Bone regeneration by means of a three‐dimensional printed scaffold in a rat cranial defect

Recently, computer‐designed three‐dimensional (3D) printing techniques have emerged as an active research area with almost unlimited possibilities. In this study, we used a computer‐designed 3D scaffold to drive new bone formation in a bone defect. Poly‐L‐lactide (PLLA) and bioactive β‐tricalcium phosphate (TCP) were simply mixed to prepare ink. PLLA + TCP showed good printability from the micronozzle and solidification within few seconds, indicating that it was indeed printable ink for layer‐by‐layer printing. In the images, TCP on the surface of (and/or inside) PLLA in the printed PLLA + TCP scaffold looked dispersed. MG‐63 cells (human osteoblastoma) adhered to and proliferated well on the printed PLLA + TCP scaffold. To assess new bone formation in vivo, the printed PLLA + TCP scaffold was implanted into a full‐thickness cranial bone defect in rats. The new bone formation was monitored by microcomputed tomography and histological analysis of the in vivo PLLA + TCP scaffold with or without MG‐63 cells. The bone defect was gradually spontaneously replaced with new bone tissues when we used both bioactive TCP and MG‐63 cells in the PLLA scaffold. Bone formation driven by the PLLA + TCP30 scaffold with MG‐63 cells was significantly greater than that in other experimental groups. Furthermore, the PLLA + TCP scaffold gradually degraded and matched well the extent of the gradual new bone formation on microcomputed tomography. In conclusion, the printed PLLA + TCP scaffold effectively supports new bone formation in a cranial bone defect.     

An additive manufacturing‐based PCL–alginate–chondrocyte bioprinted scaffold for cartilage tissue engineering

Regenerative medicine is targeted to improve, restore or replace damaged tissues or organs using a combination of cells, materials and growth factors. Both tissue engineering and developmental biology currently deal with the process of tissue self‐assembly and extracellular matrix (ECM) deposition. In this investigation, additive manufacturing (AM) with a multihead deposition system (MHDS) was used to fabricate three‐dimensional (3D) cell‐printed scaffolds using layer‐by‐layer (LBL) deposition of polycaprolactone (PCL) and chondrocyte cell‐encapsulated alginate hydrogel. Appropriate cell dispensing conditions and optimum alginate concentrations for maintaining cell viability were determined. In vitro cell‐based biochemical assays were performed to determine glycosaminoglycans (GAGs), DNA and total collagen contents from different PCL–alginate gel constructs. PCL–alginate gels containing transforming growth factor‐β (TGFβ) showed higher ECM formation. The 3D cell‐printed scaffolds of PCL–alginate gel were implanted in the dorsal subcutaneous spaces of female nude mice. Histochemical [Alcian blue and haematoxylin and eosin (H&E) staining] and immunohistochemical (type II collagen) analyses of the retrieved implants after 4 weeks revealed enhanced cartilage tissue and type II collagen fibril formation in the PCL–alginate gel (+TGFβ) hybrid scaffold. In conclusion, we present an innovative cell‐printed scaffold for cartilage regeneration fabricated by an advanced bioprinting technology. Copyright © 2013 John Wiley & Sons, Ltd.     

Cardiac regeneration using human‐induced pluripotent stem cell‐derived biomaterial‐free 3D‐bioprinted cardiac patch in vivo

One of the leading causes of death worldwide is heart failure. Despite advances in the treatment and prevention of heart failure, the number of affected patients continues to increase. We have recently developed 3D‐bioprinted biomaterial‐free cardiac tissue that has the potential to improve cardiac function. This study aims to evaluate the in vivo regenerative potential of these 3D‐bioprinted cardiac patches. The cardiac patches were generated using 3D‐bioprinting technology in conjunction with cellular spheroids created from a coculture of human‐induced pluripotent stem cell‐derived cardiomyocytes, fibroblasts, and endothelial cells. Once printed and cultured, the cardiac patches were implanted into a rat myocardial infarction model (n = 6). A control group (n = 6) without the implantation of cardiac tissue patches was used for comparison. The potential for regeneration was measured 4 weeks after the surgery with histology and echocardiography. 4 weeks after surgery, the survival rates were 100% and 83% in the experimental and the control group, respectively. In the cardiac patch group, the average vessel counts within the infarcted area were higher than those within the control group. The scar area in the cardiac patch group was significantly smaller than that in the control group. (Figure S1 ) Echocardiography showed a trend of improvement of cardiac function for the experimental group, and this trend correlated with increased patch production of extracellular vesicles. 3D‐bioprinted cardiac patches have the potential to improve the regeneration of cardiac tissue and promote angiogenesis in the infarcted tissues and reduce the scar tissue formation.     

