Laser surface modification of poly(epsilon-caprolactone) (PCL) membrane for tissue engineering applications

Ultra-thin polycaprolactone (PCL) produced by bi-axial stretching was previously shown to have significant advantage for membrane tissue engineering. However, the permeability of the membrane needs to be enhanced. In this study, ablation experiments using femtosecond laser and excimer laser were carried out to modify the PCL surface. The use of the femtosecond laser produces neat drilled-through holes while the excimer laser is employed to produce blind-holes on the membrane. The modified surface of the membrane was studied and analyzed for different laser parameters (such as pulse energy and pulse repetition rate and characterized using several techniques that include optical microscopy, scanning electron microscopy and water contact angle measurements). Results showed that the morphological surface changes with different laser parameters, and the water contact angle decreases as the surface of the membrane is modified. The decrease in water contact angle suggests that surface of the membrane had become more hydrophilic than the non-laser treated membrane. The present study demonstrated that laser surface modification on the PCL can be achieved with high degree of success and precision. This paved the way for further enhancement in membrane tissue engineering.     

Crosslinked poly(epsilon-caprolactone/D,L-lactide)/bioactive glass composite scaffolds for bone tissue engineering

A series of elastic polymer and composite scaffolds for bone tissue engineering applications were designed. Two crosslinked copolymer matrices with 90/10 and 30/70 mol % of epsilon-caprolactone (CL) and D,L-lactide (DLLA) were prepared with porosities from 45 to 85 vol % and their mechanical and degradation properties were tested. Corresponding composite scaffolds with 20-50 wt % of particulate bioactive glass (BAG) were also characterized. Compressive modulus of polymer scaffolds ranged from 190+/-10 to 900+/-90 kPa. Lactide rich scaffolds absorbed up to 290 wt % of water in 4 weeks and mainly lost their mechanical properties. Caprolactone rich scaffolds absorbed no more than 110 wt % of water in 12 weeks and kept their mechanical integrity. Polymer and composite scaffolds prepared with P(CL/DLLA 90/10) matrix and 60 vol % porosity were further analyzed in simulated body fluid and in osteoblast culture. Cell growth was compromised inside the 2 mm thick three-dimensional scaffold specimens as a static culture model was used. However, composite scaffolds with BAG showed increased osteoblast adhesion and mineralization when compared to neat polymer scaffolds.     

In vitro evaluation of chitosan/poly(lactic acid-glycolic acid) sintered microsphere scaffolds for bone tissue engineering

A three-dimensional (3-D) scaffold is one of the major components in many tissue engineering approaches. We developed novel 3-D chitosan/poly(lactic acid-glycolic acid) (PLAGA) composite porous scaffolds by sintering together composite chitosan/PLAGA microspheres for bone tissue engineering applications. Pore sizes, pore volume, and mechanical properties of the scaffolds can be manipulated by controlling fabrication parameters, including sintering temperature and sintering time. The sintered microsphere scaffolds had a total pore volume between 28% and 37% with median pore size in the range 170-200microm. The compressive modulus and compressive strength of the scaffolds are in the range of trabecular bone making them suitable as scaffolds for load-bearing bone tissue engineering. In addition, MC3T3-E1 osteoblast-like cells proliferated well on the composite scaffolds as compared to PLAGA scaffolds. It was also shown that the presence of chitosan on microsphere surfaces increased the alkaline phosphatase activity of the cells cultured on the composite scaffolds and up-regulated gene expression of alkaline phosphatase, osteopontin, and bone sialoprotein.     

Electrospun poly(epsilon-caprolactone)/gelatin nanofibrous scaffolds for nerve tissue engineering

Nerve tissue engineering is one of the most promising methods to restore nerve systems in human health care. Scaffold design has pivotal role in nerve tissue engineering. Polymer blending is one of the most effective methods for providing new, desirable biocomposites for tissue-engineering applications. Random and aligned PCL/gelatin biocomposite scaffolds were fabricated by varying the ratios of PCL and gelatin concentrations. Chemical and mechanical properties of PCL/gelatin nanofibrous scaffolds were measured by FTIR, porometry, contact angle and tensile measurements, while the in vitro biodegradability of the different nanofibrous scaffolds were evaluated too. PCL/gelatin 70:30 nanofiber was found to exhibit the most balanced properties to meet all the required specifications for nerve tissue and was used for in vitro culture of nerve stem cells (C17.2 cells). MTS assay and SEM results showed that the biocomposite of PCL/gelatin 70:30 nanofibrous scaffolds enhanced the nerve differentiation and proliferation compared to PCL nanofibrous scaffolds and acted as a positive cue to support neurite outgrowth. It was found that the direction of nerve cell elongation and neurite outgrowth on aligned nanofibrous scaffolds is parallel to the direction of fibers. PCL/gelatin 70:30 nanofibrous scaffolds proved to be a promising biomaterial suitable for nerve regeneration.     

