Cell Carriers For Tissue Engineering Research Articles

Efficient Fabrication of Uniform, Injectable, and Shape-Memory Chitosan Microsponges as Cell Carriers for Tissue Engineering

Efficient Fabrication of Uniform, Injectable, and Shape-Memory Chitosan Microsponges as Cell Carriers for Tissue Engineering

Controllable preparation of bioactive open porous microspheres for tissue engineering.

Biodegradable microspheres have been widely applied as cell carriers for tissue engineering and regenerative medicine. However, most cell carriers only have a simple planar structure and show poor biological activity and cell adherence, resulting in low cell density and unfavorable application effect. How to develop size-controllable microspheres with an open-porous structure remains a challenge, and is a key factor to extend their employment as cell/drug delivery vehicles to boost regeneration of tissues (e.g., bone). Herein, well-defined open porous microspheres of poly(lactic-co-glycolic acid) (PLGA with good biocompatibility approved by the Food and Drug Administration (FDA)) were developed by using a gas-assisted-emulsion and surface-alkalization-treatment technology (GEST). The gas-assisted-emulsion strategy enables the formation of microspheres with a large size of 200-300 μm, meanwhile, the microspheres have a large amount of micropores with diameter in the range of 10-60 μm. The following alkalization-treatment on the surface makes the microspheres form a good porous interconnectivity throughout both the surface and the interior of the microspheres. The good porous interconnectivity endows the microspheres with a highly open pore structure and a large specific surface area for nutrient exchange and cell attachment, thus promoting cell proliferation and nutrient transportation, promising their potential as an ideal cell carrier to increase cell density and bioactivity for cell therapy-based tissue engineering.

Preparation of Tissue-Specific Matrix from Decellularized Porcine Cartilage

For full decellularization of cartilage tissue when preparing tissue-specific matrices of dense tissues from decellularized porcine articular cartilage, treatment with surfactant should be followed by treatment with supercritical fluids. Ethanol introduced as a polarity modifier leads to more complete cartilage decellularization, which is associated with a reduction of destructive changes in the extracellular matrix. The preserved morphology and active proliferation of mesenchymal stromal cells of human adipose tissue in the presence of the tissue-specific matrix of porcine cartilage indicate that the matrix is promising for use as a cell carrier for tissue engineering of cartilage.

Plasma-Activated Polyvinyl Alcohol Foils for Cell Growth

Hydrogels, and not only natural polysaccharide hydrogels, are substances capable of absorbing large amounts of water and physiological fluids. In this study, we set out to optimize the process for preparing polyvinyl alcohol (PVA) hydrogels. Subsequently, we doped PVA foils with cellulose powder, with poly(ethylene glycol) (PEG) or with gold nanoparticles in PEG colloid solutions (Au). The foils were then modified in a plasma discharge to improve their biocompatibility. The properties of PVA foils were studied by various analytical methods. The use of a suitable dopant can significantly affect the surface wettability, the roughness, the morphology and the mechanical properties of the material. Plasma treatment of PVA leads to ultraviolet light-induced crosslinking and decreasing water absorption. At the same time, this treatment significantly improves the cytocompatibility of the polymer, which is manifested by enhanced growth of human adipose-derived stem cells. This positive effect on the cell behavior was most pronounced on PVA foils doped with PEG or with Au. This modification of PVA therefore seems to be most suitable for the use of this polymer as a cell carrier for tissue engineering, wound healing and other regenerative applications.

Injectable PLGA microspheres with tunable magnesium ion release for promoting bone regeneration

