Tissue Engineering Technology Research Articles

Application of rehabilitation of cruciate ligament injury during exercise based on nano-biomaterials tissue engineering treatment plan

The development and application of biomaterial tissue engineering technology provide new ideas and approaches in the rehabilitation of a cruciate ligament injury. Polyvinyl alcohol (PVA) fibre meets biosafety requirements, has no toxicity, no irritation, no genotoxicity, no carcinogenicity, and good biocompatibility to the human body. This study investigated and verified the growth of the human anterior cruciate ligament (hACL) cells on the ligament scaffold material PVA. This study shows that a PVA fibre as a tissue engineering scaffold ligament, cultured hACL cells in vitro proliferative capacity and a strong ability to secrete collagen matrix. The scaffold material has good cell compatibility, has certain swelling and mechanical properties, and is expected to develop into an ideal tissue for engineering anterior cruciate ligament scaffold material for rehabilitation treatment of a cruciate ligament injury during exercise.

Hydrogel: A potential therapeutic material for bone tissue engineering

Current surgical treatments and material applications are not ideal for the treatment of orthopedic clinical injuries, such as large bone defects, cartilage defects, and vascular tendon adhesions that occur after repair. With the continuous development of tissue engineering technology, hydrogels have become important medical biomaterials. Hydrogels are three-dimensional hydrophilic network structures composed of cross-linked polymer chains. They are a new kind of polymeric material for the treatment of orthopedic diseases. Hydrogels have good biocompatibility, biodegradability, drug-carrying capacity, and controllable drug release ability and are less toxic than nanoparticle carriers. They have been widely used in wound repair, guided tissue regeneration, bacteriostasis, hemostasis, postoperative adhesion prevention, drug delivery, and 3D printing. These characteristics can be used to develop a variety of treatments for different diseases. This paper focuses on the innovative progress of hydrogels in promoting and improving bone, cartilage, tendon, and soft tissue regeneration in orthopedic clinical applications. Current and prospective applications of hydrogels in the field of orthopedics are discussed herein.

Regenerative medicine for the hepatobiliary system: A review.

Liver transplantation, the only proven treatment for end-stage liver disease and acute liver failure, is hampered by the scarcity of donors. Regenerative medicine provides an alternative therapeutic approach. Tremendous efforts dedicated to liver regenerative medicine include the delivery of transplantable cells, microtissues, and bioengineered whole livers via tissue engineering and the maintenance of partial liver function via extracorporeal support. This brief review summarizes the current status of regenerative medicine for the hepatobiliary system. For liver regenerative medicine, the focus is on strategies for expansion of transplantable hepatocytes, generation of hepatocyte-like cells, and therapeutic potential of engineered tissues in liver disease models. For biliary regenerative medicine, the discussion concentrates on the methods for generation of cholangiocyte-like cells and strategies in the treatment of biliary disease. Significant advances have been made in large-scale and long-term expansion of liver cells. The development of tissue engineering and stem cell induction technology holds great promise for the future treatment of hepatobiliary diseases. The application of regenerative medicine in liver still lacks extensive animal experiments. Therefore, a large number of preclinical studies are necessary to provide sufficient evidence for their therapeutic effectiveness. Much remains to be done for the treatment of hepatobiliary diseases with regenerative medicine.

Improvement of Hardness of Hydroxyapatite by the Addition of Silica from Tin Tailings

The application of bone scaffolding in bone therapy is an alternative solution developed in bone tissue engineering technology to avoid bone donors' scarcity. The main requirement for a material that can be used as a scaffold is that it is biocompatible. Hydroxyapatite is a calcium phosphate ceramic that is often used as the primary material for scaffolding because it has good biocompatibility properties. However, like most ceramics, hydroxyapatite has low mechanical properties. In this study, we synthesized hydroxyapatite from cockleshell waste. To improve hydroxyapatite's mechanical properties (hardness), we added silica from tin tailings to hydroxyapatite. Through the analysis of the x-ray diffraction (XRD) pattern, it was found that hydroxyapatite was successfully synthesized from cockleshell using the co-precipitation method. Analysis of the diffraction pattern of tin tailings also shows that most of the crystals comprising tin tailings sand are silica in the ?-quartz phase. The addition of silica to hydroxyapatite followed by compaction and sintering at a temperature of 800 ? did not produce a new crystal phase. The addition still has a diffraction pattern consisting of a combined XRD pattern of hydroxyapatite and silica. Based on the hardness test using the Vickers hardness method, it is known that the addition of silica can increase the hardness of hydroxyapatite.