In vivo cartilage repair using adipose‐derived stem cell‐loaded decellularized cartilage ECM scaffolds

We have previously reported a natural, human cartilage ECM (extracellular matrix)‐derived three‐dimensional (3D) porous acellular scaffold for in vivo cartilage tissue engineering in nude mice. However, the in vivo repair effects of this scaffold are still unknown. The aim of this study was to further explore the feasibility of application of cell‐loaded scaffolds, using autologous adipose‐derived stem cells (ADSCs), for cartilage defect repair in rabbits. A defect 4 mm in diameter was created on the patellar groove of the femur in both knees, and was repaired with the chondrogenically induced ADSC–scaffold constructs (group A) or the scaffold alone (group B); defects without treatment were used as controls (group C). The results showed that in group A all defects were fully filled with repair tissue and at 6 months post‐surgery most of the repair site was filled with hyaline cartilage. In contrast, in group B all defects were partially filled with repair tissue, but only half of the repair tissue was hyaline cartilage. Defects were only filled with fibrotic tissue in group C. Indeed, histological grading score analysis revealed that an average score in group A was higher than in groups B and C. GAG and type II collagen content and biomechanical property detection showed that the group A levels approached those of normal cartilage. In conclusion, ADSC‐loaded cartilage ECM scaffolds induced cartilage repair tissue comparable to native cartilage in terms of mechanical properties and biochemical components. Copyright © 2012 John Wiley & Sons, Ltd.     

Recent advances in three‐dimensional bioprinting of stem cells

In spite of being a new field, three‐dimensional (3D) bioprinting has undergone rapid growth in the recent years. Bioprinting methods offer a unique opportunity for stem cell distribution, positioning, and differentiation at the microscale to make the differentiated architecture of any tissue while maintaining precision and control over the cellular microenvironment. Bioprinting introduces a wide array of approaches to modify stem cell fate. This review discusses these methodologies of 3D bioprinting stem cells. Fabricating a fully operational tissue or organ construct with a long life will be the most significant challenge of 3D bioprinting. Once this is achieved, a whole human organ can be fabricated for the defect place at the site of surgery.     

Tissue‐engineered trachea from a 3D‐printed scaffold enhances whole‐segment tracheal repair in a goat model

Traditional treatment therapies for tracheal stenosis often cause severe post‐operative complications. To solve the current difficulties, novel and more suitable long‐term treatments are needed. A whole‐segment tissue‐engineered trachea (TET) representing the native goat trachea was 3D printed using a poly(caprolactone) (PCL) scaffold engineered with autologous auricular cartilage cells. The TET underwent mechanical analysis followed by in vivo implantations in order to evaluate the clinical feasibility and potential. The 3D‐printed scaffolds were successfully cellularized, as observed by scanning electron microscopy. Mechanical force compression studies revealed that both PCL scaffolds and TETs have a more robust compressive strength than does the native trachea. In vivo implantation of TETs in the experimental group resulted in significantly higher mean post‐operative survival times, 65.00 ± 24.01 days (n = 5), when compared with the control group, which received autologous trachea grafts, 17.60 ± 3.51 days (n = 5). Although tracheal narrowing was confirmed by bronchoscopy and computed tomography examination in the experimental group, tissue necrosis was only observed in the control group. Furthermore, an encouraging epithelial‐like tissue formation was observed in the TETs after transplantation. This large animal study provides potential preclinical evidence around the employment of an orthotopic transplantation of a whole 3D‐printed TET.     