Nanofibrous poly(epsilon-caprolactone)/poly(vinyl alcohol)/chitosan hybrid scaffolds for bone tissue engineering using mesenchymal stem cells

In the present study, based on a biomimetic approach, novel 3D nanofibrous hybrid scaffolds consisting of poly(epsilon-caprolactone), poly(vinyl alcohol), and chitosan were developed via a multi-jet electrospinning method. The influence of chemical, physical, and structural properties of the scaffolds on the differentiation of mesenchymal stem cells into osteoblasts, and the proliferation of the differentiated cells were investigated. Osteogenically induced cultures revealed that cells were well-attached, penetrated into the construct and were uniformly distributed. The expression of early and late phenotypic markers of osteoblastic differentiation was upregulated in the constructs cultured in osteogenic medium.     

In vitro degradation of three-dimensional porous poly(D,L-lactide-co-glycolide) scaffolds for tissue engineering

In vitro degradation behaviors of three-dimensional tissue engineering porous scaffolds made from amorphous poly(D,L-lactide-co-glycolide) with three different formulations have been systematically investigated up to 26 weeks in phosphate buffer saline solution at 37 degrees C. The following properties of the scaffolds were measured as a function of degradation time: dimensions, weight, compressive strength and modulus, polymer molecular weight and its distribution, and pore morphology. Of special interest was the determination of mechanical properties in wet environment. The pH of the PBS media was also detected. According to the characteristic changes of the various properties of porous scaffolds, the degradation process is suggested to be roughly divided into three stages tentatively named as quasi-stable stage, decrease-of-strength stage, loss-of-weight and disruption-of-scaffold stage.     

Chitosan/poly(epsilon-caprolactone) blend scaffolds for cartilage repair

Chitosan (CHT)/poly(?-caprolactone) (PCL) blend 3D fiber-mesh scaffolds were studied as possible support structures for articular cartilage tissue (ACT) repair. Micro-fibers were obtained by wet-spinning of three different polymeric solutions: 100:0 (100CHT), 75:25 (75CHT) and 50:50 (50CHT) wt.% CHT/PCL, using a common solvent solution of 100 vol.% of formic acid. Scanning electron microscopy (SEM) analysis showed a homogeneous surface distribution of PCL. PCL was well dispersed throughout the CHT phase as analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The fibers were folded into cylindrical moulds and underwent a thermal treatment to obtain the scaffolds. μCT analysis revealed an adequate porosity, pore size and interconnectivity for tissue engineering applications. The PCL component led to a higher fiber surface roughness, decreased the scaffolds swelling ratio and increased their compressive mechanical properties. Biological assays were performed after culturing bovine articular chondrocytes up to 21 days. SEM analysis, live-dead and metabolic activity assays showed that cells attached, proliferated, and were metabolically active over all scaffolds formulations. Cartilaginous extracellular matrix (ECM) formation was observed in all formulations. The 75CHT scaffolds supported the most neo-cartilage formation, as demonstrated by an increase in glycosaminoglycan production. In contrast to 100CHT scaffolds, ECM was homogenously deposited on the 75CHT and 50CHT scaffolds. Although mechanical properties of the 50CHT scaffold were better, the 75CHT scaffold facilitated better neo-cartilage formation.     

Tailoring fiber diameter in electrospun poly(epsilon-caprolactone) scaffolds for optimal cellular infiltration in cardiovascular tissue engineering

