Electrospun silk fibroin‐based neural scaffold for bridging a long sciatic nerve gap in dogs

Silk fibroin (SF)‐derived silkworms represent a type of highly biocompatible biomaterial for tissue engineering. We have previously investigated biocompatibility of SF with neural cells isolated from the central nervous system or peripheral nerve system in vitro, and also developed a SF‐based nerve graft conduit or tissue‐engineered nerve grafts by introducing bone marrow mesenchymal stem cells, as support cells, into SF‐based scaffold and evaluated the outcomes of peripheral nerve repair in a rat model. As an extension of the previous study, the electrospun technique was performed here to fabricate SF‐based neural scaffold inserted with silk fibres for bridging a 30‐mm‐long sciatic nerve gap in dogs. Assessments including functional, histological and morphometrical analyses were applied 12 months after surgery. All the results indicated that the SF‐based neural scaffold group achieved satisfactory regenerative outcomes, which were close to those achieved by autologous nerve grafts as the golden‐standard for peripheral nerve repair. Overall, our results raise a potential possibility for the translation of SF‐based electrospun neural scaffolds as an alternative to nerve autografts into the clinic.     

聚乳酸-羟基乙酸输尿管支架植入后犬输尿管周围的组织学变化

背景:泌尿系统组织工程支架不仅需要生物相容性良好的生物材料,而且一定要利于组织周围细胞的生长。目的:制备聚乳酸-羟基乙酸共聚物可降解输尿管支架,观察其植入后犬输尿管周围组织学变化。方法:制备纳米聚乳酸-羟基乙酸共聚物输尿管支架,并以多聚赖氨酸对支架进行交联、改性,将交联后支架截成长约0.8cm小段,植入犬损伤输尿管中进行体内观察实验。结果与结论:①支架制备:支架具有纳米结构,孔隙率约90%,孔径(30±18)μm,多聚赖氨酸交联改性后纤维表面略显粗糙。②支架变化:支架植入30d时已完全失去原始形态,与周边组织融合,可见裂解小块。③支架植入后输尿管周围组织学变化:植入后15d炎症表现最为明显,主要是移行上皮脱落,肌层结构被破坏,固有层水肿明显;30d后,炎症已经明显好转,但组织结构依然不规则;植入后45d,输尿管全层组织基本恢复正常,组织结构成规则分布。说明聚乳酸-羟基乙酸共聚物输尿管支架具有良好的组织相容性,符合泌尿系统组织工程支架的要求。     

组织工程膀胱支架材料：应用现状及血管化策略

背景：随着组织工程膀胱研究的日益改进,组织工程膀胱组织在植入体内后的血管化问题,引起了构建组织工程膀胱者的极大关注。目的：结合近年来的相关文献,就组织工程膀胱支架材料的选择、设计与应用,支架材料植入体内后的血管化问题作一综述。方法：由第一作者应用计算机检索PubMed数据库2000年1月至2014年9月的相关文章,检索词为“tissue engineering,bladder,biomaterials/scaffolds,vascularization”;同时检索中国期刊数据库2000年1月至2014年9月的相关文章,检索词为“组织工程,膀胱,支架材料,血管化”,选择文章内容与生物支架材料在组织工程膀胱中的应用及组织工程膀胱血管化相关。结果与结论：组织工程膀胱中目前采用的支架材料主要包括天然生物材料和人工合成聚合物两大类。当前膀胱组织工程研究最主要的目标仍然是：制备接种细胞的最佳支架,确定干细胞的最佳来源,探索干细胞最优分化方式和促进植入支架新生血管和神经的再生,其中促进支架材料的血管化和构建复杂的组织是最具有挑战性的。目前来说,使支架上附着的内膜细胞精确的定向增殖、迁移和分化仍然很难控制。尽管血管网对于细胞和组织的营养供应和代谢废物清除是必要的,但促进血管生成或血管发生的策略仍有限。     

Comparative study of the osteogenic ability of four different ceramic constructs in an ectopic large animal model