Form and functional repair of long bone using 3D‐printed bioactive scaffolds

Injuries to the extremities often require resection of necrotic hard tissue. For large‐bone defects, autogenous bone grafting is ideal but, similar to all grafting procedures, is subject to limitations. Synthetic biomaterial‐driven engineered healing offers an alternative approach. This work focuses on three‐dimensional (3D) printing technology of solid‐free form fabrication, more specifically robocasting/direct write. The research hypothesizes that a bioactive calcium‐phosphate scaffold may successfully regenerate extensive bony defects in vivo and that newly regenerated bone will demonstrate mechanical properties similar to native bone as healing time elapses. Robocasting technology was used in designing and printing customizable scaffolds, composed of 100% beta tri‐calcium phosphate (β‐TCP), which were used to repair critical sized long‐bone defects. Following full thickness segmental defects (~11 mm × full thickness) in the radial diaphysis in New Zealand white rabbits, a custom 3D‐printed, 100% β‐TCP, scaffold was implanted or left empty (negative control) and allowed to heal over 8, 12, and 24 weeks. Scaffolds and bone, en bloc, were subjected to micro‐CT and histological analysis for quantification of bone, scaffold and soft tissue expressed as a function of volume percentage. Additionally, biomechanical testing at two different regions, (a) bone in the scaffold and (b) in native radial bone (control), was conducted to assess the newly regenerated bone for reduced elastic modulus (E_r) and hardness (H) using nanoindentation. Histological analysis showed no signs of any adverse immune response while revealing progressive remodelling of bone within the scaffold along with gradual decrease in 3D‐scaffold volume over time. Micro‐CT images indicated directional bone ingrowth, with an increase in bone formation over time. Reduced elastic modulus (E_r) data for the newly regenerated bone presented statistically homogenous values analogous to native bone at the three time points, whereas hardness (H) values were equivalent to the native radial bone only at 24 weeks. The negative control samples showed limited healing at 8 weeks. Custom engineered β‐TCP scaffolds are biocompatible, resorbable, and can directionally regenerate and remodel bone in a segmental long‐bone defect in a rabbit model. Custom designs and fabrication of β‐TCP scaffolds for use in other bone defect models warrant further investigation.     

Direct 3‐D printing of Ti‐6Al‐4V/HA composite porous scaffolds for customized mechanical properties and biological functions

Customized scaffold plays an important role in bone tissue regeneration. Precise control of the mechanical properties and biological functions of scaffolds still remains a challenge. In this study, metal and ceramic biomaterials are composited by direct 3‐D printing. Hydroxyapatite (HA) powders with diameter of about 25 μm and Ti‐6Al‐4V powders with diameter of 15–53 μm were mixed and modulated for preparing 3‐D printing inks formulation. Three different proportions of 8, 10, and 25 wt.% HA specimens were printed with same porosity of 72.1%. The green bodies of the printed porous scaffolds were sintered at 1,150°C in the atmosphere of argon furnace and conventional muffle furnace. The porosities of the final 3‐D‐printed specimens were 64.3 ± 0.8% after linear shrinkage of 6.5 ± 0.8%. The maximum compressive strength of the 3‐D‐printed scaffolds can be flexibly customized in a wide range. The maximum compressive strength of these scaffolds in this study ranged from 3.07 to 60.4 MPa, depending on their different preparation process. The phase composition analysis and microstructure characterization indicated that the Ti‐6Al‐4V and HA were uniformly composited in the scaffolds. The cytocompatibility and osteogenic properties were evaluated in vitro with rabbit bone marrow stromal cells (rBMSCs). Differentiation and proliferation of rBMSCs indicated good biocompatibility of the 3‐D‐printed scaffolds. The proposed 3‐D printing of Ti‐6Al‐4V/HA composite porous scaffolds with tunable mechanical and biological properties in this study is a promising candidate for bone tissue engineering.     

