Fabrication and development of artificial osteochondral constructs based on cancellous bone/hydrogel hybrid scaffold

Using tissue engineering techniques, an artificial osteochondral construct was successfully fabricated to treat large osteochondral defects. In this study, porcine cancellous bones and chitosan/gelatin hydrogel scaffolds were used as substitutes to mimic bone and cartilage, respectively. The porosity and distribution of pore size in porcine bone was measured and the degradation ratio and swelling ratio for chitosan/gelatin hydrogel scaffolds was also determined in vitro. Surface morphology was analyzed with the scanning electron microscope (SEM). The physicochemical properties and the composition were tested by using an infrared instrument. A double layer composite scaffold was constructed via seeding adipose-derived stem cells (ADSCs) induced to chondrocytes and osteoblasts, followed by inoculation in cancellous bones and hydrogel scaffolds. Cell proliferation was assessed through Dead/Live staining and cellular activity was analyzed with IpWin5 software. Cell growth, adhesion and formation of extracellular matrix in composite scaffolds blank cancellous bones or hydrogel scaffolds were also analyzed. SEM analysis revealed a super porous internal structure of cancellous bone scaffolds and pore size was measured at an average of 410 ± 59 μm while porosity was recorded at 70.6 ± 1.7 %. In the hydrogel scaffold, the average pore size was measured at 117 ± 21 μm and the porosity and swelling rate were recorded at 83.4 ± 0.8 % and 362.0 ± 2.4 %, respectively. Furthermore, the remaining hydrogel weighed 80.76 ± 1.6 % of the original dry weight after hydration in PBS for 6 weeks. In summary, the cancellous bone and hydrogel composite scaffold is a promising biomaterial which shows an essential physical performance and strength with excellent osteochondral tissue interaction in situ. ADSCs are a suitable cell source for osteochondral composite reconstruction. Moreover, the bi-layered scaffold significantly enhanced cell proliferation compared to the cells seeded on either single scaffold. Therefore, a bi-layered composite scaffold is an appropriate candidate for fabrication of osteochondral tissue.     

Poly(ε-caprolactone) scaffolds of highly controlled porosity and interconnectivity derived from co-continuous polymer blends: model bead and cell infiltration behavior

Porous structures destined for tissue engineering applications should ideally show controlled and narrow pore size distributions with fully interconnected pores. This study focuses on the development of novel poly(ε-caprolactone) (PCL) structures with fully connected pores of 84, 116, 141, and 162 μm average diameter, from melt blending of PCL with poly(ethylene oxide) (PEO) at the co-continuous composition, followed by static annealing and selective extraction of PEO. Our results demonstrate a low onset concentration for PEO continuity and a broad region of phase inversion. A novel in vitro assay was used to compare scaffold infiltration by 10-μm diameter polystyrene beads intended to mimic trypsinized human bone marrow stromal cells (hBMSCs). Beads showed a linear increase in the extent of scaffold infiltration with increasing pore size, whereas BMSCs infiltrated 162 and 141 μm pores, below which the cells aggregated and adhered near the seeding area with low infiltration into the porous device. While providing a baseline for non-aggregated systems, the beads closely mimic trypsinized cells at pore sizes equal to or larger than 141 μm, where optimal retention and distribution of hBMSCs are detected. A cytotoxicity assay using L929 cells showed that these scaffolds were cytocompatible and no cell necrosis was detected. This study shows that a melt blending approach produces porous PCL scaffolds of highly controlled pore size, narrow size distribution and complete interconnectivity, while the bead model system reveals the baseline potential for a homogeneous, non-aggregated distribution of hBMSCs at all penetration depths.     