Despite the attractive features of nanofibrous scaffolds for cell attachment in tissue-engineering (TE) applications, impeded cell ingrowth has been reported in electrospun scaffolds. Previous findings have shown that the scaffold can function as a sieve, keeping cells on the scaffold surface, and that cell migration into the scaffold does not occur in time. Because fiber diameter is directly related to the pore size of an electrospun scaffold, the objective of this study was to systematically evaluate how cell delivery can be optimized by tailoring the fiber diameter of electrospun poly(epsilon-caprolactone) (PCL) scaffolds. Five groups of electrospun PCL scaffolds with increasing average fiber diameters (3.4-12.1 microm) were seeded with human venous myofibroblasts. Cell distribution was analyzed after 3 days of culture. Cell penetration increased proportionally with increasing fiber diameter. Unobstructed delivery of cells was observed exclusively in the scaffold with the largest fiber diameter (12.1 microm). This scaffold was subsequently evaluated in a 4-week TE experiment and compared with a poly(glycolic acid)-poly(4-hydroxybutyrate) scaffold, a standard scaffold used successfully in cardiovascular tissue engineering applications. The PCL constructs showed homogeneous tissue formation and sufficient matrix deposition. In conclusion, fiber diameter is a crucial parameter to allow for homogeneous cell delivery in electrospun scaffolds. The optimal electrospun scaffold geometry, however, is not generic and should be adjusted to cell size.     

纳米羟基磷灰石/聚羟基丁酸酯骨组织工程支架的制备及性能表征

背景：高分子聚合物聚羟基丁酸酯具有优良的生物相容性、生物降解性及压电性,但也存在脆性大、亲水性较差等不足。 目的：制备不同组成比例的电纺纳米羟基磷灰石/聚羟基丁酸酯纤维支架材料,分析其结构及性能。 方法：通过气流-高压静电纺丝技术制备纳米羟基磷灰石质量百分比分别为0、10%、20%、30%的电纺纳米羟基磷灰石/聚羟基丁酸酯纤维支架,检测支架材料的微观结构、基团组成、晶相分布、热学性能及表面润湿性。 结果与结论：扫描电镜观察显示,随着纳米羟基磷灰石含量的增大,越来越多的纳米羟基磷灰石颗粒分布于复合纤维表面且分布趋于均匀,到含量达到30%时,纳米羟基磷灰石已基本布满纤维表面,纤维表面的粗糙度也随之增加;差示扫描量热法及X射线衍射结果表明,纳米羟基磷灰石的加入可以降低复合纤维中聚羟基丁酸酯的结晶度及结晶规整程度,且纳米羟基磷灰石含量越大效果越明显;随着纳米羟基磷灰石含量的增大,复合支架表面的接触角逐渐降低,亲水性有所提高。表明将纳米羟基磷灰石与聚羟基丁酸酯复合进行电纺可以有效提高材料的表面润湿性及结晶度,改善材料的亲水性及脆性,且纳米羟基磷灰石含量越高作用越明显。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

In vitro characterization of chitosan-gelatin scaffolds for tissue engineering

Recently, chitosan–gelatin scaffolds have gained much attention in various tissue engineering applications. However, the underlying cell–matrix interactions remain unclear in addition to the scaffold degradation and mechanical characteristics. In this study, we evaluated (i) the degradation kinetics of chitosan and chitosan–gelatin scaffolds in the presence of 10 mg/L of lysozyme for dimensional stability, weight loss, and pH changes for a period of 2 months, (ii) tensile and compressive properties of films and scaffolds in wet state at 37 °C, (iii) viability of fibroblasts and human umbilical vein endothelial cells (HUVECs) on scaffolds, and (iv) the alteration in cell spreading characteristics, cytoskeletal actin distribution, focal adhesion kinase (FAK) distribution and PECAM-1 expression of HUVECs under static and 4.5, 8.5, 13 and 18 dyn/cm² shear stress conditions. Degradation results showed that gelatin-containing chitosan scaffolds had faster degradation rate and significant loss of material than chitosan. Mechanical properties of chitosan are affected by the addition of gelatin although there was no clear trend. Three-dimensional chitosan and chitosan–gelatin scaffolds supported fibroblast viability equally. However, chitosan membranes decreased cell-spreading area, disrupted F-actin and localized FAK in the nucleus of HUVECs. Importantly, the lowest shear stress tested (4.5 dyn/cm²) for 3 h washed away cells on chitosan suggesting weak cell adhesion. In the blends, effect of gelatin was dominant; actin and FAK distribution were comparable to gelatin in static culture. However, at higher shear stresses, presence of chitosan inhibited shear-induced increase in cell spreading and weakened cell adhesive strength. No significant differences were observed in PECAM-1 expression. In summary, these results showed significant influence of blending gelatin with chitosan on scaffold properties and cellular behavior.     