Ultrasound augmenting injectable chemotaxis hydrogel for articular cartilage repair in osteoarthritis

The increasing incidence of osteoarthritis (OA) seriously affects life quality, posing a huge socioeconomic burden. Tissue engineering technology has become a hot topic in articular cartilage repair as one of the key treatment methods to alleviate OA. Hydrogel, one of the most commonly used scaffold materials, can provide a good extracellular matrix microenvironment for seed cells such as bone marrow mesenchymal stem cells (BMSCs), which can promote cartilage regeneration. However, the low homing rate of stem cells severely limits their role in promoting articular cartilage regeneration. Stromal cell-derived factor-1α (SDF-1α) plays a crucial role in the activation, mobilization, homing, and migration of MSCs. Herein, a novel injectable chemotaxis hydrogel, composed of chitosan-based injectable hydrogel and embedding SDF-1α-loaded nanodroplets (PFP@NDs-PEG-SDF-1α) was designed and fabricated. The ultrasound was then used to augment the injectable chemotaxis hydrogel and promote the homing migration of BMSCs for OA cartilage repair. The effect of ultrasound augmenting injectable PFP@NDs-PEG-SDF-1α/hydrogel on the migration of BMSCs was verified in vitro and in vivo, which remarkably promotes stem cell homing and the repair of cartilage in the OA model. Therefore, the treatment strategy of ultrasound augmenting injectable chemotaxis hydrogel has a bright potential for OA articular cartilage repair.

3D printed collagen structures at low concentrations supported by jammed microgels

Improving cell infiltration into engineered scaffolds and decelluarized tissue is needed for developing new and effective technologies in regenerative medicine and tissue engineering. Significant challenges associated with populating these structures with cells have persisted for many years. Here we describe a 3D bioprinting method for creating precise structures from natural extracellular matrix at low concentrations that facilitates cell infiltration after printing. We show that when printing collagen-1 solutions into a support medium made from jammed microgels, the printer’s basic operating parameters can be used to predict the resulting feature size. Microscopic examination of the printed features show that the collagen solution undergoes gelation and forms a network with the microgels excluded from the printed region. Using this method we 3D print a centimeter-scale model of a developing gut tube and we also show that cells are able to infiltrate printed collagen-1 structures. Our results demonstrate that a diversity of new approaches are possible for creating heterogeneously populated engineered tissue structures.

Developing cell therapies as drug products.

In the last 20 years, the global regulatory frameworks for drug assessment have been managing the challenges posed by using cellular products as new therapeutic tools. Currently, they are defined as "Advanced Therapy Medicinal Products", comprising a large group of cellular types that either alone or in combination with gene and tissue engineering technology. They have the potential to change the natural course of still lethal or highly debilitating diseases, including cancers, opportunistic infections and chronic inflammatory conditions. Globally, more than 50 cell-based products have obtained market authorization. This overview describes the advantages and unsolved challenges on developing cells as innovative therapeutic vehicles. The main cell therapy players and the legal framework are discussed, starting from chimeric antigen receptor T-cells for leukaemia and solid tumours, dealing then with lymphocytes as potent anti-microbiological tools and then focusing on mesenchymal stem/stromal cells whose role covers regenerative medicine, immunology and anti-tumour therapy.

The development of laminin-alginate microspheres encapsulated with Ginsenoside Rg1 and ADSCs for breast reconstruction after lumpectomy