Tissue‐engineered constructs combining bone marrow mesenchymal stem cells with biodegradable osteoconductive scaffolds are very promising for repairing large segmental bone defects. Synchronizing and controlling the balance between scaffold‐material resorption and new bone tissue formation are crucial aspects for the success of bone tissue engineering. The purpose of the present study was to determine, and compare, the osteogenic potential of ceramic scaffolds with different resorbability. Four clinically relevant granular biomaterial scaffolds (specifically, Porites coral, Acropora coral, beta‐tricalcium phosphate and banked bone) with or without autologous bone marrow stromal cells were implanted in the ectopic, subcutaneous‐pouch sheep model. Scaffold material resorption and new bone formation were assessed eight weeks after implantation. New bone formation was only detected when the biomaterial constructs tested contained MSCs. New bone formation was higher in the Porites coral and Acropora coral than in either the beta‐tricalcium phosphate or the banked bone constructs; furthermore, there was a direct correlation between scaffold resorption and bone formation. The results of the present study provide evidence that, among the biomaterials tested, coral scaffolds containing MSCs promoted the best new bone formation in the present study. Copyright © 2013 John Wiley & Sons, Ltd.     

骨组织工程支架材料及其血管化的研究进程

背景：随着骨组织工程学技术的不断发展,利用组织工程骨修复大面积骨缺损成为当今研究的热点。 目的：介绍骨组织工程中的种子细胞、细胞因子、支架材料的特性及材料血管化情况。 方法：以“骨组织工程,支架材料,血管化”为中文关键词,以“bone tissue engineering,scafold, vascularization”为英文关键词,采用计算机检索2000年1月至2012年1月CNKI数据库和PubMed数据库相关文章,选择与骨组织工程学概述、支架材料和血管化方面相关的文章进行分析。 结果与结论：种子细胞的选择、细胞因子的应用、支架材料的性能及血管化程度均对组织工程骨成功修复骨损伤产生着重要影响。适宜的种子细胞是骨组织工程的研究基础,细胞因子是骨组织工程研究的催化剂,具有良好三维结构的支架材料对于促进细胞的生长增殖、组织长入、成骨方式和血管化等方面均有积极的促进作用。但每种支架材料都有其不足之处,所以可以通过将多种材料进行复合达到综合效应来满足临床需求。另外也要积极寻求新的材料制备工艺和对已有方法进行改进,以制造出更加优良的支架材料。但血管化仍然是骨组织工程要面对的重大考验。目前所应用的促进组织工程骨血管化的方法均存在一定缺陷,如利用生长因子促进血管化时,易造成代谢异常患者病情恶化等情况发生;利用显微外科技术促进组织工程骨血管化,易导致其他部位形成创伤和畸形,不利于患者的身体康复等。     

骨组织工程支架材料的研究现状与应用前景

背景：目前组织工程骨修复骨缺损在临床应用中较为关键的问题是建立血管网,为新骨的形成提供氧气及营养物质,并为机体提供代谢途径。 目的：综述近年组织工程骨支架材料的特点,并着重介绍复合支架材料的研究现状。 方法：以“骨组织工程,血管化,支架材料,复合支架材料”为中文检索词,以“bone tissue engineedng,vascularization,scaffold,compositescaffold”英文检索词,应用计算机在中国期刊全文数据库和PubMed数据库检索2001年1月至2014年1月的相关文章,将所有文章进行初步筛选后,对保留的文章进一步详细分析、归纳并总结。 结果与结论：按照组织工程骨支架材料的来源不同,可将其分为人工合成材料、天然衍生材料和复合支架材料,单一支架材料难以作为最理想的材料修复骨缺损,复合支架材料能在不同程度上弥补单一支架材料的缺陷,因此近年来组织工程支架材料的发展由单一材料发展为复合材料,并呈现人工合成材料与天然材料有机结合的趋势。但复合支架材料在临床应用中仍然有许多尚待解决的问题,主要有控制复合材料比例,使材料降解速率与组织细胞的生长速率相适应,保持复合材料的多孔隙和高机械强度。     

Preparation and biological properties of silk fibroin/nano-hydroxyapatite/graphene oxide scaffolds with an oriented channel-like structure

