PEDOT:gelatin composites mediate brain endothelial cell adhesion.

Tissue engineering involves materials science, bioengineering, and regenerative medicine and many other disciplines. In the early stage, it aims to develop functional biological alternatives that improve, or maintain the function of lost or damaged tissue by combining the scaffold, cells, and biological molecules (such as growth factors). In addition, the ultimate goal of tissue engineering is to regenerate or repair damaged tissues with the help of the biological substitutes. Therefore, the tissue engineering scaffold should mimic the property, structure of the damaged tissue and mimic the extracellular matrix to support cell survival and growth to improve the tissue function. Moreover, the scaffold should also enhance cell proliferation and guide differentiation to regenerate or repair damaged tissues. Over the years, numerous studies have demonstrated that electrical signals can influence cellular behavior and function and conductive materials can enhance cell proliferation and guide differentiation of stem cells through promoting intercellular signaling. Traditional polymers have good process property, biodegradability, and good biocompatibility. So they are most widely used in tissue engineering, but traditional polymers are insulators, which cannot respond to signal transmission between cells to further control cellular activities, such as cell proliferation, migration and differentiation. However, researchers have discovered a variety of electrically conducting polymers in recent decades, such as polyaniline (PANi), polypyrrole (PPy), polythiophene, and their derivatives (mainly aniline oligomers and poly(3,4-ethylenedioxythiophene)) which have good biocompatibility and excellent electrical conductivity. They have been widely used in biomedical fields including drug delivery systems, biosensors, neural implants, and biological actuator, mostly used in the field of tissue engineering scaffolds. Moreover, their excellent electrical conductivity can promote cell adhesion and proliferation at the interface between the polymer and tissue by electrical stimulation, thereby promoting tissue growth. Therefore, the field of tissue engineering by conductive polymeric biomaterials has received more and more attention. However, the pure conductive polymers are brittle and their poor processability limits their applications in tissue engineering. Therefore, composite conductive polymeric biomaterials have been developed based on the above-mentioned conductive polymers and biocompatible degradable polymers, which have excellent biocompatibility, electrical conductivity, and processability. This review will summarize a variety of composite conductive polymeric biomaterials used in tissue engineering, such as pure conducting polymers, conducting blends or composite films, conducting copolymer films, conducting nanofibers, conducting hydrogels, and conducting composite three-dimensional (3D) scaffolds. In addition, recent research in tissue engineering has found that these conductive polymeric biomaterials can be used in various electrical signal sensitive tissues engineering including bone, muscle, nerve and cardiac tissue engineering. The above aspects will be discussed in detail in this paper.

Matrikines for therapeutic and biomedical applications

Some cancer-preventive agents such as selenium and green tea polyphenols effectively prevent cancer in some cases, but fail in other cases. It could be possible that the cancer-preventive actions of these agents may be altered by the interaction of cancer cells with the extracellular matrix (ECM) components, thus making this an important issue to study. Others have previously cloned a family of human prostate cancer cell lines with a common lineage that show the progression of characteristics from low to high degrees of malignancy and mimic different stages of tumor progression seen in human prostate cancer. For this study, we used these prostate cancer cell lines with increasing tumorigenicity and invasive ability: WPE1-NA22 showing the lowest, WPE1-NB14 and WPE1-NB11 showing intermediate, and WPE1-NB26 showing the greatest. The low tumorigenic cell line, WPE1-NA22 resembles noninvasive prostatic intra-epithelial neoplasia and represents a good target for chemoprevention in humans. Initially, we grew these cells on the surface of ECM components, laminin, collagen I, and fibronectin and determined the tumor cell sensitivity to methylseleninic acid (MSA) and epigallocatechin-3-gallate (EGCG). Poly-L-lysine was used as a control substratum. Cell growth was determined by sulforhodamine B staining assay. Then we determined whether these ECM proteins could enhance tumor cell resistance to MSA and EGCG. ECM components, but not polylysine, decreased tumor cell sensitivity to these agents. The effect of ECM components was prevented by β1 integrin-blocking antibodies suggesting that β1 integrin plays a role in mediating intracellular signaling conferring resistance against MSA and EGCG. Previously, we have shown an increase in expression of protein kinase Cε (PKCε) in advanced prostate tumor cells WPE1-NB26. A decrease in expression of PKCε by siRNA approach decreased the tumor cell resistance caused by ECM components. Furthermore, an inhibition of cell survival enzymes phosphoinositide-3-kinase (PI3K) with its specific inhibitor LY294002 (50 μM) as well as Akt with its specific inhibitor MK-2206 (1 μM) decreased the effect of ECM components on tumor cell survival against MSA and EGCG. WPE1-NB14, a low tumorigenic cell line having low PKCε and Akt activities, responded less to ECM components and showed higher sensitivity to MSA and EGCG. Conceivably, ECM components, laminin, collagen, and fibronectin induced β1 integrin signaling to activate cell survival pathways involving PKCε and PI3K-Akt, thereby decreasing prostate tumor cell sensitivity to MSA and EGCG. Thus, ECM may be one of the limiting factors for the action of cancer-preventive agents. Citation Format: Rayudu Gopalakrishna, Tiffany Fan, Ronald Deng, David Rayudu, Zachary W. Chen, William S. Tzeng, Usha Gundimeda. Extracellular matrix components influence prostate tumor cell sensitivity to cancer-preventive agents selenium and green tea polyphenols. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 232. doi:10.1158/1538-7445.AM2014-232