颈阔肌皮瓣联合3D打印预成型钛重建板在口腔癌整复术中的疗效评价

目的探讨颈阔肌皮瓣联合3D打印预成型钛重建板在口腔癌术中同期修复软组织缺损和重建下颌骨连续性的可行性及应用价值。方法 108例口腔癌早期的患者分别纳入对照组(55例)和实验组(53例)。在施行扩大切除口腔癌癌灶和下颌骨截骨术后,对照组采用颈阔肌皮瓣联合钛重建板同期修复软组织的缺损和重建下颌骨的连续性;实验组则采用颈阔肌皮瓣联合3D打印预成型钛重建板方法修复。结果对照组中25例伤口Ⅱ期愈合、无并发症,5例伤口感染,9例皮瓣远端坏死,6例钛板外露,8例钛钉松脱,2例继发术侧颞下颌关节功能紊乱综合征。实验组中仅1例皮瓣远端坏死,经换药后愈合;术后随访1~2年,患者自我评价外形及功能恢复情况令人满意。结论采用颈阔肌皮瓣联合3D打印预成型钛重建板方法行口腔癌整复术,不但节约手术时间、住院费用,还可能降低伤口感染、钛板外露、皮瓣坏死等并发症的发生率,值得在临床上推广应用。     

Advances in three‐dimensional bioprinting of bone: Progress and challenges

Several attempts have been made to engineer a viable three‐dimensional (3D) bone tissue equivalent using conventional tissue engineering strategies, but with limited clinical success. Using 3D bioprinting technology, scientists have developed functional prototypes of clinically relevant and mechanically robust bone with a functional bone marrow. Although the field is in its infancy, it has shown immense potential in the field of bone tissue engineering by re‐establishing the 3D dynamic micro‐environment of the native bone. Inspite of their in vitro success, maintaining the viability and differentiation potential of such cell‐laden constructs overtime, and their subsequent preclinical testing in terms of stability, mechanical loading, immune responses, and osseointegrative potential still needs to be explored. Progress is slow due to several challenges such as but not limited to the choice of ink used for cell encapsulation, optimal cell source, bioprinting method suitable for replicating the heterogeneous tissues and organs, and so on. Here, we summarize the recent advancements in bioprinting of bone, their limitations, challenges, and strategies for future improvisations. The generated knowledge will provide deep insights on our current understanding of the cellular interactions with the hydrogel matrices and help to unravel new methodologies for facilitating precisely regulated stem cell behaviour.     

基于超声的3D打印技术在心脏领域的应用进展

3D打印技术是近年来出现的新技术。随着三维超声的发展,基于超声的3D打印技术在心血管疾病诊断和治疗中逐渐被应用。3D打印技术通过获取图像、建模、实体打印三个步骤可以把三维超声图像转换为实体模型。目前基于超声的3D打印技术主要应用在左心耳封堵术、瓣膜性心脏病、先天性心脏病三个方面,有助于术前评估、术前模拟手术、医疗装置设计、血流动力学模拟及医学沟通教育。3D打印技术应用前景广阔,打印具有生物活性的组织或者结构直接应用于人体是未来的发展方向。为了让3D打印技术更好地服务临床,我们仍面临着巨大的挑战。     

基于经食管超声心动图数据的左心耳3D打印模型准确性研究

目的：应用经食管超声心动图数据重建并打印左心耳3D模型并分析其准确性。方法：选取于医院就诊并接受三维经食管超声心动图（3D-TEE）及心脏增强CT检查的患者20例，对其3D-TEE 左心耳数据进行后处理并使用软质类橡胶材料打印3D实体模型，测量左心耳模型的开口长径、短径、深度并进行解剖分型评估，将其与3D-TEE、CT的结果进行对比。结果：3D模型组与3D-TEE组的左心耳开口长径、开口短径、深度差异均无统计学意义（均P >0.05），组间ICC分别为0.97、0.98、0.98；CT组的左心耳开口长径、开口短径、深度测值均大于3D-TEE组（均P <0.05），组间ICC分别0.91、0.88、0.90。3D模型组与CT组在左心耳评估形态、分叶差异均无统计学意义（均P >0.05）；Kappa值分别为0.86、0.91（均P <0.05）。3D-TEE组与CT组在左心耳评估形态、分叶差异均无统计学意义（均P >0.05）；Kappa值分别为0.71、0.81（均P <0.05）。结论：基于经食管超声数据左心耳3D打印模型的测量径线可准确还原其数据源；与3D-TEE相比，左心耳3D模型在评估形态及分叶方面与CT重建一致性更高。     