Many technologies have been developed for breast reconstruction after lumpectomy. Although the technologies achieved promising success in clinical, there are still many shortages hanging over and trouble the researchers. Tissue engineering technology was introduced to plastic surgery that gave a light to lumpectomy patients in breast reconstruction. The unexpected absorption rate, resulting from limited vascularization and low cell survival rate, is a major factor that leads to unsatisfactory results for the previous studies in our lab. In the study, the laminin-modified alginate synthesized by a new method of low concertation of sodium periodate would be mixed with ADSCs and Rg1 in the medium; and then sprayed into a calcium chloride (CaCl2) solution to prepare into microsphere (abbreviated as ADSC–G-LAMS) by bio-electrospray with a power syringe for the mass production and smaller bead size. The developed ADSC–G-LAMS microspheres had the diameter of 232 ± 42 μm. Sustained-release of the Rg1 retained its biological activity. WST-1, live/dead staining, and chromosome aberration assay were evaluated to confirm the safety of the microspheres. In in vivo study, ADSC–G-LAMS microspheres combined with autologous adipocytes were transplanted into the dorsum of rats by subcutaneous injection. The efficacy was investigated by H&E and immunofluorescence staining. The results showed that the bioactive ADSC–G-LAMS microspheres could integrate well into the host adipose tissue with an adequate rate of angiogenesis by constantly releasing Rg1 to enhance the ADSC or adipocyte survival rate to join tissue growth and repair with adipogenesis for breast reconstruction after lumpectomy.

Collagen/heparan sulfate porous scaffolds loaded with neural stem cells improve neurological function in a rat model of traumatic brain injury.

One reason for the poor therapeutic effects of stem cell transplantation in traumatic brain injury is that exogenous neural stem cells cannot effectively migrate to the local injury site, resulting in poor adhesion and proliferation of neural stem cells at the injured area. To enhance the targeted delivery of exogenous stem cells to the injury site, cell therapy combined with neural tissue engineering technology is expected to become a new strategy for treating traumatic brain injury. Collagen/heparan sulfate porous scaffolds, prepared using a freeze-drying method, have stable physical and chemical properties. These scaffolds also have good cell biocompatibility because of their high porosity, which is suitable for the proliferation and migration of neural stem cells. In the present study, collagen/heparan sulfate porous scaffolds loaded with neural stem cells were used to treat a rat model of traumatic brain injury, which was established using the controlled cortical impact method. At 2 months after the implantation of collagen/heparan sulfate porous scaffolds loaded with neural stem cells, there was significantly improved regeneration of neurons, nerve fibers, synapses, and myelin sheaths in the injured brain tissue. Furthermore, brain edema and cell apoptosis were significantly reduced, and rat motor and cognitive functions were markedly recovered. These findings suggest that the novel collagen/heparan sulfate porous scaffold loaded with neural stem cells can improve neurological function in a rat model of traumatic brain injury. This study was approved by the Institutional Ethics Committee of Characteristic Medical Center of Chinese People's Armed Police Force, China (approval No. 2017-0007.2) on February 10, 2019.

HiPSC-Derived Cardiac Tissue for Disease Modeling and Drug Discovery.

Relevant, predictive normal, or disease model systems are of vital importance for drug development. The difference between nonhuman models and humans could contribute to clinical trial failures despite ideal nonhuman results. As a potential substitute for animal models, human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) provide a powerful tool for drug toxicity screening, modeling cardiovascular diseases, and drug discovery. Here, we review recent hiPSC-CM disease models and discuss the features of hiPSC-CMs, including subtype and maturation and the tissue engineering technologies for drug assessment. Updates from the international multisite collaborators/administrations for development of novel drug discovery paradigms are also summarized.

Human iPS Cell-derived Tissue Engineered Vascular Graft: Recent Advances and Future Directions.

Tissue engineered vascular grafts (TEVGs) generated from human primary cells represent a promising vascular interventional therapy. However, generation and application of these TEVGs may be significantly hindered by the limited accessibility, finite expandability, donor-donor functional variation and immune-incompatibility of primary seed cells from donors. Alternatively, human induced pluripotent stem cells (hiPSCs) offer an infinite source to obtain functional vascular cells in large quantity and comparable quality for TEVG construction. To date, TEVGs (hiPSC-TEVGs) with significant mechanical strength and implantability have been generated using hiPSC-derived seed cells. Despite being in its incipient stage, this emerging field of hiPSC-TEVG research has achieved significant progress and presented promising future potential. Meanwhile, a series of challenges pertaining hiPSC differentiation, vascular tissue engineering technologies and future production and application await to be addressed. Herein, we have composed this review to introduce progress in TEVG generation using hiPSCs, summarize the current major challenges, and encapsulate the future directions of research on hiPSC-based TEVGs. Graphical abstract.