Constructing an ideal bone tissue engineering scaffold has been one of the research hotspots in the biomedical field. Silk fibroin (SF), nano-hydroxyapatite (nHAp) and graphene oxide (GO) are excellent biomaterials, and have been studied and explored extensively. To better mimic natural bone, we fabricated a SF/nHAp/GO hybrid scaffold with an oriented channel-like structure by using directional temperature field freezing technology. A comparative analysis was carried out for the SF, SF/nHAp, unoriented SF/nHAp/GO and oriented SF/nHAp/GO scaffolds. The physical and chemical properties were studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and universal mechanical testing. The data showed that the oriented channel-like SF/nHAp/GO porous scaffold expressed high interconnectivity, suitable pore diameter and porosity and anisotropic mechanical properties. Cytocompatibility tests indicated that the oriented channel-like SF/nHAp/GO porous scaffold was more favorable for stimulating bone marrow mesenchymal stem cells (BMSCs) adhesion and proliferation. Additionally, human umbilical vein endothelial cells (HUVECs) grew unimpeded along the channel, indicating it had advantages for vascularization. For further testing in vitro, osteogenic induction was carried out on BMSCs inoculated on the above scaffolds, and then alkaline phosphatase (ALP) activity was tested and cell mineralization was observed. The results indicated that the oriented channel-like SF/nHAp/GO porous scaffold was more conducive to osteogenic differentiation of BMSCs. Hence, the material may prove to be a promising scaffold for bone tissue engineering.

A novel SF/nHAp/GO hybrid scaffold with oriented channel-like structure in bone tissue engineering.     

Initial evaluation of vascular ingrowth into superporous hydrogels

There is a need for new materials and architectures for tissue engineering and regenerative medicine. Based upon our recent results developing novel scaffold architecture, we hypothesized that this new architecture would foster vascularization, a particular need for tissue engineering. We report on the potential of superporous hydrogel (SPH) scaffolds for in vivo cellular infiltration and vascularization. Poly(ethylene glycol) diacrylate (PEGDA) SPH scaffolds were implanted in the dorsum of severe combined immunodeficient (SCID) mice and harvested after 4 weeks of in vivo implantation. The SPHs were visibly red and vascularized, as apparent when compared to the non‐porous hydrogel controls, which were macroscopically avascular. Host cell infiltration was observed throughout the SPHs. Blood cells and vascular structures, confirmed through staining for CD34 and smooth muscle α‐actin, were observed throughout the scaffolds. This novel soft material may be utilized for cell transplantation, tissue engineering and in combination with cell therapies. The neovasularization and limited fibrotic response suggest that the architecture may be conducive to cell survival and rapid vessel development. Copyright © 2009 John Wiley & Sons, Ltd.     

Partially oxidized polyvinyl alcohol as a promising material for tissue engineering

The desired clinical outcome after implantation of engineered tissue substitutes depends strictly on the development of biodegradable scaffolds. In this study we fabricated 1% and 2% oxidized polyvinyl alcohol (PVA) hydrogels, which were considered for the first time for tissue‐engineering applications. The final aim was to promote the protein release capacity and biodegradation rate of the resulting scaffolds in comparison with neat PVA. After physical crosslinking, characterization of specific properties of 1% and 2% oxidized PVA was performed. We demonstrated that mechanical properties, hydrodynamic radius of molecules, thermal characteristics and degree of crystallinity were inversely proportional to the PVA oxidation rate. On the other hand, swelling behaviour and protein release were enhanced, confirming the potential of oxidized PVA as a protein delivery system, besides being highly biodegradable. Twelve weeks after in vivo implantation in mice, the modified hydrogels did not elicit severe inflammatory reactions, showing them to be biocompatible and to degrade faster as the degree of oxidation increased. According to our results, oxidized PVA stands out as a novel biomaterial for tissue engineering that can be used to realize scaffolds with customizable mechanical behaviour, protein‐loading ability and biodegradability. Copyright © 2015 John Wiley & Sons, Ltd.     