Electrospun scaffolds of self-assembling peptides with poly(ethylene oxide) for bone tissue engineering

Structural, mechanical and biochemical properties have to be considered when searching for suitable extracellular matrix substitutes. Fibrous structures of synthetic or natural polymers have received increasing interest as three-dimensional scaffolds for tissue engineering applications as they can be easily produced by electrospinning with different topographical features by changing the process parameters. On the other hand, the nanobiotechnology approach suggests mimicking molecular architectures in nature through self-assembly. In particular, self-assembling peptide-based biomaterials have been successfully used as scaffolds for cell growth. In order to amalgamate these two strategies nanofibrous electrospun scaffolds of hybrid polymer were designed and obtained by mixing poly(ethylene oxide) and self-assembling peptides in aqueous solution. The results of in vitro osteoblast adhesion and proliferation assays on the electrospun scaffolds obtained using different self-assembling peptide sequences are discussed.     

In vitro and animal study of novel nano-hydroxyapatite/poly(epsilon-caprolactone) composite scaffolds fabricated by layer manufacturing process

The purpose of this study was to propose a computer-controllable scaffold structure made by a layer manufacturing process (LMP) with addition of nano- or micro-sized particles and to investigate the effects of particle size in vitro. In addition, the superiority of this LMP method over the conventional scaffolds made by salt leaching and gas forming process was investigated through animal study. Using the LMP, we have created a new nano-sized hydroxyapatite/poly(epsilon-caprolactone) composite (n-HPC) scaffold and a micro-sized hydroxyapatite/poly(epsilon-caprolactone) composite (m-HPC) scaffold for bone tissue engineering applications. The scaffold macropores were well interconnected, with a porosity of 73% and a pore size of 500 microm. The compressive modulus of the n-HPC and m-HPC scaffolds was 6.76 and 3.18 MPa, respectively. We compared the cellular responses to the two kinds of scaffolds. Both n-HPC and m-HPC exhibited good in vitro biocompatibility. Attachment and proliferation of mesenchymal stem cells were better on the n-HPC than on the m-HPC scaffold. Moreover, significantly higher alkaline phosphatase activity and calcium content were observed on the n-HPC than on the m-HPC scaffold. In an animal study, the LMP scaffolds enhanced bone formation, owing to their well-interconnected pores. Radiological and histological examinations confirmed that the new bony tissue had grown easily into the entire n-HPC scaffold fabricated by LMP. We suggest that the well-interconnected pores in the LMP scaffolds might encourage cell attachment, proliferation, and migration to stimulate cell functions, thus enhancing bone formation in the LMP scaffolds. This study shows that bioactive and biocompatible n-HPC composite scaffolds prepared using an LMP have potential applications in bone tissue engineering.     

Characterization of neural stem cells on electrospun poly(epsilon-caprolactone) submicron scaffolds: evaluating their potential in neural tissue engineering

Development of biomaterials with specific characteristics to influence cell behaviour has played an important role in exploiting strategies to promote nerve regeneration. The effect of three-dimensional (3D) non-woven electrospun poly(epsilon-caprolactone) (PCL) scaffolds on the behaviour of rat brain-derived neural stem cells (NSCs) is reported. The interaction of NSCs on the randomly orientated submicron (PCL) fibrous scaffolds, with an average fibre diameter of 750 +/- 100 nm, was investigated. The PCL scaffolds were modified with ethylenediamine (ED) to determine if amino functionalisation and changes in surface tension of the fibrous scaffolds affected the proliferation and differentiation characteristics of NSCs. Surface tension of the fibrous scaffold increased upon treatment with ED which was attributed to amine moieties present on the surface of the fibres. Although surface treatment did not change the differentiation of the NSCs, the modified scaffolds were more hydrophilic, resulting in a significant increase in the number of adhered cells, and increased spreading throughout the entirety of the scaffold. When the NSCs were seeded on the PCL scaffolds in the presence of 10% FBS, the stem cells differentiated primarily into oligodendrocytes, indicating that electrospun PCL has the capacity to direct the differentiation of NSCs towards a specific lineage. The data presented here is useful for the development of electrospun biomaterial scaffolds for neural tissue engineering, to regulate the proliferation and differentiation of NSCs.     