A bilayered scaffold with segregated hydrophilicity-hydrophobicity enables reconstruction of goat hierarchical temporomandibular joint condyle cartilage

Temporomandibular joint (TMJ) supports chewing, talking or other daily oral activities. So far, it still remains a great challenge to treat the defected TMJ condyle cartilage through tissue engineering technology. Herein, a bilayered scaffold is designed to fully reconstruct the different cartilage matrices of TMJ condyle under same induction condition. The bilayered scaffold with segregated hydrophobicity-hydrophilicity in top and bottom layer is prepared from a low and high content of polyethylene glycol (PEG) crosslinked poly (L-glutamic acid)-g-polycaprolactone (PLGA-g-PCL). The hydrophobic aggregates in top layer support the adhesion and spread of bone mesenchymal stem cells (BMSCs), thus inducing the differentation towards fibrocartilage; while aggregates (spheroids) are formed on the hydrophlic bottom layer, showing a preferable hyaline differentiation pathway under same chondrogenic induction in vitro. After 14 d in vitro induction, the scaffold/BMSCs construct is implanted in goat TMJ condyle defects. The post-operative outcome after 2 months demonstrates that the defects are fully covered by neo-cartilage. And the regenerated hierarchical TMJ condyle cartilage perfectly consist of ordered fibrocartilage and hyaline cartilage, which is same as natural condyle cartilage. These results corroborate that this bilayered scaffold with segregated hydrophilicity-hydrophobicity carrying induced BMSCs is a promising for treatment of TMJ condyle cartilage defects.

3D Bioprinting of Neural Tissues.

The human nervous system is a remarkably complex physiological network that is inherently challenging to study because of obstacles to acquiring primary samples. Animal models offer powerful alternatives to study nervous system development, diseases, and regenerative processes, however, they are unable to address some species-specific features of the human nervous system. In vitro models of the human nervous system have expanded in prevalence and sophistication, but still require further advances to better recapitulate microenvironmental and cellular features. The field of neural tissue engineering (TE) is rapidly adopting new technologies that enable scientists to precisely control in vitro culture conditions and to better model nervous system formation, function, and repair. 3D bioprinting is one of the major TE technologies that utilizes biocompatible hydrogels to create precisely patterned scaffolds, designed to enhance cellular responses. This review focuses on the applications of 3D bioprinting in the field of neural TE. Important design parameters are considered when bioprinting neural stem cells are discussed. The emergence of various bioprinted in vitro platforms are also reviewed for developmental and disease modeling and drug screening applications within the central and peripheral nervous systems, as well as their use as implants for in vivo regenerative therapies.

Bionic Silk Fibroin Film Promotes Tenogenic Differentiation of Tendon Stem/Progenitor Cells by Activating Focal Adhesion Kinase.

Background Tendon injuries are common musculoskeletal disorders in clinic. Due to the limited regeneration ability of tendons, tissue engineering technology is often used as an effective approach to treat tendon injuries. Silk fibroin (SF) films have excellent biological activities and physical properties, which is suitable for tendon regeneration. The present study is aimed at preparing a SF film with a bionic microstructure and investigating its biological effects. Methods A SF film with a smooth surface or bionic microstructure was prepared. After seeding tendon stem/progenitor cells (TSPCs) on the surface, the cell morphology, the expression level of tenogenic genes and proteins, and the focal adhesion kinase (FAK) activation were measured to evaluate the biological effect of SF films. Results The TSPCs on SF films with a bionic microstructure exhibited a slender cell morphology, promoted the expression of tenogenic genes and proteins, such as SCX, TNC, TNMD, and COLIA1, and activated FAK. FAK inhibitors blocked the enhanced expression of tenogenic genes and proteins. Conclusion SF films with a bionic microstructure may serve as a scaffold, provide biophysical cues to alter the cellular adherence arrangement and cell morphology, and enhance the tenogenic gene and protein expression in TSPCs. FAK activation plays a key role during this biological response process.