Platelet‐derived growth factor BB gene‐released scaffolds: biosynthesis and characterization

Tissue engineering generally requires three basic elements; stem/progenitor cells, inductive agents and a biomaterial scaffold; the latter is one of the key components which directly influences cellular activity and matrix formation. Commonly used scaffolds to repair defects in general do not induce stem cell recruitment, which is an essential element to tissue regeneration. In this study, fabrication of a scaffold which is capable of restoring damaged tissue through the recruitment of mesenchymal stem cells (MSCs) by gene therapy of the gene encoding platelet‐derived growth factor‐B (PDGF‐B) was investigated. PDGF‐B adenovirus (AdPDGF) was combined into novel mesoporous bioglass–silk fibrin scaffolds, which were characterized for their controlled release and sustained bioactivity. Our results demonstrate that these scaffolds can release PDGF‐B adenovirus for up to 3 weeks and increase MSC recruitment, both in vitro and following subcutaneous implantation in mice. Osseous calvarial defects in mice further demonstrate the ability of these scaffolds to enhance tissue regeneration through stem cell homing. This study demonstrates the potent ability of host stem cells to regenerate tissue defects through recruitment of MSCs via gene therapy. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterizing human decellularized crystalline lens capsules as a scaffold for corneal endothelial tissue engineering

The idea of transplanting a sheet of laboratory‐grown corneal endothelium dates back to 1978; however, the ideal scaffold is still lacking. We hypothesized that human crystalline lens capsules (LCs) could qualify as a scaffold and aimed to characterize the properties of this material for endothelial tissue engineering. LCs were isolated from donor eyes, stored at ?80 °C, and decellularized with water and trypsin‐EDTA. The decellularization was investigated by nuclear staining and counting and the capsule thickness was determined by optical coherence tomography and compared with Descemet's membrane (DM). Transparency was examined by spectrometry, and collagenase degradation was performed to evaluate its resistance to degradation. Cell‐scaffold interaction was assessed by measuring focal adhesions surface area on LC and plastic. Finally, primary corneal endothelial cells were grown on LCs to validate the phenotype. Trypsin‐EDTA decellularized most effectively, removing 99% of cells. The mean LC thickness was 35.76 ± 0.43 μm, whereas DM measured 25.93 ± 0.26 μm (p < .0001). Light transmission was 90% for both LC and DM. On a collagenase challenge, LC and amniotic membrane were digested after 13 hr, whereas DM was digested after 17 hr. The surface area of focal adhesions for cells grown on coated LCs was at least double that compared with other conditions, whereas tight junctions, ion pumps, and hexagonal morphology were well maintained when endothelial cells were cultured on LCs. In conclusion, LCs demonstrate excellent scaffolding properties for tissue engineering and sustain the cell phenotype and can be considered a suitable substrate for ocular tissue engineering or as a template for future scaffolds.     

Defining conditions for covalent immobilization of angiogenic growth factors onto scaffolds for tissue engineering

Rapid vascularization of engineered tissues in vitro and in vivo remains one of the key limitations in tissue engineering. We propose that angiogenic growth factors covalently immobilized on scaffolds for tissue engineering can be used to accomplish this goal. The main objectives of this work were: (a) to derive desirable experimental conditions for the covalent immobilization of vascular endothelial growth factor (VEGF) and angiopoietin‐1 (Ang1) on porous collagen scaffolds; and (b) to determine whether primary endothelial cells respond to these scaffolds with covalently immobilized angiogenic factors. VEGF and Ang1 were covalently immobilized onto porous collagen scaffolds, using 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride (EDC) chemistry. To improve covalent immobilization conditions: (a) different reaction buffers [phosphate‐buffered saline (PBS), distilled water, or 2‐(N‐morpholino)ethanesulphonic acid (MES)] were used; and (b) step immobilization was compared to bulk immobilization. In step immobilization, growth factors are applied after EDC activation of the scaffold, while in bulk immobilization, reagents are simultaneously applied to the scaffold. PBS as the reaction buffer resulted in higher amounts of VEGF and Ang1 immobilized (ELISA), higher cell proliferation rates (XTT) and increased lactate metabolism compared to water and MES as the reaction buffers. Step immobilization in PBS buffer was also more effective than bulk immobilization. Immobilized growth factors resulted in higher cell proliferation and lactate metabolism compared to soluble growth factors used at comparable concentrations. Tube formation by CD31‐positive cells was also observed in collagen scaffolds with immobilized VEGF or Ang1 using H5V and primary rat aortic endothelial cells but not on control scaffolds. Copyright © 2010 John Wiley & Sons, Ltd.     

