Recent advances in tailoring stimuli-responsive hybrid scaffolds for cardiac tissue engineering and allied applications.

To recapitulate bio-physical properties and functional behaviour of native heart tissues, recent tissue engineering-based approaches are focused on developing smart/stimuli-responsive materials for interfacing cardiac cells. Overcoming the drawbacks of the traditionally used biomaterials, these smart materials portray outstanding mechanical and conductive properties while promoting cell-cell interaction and cell-matrix transduction cues in such excitable tissues. To date, a large number of stimuli-responsive materials have been employed for interfacing cardiac tissues alone or in combination with natural/synthetic materials for cardiac tissue engineering. However, their comprehensive classification and a comparative analysis of the role played by these materials in regulating cardiac cell behaviour and in vivo metabolism are much less discussed. In an attempt to cover the recent advances in fabricating stimuli-responsive biomaterials for engineering cardiac tissues, this review details the role of these materials in modulating cardiomyocyte behaviour, functionality and surrounding matrix properties. Furthermore, concerns and challenges regarding the clinical translation of these materials and the possibility of using such materials for the fabrication of bio-actuators and bioelectronic devices are discussed.

A facile 3D bio-fabrication of customized tubular scaffolds using solvent-based extrusion printing for tissue-engineered tracheal grafts.

Tracheal implantation remains a major therapeutic challenge due to the unavailability of donors and the lack of biomimetic tubular grafts. Fabrication of biomimetic tracheal scaffolds of suitable materials with matched rigidity, enhanced flexibility and biocompatibility has been a major challenge in the field of tracheal reconstruction. In this study, customized tubular grafts made up of FDA-approved polycaprolactone ( PCL ) and polyurethane ( PU ) were fabricated using a novel solvent-based extrusion 3D printing. The printed scaffolds were investigated by various physical, thermal, and mechanical characterizations such as contact angle measurement, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), radial compression, longitudinal compression, and cyclic radial compression. In this study, the native goat trachea was used as a reference for the fabrication of different types of scaffolds (cylindrical, bellow-shaped, and spiral-shaped). The mechanical properties of the goat trachea were also compared to find suitable formulations of PCL / PU . Spiral-shaped scaffolds were found to be an ideal shape based on longitudinal compression and torsion load maintaining clear patency. To check the long-term implantation, in vitro degradation test was performed for all the 3D printed scaffolds and it was found that blending of PU with PCL reduced the degradation behavior. The printed scaffolds were further evaluated for biocompatibility assay, live/dead assay, and cell adhesion assay using bone marrow-derived human mesenchymal stem cells (hMSCs). From biomechanical and biological assessments, PCL 70 / PU 30 of spiral-shaped scaffolds could be a suitable candidate for the development of tracheal regenerative applications.

Virology of SARS-CoV-2 and management of nCOVID-19 utilizing immunomodulation properties of human mesenchymal stem cells-a literature review.

OBJECTIVE: The objective of this review article is to outline the pathology, virology and mechanism of severe acute respiratory syndrome-corona virus-2 (SARS-CoV-2) and to study the regenerative role of mesenchymal stem cells (MSCs) to tackle the lung damage caused by SARS-CoV-2. BACKGROUND: The MSCs possess trophic potentialities which enable them to find out the sites of injury or inflammation and because of their pleiotropic and pericytic nature, these cells are capable of differentiating into different cell types. The MSCs can be derived from a variety of tissue sources be it adult or embryonic origin. The one major characteristic of MSCs is that they are immunologically naïve in terms of expression of MHC Class II. This very low or no expression of MHC class II makes them useful in clinical settings where they can be used in allogenic transplant cases. This allogenic transplant possibilities of these MSCs makes them one of the most researched stem cells and investigated for cell-based therapies. Though these MSCs are in clinical settings for long the one even more important characteristic which makes them even more in demand is their immunomodulatory properties which have been used in various cases to mitigate the effect of overstimulation of the immune system. In recent times after the pandemic of the novel corona virus disease 2019 (nCOVID-19) generated by SARS-CoV-2, the effect of various MSCs isolated from various tissue sources are being utilized to curb the overstimulation of immune response, so that the immune system can be brought under some regulation to ultimately reduce the effect of inflammation. METHODS: In this review article, we have reviewed the existing literature, data and ongoing clinical trials by using keywords like novel coronavirus, COVID-19, SARS-CoV-2, MERS-CoV, acute respiratory distress syndrome, mesenchymal stem cells, immunomodulation properties of stem cells, regenerative properties of stem cells, cell therapy, clinical trials of stem cells, clinical trials of COVID-19 and stem cells till 20th August 2020 using database named PubMed, NCBI, Google Scholar, Scopus, Research Gate and Clinicaltrials.gov. CONCLUSIONS: Thus, concluding the therapeutic potential of MSCs in managing and treating COVID-19.