Design, Fabrication, and Application of Mini-Scaffolds for Cell Component in Tissue Engineering

publishersversionPeer reviewe

Normal approximation for strong demimartingales

We consider a sequence of strong demimartingales. For these random objects, a central limit theorem is obtained by utilizing Zolotarev’s ideal metric and the fact that a sequence of strong demimartingales is ordered via the convex order with the sequence of its independent duplicates. The CLT can also be applied to demimartingale sequences with constant mean. Newman (1984) conjectures a central limit theorem for demimartingales but this problem remains open. Although the result obtained in this paper does not provide a solution to Newman’s conjecture, it is the first CLT for demimartingales available in the literature

ROLE OF MESENCHYMAL MULTIPOTENT STROMAL CELLS IN REMODELING OF BONE DEFECTS

Ability of mesenchymal multipotent stromal cells (MSCs) to differentiate into several types of mesenchymal tissues allows to consider these cells the main candidates for creating tissue engineering constructions for regenerative medicine. MSCs promote integration of bio-implants into the native bone and stimulate osteogenesis. MSCs are characterized by immunomodulatory properties, due to inflammation control and modification of immune cells. MSCs affect not only the in vivo immune response by preventing immunological rejection of implanted tissue engineering designs, but it can also influence the bone tissue immunity. MSCs play an important role in bone regeneration, by regulating the osteoblastic generation, and suppressing activity of inflammation effectors and osteoclastogenesis. Some pre-clinical and first clinical trials of bone bio-implants colonized with MSC, demonstrate promising outlooks for this strategy in order to obtain tissue engineering constructions for bone regeneration

Commercial articulated collaborative in situ 3D bioprinter for skin wound healing

In situ bioprinting is one of the most clinically relevant techniques in the emerging bioprinting technology because it could be performed directly on the human body in the operating room and it does not require bioreactors for post-printing tissue maturation. However, commercial in situ bioprinters are still not available on the market. In this study, we demonstrated the benefit of the originally developed first commercial articulated collaborative in situ bioprinter for the treatment of full-thickness wounds in rat and porcine models. We used an articulated and collaborative robotic arm from company KUKA and developed original printhead and correspondence software enabling in situ bioprinting on curve and moving surfaces. The results of in vitro and in vivo experiments show that in situ bioprinting of bioink induces a strong hydrogel adhesion and enables printing on curved surfaces of wet tissues with a high level of fidelity. The in situ bioprinter was convenient to use in the operating room. Additional in vitro experiments (in vitro collagen contraction assay and in vitro 3D angiogenesis assay) and histological analyses demonstrated that in situ bioprinting improves the quality of wound healing in rat and porcine skin wounds. The absence of interference with the normal process of wound healing and even certain improvement in the dynamics of this process strongly suggests that in situ bioprinting could be used as a novel therapeutic modality in wound healing.publishersversionPeer reviewe

Сверхвысокомолекулярный полиэтилен (СВМПЭ) как основа клеточного матрикса для создания 3D клеточной культуры

The study is devoted to the development of an artificial material based on the ultrahigh-molecular weight polyethylene (UHMWPE) with a porous or cellular 3D structure as a cellular matrix – a framework for growing cell cultures. The development of such matrix provides support for neuronal cell culture under conditions that mimick those that exist in the living body. Typically, in vitro cellular studies are conducted in a 2D format, which limits intercellular interactions, morphology, differentiation, survival, signaling responses, gene expression and proliferation that are found in vivo. Here, we propose to use UHMWPE as a material of the cellular matrix, the ultra-high molecular weight polyethylene. UHMWP is a bioinert substance, wich allows forming a system of open connected pores needed to provide cellular life conditions with supply of nutrients and oxygen as well as the removal of waste products, the possibility of intercellular communication, etc. As a result, the use of UHMWPE as a cellular matrix will allow to study the processes occurring in cells in the 3D environment.Работа посвящена анализу свойств искусственного материала на основе сверхвысокомолекулярного полиэтилена (СВМПЭ) с пористой или ячеистой 3D-структурой, который используется в качестве клеточного матрикса – каркаса для выращивания культуры клеток. Разработка такого каркаса обеспечивает культивирование клеточной культуры в условиях, приближенных к тем, которые существуют в живом организме. Как правило, клеточные исследования in vitro проводят в 2D-формате, который по своей природе ограничивает межклеточные взаимодействия, морфологию, дифференцировку, выживаемость, сигнальные ответы, экспрессию генов и пролиферацию, наблюдаемые in vivo. В качестве материала клеточного матрикса предлагается использовать биоинертный сверхвысокомолекулярный полиэтилен (СВМПЭ), который позволяет сформировать систему открытых связанных пор с целью обеспечения клеточной жизнедеятельности – “подвод” питания и кислорода, удаление продуктов жизнедеятельности, возможность осуществления межклеточных связей и т.д. В результате использование СВМПЭ в качестве клеточного матрикса позволит изучить процессы, протекающие в клетках в условиях 3D-среды

Future of additive manufacturing: Overview of 4D and 3D printed smart and advanced materials and their applications

© 2020 Elsevier B.V. 4D printing is an emerging field in additive manufacturing of time responsive programmable materials. The combination of 3D printing technologies with materials that can transform and possess shape memory and self-healing capabilities means the potential to manufacture dynamic structures readily for a myriad of applications. The benefits of using multifunctional materials in 4D printing create opportunities for solutions in demanding environments including outer space, and extreme weather conditions where human intervention is not possible. The current progress of 4D printable smart materials and their stimuli-responsive capabilities are overviewed in this paper, including the discussion of shape-memory materials, metamaterials, and self-healing materials and their responses to thermal, pH, moisture, light, magnetic and electrical exposures. Potential applications of such systems have been explored to include advancements in health monitoring, electrical devices, deployable structures, soft robotics and tuneable metamaterials

Design and mechanical properties of 3D-printed auxetic honeycomb structure

The combination of theoretical calculations, computer simulations, and experimental evaluation of Poisson's ratio was carried out for re-entrant honeycomb auxetic structure. Optimal honeycomb cell parameters were determined for 3D-printed samples made from thermoplastic polyurethane (TPU). The low-cycle compression tests of 3D-printed re-entrant honeycomb auxetic samples showed that the structure based on auxetic hexagonal cell can withstand almost 1.75 times more very low cycle fatigue cycles than the similar non-auxetic structure. Neither failure nor layer delamination in 3D structures were detected in the auxetic sample after 500 compression cycles. 3D-printed auxetic structures offer a promising candidate for applications in medicine and sports