Construction of engineering adipose‐like tissue in vivo utilizing human insulin gene‐modified umbilical cord mesenchymal stromal cells with silk fibroin 3D scaffolds

We evaluated the use of a combination of human insulin gene‐modified umbilical cord mesenchymal stromal cells (hUMSCs) with silk fibroin 3D scaffolds for adipose tissue engineering. In this study hUMSCs were isolated and cultured. HUMSCs infected with Ade–insulin–EGFP were seeded in fibroin 3D scaffolds with uniform 50–60 µm pore size. Silk fibroin scaffolds with untransfected hUMSCs were used as control. They were cultured for 4 days in adipogenic medium and transplanted under the dorsal skins of female Wistar rats after the hUMSCs had been labelled with chloromethylbenzamido‐1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (CM‐Dil). Macroscopical impression, fluorescence observation, histology and SEM were used for assessment after transplantation at 8 and 12 weeks. Macroscopically, newly formed adipose tissue was observed in the experimental group and control group after 8 and 12 weeks. Fluorescence observation supported that the formed adipose tissue originated from seeded hUMSCs rather than from possible infiltrating perivascular tissue. Oil red O staining of newly formed tissue showed that there was substantially more tissue regeneration in the experimental group than in the control group. SEM showed that experimental group cells had more fat‐like cells, whose volume was larger than that of the control group, and degradation of the silk fibroin scaffold was greater under SEM observation. This study provides significant evidence that hUMSCs transfected by adenovirus vector have good compatibility with silk fibroin scaffold, and adenoviral transfection of the human insulin gene can be used for the construction of tissue‐engineered adipose. Copyright © 2013 John Wiley & Sons, Ltd.     

A double chamber rotating bioreactor for enhanced tubular tissue generation from human mesenchymal stem cells: a promising tool for vascular tissue regeneration

Cardiovascular diseases represent a major global health burden, with high rates of mortality and morbidity. Autologous grafts are commonly used to replace damaged or failing blood vessels; however, such approaches are hampered by the scarcity of suitable graft tissue, donor site morbidity and poor long‐term stability. Tissue engineering has been investigated as a means by which exogenous vessel grafts can be produced, with varying levels of success to date, a result of mismatched mechanical properties of these vessel substitutes and inadequate ex vivo vessel tissue genesis. In this work, we describe the development of a novel multifunctional dual‐phase (air/aqueous) bioreactor, designed to both rotate and perfuse small‐diameter tubular scaffolds and encourage enhanced tissue genesis throughout such scaffolds. Within this novel dynamic culture system, an elastomeric nanofibrous, microporous composite tubular scaffold, composed of poly(caprolactone) and acrylated poly(lactide‐co‐trimethylene‐carbonate) and with mechanical properties approaching those of native vessels, was seeded with human mesenchymal stem cells (hMSCs) and cultured for up to 14 days in inductive (smooth muscle) media. This scaffold/bioreactor combination provided a dynamic culture environment that enhanced (compared with static controls) scaffold colonization, cell growth, extracellular matrix deposition and in situ differentiation of the hMSCs into mature smooth muscle cells, representing a concrete step towards our goal of creating a mature ex vivo vascular tissue for implantation. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of 3D PVA scaffolds for cardiac tissue engineering and cell screening applications

The aim of this study was the design of a 3D scaffold composed of poly(vinyl) alcohol (PVA) for cardiac tissue engineering (CTE) applications. The PVA scaffold was fabricated using a combination of gas foaming and freeze-drying processes that did not need any cross-linking agents. We obtained a biocompatible porous matrix with excellent mechanical properties. We measured the stress–strain curves of the PVA scaffolds and we showed that the elastic behavior is similar to that of the extracellular matrix of muscles. The SEM observations revealed that the scaffolds possess micro pores having diameters ranging from 10 μm to 370 μm that fit to the dimensions of the cells. A further purpose of this study was to test scaffolds ability to support human induced pluripotent stem cells growth and differentiation into cardiomyocytes. As the proliferation tests show, the number of live stem cells on the scaffold after 12 days was increased with respect to the initial number of cells, revealing the cytocompatibility of the substrate. In addition, the differentiated cells on the PVA scaffolds expressed anti-troponin T, a marker specific of the cardiac sarcomere. We demonstrated the ability of the cardiomyocytes to pulse within the scaffolds. In conclusion, the developed scaffold show the potential to be used as a biomaterial for CTE applications.