In vivo tissue engineering of bone using poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) and collagen scaffolds

Porous poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) and calcium phosphate-loaded collagen (CaP-Gelfix) foams were seeded with rat bone marrow stromal cells and implanted into defects created in rat femurs to study in vivo bone formation and to test their suitability for use in bone tissue engineering. At 3 and 6 weeks, new bone formation was evaluated by macroscopy, radiography, dual-energy X-ray absorptiometry (DEXA), and quantitative computerized tomography (QCT). Atomic contents of the implants were further assessed by QCT. Some initial inflammation that significantly decreased with time was observed in the CaP-Gelfix group. PHBV inflammation was minimal at all stages. Fibrous tissue formation in the CaP-Gelfix group was more than in the PHBV group. Both cell-loaded and cell-free PHBV matrices elicited minimal fibrous tissue formation during the 6-week implantation duration. Macroscopic and radiological studies demonstrated better healing with PHBV matrices than with CaP-Gelfix in 3 weeks. Histologically, fibrous connective tissue establishment and inflammation scores were significantly higher in the CaP-Gelfix group when compared with the PHBV group at both time intervals. At 6 weeks, however, the extent of healing was almost the same with both implants. DEXA and QCT results indicated that there was an increase in bone mineral density in both PHBV and CaP-Gelfix implants at the end of 6 weeks. This study suggests that even though PHBV and CaP-Gelfix have different bulk and surface chemistries they both are promising cell carriers that may be suitable for use in bone tissue engineering.     

Synthesis of macroporous poly(dimethylsiloxane) scaffolds for tissue engineering applications

Macroporous, biostable scaffolds with controlled porous architecture were prepared from poly(dimethylsiloxane) (PDMS) using sodium chloride particles and a solvent casting and particulate leaching technique. The effect of particulate size range and overall porosity on the resulting structure was evaluated. Results found 90% v/v scaffolds and particulate ranges above 100?μm to have the most optimal open framework and porosity. Resulting hydrophobic PDMS scaffolds were coated with fibronectin and evaluated as a platform for adherent cell culture using human mesenchymal stem cells. Biocompatibility of PDMS scaffolds was also evaluated in a rodent model, where implants were found to be highly biocompatible and biostable, with positive extracellular matrix deposition throughout the scaffold. These results demonstrate the suitability of macroporous PDMS scaffolds for tissue engineering applications where strong integration with the host is desired.     

Porous poly(alpha-hydroxyacid)/Bioglass composite scaffolds for bone tissue engineering. I: Preparation and in vitro characterisation

Highly porous composites scaffolds of poly-D,L-lactide (PDLLA) and poly(lactide-co-glycolide) (PLGA) containing different amounts (10, 25 and 50 wt%) of bioactive glass (45S5 Bioglass)were prepared by thermally induced solid-liquid phase separation (TIPS) and subsequent solvent sublimation. The addition of increasing amounts of Bioglass into the polymer foams decreased the pore volume. Conversely, the mechanical properties of the polymer materials were improved. The composites were incubated in phosphate buffer saline at 37 degrees C to study the in vitro degradation of the polymer by measurement of water absorption, weight loss as well as changes in the average molecular weight of the polymer and in the pH of the incubation medium as a function of the incubation time. The addition of Bioglass to polymer foams increased the water absorption and weight loss compared to neat polymer foams. However, the polymer molecular weight, determined by size exclusion chromatography, was found to decrease more rapidly and to a larger extent in absence of Bioglass. The presence of the bioactive filler was therefore found to delay the degradation rate of the polymer as compared to the neat polymer foams. Formation of hydroxyapatite on the surface of composites, as an indication of their bioactivity, was recorded by EDXA, X-ray diffractometry and confirmed by Raman spectroscopy.     

Nanohydroxyapatite/poly(ester urethane) scaffold for bone tissue engineering

Biodegradable viscoelastic poly(ester urethane)-based scaffolds show great promise for tissue engineering. In this study, the preparation of hydroxyapatite nanoparticles (nHA)/poly(ester urethane) composite scaffolds using a salt-leaching-phase inverse process is reported. The dispersion of nHA microaggregates in the polymer matrix were imaged by microcomputed X-ray tomography, allowing a study of the effect of the nHA mass fraction and process parameters on the inorganic phase dispersion, and ultimately the optimization of the preparation method. How the composite scaffold’s geometry and mechanical properties change with the nHA mass fraction and the process parameters were assessed. Increasing the amount of nHA particles in the composite scaffold decreased the porosity, increased the wall thickness and consequently decreased the pore size. The Young’s modulus of the poly(ester urethane) scaffold was improved by 50% by addition of 10 wt.% nHA (from 0.95 ± 0.5 to 1.26 ± 0.4 MPa), while conserving poly(ester urethane) viscoelastic properties and without significant changes in the scaffold macrostructure. Moreover, the process permitted the inclusion of nHA particles not only in the poly(ester urethane) matrix, but also at the surface of the scaffold pores, as shown by scanning electron microscopy. nHA/poly(ester urethane) composite scaffolds have great potential as osteoconductive constructs for bone tissue engineering.     

