic acid) scaffolds with interconnected spherical macropores

Biodegradable polymers have been used extensively as scaffolding materials to regenerate new tissues. These scaffolds should possess certain physical characteristics including a three-dimensional structure, high porosity with an interconnected pore structure, and a suitable surface structure for cell attachment, proliferation, and differentiation. To mimic the fibrous architecture of type I collagen, nano-fibrous matrices have been created in our laboratory using a phase-separation technique of poly(L-lactic acid) (PLLA) solutions. In addition, biodegradable scaffolds with controlled interconnected spherical pore networks have been fabricated in our laboratory. In this work, these two techniques were combined to yield scaffolds with highly interconnected spherical macroporous structures and nano-fibrous architectures. Paraffin spheres were first fabricated with a dispersion method, and were thermally bonded to form an interconnected mold. PLLA solutions were cast over the paraffin sphere assembly and were thermally phase-separated to form nano-fibrous matrices. After leaching out the paraffin, synthetic nano-fibrous extracellular matrices with interconnected spherical pores were yielded. By utilizing this fabrication process, we are able to control the architecture of the scaffolds at several different levels, including the macroscopic shape of the scaffold, the spherical pore size, interfiber distance, and the fiber diameter at the nano-size scale. The inter-pore connectivity could be controlled by varying the heat treatment time of the paraffin spheres, and mechanical properties could be controlled by varying the porosity of the scaffolds. With an interconnected macroporous structure that promotes cell seeding throughout the interstices of the scaffold, and a synthetic collagen-like matrix, these novel matrices may be an excellent scaffold for tissue engineering.     

Preparation and characterization of a three-dimensional printed scaffold based on a functionalized polyester for bone tissue engineering applications

At present there is a strong need for suitable scaffolds that meet the requirements for bone tissue engineering applications. The objective of this study was to investigate the suitability of porous scaffolds based on a hydroxyl functionalized polymer, poly(hydroxymethylglycolide-co-ε-caprolactone) (pHMGCL), for tissue engineering. In a recent study this polymer was shown to be a promising material for bone regeneration. The scaffolds consisting of pHMGCL or poly(ε-caprolactone) (PCL) were produced by means of a rapid prototyping technique (three-dimensional plotting) and were shown to have a high porosity and an interconnected pore structure. The thermal and mechanical properties of both scaffolds were investigated and human mesenchymal stem cells were seeded onto the scaffolds to evaluate the cell attachment properties, as well as cell viability and differentiation. It was shown that the cells filled the pores of the pHMGCL scaffold within 7 days and displayed increased metabolic activity when compared with cells cultured in PCL scaffolds. Importantly, pHMGCL scaffolds supported osteogenic differentiation. Therefore, scaffolds based on pHMGCL are promising templates for bone tissue engineering applications.     

Interactions of coronary artery smooth muscle cells with 3D porous polyurethane scaffolds

One strategy in vascular tissue engineering is the design of hybrid vascular substitutes where vascular cells infiltrate biostable porous scaffolds that provides favorable environment for guided cell repopulation and acts as a mechanically supporting layer after the tissue regeneration process. The aim of the present work was to study the interaction of human coronary artery smooth muscle cells (HCASMC) with 3D porous polyurethane scaffolds. We therefore fabricated porous and highly interconnected 3D polyurethane scaffolds that can promote HCASMC attachment, proliferation, and migration. SEM and microCT studies of the fabricated scaffolds showed that the current scaffolds had highly open and interconnected pore structures, with an average porosity of 84%. HCASMC interaction on polyurethane films revealed that cells adhere and express specific marker proteins (vinculin and h-caldesmon). This expression was further enhanced by coating the polyurethane with Matrigel. On uncoated 3D scaffolds, dense spherical aggregates of cells were often encountered with little adhesion of individual cells alongside the struts of the scaffold, independent of the porogens used. In contrast, when cultured on Matrigel-coated scaffolds, cell numbers quickly increased after 14 days and spread along the entire scaffold. At the upper scaffold surface, elongated cells were seen adhering to one another and also to the scaffold surface. These cells were elongated, aligned in parallel and contained abundant F-actin bundles suggesting a differentiated contractile phenotype. Deep into the scaffold, cells were encountered that formed actin-rich lamellipodial extensions spreading along the strut and lacked stress fibers, suggesting active cell migration along the substrate.     