体外壳聚糖-明胶-生长因子缓释支架对骨髓间充质干细胞增殖的影响

制备具有缓释功能的壳聚糖-明胶-碱性成纤维细胞生长因子(bFGF)-肝细胞生长因子(HGF)三维大孔支架,探讨两种生长因子在体外对骨髓间充质干细胞(BMSCs)增殖的协同作用。方法:采用冷冻干燥法,将不同比例的壳聚糖、明胶、bFGF和HGF依次混合,使其成为具有一定孔径的三维缓释支架。取SD大鼠乳鼠股骨和胫骨骨髓,分离、培养BMSCs。取生长状态良好的第三代BMSCs,将其接种于96孔板后,加入支架混合培养,5d后进行MTT细胞增殖测定。结果:在与含1μg/mL的bFGF支架混合培养,以及与同时含1μg/mL的bFGF、1μg/mL的HGF支架混合培养后,BMSCs增殖明显(P<0.05),但这二组间无统计学差异(P>0.05)。分别与含0.1μg/mL的bFGF支架、0.01μg/mL的bFGF支架、1μg/mL的HGF支架混合培养后,细胞增殖无统计学意义(P>0.05)。结论:壳聚糖-明胶可作为生长因子缓释支架材料;bFGF具有促进BMSCs增殖的作用,促进作用的大小与加入bFGF的量有关;HGF对BMSCs不具有增殖作用;在实验浓度范围内bFGF和HGF体外促进BMSCs增殖上不具有协同性。     

An ordered electrospun polycaprolactone–collagen–silk fibroin scaffold for hepatocyte culture

Nanofiber scaffolds are widely used as the platform for three-dimensional culture of hepatocytes in vitro. The pore size of scaffolds plays an important role in promoting the infiltration and proliferation of hepatocyte. We show that the average pore size of electrospun scaffold increases from ~ 7.6 to 13.2 μm, while the average fiber diameter decreases from ~ 2.0 to 1.5 μm when collected by probe array collectors. Though increase in pore size decreases the tensile stress of scaffolds, it leads to enhance the proliferation and attachment of hepatocytes. Specifically, a 6 × 6 array scaffold which was prepared by probe collector was orderly arrayed. Compared with the conventional scaffold, the pore size of the arrayed scaffold doubled and the hydrophilicity was improved. When HepG₂ cells were seeded on the arrayed scaffold, cells showed superior adhesion ability, better cell morphology and three-dimensional growth. These results indicated that the ordered 6 × 6 array scaffold has the potential as a suitable substratum for in vitro culture of hepatocytes.     

Preparation and characterisation of poly(lactide-co-glycolide) (PLGA) and PLGA/Bioglass® composite tubular foam scaffolds for tissue engineering applications

Polylactide-co-glycolide (PLGA) and PLGA/Bioglass® foams of tubular shape have been prepared with a 1 wt.% 45S5 Bioglass® content. Porous membranes with varying thickness and porosity were fabricated via a thermally induced phase separation process, from which tubes of controlled diameter and wall thickness in the range 1.5–3 mm were produced. Scanning electron microscopy (SEM) revealed that the structure of the tubular foams consisted of radially oriented and highly interconnected pores with two distinct pore sizes, i.e. macropores ∼100-μm average diameter and interconnected micropores of 10–50-μm diameter. Foams with Bioglass® inclusions showed similarly well-defined tubular and interconnected pore morphology. Cell culture studies using mouse fibroblasts (L929) were conducted to assess the biocompatibility of the scaffolds in vitro. L929 fibroblasts cultured in medium that was pre-conditioned by incubating with PLGA tubes containing Bioglass® had a significant reduction in cell proliferation compared with fibroblasts grown in unconditioned medium (p<0.0001).The PLGA and PLGA/Bioglass® tubular foams developed here are candidate materials for soft-tissue engineering scaffolds, holding promise for the regeneration of tissues requiring a tubular shape scaffold, such as intestine, trachea and blood vessels.     

Nano-composite scaffolds for bone tissue engineering containing silver nanoparticles: preparation, characterization and biological properties

In this study nano-composite scaffolds to be used as bone grafts have been endowed with antibacterial properties owing to the presence of silver nanoparticles. The alginate/hydroxyapatite composite scaffolds were prepared by internal gelation followed by a freeze-drying procedure to obtain a porous structure. The nanoparticles were prepared in presence of a lactose modified-chitosan and this colloidal solution was adsorbed on the scaffolds by exploiting electrostatic interactions. The adsorption and release of the silver from the composite scaffold was measured by ICP-AES and spectrofluorimetry measurements. Micro-computed tomography analysis of the scaffolds showed a homogeneous porous structure with average pore sizes of 341.5 μm and porosity of 80 %. In vitro biological tests (MTS and killing kinetics assays) demonstrated that silver does not affect the ability of the scaffolds to promote osteoblasts proliferation and that at the same time it exerts a strong bactericidal effect against both Gram+ and Gram? bacterial strains. Overall, the combined results indicate that these biocompatible antimicrobial scaffolds possess ideal characteristics for tissue engineering applications.     