Smart label technology such as indicators is a growing field due to society's demand for Internet of Things devices. New materials and technologies are continuously being discovered and developed in order to provide better resolution, better performance, or more environmentally friendly devices. Within this report, screen printing technology is combined with vapor phase polymerization to synthesize three conductive polymers; poly(3,4‐ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polythiophene (PTh). The conductive polymers are created in micrometer resolution and investigated for their electrochromic properties. PEDOT and PPy samples are combined into printed, laminated, transmissive electrochromic displays. The technology is further advanced to establish separate PEDOT, PPy, and PTh all‐printed electrochromic displays using several screen printed layers. The PEDOT displays show improved color retention as compared to displays created with commercially available PEDOT:poly(styrene sulfonate) (PSS) with comparable contrast and switching behavior. All‐printed PPy and PTh electrochromic displays with impressive electrochromic behavior are demonstrated. More complex patterns of 7‐segment displays are created, thereby highlighting flexibility and individually switched sections of the conductive polymers. This research extends the screen printing and vapor phase polymerization combination to other conductive polymers and the potential commercialization of multicolor electrochromic displays that has been otherwise dominated by monochromatic PEDOT:PSS.

ABSTRACTIntroduction: The applications of naturally obtained polymers are tremendously increased due to them being biocompatible, biodegradable, environmentally friendly and renewable in nature. Among them, polyhydroxyalkanoates are widely studied and they can be utilized in many areas of human life research such as drug delivery, tissue engineering, and other medical applications.Areas covered: This review provides an overview of the polyhydroxyalkanoates biosynthesis and their possible applications in drug delivery in the range of micro- and nano-size. Moreover, the possible applications in tissue engineering are covered considering macro- and microporous scaffolds and extracellular matrix analogs.Expert commentary: The majority of synthetic plastics are non-biodegradable so, in the last years, a renewed interest is growing to develop alternative processes to produce biologically derived polymers. Among them, PHAs present good properties such as high immunotolerance, low toxicity, biodegradability, so, they are promisingly using as biomaterials in biomedical applications.

The rise of paper electronics has been accelerated due to the public push for sustainability. Electronic waste can potentially be avoided if certain materials in electronic components can be substituted for greener alternatives such as paper. Within this report, it is demonstrated that conductive polymers poly(3,4‐ethylenedoxythiophene) (PEDOT), polypyrrole, and polythiophene, can be synthesized by screen printing combined with vapor phase polymerization on paper substrates and further incorporated into functional electronic components. High patterning resolution (100 µm) is achieved for all conductive polymers, with PEDOT showing impressive sheet resistance values. PEDOT is incorporated as conductive circuitry and as the active material in all‐printed electrochromic displays. The conductive polymer circuits allow for functional light emitting diodes, while the electrochromic displays are comparable to commercial displays utilizing PEDOT on plastic substrates.

Robot-assisted orthotopic and heterotopic ovarian tissue transplantation techniques: surgical advances since our first success in 2000

Extracellular matrix (ECM)-based scaffold materials have been used successfully in both preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. Results of numerous studies have shown that ECM scaffolds are capable of supporting the growth and differentiation of multiple cell types in vitro and of acting as inductive templates for constructive tissue remodeling after implantation in vivo. Adipose tissue represents a potentially abundant source of ECM and may represent an ideal substrate for the growth and adipogenic differentiation of stem cells harvested from this tissue. Numerous studies have shown that the methods by which ECM scaffold materials are prepared have a dramatic effect upon both the biochemical and structural properties of the resultant ECM scaffold material as well as the ability of the material to support a positive tissue remodeling outcome after implantation. The objective of the present study was to characterize the adipose ECM material resulting from three methods of decellularization to determine the most effective method for the derivation of an adipose tissue ECM scaffold that was largely free of potentially immunogenic cellular content while retaining tissue-specific structural and functional components as well as the ability to support the growth and adipogenic differentiation of adipose-derived stem cells. The results show that each of the decellularization methods produced an adipose ECM scaffold that was distinct from both a structural and biochemical perspective, emphasizing the importance of the decellularization protocol used to produce adipose ECM scaffolds. Further, the results suggest that the adipose ECM scaffolds produced using the methods described herein are capable of supporting the maintenance and adipogenic differentiation of adipose-derived stem cells and may represent effective substrates for use in tissue engineering and regenerative medicine approaches to soft tissue reconstruction.