The aim of this study was the design of a 3D scaffold composed of poly(vinyl) alcohol (PVA) for cardiac tissue engineering (CTE) applications.     

Alveolar bone tissue engineering in critical‐size defects of experimental animal models: a systematic review and meta‐analysis

Regeneration of large, ‘critical‐size’ bone defects remains a clinical challenge. Bone tissue engineering (BTE) is emerging as a promising alternative to autogenous, allogeneic and biomaterial‐based bone grafting. The objective of this systematic review was to answer the focused question: in animal models, do cell‐based BTE strategies enhance regeneration in alveolar bone critical‐size defects (CSDs), compared with grafting with only biomaterial scaffolds or autogenous bone? Following PRISMA guidelines, electronic databases were searched for controlled animal studies reporting maxillary or mandibular CSD and implantation of mesenchymal stem cells (MSCs) or osteoblasts (OBs) seeded on biomaterial scaffolds. A random effects meta‐analysis was performed for the outcome histomorphometric new bone formation (%NBF). Thirty‐six studies were included that reported on large‐ (monkeys, dogs, sheep, minipigs) and small‐animal (rabbits, rats) models. On average, studies presented with an unclear‐to‐high risk of bias and short observation times. In most studies, MSCs or OBs were used in combination with alloplastic mineral‐phase scaffolds. In five studies, cells were modified by ex vivo gene transfer of bone morphogenetic proteins (BMPs). The meta‐analysis indicated statistically significant benefits in favour of: (1) cell‐loaded vs. cell‐free scaffolds [weighted mean difference (WMD) 15.59–49.15% and 8.60–13.85% NBF in large‐ and small‐animal models, respectively]; and (2) BMP‐gene‐modified vs. unmodified cells (WMD 10.06–20.83% NBF in small‐animal models). Results of cell‐loaded scaffolds vs. autogenous bone were inconclusive. Overall, heterogeneity in the meta‐analysis was high (I² > 90%). In summary, alveolar bone regeneration is enhanced by addition of osteogenic cells to biomaterial scaffolds. The direction and estimates of treatment effect are useful to predict therapeutic efficacy and guide future clinical trials of BTE. Copyright © 2016 John Wiley & Sons, Ltd.     

Treatment of growth plate injury using IGF‐I‐loaded PLGA scaffolds

Growth plate fracture can lead to retarded growth and unequal limb length, which may have a lifelong effect on a person's physical stature. The goal of this research was to develop an in vivo tissue‐engineering approach for the treatment of growth plate injury via localized delivery of insulin‐like growth factor I (IGF‐I) from cell‐free poly(lactic‐co‐glycolic acid) (PLGA) scaffolds. Mass loss and drug release studies were conducted to study the scaffold degradation and IGF‐I release patterns. In vitro cell studies showed that rat bone marrow stromal cells seeded on the porous scaffolds colonized the pores and deposited matrix within the scaffolds. These in vitro evaluations were followed by a proof‐of‐concept animal study involving implantation of scaffolds in proximal tibial growth plate defects in New Zealand white rabbits. Histological analysis of tissue sections from the in vivo studies showed regeneration of cartilage, albeit with disorganized structure, at the site of implantation of IGF‐I‐releasing scaffolds; in contrast, only bone was formed in empty defects and those treated with IGF‐free scaffolds. The present findings show the potential for treating growth plate injury using in vivo tissue engineering techniques. Copyright © 2012 John Wiley & Sons, Ltd.     