Silk fibroin/chitosan scaffold: preparation,characterization, and culture with HepG2 cell

Tissue engineering requires the development of three-dimensional water-stable scaffolds. In this study, silk fibroin/chitosan (SFCS) scaffold was successfully prepared by freeze-drying method. The scaffold is water-stable, only swelling to a limited extent depending on its composition. Fourier Transform Infrared (FTIR) spectra and X-Ray diffraction curves confirmed the different structure of SFCS scaffolds from both chitosan and silk fibroin. The homogeneous porous structure, together with nano-scale compatibility of the two naturally derived polymers, gives rise to the controllable mechanical properties of SFCS scaffolds. By varying the composition, both the compressive modulus and compressive strength of SFCS scaffolds can be controlled. The porosity of SFCS scaffolds is above 95% when the total concentration of silk fibroin and chitosan is below 6 wt%. The pore sizes of the SFCS scaffolds range from 100 μm to 150 μm, which can be regulated by changing the total concentration. MTT assay showed that SFCS scaffolds can promote the proliferation of HepG2 cells (human hepatoma cell line) significantly. All these results make SFCS scaffold a suitable candidate for tissue engineering.     

Preparation of 3-D regenerated fibroin scaffolds with freeze drying method and freeze drying/foaming technique

Although three-dimensional fibroin scaffolds have been prepared with freeze drying method, the porosity and pore sizes still can not satisfy the requirement of tissue engineering. In this article, fibroin porous scaffold with high porosity and > 100μm diameter interconnected pores was firstly prepared with freeze drying method through adjusting fibroin concentration. The morphology of different scaffolds lyophilized from different fibroin concentration was observed by SEM. A novel freeze drying improved method, freeze drying/foaming technique, was also devised to prepare fibroin scaffolds at different fibroin concentrations. Using the said method, the porosity and pore size of fibroin scaffolds prepared from 12% concentration were 85.8 ± 4% and 109 ± 20 μm respectively with yield strength up to 450 ± 6 KPa while the porosity and pore size of fibroin scaffolds prepared from 8% concentration were 96.9 ± 3.6% and 120 ± 30 μm respectively with yield strength up to 30 ± 1 KPa. The freeze drying/foaming technique produced scaffolds with a useful combination of high yield strength, interconnected pores, and pore sizes greater than 100 μm in diameter. Through adjusting fibroin concentration and thawing time, the porosity, pore sizes and mechanical properties could be controlled to satisfy the different requirements of tissue engineering. The results suggested that fibroin scaffolds prepared with the above methods could be formed for utility in biomaterial application.     

Preparation and HL-7702 cell functionality of titania/chitosan composite scaffolds

Titania/chitosan composite scaffolds were prepared through a freeze-drying technique. The composite scaffolds were highly porous with the average pore size of 120–300 μm, and the titania (TiO₂) powders were uniformly dispersed on the surface of the pore walls. The compressive strength of the composite scaffolds was significantly improved compared to that of pure chitosan scaffolds. Composite scaffold with 0.3 of TiO₂/chitosan weight ratio showed the maximum compressive strength of 159.7 ± 21 kPa. Hepatic immortal cell line HL-7702 was used as seeding cells on the scaffolds, and after different culture periods, cell attachment and function was analyzed. HL-7702 cells attached on the pore walls of the scaffolds with the spheroid shape after 1 day of culture, but more cell aggregations formed within the TiO₂/chitosan composite scaffolds as compared to pure chitosan scaffolds. Liver-specific functions, albumin secretion and urea synthesis were detected using a spectrometric method. The results showed that albumin secretion and urea synthesis rate of HL-7702 cells slightly decreased with the culture time, and there was no significant difference between composite scaffolds and pure chitosan scaffolds. In conclusion, the TiO₂/chitosan composite scaffolds possessed an improved mechanical strength compared to pure chitosan scaffolds and supported the attachment and functional expression of hepatocyte, implying their potential application in liver tissue engineering.     