Correlation Between Cryogenic Parameters and Physico-Chemical Properties of Porous Gelatin Cryogels

In the present work, we have performed an in-depth physico-chemical and bio-physical evaluation of a series of previously described porous gelatin scaffolds (S. VanVlierberghe, V. Cnudde, P. Dubruel, B. Masschaele, A. Cosijns, I. DePaepe, P.J.S. Jacobs, L. VanHoorebeke, J.P. Remon and E. Schacht, Biomacromolecules 8, 331 (2007)). All scaffolds were prepared by a cryogenic treatment and subsequent freeze-drying. Three types of scaffolds were prepared by using different gelatin concentrations and cooling protocols. Type-I hydrogels were composed of cone-like pores with decreasing diameter from top (330 μm) to bottom (20–30 μm). Type-II and type-III scaffolds contained spherical pores with an average diameter of 135 (type II) and 65 μm (type III), respectively. The physico-chemical and bio-physical properties studied include the water uptake capacity and kinetics, the mechanical properties and the enzyme-mediated degradation. We can conclude that the pore geometry affects the water uptake capacity, the mechanical properties and the degradation profile of the hydrogels. Type-I hydrogels possess the highest water uptake, the lowest compression modulus and the fastest enzyme mediated degradation, indicating a clear effect of the pore morphology (elongated channels for type I versus spherical pores for types II and III) on the physico-chemical and bio-physical properties of the materials. In contrast to the effect of the pore geometry (channel-like versus spherical), the pore size does not significantly affect the water uptake, the mechanical properties and the enzyme mediated degradation in the investigated pore size range (65–135 μm). To the best of our knowledge, this is the first report in which the effects of a cryogenic treatment on the hydrogel network properties are investigated in such detail.     

The effect of anisotropic collagen-GAG scaffolds and growth factor supplementation on tendon cell recruitment, alignment, and metabolic activity

Current surgical and tissue engineering approaches for treating tendon injuries have shown limited success, suggesting the need for new biomaterial strategies. Here we describe the development of an anisotropic collagen-glycosaminoglycan (CG) scaffold and use of growth factor supplementation strategies to create a 3D platform for tendon tissue engineering. We fabricated cylindrical CG scaffolds with aligned tracks of ellipsoidal pores that mimic the native physiology of tendon by incorporating a directional solidification step into a conventional lyophilization strategy. By modifying the freezing temperature, we created a homologous series of aligned CG scaffolds with constant relative density and degree of anisotropy but a range of pore sizes (55-243?μm). Equine tendon cells showed greater levels of attachment, metabolic activity, and alignment as well as less cell-mediated scaffold contraction, when cultured in anisotropic scaffolds compared to an isotropic CG scaffold control. The anisotropic CG scaffolds also provided critical contact guidance cues for cell alignment. While tendon cells were randomly oriented in the isotropic control scaffold and the transverse (unaligned) plane of the anisotropic scaffolds, significant cell alignment was observed in the direction of the contact guidance cues in the longitudinal plane of the anisotropic scaffolds. Scaffold pore size was found to significantly influence tendon cell viability, proliferation, penetration into the scaffold, and metabolic activity in a manner predicted by cellular solids arguments. Finally, the addition of the growth factors PDGF-BB and IGF-1 to aligned CG scaffolds was found to enhance tendon cell motility, viability, and metabolic activity in dose-dependent manners. This work suggests a composite strategy for developing bioactive, 3D material systems for tendon tissue engineering.     

Porous alginate/hydroxyapatite composite scaffolds for bone tissue engineering: preparation, characterization, and in vitro studies

In this study a series of alginate/hydroxyapatite (HAP) composite scaffolds was prepared by phase separation. HAP was incorporated into the alginate gel solution to improve both the mechanical and cell-attachment properties of the scaffolds. These scaffolds had a well-interconnected porous structure with an average pore size of 150 microm and over 82% porosity. The alginate/HAP scaffold prepared at -40 degrees C with a 50% HAP content showed the best mechanical properties. The morphology of scaffolds could be manipulated by tuning the quenching temperature during the preparation. The dissolution of alginate/HAP composite scaffolds could be slowed by the pretreating them by immersion in 1.0 M CaCl(2) solution. The rat osteosarcoma UMR106 cells, an osteoblastic cell line, seeded in the scaffolds, displayed better cell attachment to the 75/25 and 50/50 alginate/HAP composite scaffolds than to the pure alginate scaffold. The natural polymeric sponges that fabricated in this study may be a promising approach for tissue-engineering applications.     