The importance of decellularized extracellular matrix (dECM) as a natural biomaterial in tissue engineering and regenerative medicine is rapidly growing. The core objective of the decellularization process is to eliminate cellular components while maximizing the preservation of the ECM's primary structure and components. Establishing a rapid, effective, and minimally destructive decellularization technique is essential for obtaining high-quality dECM to construct regenerative organs. This study focused on human umbilical cord tissue, designing different reagent combinations for decellularization protocols while maintaining a consistent processing time. The impact of these protocols on the decellularization efficiency of human umbilical cord tissue was evaluated. The results suggested that the composite decellularization strategy utilizing trypsin/EDTA + Triton X-100 + sodium deoxycholate was the optimal approach in this study for preparing decellularized human umbilical cord dECM. After 5 h of decellularization treatment, most cellular components were eliminated, confirmed through dsDNA quantitative detection, hematoxylin and eosin (HE) staining, and DAPI staining. Meanwhile, Masson staining, periodic acid-silver methenamine (PASM) staining, periodic acid-Schiff (PAS) staining, and immunofluorescent tissue section staining results revealed that the decellularized scaffold retained extracellular matrix components, including collagen and glycosaminoglycans (GAGs). Compared to native umbilical cord tissue, electron microscopy results demonstrated that the microstructure of the extracellular matrix was well preserved after decellularization. Furthermore, Fourier-transform infrared spectroscopy (FTIR) findings indicated that the decellularization process successfully retained the main functional group structures of extracellular matrix (ECM) components. The quantitative analysis of collagen, elastin, and GAG content validated the advantages of this decellularization process in preserving and purifying ECM components. Additionally, it was confirmed that this decellularized matrix exhibited no cytotoxicity in vitro. This study achieved short-term decellularization preparation for umbilical cord tissue through a combined decellularization strategy.

Conductive polymers have been widely applied as counter electrodes in dye-sensitized solar cells. However, as one of many materials in the conductive polymer family, polypyrrole attracts little attention in this field. In this paper, polypyrrole (PPy) was synthesized by vapour phase polymerization (VPP) and electropolymerization (EP) and these PPys were employed as counter electrodes in dye-sensitized solar cells. Comparing this to the regularly used Pt counter electrode, both of them show good catalytic behaviour in dye-sensitized solar cells though the PPy electrodes have a slightly lower fill factor. Such investigation will broaden the application of conductive polymers in DSCs. Our study indicates that polypyrrole is a good candidate to replace the Pt counter electrode in DSCs. Taking into consideration the regular solvent used in DSCs, it is recommended that an insoluble conductive polymer is a good choice for the counter electrode in DSCs.

The metazoan extracellular matrix (ECM), an extracellular system of insoluble networks, sheets and fibrils of proteinaceous material, is a central mediator of multicellularity that is required for developmental processes, tissue organisation, homoeostasis and control of cell phenotypes throughout life. Comparative genomics enables the repertoire of ECM components encoded by species from different phyla to be examined systematically. These studies have identified a core ECM adhesome that arose apparently on the metazoan stem lineage through gene and domain innovations and domain shuffling. In vertebrates, additional complexity of ECM structure and function has arisen through expansion of gene families, splice variants and the inception of novel ECM components including fibril‐associated collagen with interrupted triple helices collagens, fibronectin, hyaluronan, tenascins and secreted proteoglycans of bone and cartilage. Protostome phyla also include many lineage‐specific ECM innovations and diversifications that function in prey‐capture mechanisms, the assembly of protective exterior structures, and internal organs. Key Concepts: The extracellular matrix (ECM) is an insoluble network of collagens, glycoproteins, proteoglycans and glycosaminoglycans. Different morphological forms of ECM are apparent in early diverging and bilaterian animals. Comparative genomics has identified a conserved core ECM adhesome, that includes integrin adhesion receptors, matrix proteases and the central ECM components of connective ECM and basement membranes. The ECM components of this core adhesome are specific to the metazoa. It is likely that the ECM components of the core adhesome were important for evolution of multi‐cellularity in the metazoa. Additional ECM diversity has arisen in vertebrates through large‐scale genome duplication events, domain innovations, and novel ECM components. Lineage‐specific ECM diversity is also apparent in invertebrates; in cuticles, shells and specialised structures as well as internal organs. Overall, the metazoan ECM shows extensive adaptive radiation as well as great conservation of the core ECM components.