Validation of an implantable bioink using mechanical extraction of human skin cells: First steps to a 3D bioprinting treatment of deep second degree burn

Clinical grade cultured epithelial autograft (CEA) are routinely used to treat burns covering more than 60% of the total body surface area. However, although the epidermis may be efficiently repaired by CEA, the dermal layer, which is not spared in deep burns, requires additional treatment strategies. Our aim is to develop an innovative method of skin regeneration based on in situ 3D bioprinting of freshly isolated autologous skin cells. We describe herein bioink formulation and cell preparation steps together with experimental data validating a straightforward enzyme‐free protocol of skin cell extraction. This procedure complies with both the specific needs of 3D bioprinting process and the stringent rules of good manufacturing practices. This mechanical extraction protocol, starting from human skin biopsies, allows harvesting a sufficient amount of both viable and growing keratinocytes and fibroblasts. We demonstrated that a dermis may be reconstituted in vitro starting from a medical grade bioink and mechanically extracted skin cells. In these experiments, proliferation of the extracted cells can be observed over the first 21 days period after 3D bioprinting and the analysis of type I collagen exhibited a de novo production of extracellular matrix proteins. Finally, in vivo experiments in a murine model of severe burn provided evidences that a topical application of our medical grade bioink was feasible and well‐tolerated. Overall, these results represent a valuable groundwork for the design of future 3D bioprinting tissue engineering strategies aimed at treating, in a single intraoperative step, patients suffering from extended severe burns.     

Personalized assistive device manufactured by 3D modelling and printing techniques

Abstract

Aim: To design and manufacture a patient-specific assistive device optimized for patient function after estimating the disability status of a patient with brain injury through 3D printing technique

Materials and methods: The left hand of a man with right-side hemiparesis was scanned with a three-dimensional scanner, and the left-hand image was flipped over to the right side to design the orthosis. To change devices easily, a connector was designed to connect the devices and was easily detachable with the orthosis by using the magnetics. To enable the writing, a round-shaped ring was attached to the orthosis to fix a pen. The Jebsen–Taylor Hand Function Test (JHFT) and Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) were evaluated one month after the application.

Results: The JHFT score improved after application 3D printed devices. In most QUEST items, 3D printed devices showed better results than ready-made assistive devices. The typing speed became faster in 3D printed devices than in ready-made assistive devices. The patient was satisfied with the orthosis in writing a pen, eating food and typing keyboard because of its fitness to his hand and easy-to-use.

Conclusion: We designed and manufactured a patient-specific assistive device optimized for patient function after estimating the disability status of a patient with brain injury through 3D printing techniques. We hope to provide low-cost, customized devices to disabled patients through 3D printing techniques.

• Implications for Rehabilitation

• We designed and manufactured a patient-specific assistive device optimized for patient function through 3D printing technique.

• We hope to provide low-cost, customized devices to disabled patients through 3D printing techniques

     

Auricular cartilage repair using cryogel scaffolds loaded with BMP‐7‐expressing primary chondrocytes

The loss of cartilage tissue due to trauma, tumour surgery or congenital defects, such as microtia and anotia, is one of the major concerns in head and neck surgery. Recently tissue‐engineering approaches, including gene delivery, have been proposed for the regeneration of cartilage tissue. In this study, primary chondrocytes were genetically modified with plasmid‐encoding bone morphogenetic protein‐7 (BMP‐7) via the commercially available non‐viral Turbofect vector, with the aim of bringing ex vivo transfected chondrocytes to resynthesize BMP‐7 in vitro as they would in vivo. Genetically modified cells were implanted into gelatin–oxidized dextran scaffolds and cartilage tissue formation was investigated in 15 × 15 mm auricular cartilage defects in vivo in 48 New Zealand (NZ) white rabbits for 4 months. The results were evaluated via histology and early gene expression. Early gene expression results indicated a strong effect of exogenous BMP‐7 on matrix synthesis and chondrocyte growth. In addition, histological analysis results exhibited significantly better cartilage healing with BMP‐7‐modified (transfected) cells than in the non‐modified (non‐transfected) group and as well as the control. Copyright © 2012 John Wiley & Sons, Ltd.     