Magnesium ions (Mg2+) are bioactive and proven to promote bone tissue regeneration, in which the enhancement efficiency is closely related to Mg2+ concentrations. Currently, there are no well-established bone tissue engineering scaffolds that can precisely control Mg2+ release, although this capability could have a marked impact in bone regeneration. Leveraging the power of biodegradable microspheres to control the release of bioactive factors, we developed lactone-based biodegradable microspheres that served as both injectable scaffolds and Mg2+ release system for bone regeneration. The biodegradable microsphere (PMg) was prepared from poly(lactide-co-glycolide) (PLGA) microspheres co-embedded with MgO and MgCO3 at a fixed total loading amount (20 wt%) with different weight ratios (1:0; 3:1; 1:1; 1:3; 0:1). The PMg microspheres demonstrated controlled release of Mg2+ by tuning the MgO/MgCO3 ratios. Specifically, faster release with higher initial concentrations of Mg2+ were detected at higher MgO fractions, while long-term sustained release with lower concentrations of Mg2+ was obtained at higher MgCO3 fractions. All prepared PMg microspheres were non-cytotoxic. Furthermore, they promoted attachment, proliferation, osteogenic differentiation, especially, cell migration of bone marrow mesenchymal stromal cells (BMSCs). Among these microspheres, PMg-III microspheres (MgO/MgCO3 in 1:1) exhibited the strongest promotion of mineral depositions and osteogenic differentiation of BMSCs. PMg-III microspheres were injected into the critical-sized calvarial defect of a rat model, resulting in significant bone regeneration when compared to the control group filled with PLGA microspheres. In the PMg-III group, the new bone volume fraction (BV/TV) and bone mineral density (BMD) reached 32.9 ± 5.6% and 325.7 ± 20.2 mg/cm3, respectively, which were much higher than the values 8.1 ± 2.5% (BV/TV) and 124 ± 35.8 mg/cm3 (BMD) in the PLGA group. These findings indicated that bioresorbable microspheres possessing controlled Mg2+ release features were efficient in treating bone defects and promising for future in vivo applications. Statement of SignificanceMagnesium plays pivotal roles in regulating osteogenesis, which exhibits concentration-dependent behaviors. However, no generally accepted controlled-release system is reported to correlate Mg2+ concentration with efficient bone regeneration. Biodegradable microspheres with injectability are excellent cell carriers for tissue engineering, moreover, good delivery systems for bioactive factors. By co-embedding magnesium compounds (MgO, MgCO3) with different dissolution rates in various ratios, tunable release of Mg2+ from the microspheres was readily achieved. Accordingly, significant promotion in bone defect regeneration is achieved with microspheres displaying proper sustained release of Mg2+. The developed strategy may serve as valuable guidelines for bone tissue engineering scaffold design, which allows precise control on the release of bioactive metal ions like Mg2+ toward potential clinical translation.

Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering

Adv. Funct. Mater. 2018, 28, 1800874 The initially published version of the manuscript unfortunately contains an error in the second sentence of the abstract of the html version. The correct sentence should read as in the pdf version, which is as follows: “…Here, a novel and highly efficient method is presented for preparation of porous microbeads of tailorable dimensions (in the range ≈300–1500 μm) and with a uniform and fully interconnected internal porous texture…” We apologize for any inconvenience or misunderstanding that this error may have caused.

Energy Harvesting: Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering

Energy Harvesting: Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering

Energy Harvesting: Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering (Adv. Funct. Mater. 20/2018)

Energy Harvesting: Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering (Adv. Funct. Mater. 20/2018)

Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering

AbstractInjection of cell‐laden scaffolds in the form of mesoscopic particles directly to the site of treatment is one of the most promising approaches to tissue regeneration. Here, a novel and highly efficient method is presented for preparation of porous microbeads of tailorable dimensions (in the range ≈300–1500 mm) and with a uniform and fully interconnected internal porous texture. The method starts with generation of a monodisperse oil‐in‐water emulsion inside a flow‐focusing microfluidic device. This emulsion is later broken‐up, with the use of electric field, into mesoscopic double droplets, that in turn serve as a template for the porous microbeads. By tuning the amplitude and frequency of the electric pulses, the template droplets and the resulting porous bead scaffolds are precisely produced. Furthermore, a model of pulsed electrodripping is proposed that predicts the size of the template droplets as a function of the applied voltage. To prove the potential of the porous microbeads as cell carries, they are tested with human mesenchymal stem cells and hepatic cells, with their viability and degree of microbead colonization being monitored. Finally, the presented porous microbeads are benchmarked against conventional microparticles with nonhomogenous internal texture, revealing their superior performance.