As an Extracellular Matrix (ECM) component, Hyaluronic acid (HA) plays a multi-faceted role in cell migration, proliferation and differentiation at micro level and system level events such as tissue water homeostasis. Among its biological functions, it is known to interact with cytokines and contribute to their retention in ECM microenvironment. In addition to its biological functions, it has advantageous physical properties which result in the industrial endeavors in the synthesis and extraction of HA for variety of applications ranging from medical to cosmetic. Recently, HA and its derivatives have been the focus of active research for applications in biomedical device coatings, drug delivery systems and in the form of scaffolds or cell-laden hydrogels for tissue engineering. A specific reason for the increase in use of HA based structures is their immunomodulatory and regeneration inducing capacities. In this context, this article reviews recent literature on modulation of the implantable biomaterial microenvironment by systems based on HA and its derivatives, particularly hydrogels and microscale coatings that are able to deliver cytokines in order to reduce the adverse immune reactions and promote tissue healing.

The ability to artificially simulate the ‘mechanical’ niche, broadly termed as Extracellular Matrix (ECM), of the bone marrow determines success for stem cell growth, architectural organization and differentiation viz. tissue engineering. The advent of various natural and synthetic polymers has greatly influenced tissue engineering. The focus of the review is on various artificial niche simulations, ECM, scaffolds such as hydrogels, electrospun nano and micro fibers, bone-strengthening scaffolds and tissue infills. The utility of the ECMs in the treatment of various medical conditions including bone and cartilage tissues, nervous tissues, spinal cord and tendon tissues as well as wound healing, along with the ability of some ECMs in entrapment of elusive cell secretomes will be discussed. The future of tissue engineering has indeed got a new lease of life with polymer scaffolds and it is feasible that certain goals, thought of impossible so far, may become possible.

The main task of tissue engineering (TE) is to reproduce, replicate, and mimic all kinds of tissues in the human body. Nowadays, it has been proven useful in TE to mimic the natural extracellular matrix (ECM) by an artificial ECM (scaffold) based on synthetic or natural biomaterials to regenerate the physiological tissue/organ architecture and function. Hydrogels have gained interest in the TE community because of their ability to absorb water similar to physiological tissues, thus mechanically simulating the ECM. In this work, we present a novel hydrogel platform based on poly(2-ethyl-2-oxazoline)s, which can be processed to 3D microstructures via two-photon polymerization (2PP) with tunable mechanical properties using monomers and crosslinker with different degrees of polymerization (DP) for future applications in TE. The ideal parameters (laser power and writing speed) for optimal polymerization via 2PP were obtained using a specially developed evaluation method in which the obtained structures were binarized and compared to the computer-aided design (CAD) model. This evaluation was performed for each composition. We found that it was possible to tune the mechanical properties not only by application of different laser parameters but also by mixing poly(2-ethyl-2-oxazoline)s with different chain lengths and variation of the crosslink density. In addition, the swelling behavior of different fabricated hydrogels were investigated. To gain more insight into the viscoelastic behavior of different fabricated materials, stress relaxation tests via nanoindentation experiments were performed. These new hydrogels can be processed to 3D microstructures with high structural integrity using optimal laser parameter settings, opening a wide range of application properties in TE for this material platform.

Tissue engineering (TE) is a modern approach to improve or restore tissues that has been diseased or damaged by combining the factors in growth signaling and appropriate cells to form compatible biomaterial scaffold. Bone repair has been a major global health challenge in recent decades. Bone transplantation is widely used as an effective clinical treatment for this purpose. However, there are several serious issues with transplantation, including a shortage of autologous bone, immune rejection, the risk of virus transmission with allogeneic bone, and postoperative complications. In recent years, scaffolds for bone tissue engineering have emerged as a promising alternative for bone repair. These scaffolds have porous structures that mimic the extracellular matrix, which can enhance the migration, proliferation, and differentiation of osteoblasts. This process accelerates the repair of bone defects.The usage of bioactive materials has become important tool in tissue engineering and regenerative medicine application as they are to mimic tissues mechanically, chemically, and physically. Polymeric scaffold provides numerous advantageous for tissue engineering since the physicochemical properties such as porosity, pore size, solubility and biocompatibility can be controlled. Therefore, research works were carried out to explore the potential of various materials in producing bone scaffolds in tissue engineering technology. As for both newcomers and experts, this review paper will help them to find information on various types of biomaterials in imparting or enhancing their biological properties such as biocompatibility, bacterial inhibition, tissue regeneration and cell growth, bio inertness, bioactive and resorbability for bone scaffold tissue engineering application.