Proof of concept,design, and manufacture via 3‐D printing of a mesh with bactericidal capacity: Behaviour in vitro and in vivo

Currently, hernia treatment involves implantation of a mesh prosthesis, usually made of polypropylene, and the primary complication is infection of the device, which leads to an exponential increase in morbidity. Three‐dimensional printing offers a method of dealing with complications of this magnitude. Therefore, in this study, the bactericidal properties and effectiveness of three‐dimensional‐printed meshes with polycaprolactone (PCL) and gentamicin were evaluated in vitro in Escherichia coli cultures, and their histological behaviour was examined in vivo. Different PCL meshes were implanted into four groups of rats, with 10 rats in each group: PCL meshes, PCL meshes with alginate and calcium chloride, PCL meshes with gentamicin, and PCL meshes with alginate and gentamicin. Thirty‐six microporous meshes were manufactured, and their bactericidal properties were assessed. When the meshes did not include an antibiotic, an inhibition halo was not observed; when the gentamicin was free, an asymmetric inhibition area of 5.65 ± 0.46 cm² was present; when the gentamicin was encapsulated, a rectangular area of 5.40 ± 0.38 cm² was observed. In the rats, macroporous and microporous mesh implants produced mild inflammation and substantial fibrosis with collagen and neovascular foci. A significant difference was observed in fibroblastic activity between the PCL with alginate group and the PCL with alginate and gentamicin group microporous meshes (p = .013) and in collagen deposits between the macroporous and microporous meshes in the PCL mesh group (p = .033). The feasibility of manufacturing drug‐doped printed PCL meshes containing alginate and gentamicin was verified, and the meshes exhibited bactericidal effects and good histopathological behaviour.     

Hybrid 3D printing: a game-changer in personalized cardiac medicine?

Three-dimensional (3D) printing in congenital heart disease has the potential to increase procedural efficiency and patient safety by improving interventional and surgical planning and reducing radiation exposure. Cardiac magnetic resonance imaging and computed tomography are usually the source datasets to derive 3D printing. More recently, 3D echocardiography has been demonstrated to derive 3D-printed models. The integration of multiple imaging modalities for hybrid 3D printing has also been shown to create accurate printed heart models, which may prove to be beneficial for interventional cardiologists, cardiothoracic surgeons, and as an educational tool. Further advancements in the integration of different imaging modalities into a single platform for hybrid 3D printing and virtual 3D models will drive the future of personalized cardiac medicine.     

Cell factory‐derived bioactive molecules with polymeric cryogel scaffold enhance the repair of subchondral cartilage defect in rabbits

We have explored the potential of cell factory‐derived bioactive molecules, isolated from conditioned media of primary goat chondrocytes, for the repair of subchondral cartilage defects. Enzyme‐linked immunosorbent assay (ELISA) confirms the presence of transforming growth factor‐β1 in an isolated protein fraction (12.56 ± 1.15 ng/mg protein fraction). These bioactive molecules were used alone or with chitosan–agarose–gelatin cryogel scaffolds, with and without chondrocytes, to check whether combined approaches further enhance cartilage repair. To evaluate this, an in vivo study was conducted on New Zealand rabbits in which a subchondral defect (4.5 mm wide × 4.5 mm deep) was surgically created. Starting after the operation, bioactive molecules were injected at the defect site at regular intervals of 14 days. Histopathological analysis showed that rabbits treated with bioactive molecules alone had cartilage regeneration after 4 weeks. However, rabbits treated with bioactive molecules along with scaffolds, with or without cells, showed cartilage formation after 3 weeks; 6 weeks after surgery, the cartilage regenerated in rabbits treated with either bioactive molecules alone or in combinations showed morphological similarities to native cartilage. No systemic cytotoxicity or inflammatory response was induced by any of the treatments. Further, ELISA was done to determine systemic toxicity, which showed no difference in concentration of tumour necrosis factor‐α in blood serum, before or after surgery. In conclusion, intra‐articular injection with bioactive molecules alone may be used for the repair of subchondral cartilage defects, and bioactive molecules along with chondrocyte‐seeded scaffolds further enhance the repair. Copyright © 2015 John Wiley & Sons, Ltd.     