Manipulation of chemical composition and architecture of non-biodegradable poly(ethylene terephthalate)/chitosan fibrous scaffolds and their effects on L929 cell behavior

Microporous, non-woven fibrous scaffolds made of poly(ethylene terephthalate) and chitosan were produced by electrospinning. Fiber morphology, diameter, pore size, and wettability were manipulated by varying the chemical composition of the electrospinning solution, i.e. chitosan concentration and molecular weight, and by post-electrospinning treatment with glutaraldehyde. In vitro studies were conducted using a fibroblast cell line toward a comprehensive understanding of how scaffolds characteristics can modulate the cell behavior, i.e. viability, adhesion, proliferation, extracellular matrix secretion, and three-dimensional colonization. Substantial differences were found as a result of scaffold morphological changes. Higher levels of adhesion, spreading, and superficial proliferation were achieved for scaffolds with smaller fiber and pore diameters while cell penetration and internal colonization were enhanced for scaffolds with larger pores. Additionally, the available area for cell adhesion, which is related to fiber and pore size, was a crucial factor for the viability of L929 cells. This paper provides significant insights for the development and optimization of electrospun scaffolds toward an improved biological performance.     

Physicochemical properties and cytotoxicities of Sr-containing biphasic calcium phosphate bone scaffolds

This study demonstrates a new biomaterial system composed of Sr-containing hydroxyapatite (Sr-HA) and Sr-containing tricalcium phosphate (Sr-TCP), termed herein Sr-containing biphasic calcium phosphate (Sr-BCP). Furthermore, a series of new Sr-BCP porous scaffolds with tunable structure and properties has also been developed. These Sr-BCP scaffolds were obtained by in situ sintering of a series of composites formed by casting various Sr-containing calcium phosphate cement (Sr-CPC) into different rapid prototyping (RP) porous phenol formaldehyde resins, which acted as the negative moulds for controlling pore structures of the final scaffolds. Results show that the porous Sr-BCP scaffolds are composed of Sr-HA and Sr-TCP. The phase composition and the macro-structure of the Sr-BCP scaffold could be adjusted by controlling the processing parameters of the Sr-CPC pastes and the structure parameters of the RP negative mould, respectively. It is also found that both the compressive strength (CS) and the dissolving rate of the Sr-BCP scaffold significantly vary with their phase composition and macropore percentage. In particular, the compressive strength achieves a maximum CS level of 9.20 ± 1.30 MPa for the Sr-BCP scaffold with a Sr-HA/Sr-TCP weight ratio of 78:22, a macropore percentage of 30% (400–550 μm in size) and a total-porosity of 63.70%, significantly higher than that of the Sr-free BCP scaffold with similar porosity. All the extracts of the Sr-BCP scaffold exhibit no cytotoxicity. The current study shows that the incorporation of Sr plays an important role in positively improving the physicochemical properties of the BCP scaffold without introducing obvious cytotoxicity. It also reveals a potential clinical application for this material system as bone tissue engineering (BTE) scaffold.     

Fabrication of three-dimensional poly(ε-caprolactone) scaffolds with hierarchical pore structures for tissue engineering

The physical properties of tissue engineering scaffolds such as microstructures play important roles in controlling cellular behaviors and neotissue formation. Among them, the pore size stands out as a key determinant factor. In the present study, we aimed to fabricate porous scaffolds with pre-defined hierarchical pore sizes, followed by examining cell growth in these scaffolds. This hierarchical porous microstructure was implemented via integrating different pore-generating methodologies, including salt leaching and thermal induced phase separation (TIPS). Specifically, large (L, 200–300 μm), medium (M, 40–50 μm) and small (S, < 10 μm) pores were able to be generated. As such, three kinds of porous scaffolds with a similar porosity of ~ 90% creating pores of either two (LS or MS) or three (LMS) different sizes were successfully prepared. The number fractions of different pores in these scaffolds were determined to confirm the hierarchical organization of pores. It was found that the interconnectivity varied due to the different pore structures. Besides, these scaffolds demonstrated similar compressive moduli under dry and hydrated states. The adhesion, proliferation, and spatial distribution of human fibroblasts within the scaffolds during a 14-day culture were evaluated with MTT assay and fluorescence microscopy. While all three scaffolds well supported the cell attachment and proliferation, the best cell spatial distribution inside scaffolds was achieved with LMS, implicating that such a controlled hierarchical microstructure would be advantageous in tissue engineering applications.     

