Antibacterial Electrospun Polycaprolactone Membranes Coated with Polysaccharides and Silver Nanoparticles for Guided Bone and Tissue Regeneration

Electrospun polycaprolactone (PCL) membranes have been widely explored in the literature as a solution for several applications in tissue engineering and regenerative medicine. PCL hydrophobicity and its lack of bioactivity drastically limit its use in the medical field. To overcome these drawbacks, many promising strategies have been developed and proposed in the literature. In order to increase the bioactivity of electrospun PCL membranes designed for guided bone and tissue regeneration purposes, in the present work, the membranes were functionalized with a coating of bioactive lactose-modified chitosan (CTL). Since CTL can be used for the synthesis and stabilization of silver nanoparticles, a coating of this compound was employed here to provide antibacterial properties to the membranes. Scanning electron microscopy imaging revealed that the electrospinning process adopted here allowed us to obtain membranes with homogeneous fibers and without defects. Also, PCL membranes retained their mechanical properties after several weeks of aging in simulated body fluid, representing a valid support for cell growth and tissue development. CTL adsorption on membranes was investigated by fluorescence microscopy using fluorescein-labeled CTL, resulting in a homogeneous and slow release over time. Inductively coupled plasma-mass spectrometry was used to analyze the release of silver, which was shown to be stably bonded to the CTL coating and to be slowly released over time. The CTL coating improved MG63 osteoblast adhesion and proliferation on membranes. On the other hand, the presence of silver nanoparticles discouraged biofilm formation by Pseudomonas aeruginosa and Staphylococcus aureus without being cytotoxic. Overall, the stability and the biological and antibacterial properties make these membranes a valid and versatile material for applications in guided tissue regeneration and in other biomedical fields like wound healing.

A Critical Review on the Production of Electrospun Nanofibres for Guided Bone Regeneration in Oral Surgery

Nanofibre-based membranes or scaffolds exhibit high surface-to-volume ratio, which allows an improved cell adhesion, representing an attractive subgroup of biomaterials due to their unique properties. Among several techniques of nanofiber production, electrospinning is a cost-effective technique that has been, to date, attractive for several medical applications. Among these, guided bone regeneration is a surgical procedure in which bone regeneration, due to bone atrophy following tooth loss, is "guided" by an occlusive barrier. The membrane should protect the initial blood clot from any compression, shielding the bone matrix during maturation from infiltration of soft tissues cells. This review will focus its attention on the application of electrospinning (ELS) in oral surgery bone regeneration. Despite the abundance of published papers related to the electrospinning technique applied in the field of bone regeneration of the jaws, to the authors' knowledge, no articles report clinical application of these structures. Moreover, only a few records can be found with in vivo application. Therefore, no human studies have to date been detectable. New approaches such as multifunctional multilayering and coupling with bone promoting factors or antimicrobial agents, makes this technology very attractive. However, greater efforts should be made by researchers and companies to turn these results into clinical practice.

* Engineering Membranes for Bone Regeneration

This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess to improve the regeneration of bone. Afterward, several techniques to engineer bone membranes by using "bulk"-like methods are discussed, where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach is discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible, the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties, or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.

Enhanced Osteogenesis of ADSCs by the Synergistic Effect of Aligned Fibers Containing Collagen I

The topographical features and material composition of scaffolds have a powerful influence on cell behaviors such as proliferation and differentiation. Here, scaffolds consisting of aligned fibers with incorporated bioactive collagen I were tested for their ability to enhance osteogenesis in vitro. Rat adipose-derived mesenchymal stem cells (ADSCs) were seeded on the scaffolds and their morphology, proliferation, and osteogenic differentiation were examined. Aligned scaffolds with collagen I showed the best osteogenic properties. Also, adhesion-related genes showed the higher expression on aligned scaffolds with collagen I. Our findings indicate that fiber alignment combined with incorporation of collagen I increases the capacity of electrospun scaffolds to induce enhanced and directed osteogenesis. Such scaffolds may, therefore, have potential for improving guided oral bone regeneration.

Enhancement of stem cell differentiation to osteogenic lineage on hydroxyapatite-coated hybrid PLGA/gelatin nanofiber scaffolds

A combination of polymeric materials and bioceramics has recently received a great deal of attention for bone tissue engineering applications. In the present study, hybrid nanofibrous scaffolds were fabricated from PLGA and gelatin via electrospinning and then were coated with hydroxyapatite (HA). They were then characterized and used in stem cell culture studies for the evaluation of their biological behavior and osteogenic differentiation in vitro. This study showed that all PLGA, hybrid PLGA/gelatin and HA-PLGA/gelatin scaffolds were composed of ultrafine fibers with smooth morphology and interconnected pores. The MTT assay confirmed that the scaffolds can support the attachment and proliferation of stem cells. During osteogenic differentiation, bone-related gene expression, ALP activity and biomineralization on HA-PLGA/gelatin scaffolds were higher than those observed on other scaffolds and TCPS. PLGA/gelatin electrospun scaffolds also showed higher values of these markers than TCPS. Taking together, it was shown that nanofibrous structure enhanced osteogenic differentiation of adipose-tissue derived stem cells. Furthermore, surface-coated HA stimulated the effect of nanofibers on the commitment of stem cells toward osteolineage. In conclusion, HA-PLGA/gelatin electrospun scaffolds were demonstrated to have significant potential for bone tissue engineering applications.

In vitro and in vivo evaluation of the wound healing capability of electrospun gelatin/PLLCL nanofibers

Recent progress in tissue-engineered skin grafts has alleviated the demand for autologous split thickness skin grafts for treatment of large skin wounds. In this study, a series of cost-effective nanofibrous scaffolds aimed at full-thickness wound healing are fabricated by blending gelatin (Gel) with poly(l-lactic acid)-b-poly( ε-caprolactone) (PLLCL) and electrospun to obtain composite Gel/PLLCL nanofibers in four different weight ratios (w/w) of 80:20 [Gel/PLLCL(20)], 70:30 [Gel/PLLCL(30)], 60:40 [Gel/PLLCL(40)], and 50:50 [Gel/PLLCL(50)]. The mechanical properties of these nanofibrous scaffolds were evaluated in both dry and wet conditions, and the Gel/PLLCL(40) retained suitable tensile stress (1.16 ± 0.03 MPa) to be handled even in wet conditions. Moreover, the proliferations of fibroblast cells on Gel/PLLCL(40) were 15%, 7% and 10% higher compared to cell proliferations on Gel/PLLCL(20), Gel/PLLCL(30), and Gel/PLLCL(50), respectively. In vitro results confirmed Gel/PLLCL(40) as the optimized scaffold composition suitable for skin tissue engineering. The healing ability of this scaffold was studied in vivo using mouse models. The Gel/PLLCL(40) greatly accelerated wound closure and regeneration occurring in the first 10 days of implantation compared to the control group. In addition, newly regenerated epidermis was only found in the nanofibrous scaffolds–treated group, and it was comparable to the epidermis of normal skin.