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.

Tracheal tissue engineering has been an alternative treatment for long-term tracheal stenosis due to the lack of donors and suitable tracheal implants. This work is meant to construct a novel hybrid tracheal support of synthetic and natural polymers using direct ink writing. A blend of polycaprolactone (PCL) and medical-grade polyurethane (PU) as synthetic material was used to fabricate tubular grafts. The synthetic graft was coated with various combinations of alginate (A) and gelatin (G) solutions using 3D printing to prepare hybrid tracheal scaffolds. The novelty in this method was the coating of the natural polymeric solution by extruding the solution over a rotating tubular graft by exploiting the advantages of 3D printing. The synthetic part has mechanical support, and the coated natural material has enhanced biological activities. Key assessments such as rheological investigations and printability studies were performed to characterize the flow behavior and fidelity of the printed constructs. Based on the above investigations, suitable combinations of alginate and gelatin (A/G) were chosen and used for further investigations. The effect of natural polymer coating using 3D printing over PCL/PU scaffold was carefully investigated using various physicochemical, morphological and mechanical investigations. Further, the hybrid tracheal scaffolds were evaluated for biological assessments such as proliferation, cytotoxicity and cell adhesion assay using human mesenchymal stem cells (hMSCs). The biological investigations showed that the coated scaffolds yielded improved biocompatibility compared to synthetic scaffolds and could be a potential tissue-engineered solution to tracheal regeneration.

The worldwide incidence of bone disorders has trended steeply upward and is expected to get doubled by 2030. The biological mechanism of bone repair involves both osteoconductivity and osteoinductivity. Despite the self-healing functionality after injury, bone tissue faces a multitude of pathological challenges. Several innovative approaches have been developed to prepare biomaterial-based bone grafts. To design a suitable bone material, the freeze-drying technique has achieved significant importance among the other conventional methods. However, the functionality of the polymeric freeze-dried scaffold in in-vivo osteogenesis is in a nascent stage. In this study facile, freeze-dried, biomaterial-based load-bearing three-dimensional porous composite scaffolds have been prepared. The biocompatible scaffolds have been made by using chitosan (C), polycaprolactone (P), hydroxyapatite (H), glass ionomer (G), and graphene (gr). Scaffolds of eight different groups (C, P, CP, CPH, CPHG, CPHGgr1, CPHGgr2, CPHGgr3) have been designed and characterized to evaluate their applicability in orthopedics. To evaluate the efficacy of the scaffolds a series of physio-chemical, morphological, and in-vitro and in-vivo biological experiments have been performed. From the obtained results it was observed that the CPHGgr1 is the ideal compatible material for Wharton’s jelly-derived mesenchymal stem cells (MSCs) and the blood cells. The in-vitro bone-specific gene expression study revealed that the scaffold assists MSCs osteogenic differentiation. Additionally, the in-vivo study on the mice model was also performed for a period of four and eight weeks. The subcutaneous implantation of the designed scaffolds did not show any altered physiological condition in the animals, which indicated the in-vivo biocompatibility of the designed material. The histopathological study revealed that after eight weeks of implantation, the CPHGgr1 scaffold supported significantly better collagen deposition and calcification. The facile designing of the CPHGgr1 multicomponent nanocomposite provided an osteo-regenerative biomaterial with desired mechanical strength as an ideal regenerative material for cancellous bone tissue regeneration.

Objectives: The benefits of physical activity during and after pregnancy are well established. However, activity levels decline substantially in both inactive and active women. There is limited information on the barriers and facilitators for physical activity participation in active women, which is vital for the development of tailored interventions. The primary aim of this study is to identify the barriers and facilitators for physical activity (PA) in already active women during pregnancy and postpartum. We also explore their views on, and requirements for, the development of an intervention to support maintenance of or increase in physical activity.

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$$ \mathrm{PCL} $$) and polyurethane (PU$$ \mathrm{PU} $$) 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$$ \mathrm{PCL}/\mathrm{PU} $$. 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$$ \mathrm{PU} $$ with PCL$$ \mathrm{PCL} $$ 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, PCL70/PU30$$ \mathrm{PCL}70/\mathrm{PU}30 $$ of spiral-shaped scaffolds could be a suitable candidate for the development of tracheal regenerative applications.

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.

Background – Activity levels decline substantially in both inactive and active women during pregnancy and postpartum. There is limited information on the barriers and facilitators for physical activity participation in active women during this period. The primary aim of this study is to identify the barriers and facilitators for physical activity in already active women during pregnancy and postpartum. We also explore their views on, and requirements for, the development of an intervention to support the maintenance of or increase in physical activity. Methods - Five focus groups, with a total of 19 participants, were conducted. Transcripts were analysed using a thematic analysis approach. Results – Out of the 19 participants, four were postpartum, and 15 were pregnant. Analysing the focus group transcripts, 22 codes were generated and grouped into eight themes: 1-cognizant of physical activity’s benefits, 2-sources of advice, 3-reasons to be active during pregnancy, 4-reasons for reducing physical activity levels during pregnancy, 5-barriers to physical activity during and after pregnancy, 6-facilitators of physical activity during and after pregnancy, 7-ideal physical activity intervention, and 8-evaluation support. Conclusions – Among already active pregnant and postpartum women, factors such as pregnancy-related body changes, childcare and lack of targeted activities deter participation in physical activity. A new programme with social and group elements, including both familiar and new activities, and providing ‘satisfaction and fun’ should be developed to help increase or maintain their activity levels.