Cholesterol-modified superporous poly(2-hydroxyethyl methacrylate) scaffolds for tissue engineering

Modifications of poly(2-hydroxyethyl methacrylate) (PHEMA) with cholesterol and laminin have been developed to design scaffolds that promote cell–surface interaction. Cholesterol-modified superporous PHEMA scaffolds have been prepared by the bulk radical copolymerization of 2-hydroxyethyl methacrylate (HEMA), cholesterol methacrylate (CHLMA) and the cross-linking agent ethylene dimethacrylate (EDMA) in the presence of ammonium oxalate crystals to introduce interconnected superpores in the matrix. With the aim of immobilizing laminin (LN), carboxyl groups were also introduced to the scaffold by the copolymerization of the above monomers with 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA). Subsequently, the MCMEMA moiety in the resulting hydrogel was hydrolyzed to [2-(methacryloyloxy)ethoxy]acetic acid (MOEAA), and laminin was immobilized via carbodiimide and N-hydroxysulfosuccinimide chemistry. The attachment, viability and morphology of mesenchymal stem cells (MSCs) were evaluated on both nonporous and superporous laminin-modified as well as laminin-unmodified PHEMA and poly(2-hydroxyethyl methacrylate-co-cholesterol methacrylate) P(HEMA–CHLMA) hydrogels. Neat PHEMA and laminin-modified PHEMA (LN–PHEMA) scaffolds facilitated MSC attachment, but did not support cell spreading and proliferation; the viability of the attached cells decreased with time of cultivation. In contrast, MSCs spread and proliferated on P(HEMA–CHLMA) and LN-P(HEMA–CHLMA) hydrogels.     

Biomimetic poly(lactide) based fibrous scaffolds for ligament tissue engineering

The aim of this study was to fabricate a fibrous scaffold that closely resembled the micro-structural architecture and mechanical properties of collagen fibres found in the anterior cruciate ligament (ACL). To achieve this aim, fibrous scaffolds were made by electrospinning l-lactide based polymers. l-Lactide was chosen primarily due to its demonstrated biocompatibility, biodegradability and high modulus. The electrospun fibres were collected in tension on a rotating wire mandrel. Upon treating these fibres in a heated aqueous environment, they possessed a crimp-like pattern having a wavelength and amplitude similar to that of native ACL collagen. Of the polymer fibre scaffolds studied, those made from poly(l-lactide-co-d,l-lactide) PLDLA exhibited the highest modulus and were also the most resilient to in vitro hydrolytic degradation, undergoing a slight decrease in modulus compared to the other polymeric fibres over a 6 month period. Bovine fibroblasts seeded on the wavy, crimp-like PLDLA fibres attached, proliferated and deposited extracellular matrix (ECM) molecules on the surface of the fibrous scaffold. In addition, the deposited ECM exhibited bundle formation that resembled the fascicles found in native ACL. These findings demonstrate the importance of replicating the geometric microenvironment in developing effective tissue engineering scaffolds.     

Pentapeptide-modified poly(N,N-diethylacrylamide) hydrogel scaffolds for tissue engineering

Poly(N,N-diethylacrylamide) (PDEAAm) hydrogel scaffolds were prepared by radical copolymerization of N,N-diethylacrylamide (DEAAm), N,N'-methylenebisacrylamide and methacrylic acid in the presence of (NH?)?SO? or NaCl. The hydrogels were characterized by low-vacuum scanning electron microscopy in the water-swollen state, water and cyclohexane regain, and by mercury porosimetry. The pentapeptide, YIGSR-NH?, was immobilized on the hydrogel. Human embryonic stem cells (hESCs) were cultured with the hydrogels to test their biocompatibility. The results suggest that the PDEAAm hydrogel scaffolds are nontoxic and support hESC attachment and proliferation, and that interconnected pores of the scaffolds are important for hESC cultivation. Immobilization of YIGSR-NH? pentapeptide on the PDEAAm surface improved both adhesion and growth of hESCs compared with the unmodified hydrogel. The YIGSR-NH?-modified PDEAAm hydrogels may be a useful tool for tissue-engineering purposes.