Development of a synthetic tissue engineered three‐dimensional printed bioceramic‐based bone graft with homogenously distributed osteoblasts and mineralizing bone matrix in vitro

Over the last decade there have been increasing efforts to develop three‐dimensional (3D) scaffolds for bone tissue engineering from bioactive ceramics with 3D printing emerging as a promising technology. The overall objective of the present study was to generate a tissue engineered synthetic bone graft with homogenously distributed osteoblasts and mineralizing bone matrix in vitro, thereby mimicking the advantageous properties of autogenous bone grafts and facilitating usage for reconstructing segmental discontinuity defects in vivo. To this end, 3D scaffolds were developed from a silica‐containing calcium alkali orthophosphate, using, first, a replica technique – the Schwartzwalder–Somers method – and, second, 3D printing, (i.e. rapid prototyping). The mechanical and physical scaffold properties and their potential to facilitate homogenous colonization by osteogenic cells and extracellular bone matrix formation throughout the porous scaffold architecture were examined. Osteoblastic cells were dynamically cultured for 7 days on both scaffold types with two different concentrations of 1.5 and 3 × 10⁹ cells/l. The amount of cells and bone matrix formed and osteogenic marker expression were evaluated using hard tissue histology, immunohistochemical and histomorphometric analysis. 3D‐printed scaffolds (RPS) exhibited more micropores, greater compressive strength and silica release. RPS seeded with 3 × 10⁹ cells/l displayed greatest cell and extracellular matrix formation, mineralization and osteocalcin expression. In conclusion, RPS displayed superior mechanical and biological properties and facilitated generating a tissue engineered synthetic bone graft in vitro, which mimics the advantageous properties of autogenous bone grafts, by containing homogenously distributed terminally differentiated osteoblasts and mineralizing bone matrix and therefore is suitable for subsequent in vivo implantation for regenerating segmental discontinuity bone defects. Copyright © 2016 John Wiley & Sons, Ltd.     

Magnetic-targeting of polyethylenimine-wrapped iron oxide nanoparticle labeled chondrocytes in a rabbit articular cartilage defect model

Osteoarthritis (OA) is the most prevalent form of joint disease and lacks effective treatment. Cell-based therapy through intra-articular injection holds great potential for effective intervention at its early stage. Despite the promising outcomes, major barriers for successful clinical application such as lack of specific targeting of transplanted cells still remain. Here, novel polyethylenimine-wrapped iron oxide nanoparticles (PEI/IONs) were utilized as a magnetic agent, and the in vitro efficiency of PEI/ION labeling, and the influence on the chondrogenic properties of chondrocytes were evaluated; the in vivo feasibility of magnetic-targeting intra-articular injection with PEI/ION labeled autologous chondrocytes was investigated using a rabbit articular cartilage defect model. Our data showed that chondrocytes were conveniently labeled with PEI/IONs in a time- and dose-dependent manner, while the viability was unaffected. No significant decrease in collagen type-II synthesis of labeled chondrocytes was observed at low concentration. Macrographic and histology evaluation at 1 week post intra-articular injection revealed efficient cell delivery at chondral defect sites in the magnetic-targeting group. In addition, chondrocytes in the defect area presented a normal morphology, and the origin of cells within was confirmed by immunohistochemistry staining against BrdU and Prussian blue staining. The present study shows proof of concept experiments in magnetic-targeting of PEI/ION labeled chondrocytes for articular cartilage repair, which might provide new insight to improve current cartilage repair strategies.

Magnetic-targeting outcome in the knee joint of experimental rabbit model at 1 week post intra-articular injection.