Daikelly Iglesias Braghirolli

Electrospinning for regenerative medicine: a review of the main topics

Electrospun fibers are promising tissue engineering scaffolds that offer the cells an environment that mimics the native extracellular matrix. Fibers with different characteristics can be produced by the electrospinning technique according to the needs of the tissue to be repaired. In this review, the process of electrospinning was examined, providing a description of the common techniques used for the physicochemical and biological characterization of electrospun fibers. The review also discusses the potential applications of electrospun scaffolds for tissue engineering, based on scientific literature.

The effect of sterilization methods on electronspun poly(lactide‐co‐glycolide) and subsequent adhesion efficiency of mesenchymal stem cells

The sterilization of scaffolds is an essential step for tissue engineering in vitro and, mainly, clinical biomaterial use. However, this process can cause changes in the structure and surface of the scaffolds. Therefore, the objective of this study was to investigate the effect of sterilization by ethanol, ultraviolet radiation (UVR) or antimicrobial solution (AMS) on poly(lactide-co-glycolide) (PLGA) scaffolds produced by the electrospinning technique. The properties of nanofibers and the cellular adhesion of mesenchymal stem cells to the scaffolds were analyzed after the treatments. All methods generated sterile scaffolds but showed some kind of damage to the scaffolds. Ethanol and AMS caused changes in the morphology and scaffold dimensions, which were not observed when using the UVR method. However, UVR caused a greater reduction in polymeric molecular weight, which increased proportionally with exposure time of treatment. Nanofibers sterilized with AMS for 1 h and 2 h showed greater cellular adhesion than the other methods, demonstrating their potential as a method for sterilizing PLGA nanofibers.

Viability of mesenchymal stem cells during electrospinning

Tissue engineering is a technique by which a live tissue can be re-constructed and one of its main goals is to associate cells with biomaterials. Electrospinning is a technique that facilitates the production of nanofibers and is commonly used to develop fibrous scaffolds to be used in tissue engineering. In the present study, a different approach for cell incorporation into fibrous scaffolds was tested. Mesenchymal stem cells were extracted from the wall of the umbilical cord and mononuclear cells from umbilical cord blood. Cells were re-suspended in a 10% polyvinyl alcohol solution and subjected to electrospinning for 30 min under a voltage of 21 kV. Cell viability was assessed before and after the procedure by exclusion of dead cells using trypan blue staining. Fiber diameter was observed by scanning electron microscopy and the presence of cells within the scaffolds was analyzed by confocal laser scanning microscopy. After electrospinning, the viability of mesenchymal stem cells was reduced from 88 to 19.6% and the viability of mononuclear cells from 99 to 8.38%. The loss of viability was possibly due to the high viscosity of the polymer solution, which reduced the access to nutrients associated with electric and mechanical stress during electrospinning. These results suggest that the incorporation of cells during fiber formation by electrospinning is a viable process that needs more investigation in order to find ways to protect cells from damage.

Association of electrospinning with electrospraying: a strategy to produce 3D scaffolds with incorporated stem cells for use in tissue engineering.

In tissue engineering, a uniform cell occupation of scaffolds is crucial to ensure the success of tissue regeneration. However, this point remains an unsolved problem in 3D scaffolds. In this study, a direct method to integrate cells into fiber scaffolds was investigated by combining the methods of electrospinning of fibers and bioelectrospraying of cells. With the associating of these methods, the cells were incorporated into the 3D scaffolds while the fibers were being produced. The scaffolds containing cells (SCCs) were produced using 20% poly(lactide-co-glycolide) solution for electrospinning and mesenchymal stem cells from deciduous teeth as a suspension for bioelectrospraying. After their production, the SCCs were cultivated for 15 days at 37°C with an atmosphere of 5% CO2. The 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide test demonstrated that the cells remained viable and were able to grow between the fibers. Scanning electron microscopy showed the presence of a high number of cells in the structure of the scaffolds and confocal images demonstrated that the cells were able to adapt and spread between the fibers. Histological analysis of the SCCs after 1 day of cultivation showed that the cells were uniformly distributed throughout the thickness of the scaffolds. Some physicochemical properties of the scaffolds were also investigated. SCCs exhibited good mechanical properties, compatible with their handling and further implantation. The results obtained in the present study suggest that the association of electrospinning and bioelectrospraying provides an interesting tool for forming 3D cell-integrated scaffolds, making it a viable alternative for use in tissue engineering.

Nanofiber Scaffolds Support Bone Regeneration Associated with Pulp Stem Cells

Currently, there are a number of alternatives for bone grafting, though when used correctly they present physical, chemical or biological limitations, which justifies the pursuit for new alternatives for bone regeneration. This study gives a report on the potential for bone regeneration in the use of biodegradable nanofibers from poly (lactic-co-glycolic acid) (PLGA) in association with human mesenchymal stem cells from dental pulp of deciduous teeth (SCDT). Five samples of SCDT were seeded with scaffolds (test) or without scaffolds (control) for cell adhesion and viability assay. To evaluate the ability of the association in promoting bone formation, critical defects were made in the calvarium of rats (n=20), which were then divided into the following groups: I--sham group; II--implant of scaffolds; III--scaffolds/ SCDT; and IV--scaffolds/SCDT. They were kept for 13 days in osteogenic media. After 60 days, the histomorphometric analysis was performed. It was observed that the adherence and viability of SCDT in the control and test group were similar throughout the experiment (p>0.05). The association of scaffolds/SCDT maintained in osteogenic media, showed greater bone formation than the other groups (p<0.05). The study demonstrated that the association of SCDT seeded in biodegradable PLGA scaffolds has the ability to promote bone regeneration in rats, which is a promising alternative for application in regenerative medicine.

Update on the main use of biomaterials and techniques associated with tissue engineering

Regenerative medicine involves the study of cells, signaling cues and biomatrices to restore normal function of tissues and organs. To develop the matrices for use in tissue engineering there are three main groups of biomaterials: (i) naturally derived materials; (ii) synthetic polymers; and (iii) decellularized organ or tissue scaffolds. These biomaterials, in various forms such as hydrogels, nanofibers and 3D scaffolds, among others, have been employed for different tissue regeneration purposes, with several techniques involved in their production, including rapid prototyping, tissue decellularization and electrospinning. In this review, the main topics of hydrogels, 3D printing and electrospun scaffolds, other biomaterials and decellularization and recellularization will be discussed.

Mesenchymal stem cells and nanofibers as scaffolds for the regeneration of thyroid cartilage.

The aim of this study has been to establish an alternative approach in the form of regeneration of the thyroid cartilage.

Evaluation of semi-automated cells counting in peritoneal fluid

Introduction:Currently, the cytological analysis of biological fluids, such as peritoneal fluid, is performed by manually cells counting in Fuchs-Rosenthal chamber. However, this method has a number of limitations. Because of these limitations, automatic counters have been evaluated for cell counting in this type of sample in order to make it faster and more reliable test.Objective:The aim of this study is to compare the manual and semi-automated leukocytes and erythrocytes counting in peritoneal fluid.Materials and methods:The samples were analyzed manually and using the CountessTM(Invitrogen).Results:The results showed that although there is a correlation between the two counting methods, the correlation is relatively low, for both leukocytes and erythrocytes analysis.Conclusion:The results suggest that peritoneal fluid should continue to be analyzed in Fuchs-Rosenthal chamber. However, further studies should be conducted with a greater number of samples to investigate the possibility of using automated cells counting in serous fluids and, thus, provide greater speed and quality of results.