Chitosan scaffolds for in vitro buffalo embryonic stem-like cell culture: an approach to tissue engineering

Three-dimensional (3D) porous chitosan scaffolds are attractive candidates for tissue engineering applications. Chitosan scaffolds of 70, 88, and 95% degree of deacetylation (% DD) with the same molecular weight were developed and their properties with buffalo embryonic stem-like (ES-like) cells were investigated in vitro. Scaffolds were fabricated by freezing and lyophilization. They showed open pore structure with interconnecting pores under scanning electron microscopy (SEM). Higher % DD chitosan scaffolds had greater mechanical strength, slower degradation rate, lower water uptake ability, but similar water retention ability, when compared to lower % DD chitosan. As a strategy to tissue engineering, buffalo ES-like cells were cultured on scaffolds for 28 days. It appeared that chitosan was cytocompatible and cells proliferated well on 88 and 95% DD scaffolds. In addition, the buffalo ES-like cells maintained their pluripotency during the culture period. Furthermore, the SEM and histological study showed that the polygonal buffalo ES-like cells proliferated well and attached to the pores. This study proved that 3D biodegradable highly deacetylated chitosan scaffolds are promising candidates for ES-like cell based tissue engineering and this chitosan scaffold and ES cell based system can be used as in vitro model for subsequent clinical applications.     

Alginate/poly (lactic-co-glycolic acid)/calcium phosphate cement scaffold with oriented pore structure for bone tissue engineering

In this study, the alginate/calcium phosphate cement (CPC) scaffolds with oriented pore structure were fabricated by unidirectional freeze casting and poly (lactic-co-glycolic acid) (PLGA) was used to infiltrate into the macropores to strengthen the scaffolds. By modifying the liquid to powder ratio, the porosity and pore size of the alginate/CPC scaffold could be controlled. At the liquid to powder (L/P) ratio of 3.25, scaffolds possessing open directional macropores and a total porosity of 89.24% could be achieved. The size of the tubule-like macropores could reach 100-200 mum in their radial dimension and more than 1000 mum in the axial one, with macropores well-regulated arrayed. Increasing the L/P ratio would significantly decrease the mechanical strength of alginate/CPC scaffolds. The compressive strength and toughness of scaffolds could be greatly improved via PLGA reinforcement. Three mechanisms of PLGA reinforcement ran as follows: participating in the external load, strengthening the matrix, and patching the defects of CPC pores wall. Alginate/PLGA/CPC scaffold preserved the open directional macropores and might be a potential scaffold for bone tissue engineering.     

Fabrication and Characterization of Waterborne Biodegradable Polyurethanes 3-Dimensional Porous Scaffolds for Vascular Tissue Engineering

In this study, a series of 3-D interconnected porous scaffolds with various pore diameters and porosities was fabricated by freeze-drying with non-toxic biodegradable waterborne polyurethane (WBPU) emulsions of different concentration. The structures of these porous scaffolds were characterized by scanning electron microscopy (SEM), and the pore diameters were calculated using CIAS 3.0 software. The pores obtained were 3-D interconnected in the scaffolds. The scaffolds obtained at different pre-freeze temperatures showed a pore diameter ranging from 2.8 to 99.9 μm with a pre-freezing temperature of ?60°C and from 13.1 to 229.1 μm with a pre-freezing temperature of ?25°C. The scaffolds fabricated with WBPU emulsions of different concentration at the same pre-freezing temperature (?25°C) had pores with mean pore diameter between 90.8 and 39.6 μm and porosity between 92.0 and 80.0%, depending on the emulsion concentration. The effect of porous structure of the scaffolds on adhesion and proliferation of human umbilical vein endothelial cells (HUVECs) cultured in vitro was evaluated using the MTT assay and environmental scanning electron microscopy (ESEM). It was found that the better adhesion and proliferation of HUVECs on 3-D scaffolds of WBPU with relative smaller pore diameter and lower porosity than those on scaffolds with larger pore and higher porosity and film. Our work suggests that fabricating a scaffold with controllable pore diameter and porosity could be a good method to be used in tissue-engineering applications to obtain carriers for cell culture in vitro.