Тканеинженерные конструкции для регенеративной медицины на основе мезенхимальных клеток пульпы молочного зуба и полимерных матриксов нового поколения

The aim of the present work was to develop an approach for producing tissue engineered constructs based on mesenchymal stromal cell culture and new-generation biodegradable synthetic polymer matrices obtained by the technology of surface-selective laser sintering. Primary mesenchymal stromal cells were derived from the pulp of naturally shed deciduous teeth. Following seeding, the cells were cultured on matrices for ten days. Cell viability was quantitatively assessed using CytoTox Assay (Promega) based on the colorimetric measurement of mitochondrial dehydrogenase activity. Cellular structure and spatial arrangement within a tissue-engineered matrix was visualized by scanning electron microscopy (SEM), using supravital lanthanoid staining. The results obtained showed that matrices under development enable good cell adhesion and proliferation, and hence can be used as a cell carrier in tissue engineering. Thus, the techniques of surface-selective laser sintering, which was developed by us, could find wide use in regenerative medicine.

Improved genistein loading and release on electrospun chitosan nanofiber blends

Chitosan is a natural polysaccharide exhibiting excellent biocompatibility, biodegradability and nontoxicity, making Chitosan–based biomaterials ideal drug delivery systems and cell carriers for tissue engineering. The electrospinning technique, with optimized parameters, was used to fabricate chitosan/PVA as-spun mats. Field emission scanning electron microscopy (FESEM) was used to investigate the morphologies of the as-spun mats. We present a novel electrospun nanofiber-based drug delivery. In this system, genistein was loaded on nanofiber mats via three methods namely; passive loading, crosslinking after passive loading, and active loading. The way in which genistein was loaded significantly influenced its in-vitro drug release characteristics. The in-vitro release studies revealed that physical cross-linked nanofibers have a significantly delayed release demonstrating 21% progressive release after 30min and 69% after 24h, which is considered a superior drug delivery system compared to those reported before for genistein release.

Preparation of highly monodispersed porous-channeled poly(caprolactone) microspheres by a microfluidic system

Microspheres with a porous structure are promising cell carriers for tissue engineering. Here we explored monodisperse porous poly(caprolactone) (PCL) microspheres produced by a microfluidic system. The microfluidic device could generate homogeneous structured microspheres with excellent monodispersity. The microsphere size was tunable from 210 to 330µm by adjusting the sheath flow rate from 170 to 330µm. Camphene, used as a pore-generating material, was effective in creating open-channels, and the channel structure was significantly influenced by the solidification temperature and content of camphene. The size-tunable, monodisperse, and channeled-microspheres developed by using camphene and microfluidic device may be a potential platform in many areas, including biomolecule separation, drug delivery, and cell culture.

Alginates and similar exopolysaccharides in biomedical application and pharmacy: Controled delivery of drugs

Due to its biocompatibility, biodegradability, hydrophility, technological properties and vast availability, polysaccharides are widely used as natural non-toxic polymers in different branches of industry (food, cosmetic, textile, construction industries). Exopolysaccharides (as dextran, pullulan) have recently taken up a significant position in pharmaceutical industry. Alginate has an irreplaceable role in biomedicine, since its hydrogel form is successfully applied for immobilization of a wide range of enzymes, therapeutics, biochemical agents and different kinds of microorganisms and cells (herbal, animal or human). Alginate microspheres and microcapsules are used for controlled release of biologically active molecules, as well as cell carriers in tissue engineering. Special benefits are brought by the simplicity of configuration of alginate hydrogel, including the possibility of the controlled production of micro- and nanoparticles. Taking into account a very important role of alginates in the form of hydrogel in biomedicine, in this paper a specific attention is paid on the preparation and application of alginate matrices, microspheres and microcapsules that may have essential and unexchangeable usage/application. This paper therefore displays various possibilities of use of polysaccharide matrices for biomolecules, polysaccharide as excipients of pharmaceutical products for oral or local application, and provides a review of the examples of innovative applications.

Self-Assembling Peptide Nanofibrous Hydrogel as a Versatile Drug Delivery Platform.