Attachment of stem cells on porous chitosan scaffold crosslinked by Na5P3O10

In this study, porous chitosan scaffolds were prepared by freeze-dried method using Na₅P₃O₁₀ as a crosslinking agent. The three-dimensional pore structure of the scaffold was interconnected with a mean pore size about 40 to 100 μm. The remained weight of crosslinked scaffold was about 76% after being exposed to PBS for 30 days. Mouse embryonic stem (E. S.) cells could grow on these crosslinked scaffolds. E. S. cells differentiated to other cells after 21 days of culturing on the scaffolds. The growth rate of E. S. cells was improved by post surface treatment of the scaffolds with collagen. However, there was no significant increase in growth rate of E. S. cells when scaffolds were surface treated with argon plasma. These porous chitosan scaffolds present a promising approach for tissue engineering applications.     

In vitro characterization of chitosan scaffolds: influence of composition and deacetylation degree

In this study, the influence of degree of deacetylation (DD) and composition on some structural and biological properties of chitosan scaffolds were examined in vitro. 3D chitosan scaffolds of 2% (w/v) and 3% (w/v) composition in different DDs i.e. 75–85% and >85% were prepared by freeze-drying method at −80 °C. We noticed that >85% deacetylated chitosan scaffolds of 2% (w/v) composition has a highly interconnected morphological structure having ∼100 μm pore size with 0.0917 N/mm² compression modulus. L929 fibroblastic cells were cultured on chitosan scaffolds in order to evaluate their biocompatibilities. Cell culture studies demonstrated that fibroblastic cell attachment and proliferation is affected by DD. The higher deacetylated chitosan scaffolds strongly supported the attachment and proliferation when compared with the lower deacetylated scaffolds. MTT assay indicated that >85% deacetylated chitosan scaffolds of 2% (w/v) composition, having the highest specific growth rate 0.017 h⁻¹ of all, was found to be the most suitable for cell culture studies and a potential candidate for tissue engineering with enhanced biostability and good biocompatibility.     

Fabrication and in vitro evaluations with osteoblast-like MG-63 cells of porous hyaluronic acid-gelatin blend scaffold for bone tissue engineering applications

In this study, hyaluronic acid–gelatin (HyA–Gel) scaffolds were prepared with HyA:Gel ratios of 15:85, 50:50, and 85:15 with the goal of obtaining a porous biocompatible scaffold for bone tissue engineering applications. Scanning electron microscopy and Fourier-transform infrared spectroscopy were done to characterize the morphological orientations of the scaffolds. The biocomposite structure was highly porous and the pores in the scaffolds were interconnected. The compressive strength of the scaffold was 7.39 ± 0.2 MPa for the HyA–Gel when fabricated at a ratio of 15:85. To assess the biocompatibility and cell behavior on the HyA–Gel biocomposite, the proliferation of MG-63 osteoblast cell on the scaffolds was examined using the MTT assay, optical microscopy, and confocal microscopy. Collagen type I and osteopontin expression of cells cultured on the scaffolds were examined using immunoblotting. The scaffolds fabricated with a 15:85—HyA:Gel ratio showed excellent biocompatibility, good mechanical properties, and high porosity, which suggest that the highly porous scaffold holds great promise for use in bone tissue engineering applications.     

Polyelectrolyte-complex nanostructured fibrous scaffolds for tissue engineering

In the current work, polyelectrolyte complex (PEC) fibrous scaffolds for tissue engineering have been synthesized and a mechanism of their formation has been investigated. The scaffolds are synthesized using polygalacturonic acid and chitosan using the freeze drying methodology. Highly interconnected pores of sizes in the range of 5–20 µm are observed in the scaffolds. The thickness of the fibers was found to be in the range of 1–2 µm. Individual fibers have a nanogranular structure as observed using AFM imaging. In these scaffolds, PEC nanoparticles assemble together at the interface of ice crystals during freeze drying process. Further investigation shows that the freezing temperature and concentration have a remarkable effect on structure of scaffolds. Biocompatibility studies show that scaffold containing chitosan, polygalacturonic acid and hydroxyapatite promotes cell adhesion and proliferation. On the other hand, cells on scaffolds fabricated without hydroxyapatite nanoparticles showed poor adhesion.     

Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1). Moreover, the biocompatibility, bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at four and eight weeks after surgery, respectively. The results showed that each of the studied scaffolds had its own specific merits and drawbacks. Three-dimensional printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSC cell proliferation and differentiation to osteogenic cells. The outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference in inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery.     

