Microstructural, mechanical, and histological evaluation of modified alginate-based scaffolds

Fabrication of hybrid scaffolds obtained from combinations of PCL with gelatin or collagen via electrospinning for skeletal muscle tissue engineering

The creation of skeletal muscle tissue in vitro is a major topic of interest today in the field of biomedical research, due to the lack of treatments for muscle loss due to traumatic accidents or disease. For this reason, the intrinsic properties of nanofibrillar structures to promote cell adhesion, proliferation, and cell alignment presents an attractive tool for regenerative medicine to recreate organized tissues such as muscle. Electrospinning is one of the processing techniques often used for the fabrication of these nanofibrous structures and the combination of synthetic and natural polymers is often required to achieve optimal mechanical and physiochemical properties. Here, polycaprolactone (PCL) is selected as a synthetic polymer used for the fabrication of scaffolds, and the effect of protein addition on the final scaffolds' properties is studied. Collagen and gelatin were the proteins selected and two different concentrations were analyzed (2 and 4 wt/vol%). Different PCL/protein systems were prepared, and a structural, mechanical and functional characterization was performed. The influence of fiber alignment on the properties of the final scaffolds was assessed through morphological, mechanical and biological evaluations. A bioreactor was used to promote cell proliferation and differentiation within the scaffolds. The results revealed that protein addition produced a decrease in the fiber size of the membranes, an increase in their hydrophilicity, and a softening of their mechanical properties. The biological study showed the ability of the selected systems to harbor cells, allow their growth and, potentially, develop musculoskeletal tissues.

Polymer-Based Scaffolds for Soft-Tissue Engineering

Biomaterials have been used since ancient times. However, it was not until the late 1960s when their development prospered, increasing the research on them. In recent years, the study of biomaterials has focused mainly on tissue regeneration, requiring a biomaterial that can support cells during their growth and fulfill the function of the replaced tissue until its regeneration. These materials, called scaffolds, have been developed with a wide variety of materials and processes, with the polymer ones being the most advanced. For this reason, the need arises for a review that compiles the techniques most used in the development of polymer-based scaffolds. This review has focused on three of the most used techniques: freeze-drying, electrospinning and 3D printing, focusing on current and future trends. In addition, the advantages and disadvantages of each of them have been compared.

Polymeric Carriers for Delivery Systems in the Treatment of Chronic Periodontal Disease

Periodontitis (PD) is a chronic inflammatory disease of periodontal tissues caused by pathogenic microorganisms and characterized by disruption of the tooth-supporting structures. Conventional drug administration pathways in periodontal disease treatment have many drawbacks such as poor biodistribution, low selectivity of the therapeutic effect, burst release of the drug, and damage to healthy cells. To overcome this limitation, controlled drug delivery systems have been developed as a potential method to address oral infectious disease ailments. The use of drug delivery devices proves to be an excellent auxiliary method in improving the quality and effectiveness in periodontitis treatment, which includes inaccessible periodontal pockets. This review explores the current state of knowledge regarding the applications of various polymer-based delivery systems such as hydrogels, liposomes, micro-, and nanoparticles in the treatment of chronic periodontal disease. Furthermore, to present a more comprehensive understanding of the difficulties concerning the treatment of PD, a brief description of the mechanism and development of the disease is outlined.

Cryostructuring of Polymeric Systems. 50.† Cryogels and Cryotropic Gel-Formation: Terms and Definitions

A variety of cryogenically-structured polymeric materials are of significant scientific and applied interest in various areas. However, in spite of considerable attention to these materials and intensive elaboration of their new examples, as well as the impressive growth in the number of the publications and patents on this topic over the past two decades, a marked variability of the used terminology and definitions is frequently met with in the papers, reviews, theses, patents, conference presentations, advertising materials and so forth. Therefore, the aim of this brief communication is to specify the basic terms and definitions in the particular field of macromolecular science.

Graphene Improves the Biocompatibility of Polyacrylamide Hydrogels: 3D Polymeric Scaffolds for Neuronal Growth

In tissue engineering strategies, the design of scaffolds based on nanostructures is a subject undergoing intense research: nanomaterials may affect the scaffolds properties, including their ability to interact with cells favouring cell growth and improving tissue performance. Hydrogels are synthetic materials widely used to obtain realistic tissue constructs, as they resemble living tissues. Here, different hydrogels with varying content of graphene, are synthesised by in situ radical polymerization of acrylamide in aqueous graphene dispersions. Hydrogels are characterised focusing on the contribution of the nanomaterial to the polymer network. Our results suggest that graphene is not a mere embedded nanomaterial within the hydrogels, rather it represents an intrinsic component of these networks, with a specific role in the emergence of these structures. Moreover, a hybrid hydrogel with a graphene concentration of only 0.2 mg mL-1 is used to support the growth of cultured brain cells and the development of synaptic activity, in view of exploiting these novel materials to engineer the neural interface of brain devices of the future. The main conclusion of this work is that graphene plays an important role in improving the biocompatibility of polyacrylamide hydrogels, allowing neuronal adhesion.

Cartilage suspension using a poly (lactic-co-glycolic) acid system

BACKGROUND

This study aims to determine whether a bar-like implant made of poly lactic-co-glycolic acid (PLGA) could be used for cartilage suspension and whether the implant would be suitable for rhinoplasty.

METHODS

Three types of in vivo animal experiments were performed. First, the ear cartilage was incised in a full-thickness pattern, and the PLGA system was placed between the upper and lower cartilage to offer support to the tissue. Second, after the ear cartilage was forcibly bent, an implant was placed in the cartilage. For these rabbits, the outer aspect of the ear cartilage was assessed at 2, 4, 8, 10, and 12 weeks postoperatively. In addition, tissue samples were collected for histological evaluation 12 weeks after surgery. Third, the bar-like nasal implant was used for nasal septal suspension. We obtained micro-computed tomography (CT) images and evaluated the inflammatory reaction at 12 weeks postoperatively.

RESULTS

The results of both the ear suspension and bending retention tests revealed that the characteristic shapes of the cartilage were well preserved at 12 weeks postoperatively. Moreover, no abnormal inflammatory reaction was present in any site in the experimental group. We successfully implanted the bar-like nasal implant in the rabbit's septum, and no complications occurred. Furthermore, the physical examination and the micro-CT images did not reveal any nasal obstruction or inflammation.

CONCLUSIONS

We confirmed that an implant made of PLGA can be maintained in the cartilage tissue and believe that this can be applied in rhinoplasty as an alternative to autologous cartilage.