Study of a new nano-hydroxyapatite/basic fibroblast growth factor composite promoting periodontal tissue regeneration

Tissue engineering technology provides a new method for periodontal regeneration. Finding or preparing a suitable scaffold is the key to periodontal tissue engineering. Here, we use nano-hydroxyapatite-modified collagen biomimetic material (nHAC) as the packaging material, and carry fibroblast growth factor (bFGF) for the regeneration and repair of periodontal tissue. Due to its low cytotoxicity and high biocompatibility, nHAC shows unique advantages in the construction of periodontal tissue scaffolds. The nHAC periodontal tissue scaffold material has a dense and porous three-dimensional network structure, has a high loading rate of bFGF, and can firmly lock human periodontal ligament cells (HPDLCs), which is easy for cell growth and attachment. In vivo experiments have shown that, in artificial animal periodontal tissue models, the nHAC-loaded bFGF periodontal scaffold covered by Geistlich Bio-Gide (GBG) membrane is better than the simple GBG membrane and the blank group, the nHAC/bFGF-GBG composite membrane It is beneficial to promote the growth of new alveolar bone and cement formation, and realize the regeneration of periodontal tissue.

The VALVE REGEN project. Developing an innovative tissue engineered heart valve, in vitro and in vivo testing – preliminary results

Abstract Background Regenerative Medicine and Tissue Engineering are the grounds on which multidisciplinary teams aspire to obtain the perfect valvular substitute, which overcomes shortcomings of the present prostheses. Purpose Was to obtain a tissue engineered heart valve (TEHV) by repopulating with valvular resident cells – endothelial (EC) and fibroblasts (FB) a decellularized heart valve scaffold. Then their functionality and behavior was assessed in vitro and in vivo. Methods This study is part of a research grant approved by the Ethics Committee of the University. Six ovine pulmonary valves underwent a perfusion based decellularization protocol. Using a sequence of chemical and enzymatic treatment under a pressure gradient, cell removal was achieved and attested by histological investigations (DAPI nuclear staining –4',6-diamidino-2-phenylindol and haematoxylin-eosin) and DNA extraction. Ovine sub-dermal adipose tissue was harvested followed by stem cells isolation and culture. Using Endothelial Cell Growth Supplement and mechanical stimuli EC were differentiated and with Transforming Growth Factor-B1, FB were obtained. FB were internally seeded into cuspis bases using a 22 gauge needle and externally on the adventitia by using a rotator allowing a uniform distribution and seeding of cells. EC were seeded into leaflets pockets and intra-luminal also using the rotator. The repopulated valves were preconditionated in a bioreactor by gradually exposing them to the pulmonary hemodynamic regimen. By using a high speed camera, their behavior was examined when exposed to in vivo conditions. The in vivo testing was performed by surgical implantation in the gold model considered animal – the sheep. By transesophageal ultrasound (TEE US) and epicardic US, their intra-operatory function was evaluated. Post-procedure, evaluation was performed by periodic trans-thoracic (TTE US). Results Six TEHV were obtained. The decellularization histology assessment revealed acellular scaffolds and non-detectable nucleic material at the DNA extraction. Six adipose derived stem cells cultures were obtained and subsequently specialized towards EC and FB lines. The repopulation procedures underwent without incidents. During the bioreactor preconditioning, the TEHV showed complete opening and competent central coaptation. Leaflets presented physiological movement and absence of damage of valvular apparatus. The TEE US evaluation in vivo revealed normal valvular function without signs of stenosis or regurgitation. The periodic TTE US showed preserved valvular function. Conclusions Our preliminary results point out a manufactured TEHV with physiological behavior when tested in vitro and in vivo. Their interaction with a living body will be pointed out only in the explant phase, after histology analysis. The present results appear optimistic but only extended studies and follow-ups will certify their superiority in terms of performances and behavior. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): This paper was financed by a grant from the Competitiveness Operational Programme 2014-2020, Tissue engineering technologies for cardiac valve regeneration, valve-regen, id P_37_673, Mysmis code: 103431, contract 50/05.09.2016.