Hybrid scaffolds based on PLGA and silk for bone tissue engineering

Porous silk scaffolds, which are considered to be natural polymers, cannot be used alone because they have a long degradation rate, which makes it difficult for them to be replaced by the surrounding tissue. Scaffolds composed of synthetic polymers, such as PLGA, have a short degradation rate, lack hydrophilicity and their release of toxic by‐products makes them difficult to use. The present investigations aimed to study hybrid scaffolds fabricated from PLGA, silk and hydroxyapatite nanoparticles (Hap NPs) for optimized bone tissue engineering. The results from variable‐pressure field emission scanning electron microscopy (VP–FE–SEM), equipped with EDS, confirmed that the fabricated scaffolds had a porous architecture, and the location of each component present in the scaffolds was examined. Contact angle measurements confirmed that the introduction of silk and HAp NPs helped to change the hydrophobic nature of PLGA to hydrophilic, which is the main constraint for PLGA used as a biomaterial. Thermo‐gravimetric analysis (TGA) and FT–IR spectroscopy confirmed thermal decomposition and different vibrations caused in functional groups of compounds used to fabricate the scaffolds, which reflected improvement in their mechanical properties. After culturing osteoblasts for 1, 7 and 14 days in the presence of scaffolds, their viability was checked by MTT assay. The fluorescent microscopy results revealed that the introduction of silk and HAp NPs had a favourable impact on the infiltration of osteoblasts. In vivo experiments were conducted by implanting scaffolds in rat calvariae for 4 weeks. Histological examinations and micro‐CT scans from these experiments revealed beneficial attributes offered by silk fibroin and HAp NPs to PLGA‐based scaffolds for bone induction. Copyright © 2015 John Wiley & Sons, Ltd.     

Application of marrow mesenchymal stem cell‐derived extracellular matrix in peripheral nerve tissue engineering

To advance molecular and cellular therapy into the clinic for peripheral nerve injury, modification of neural scaffolds with the extracellular matrix (ECM) of peripheral nerves has been established as a promising alternative to direct inclusion of support cells and/or growth factors within a neural scaffold, while cell‐derived ECM proves to be superior to tissue‐derived ECM in the modification of neural scaffolds. Based on the fact that bone marrow mesenchymal stem cells (BMSCs), just like Schwann cells, are adopted as support cells within a neural scaffold, in this study we used BMSCs as parent cells to generate ECM for application in peripheral nerve tissue engineering. A chitosan nerve guidance conduit (NGC) and silk fibroin filamentous fillers were respectively prepared for co‐culture with purified BMSCs, followed by decellularization to stimulate ECM deposition. The ECM‐modified NGC and lumen fillers were then assembled into a chitosan–silk fibroin‐based, BMSC‐derived, ECM‐modified neural scaffold, which was implanted into rats to bridge a 10 mm‐long sciatic nerve gap. Histological and functional assessments after implantation showed that regenerative outcomes achieved by our engineered neural scaffold were better than those achieved by a plain chitosan–silk fibroin scaffold, and suggested the benefits of BMSC‐derived ECM for peripheral nerve repair. Copyright © 2016 John Wiley & Sons, Ltd.     

Hierarchical starch‐based fibrous scaffold for bone tissue engineering applications

Fibrous structures mimicking the morphology of the natural extracellular matrix are considered promising scaffolds for tissue engineering. This work aims to develop a novel hierarchical starch‐based scaffold. Such scaffolds were obtained by a combination of starch–polycaprolactone micro‐ and polycaprolactone nano‐motifs, respectively produced by rapid prototyping (RP) and electrospinning techniques. Scanning electron microscopy (SEM) and micro‐computed tomography analysis showed the successful fabrication of a multilayer scaffold composed of parallel aligned microfibres in a grid‐like arrangement, intercalated by a mesh‐like structure with randomly distributed nanofibres (NFM). Human osteoblast‐like cells were dynamically seeded on the scaffolds, using spinner flasks, and cultured for 7 days under static conditions. SEM analysis showed predominant cell attachment and spreading on the nanofibre meshes, which enhanced cell retention at the bulk of the composed/hierarchical scaffolds. A significant increment in cell proliferation and osteoblastic activity, assessed by alkaline phosphatase quantification, was observed on the hierarchical fibrous scaffolds. These results support our hypothesis that the integration of nanoscale fibres into 3D rapid prototype scaffolds substantially improves their biological performance in bone tissue‐engineering strategies. Copyright © 2008 John Wiley & Sons, Ltd.