Molecular hydrogels have been widely explored in various biomedical applications, such as cell culture, tissue engineering and drug delivery. Peptide-based hydrogel nanoparticles represent a promising alternative to current drug delivery approaches and cell carriers for tissue engineering, due to their encapsulation stability, water solubility and biocompatibility. This review focuses on recent advances in the use of self-assembling peptide nanogels for applications in drug delivery. We firstly introduce a self-assembly mechanism for small molecules used in the peptide hydrogel, and then describe recent methods for controlling the assembly of molecular hydrogelations. A particular emphasis is placed on recent advances in the use of different types of peptide hydrogels as drug delivery carriers. Lastly, the current challenges and future perspectives for self-assembling peptide hydrogels in drug delivery applications are discussed.

Fibrin gel as an injectable biodegradable scaffold and cell carrier for tissue engineering.

Due to the increasing needs for organ transplantation and a universal shortage of donated tissues, tissue engineering emerges as a useful approach to engineer functional tissues. Although different synthetic materials have been used to fabricate tissue engineering scaffolds, they have many limitations such as the biocompatibility concerns, the inability to support cell attachment, and undesirable degradation rate. Fibrin gel, a biopolymeric material, provides numerous advantages over synthetic materials in functioning as a tissue engineering scaffold and a cell carrier. Fibrin gel exhibits excellent biocompatibility, promotes cell attachment, and can degrade in a controllable manner. Additionally, fibrin gel mimics the natural blood-clotting process and self-assembles into a polymer network. The ability for fibrin to cure in situ has been exploited to develop injectable scaffolds for the repair of damaged cardiac and cartilage tissues. Additionally, fibrin gel has been utilized as a cell carrier to protect cells from the forces during the application and cell delivery processes while enhancing the cell viability and tissue regeneration. Here, we review the recent advancement in developing fibrin-based biomaterials for the development of injectable tissue engineering scaffold and cell carriers.

Bioengineering of Dental Pulp Stem Cells in a Microporous PNIPAAm-PLGA Scaffold

In the present article a novel bio absorbable polymeric scaffold using poly(N-isopropyl acrylamide-block-poly(L-lactide-co-glycolide) (PNIPAAm-b-PLGA) copolymers is developed for in vitro culture of human dental pulp stem cells (DPSCs). The processing of porous scaffolds has been carried out by emulsion freeze-drying and salt leaching out methods. DPSCs were cultured on scaffolds for up to 14 days. The morphology of the scaffolds, cell viability and interaction between DPSCs and scaffold was characterized by using SEM. The results of cells implantation indicated that scaffold has good cell biocompatibility. Therefore PNIPAAm-PLGA scaffolds have great potential to be used as cell carrier in tissue engineering.

Polysaccharides as Cell Carriers for Tissue Engineering: the Use of Cellulose in Vascular Wall Reconstruction

Polysaccharides are long carbohydrate molecules of monosaccharide units joined together by glycosidic bonds. These biological polymers have emerged as promising materials for tissue engineering due to their biocompatibility, mostly good availability and tailorable properties. This complex group of biomolecules can be classified using several criteria, such as chemical composition (homo- and heteropolysaccharides), structure (linear and branched), function in the organism (structural, storage and secreted polysaccharides), or source (animals, plants, microorganisms). Polysaccharides most widely used in tissue engineering include starch, cellulose, chitosan, pectins, alginate, agar, dextran, pullulan, gellan, xanthan and glycosaminoglycans. Polysaccharides have been applied for engineering and regeneration of practically all tissues, though mostly at the experimental level. Polysaccharides have been tested for engineering of blood vessels, myocardium, heart valves, bone, articular and tracheal cartilage, intervertebral discs, menisci, skin, liver, skeletal muscle, neural tissue, urinary bladder, and also for encapsulation and delivery of pancreatic islets and ovarian follicles. For these purposes, polysaccharides have been applied in various forms, such as injectable hydrogels or porous and fibrous scaffolds, and often in combination with other natural or synthetic polymers or inorganic nanoparticles. The immune response evoked by polysaccharides is usually mild, and can be reduced by purifying the material or by choosing appropriate crosslinking agents.