Osteoinductive Properties of Secretome of Human Mesenchymal Stem Cells, Obtained with Automatic Cell Culture System

The secretome of human mesenchymal stem cells (MSCs) after osteogenic differentiation of FetMSC cells in vitro was obtained to develop tissue engineering technologies for bone tissue. For standard secretome samples a large number of FetMSC cells (7 × 108 cells) were cultured in serum-free conditioned medium (SFCM). All steps of cell processing were performed in the CompacT SelecT automatic system (Sartorius, United Kingdom). The SFCM was concentrated by ultrafiltration, then subjected to dialysis and dried in a vacuum rotary evaporator. The osteoinductive properties of SFCM concentrate (SFCMC) were tested on FetMSC cells by means of adding it to the growth medium at different concentrations. There were no changes in cell morphology during cultivation in the presence of SFCMC. Analysis of the transcription factors Runx2 and YAP1 (markers of osteogenic differentiation) expression using immunofluorescence staining and real-time polymerase chain reaction (RT-PCR) showed an increase in their level of expression in the presence of SFCMC. These findings demonstrate that it is possible to use SFCMC obtained from osteogenic MSCs to induce differentiation of other (undifferentiated) MSCs. The results are useful for the development of cell therapy products for bone restoration based on MSCs secretome.

The Immune System and Its Contribution to Variability in Regenerative Medicine.

The immune system plays a critical role in directing tissue repair and regeneration outcomes. Tissue engineering technologies that are designed to promote new tissue growth will therefore be impacted by immune factors that are present in patients both locally at the site of intervention and systemically. The immune state of patients can be influenced by many factors, including infection, nutrition, and other disease comorbidities. As a result, the immune state is highly variable and may be a source of variability in tissue-engineered products in the clinic, which is not found in preclinical models. In this review, we will summarize key immune cells and evidence of their activity in tissue repair and potential in tissue engineering systems. We also discuss how clinical translation of tissue engineering strategies, in particular stem cells, helped elucidate the importance of the immune system. With increased understanding of the immune system's role in repair and tissue engineering systems, it will likely become a therapeutic target and component of future therapies.

Quantitative Investigation of the Process Parameters of Electrohydrodynamic Direct-Writing and Their Effects on Fiber Surface Roughness and Cell Adhesion

Electrohydrodynamic (EHD) direct-writing has been widely used to fabricate micro/nanofibers that can serve as a building block in tissue engineering scaffolds. However, the application of EHD direct-writing in tissue engineering is limited by the lack of fundamental knowledge in the correlations among the process parameters, the fiber surface roughness, and the cell adhesion performance. Without a standardized experimental setting and the quantitative database, inconsistent results have been reported. Here, we quantitatively investigate the process–structure–property relationships as the first step towards a better understanding of the EHD direct-writing technology for tissue engineering. Polycaprolactone (PCL) solution is used as a model ink material, and human mesenchymal stem cells (hMSCs) are used to study cell adhesion on PCL fibers. We investigate the different jetting modes defined by the applied voltage, the feed rate, and the nozzle–collector distance. The quantitative effects of process parameters on the fiber surface roughness and the cell adhesion performance are experimentally determined. The quantitative process–structure–property relationships revealed in this study provide guidelines for controlling the surface roughness and the cell adhesion performance of EHD direct-written fibers. This study will facilitate the application of EHD direct-writing in tissue engineering.

Artificial lungs--Where are we going with the lung replacement therapy?

Lung transplantation may be a final destination therapy in lung failure, but limited donor organ availability creates a need for alternative management, including artificial lung technology. This invited review discusses ongoing developments and future research pathways for respiratory assist devices and tissue engineering to treat advanced and refractory lung disease. An overview is also given on the aftermath of the coronavirus disease 2019 pandemic and lessons learned as the world comes out of this situation. The first order of business in the future of lung support is solving the problems with existing mechanical devices. Interestingly, challenges identified during the early days of development persist today. These challenges include device-related infection, bleeding, thrombosis, cost, and patient quality of life. The main approaches of the future directions are to repair, restore, replace, or regenerate the lungs. Engineering improvements to hollow fiber membrane gas exchangers are enabling longer term wearable systems and can be used to bridge lung failure patients to transplantation. Progress in the development of microchannel-based devices has provided the concept of biomimetic devices that may even enable intracorporeal implantation. Tissue engineering and cell-based technologies have provided the concept of bioartificial lungs with properties similar to the native organ. Recent progress in artificial lung technologies includes continued advances in both engineering and biology. The final goal is to achieve a truly implantable and durable artificial lung that is applicable to destination therapy.