A novel bioactive three-dimensional β-tricalcium phosphate/chitosan scaffold for periodontal tissue engineering

The development of suitable bioactive three-dimensional scaffold for the promotion of cellular proliferation and differentiation is critical in periodontal tissue engineering. In this study,porous β-tricalcium phosphate/chitosan composite scaffolds were prepared through a freeze-drying method. These scaffolds were evaluated by analysis of microscopic structure, porosity, and cytocompatibility. The gene expression of bone sialoprotein (BSP) and cementum attachment protein (CAP) was detected with RT-PCR after human periodontal ligament cells (HPLCs) were seeded in these scaffolds. Then cell–scaffold complexes were implanted subcutaneously into athymic mice. The protein expression of alkaline phosphatase (ALP) and osteopontin (OPN) was detected in vivo. Results indicated that composite scaffolds displayed a homogeneous three-dimensional microstructure; suitable pore size (120 μm) and high porosity (91.07%). The composite scaffold showed higher proliferation rate than the pure chitosan scaffold, and up-regulated the gene expression of BSP and CAP. In vivo, HPLCs in the composite scaffold not only proliferated but also recruited vascular tissue ingrowth. The protein expression of ALP and OPN was up-regulated in the composite scaffold. Therefore, it was suggested that the composite scaffold could promote the differentiation of HPLCs towards osteoblast and cementoblast phenotypes.     

Electrospun antimicrobial microfibrous scaffold for annulus fibrosus tissue engineering

In this study, polycaprolactone (PCL) microfibrous scaffolds with berberine were fabricated to mimic the natural extracellular matrix (ECM) architecture and provide antimicrobial activity for annulus fibrosus tissue engineering. Morphological characterization showed that there was a significant decrease of the average fiber diameter in the berberine-loaded microfibrous scaffolds (B-MFS, 0.40 ± 0.02 μm) compared with that of the non-drug-loaded microfibrous scaffolds (MFS, 1.89 ± 0.15 μm). The antimicrobial activity, drug release profile, and biocompatibility of the scaffolds were evaluated. The B-MFS displayed excellent antimicrobial activities against Gram-positive bacteria (S. aureus 6538), Gram-negative bacteria (E. coli 15597), fungus (C. albicans 10231) and drug-resistant bacteria (methicillin-resistant S. aureus BAA-811, or MRSA BAA-811). After seeding with porcine AF cells, the in vitro biocompatibility of the scaffolds was determined by measuring cell attachment, cell proliferation, and ECM production. Total cell number, sGAG and collagen content gradually increased from day 1 to day 7 in both groups. When compared to MFS, the B-MFS group displayed higher levels of cell proliferation throughout the experimental period. These results indicate that PCL microfibrous loaded with berberine are novel biocompatible scaffolds with a broad-spectrum antimicrobial activity for AF tissue engineering.     

Preparation and characterization of bimodal porous poly(γ-benzyl-L-glutamate) scaffolds for bone tissue engineering

An ideal scaffold in bone tissue-engineering strategy should provide biomimetic extracellular matrix-like architecture and biological properties. Poly(γ-benzyl-L-glutamate) (PBLG) has been a popular model polypeptide for various potential biomedical applications due to its good biocompatibility and biodegradability. This study developed novel bimodal porous PBLG polypeptide scaffolds via a combination of biotemplating method and in situ ring-opening polymerization of γ-benzyl-L-gIutamate N-carboxyanhydride (BLG-NCA). The PBLG scaffolds were characterized by proton nuclear magnetic resonance spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscope (SEM) and mechanical test. The results showed that the semi-crystalline PBLG scaffolds exhibited an anisotropic porous structure composed of honeycomb-like channels (100–200 μm in diameter) and micropores (5–20 μm), with a very high porosity of 97.4 ± 1.6%. The compressive modulus and glass transition temperature were 402.8 ± 20.6 kPa and 20.2 °C, respectively. The in vitro biocompatibility evaluation with MC3T3-E1 cells using SEM, fluorescent staining and MTT assay revealed that the PBLG scaffolds had good biocompatibility and favored cell attachment, spread and proliferation. Therefore, the bimodal porous polypeptide scaffolds are promising for bone tissue engineering.