전기분사법에 의한 다공성 실크 피브로인 미세입자의 제조

실크 피브로인은 뛰어난 생체적합성 및 생분해성으로 인해 의료용 천연고분자소재로 각광받고 있으며 다양한 형태로 제조되어 이용되고 있다. 전기분사법은 고분자 용액에 고전압을 적용하여 미세입자를 제조하는 방법으로 진행과정이 간단하고 첨가제를 필요로 하지 않는다는 장점을 지닌다. 본 연구에서는 실크 피브로인 다공성 미세입자를 제조하기 위하여 폴리(에틸렌 글리콜)(PEG)을 첨가한 후 전기분사를 실시하였다. PEG를 첨가함으로써 분사원액의 전도도는 감소하였고 점도는 증가하였다. 제조된 미세입자의 크기는 PEG 첨가에 따라 감소하였는데 이는 분사용액의 전도도 및 점도보다는 피브로인과 PEG간의 상분리에 의한 효과인 것으로 보인다. 제조된 실크 피브로인 미세입자를 물에 침지한 결과 PEG가 제거되었으며 최종적으로 실크 피브로인 다공성 입자를 제조할 수 있었다. 제조된 다공성 실크 피브로인 미세입자는 약물전달체 및 조직공학용 세포전달체로 이용가능성이 높을 것으로 기대된다. Nowadays, silk fibroin receives a lot of attention as novel natural biomaterials due to its excellent biocompatibility and biodegradability. Electrohydrodynamic spraying (EHDS) is one of the method for the preparation of micro or nanoparticles by applying high voltage to the polymer solution. In this research, we fabricated silk fibroin porous microparticles by electrohydrodynamic spraying. Poly(ethylene glycol) (PEG) was added to the fibroin solution to give pores to silk fibroin microparticles. By the addition of PEG, the microparticle size was decreased despite of the decrease in conductivity and the increase of viscosity of the spraying solution. It seems that the immiscibility of silk fibroin and PEG affected much more to the microparticle size than the conductivity and viscosity. Immersing the as-sprayed microparticles into the water removed the phase-separated PEG, and finally, porous silk fibroin microparticles were prepared. The porous silk fibroin microparticles are expected to be applied as drug carriers in drug delivery or cell carriers in tissue engineering.

Alginate-Based Biomaterials for Regenerative Medicine Applications.

Alginate is a natural polysaccharide exhibiting excellent biocompatibility and biodegradability, having many different applications in the field of biomedicine. Alginate is readily processable for applicable three-dimensional scaffolding materials such as hydrogels, microspheres, microcapsules, sponges, foams and fibers. Alginate-based biomaterials can be utilized as drug delivery systems and cell carriers for tissue engineering. Alginate can be easily modified via chemical and physical reactions to obtain derivatives having various structures, properties, functions and applications. Tuning the structure and properties such as biodegradability, mechanical strength, gelation property and cell affinity can be achieved through combination with other biomaterials, immobilization of specific ligands such as peptide and sugar molecules, and physical or chemical crosslinking. This review focuses on recent advances in the use of alginate and its derivatives in the field of biomedical applications, including wound healing, cartilage repair, bone regeneration and drug delivery, which have potential in tissue regeneration applications.

Understanding the host response to cell-laden poly(ethylene glycol)-based hydrogels

Poly(ethylene glycol) (PEG)-based hydrogels are promising in situ cell carriers for tissue engineering. However, their success in vivo will in part depend upon the foreign body reaction (FBR). This study tests the hypothesis that the FBR affects cells encapsulated within PEG hydrogels, and in turn influences the severity of the FBR. Fibroblasts were encapsulated within PEG hydrogels containing RGD to support cell attachment. Macrophages were seeded on top of cell-laden hydrogels to mimic in vivo macrophage interrogation and treated with lipopolysaccharide to induce an inflammatory phenotype. The presence of activated macrophages reduced fibroblast gene expression for extracellular matrix molecules and remodeling, but stimulated VEGF and IL-1β gene expression. Fibroblasts impacted macrophage phenotype leading to increased iNOS, IL-1β and TNF-α expressions. Syngeneic cell-laden and acellular hydrogels were also implanted subcutaneously into C57bl/6 mice for 2, 7 and 28 days. Encapsulated fibroblasts secreted collagen type I during the first week, but tissue deposition and cellularity decreased by 28 days. The presence of encapsulated fibroblasts led to greater acute inflammation, but did not influence the fibrotic response. In summary, this work emphasizes the importance of the host response in tissue engineering, and the potentially deleterious impact it may have on cell-laden synthetic scaffolds.