Advances in electrospun nanofibers for bone and cartilage regeneration.

Regeneration of bone and cartilage tissues has been an important issue for biological repair in the field of regenerative medicine. The rapidly emerging field of tissue engineering holds great promise for repair and generation of functional bone and cartilage substitutes with a combination of biomaterials, cells, drugs and growth factors. Scaffolds play a pivotal role in tissue engineering as they mimic the natural extracellular matrix (ECM) and play an important role in guiding cell adhesion and proliferation, and maintaining the normal phenotype of the tissues. The use of tissue-engineered grafts based on scaffolds has found to be a more effective method than conventional implantations of autograft, allograft, xenograft. In recent years much attention has been given to electrospinning as a feasible and versatile technique for fabrication of nanofibrous scaffolds, with large surface area to volume ratio, high porosity, mechanical properties and physical dimension similar to the ECM of natural tissues. Extensive research has been carried out for fabrication polymeric nanofibrous substrates with incorporation of hydroxyapatite nanoparticles or bone morphogenetic protein molecules for efficient tissue repair. Here we review on the literature of electrospun nanofibrous scaffolds, their modifications, and advances aimed towards the rapid regeneration of bone and cartilage.

Bioactive glasses and glass-ceramics versus hydroxyapatite: Comparison of angiogenic potential and biological responsiveness.

Different bioactive glasses (BGs), bioceramics, and their composites were extensively analyzed in terms of biological responsiveness and angiogenic potential. In particular several inorganic materials were considered, namely the widely used 45S5 BG, an experimental BG with low tendency to crystallize, other three experimental BGs doped with strontium and/or magnesium, a commercial hydroxyapatite (HA), and two BG-HA composites (with varying percentages of BG and HA). All these materials were ad hoc prepared and in vitro tested by means of an extensive biological analysis, such as MC3T3-E1 cell viability and proliferation by direct contact assay, alkaline phosphatase activity, mineralized matrix deposition analysis by alizarin red staining, as well as evaluation of angiogenic potential and vascular endothelial growth factor release using ST2 cells. Thus, this investigation allows gaining a deeper insight into the biological performance of different inorganic material categories, and to critically compare the different possible solutions, as bone/tissue substitutes for enhanced healing and repair, in terms of bioactivity and regenerative potential.

Ag modified mesoporous bioactive glass nanoparticles for enhanced antibacterial activity in 3D infected skin model.

Bioactive glasses (BG) are versatile materials for various biomedical applications, including bone regeneration and wound healing, due to their bone bonding, antibacterial, osteogenic, and angiogenic properties. In this study, we aimed to enhance the antibacterial activity of SiO2-CaO mesoporous bioactive glass nanoparticles (MBGN) by incorporating silver (Ag) through a surface modification approach. The modified Ag-containing nanoparticles (Ag-MBGN) maintained spherical shape, mesoporous structure, high dispersity, and apatite-forming ability after the surface functionalization. The antibacterial activity of Ag-MBGN was assessed firstly using a planktonic bacteria model. Moreover, a 3D tissue-engineered infected skin model was used for the first time to evaluate the antibacterial activity of Ag-MBGN at the usage dose of 1 mg/mL. In the planktonic bacteria model, Ag-MBGN exhibited a significant antibacterial effect against both Pseudomonas aeruginosa and Staphylococcus aureus in comparison to non-engineered (Ag-free) MBGN and the blank control. Moreover, Ag-MBGN did not show cytotoxicity towards fibroblasts at the usage dose. However, in the 3D infected skin model, Ag-MBGN only demonstrated antibacterial activity against S. aureus whereas their antibacterial action against P. aeruginosa was inhibited. In conclusion, surface modification by Ag incorporation is a feasible approach to enhance the antibacterial activity of MBGN without significantly impacting their morphology, polydispersity, and apatite-forming ability. The prepared Ag-MBGN are attractive building blocks for the development of 3D antibacterial scaffolds for tissue engineering.

Micro-Computed-Tomography-Guided Analysis of In Vitro Structural Modifications in Two Types of 45S5 Bioactive Glass Based Scaffolds.

Three-dimensional 45S5 bioactive glass (BG)-based scaffolds are being investigated for bone regeneration. Besides structural properties, controlled time-dependent alteration of scaffold morphology is crucial to achieve optimal scaffold characteristics for successful bone repair. There is no in vitro evidence concerning the dependence between structural characteristics and dissolution behavior of 45S5 BG-based scaffolds of different morphology. In this study, the dissolution behavior of scaffolds fabricated by the foam replica method using polyurethane foam (Group A) and maritime sponge Spongia Agaricina (Group B) as sacrificial templates was analyzed by micro-computed-tomography (µCT). The scaffolds were immersed in Dulbecco's Modified Eagle Medium for 56 days under static cell culture conditions and underwent µCT-analysis initially, and after 7, 14, and 56 days. Group A showed high porosity (91%) and trabecular structure formed by macro-pores (average diameter 692 µm ± 72 µm). Group-B-scaffolds were less porous (51%), revealing an optimal pore size distribution within the window of 110-500 µm pore size diameter, combined with superior mechanical stability. Both groups showed similar structural alteration upon immersion. Surface area and scaffold volume increased whilst density decreased, reflecting initial dissolution followed by hydroxycarbonate-apatite-layer-formation on the scaffold surfaces. In vitro- and/or in vivo-testing of cell-seeded BG-scaffolds used in this study should be performed to evaluate the BG-scaffolds' time-dependent osteogenic properties in relation to the measured in vitro structural changes.

Posterior Iris Fixated Intraocular Lens for Pediatric Traumatic Cataract.

PURPOSE: To evaluate the postoperative visual outcomes and complications of posterior iris fixated intraocular lens (IFIOL) implantation for pediatric traumatic cataract. METHODS: A retrospective clinical audit was performed of all the pediatric traumatic cataract patients who underwent lens removal and iris fixated lens implantation due to inadequate capsular support with or without corneal tear repair between January 2009 and December 2013. Data were collected and analyzed on the preoperative and postoperative visual outcomes and complications. RESULTS: Twenty-five children (25 eyes; 21 males and 4 females) were enrolled with the mean age of 11 ± 4.0 years. There were 72% of eyes that underwent primary cataract removal with IFIOL implantation. Twenty-eight percent of eyes underwent corneal tear repair prior to intraocular lens (IOL) implantation. Preoperative best corrected visual acuity (BCVA) was hand motion in 32% eyes, counting fingers in 24%, and perception of light in 44%. Postoperative BCVA of 0-0.2 logarithm of minimum angle of resolution was reported in the 64% of eyes. One eye developed secondary glaucoma, one eye underwent re-enclavation, and none developed retinal complications. CONCLUSION: Posterior IFIOL implantation resulted in an improved visual outcome, low incidence of postoperative complications, and is a good alternative to other IOL, in the cases of pediatric traumatic cataract without adequate capsular support.

Iris-claw versus posterior chamber fixation intraocular lens implantation in pediatric traumatic cataract.

AIM: This study aims to compare visual outcomes and complications of iris-fixated (claw) intraocular lens (IFIOL) implantation with those of posterior chamber intraocular lens (PCIOL) implantation in children with traumatic cataract. SETTINGS AND DESIGN: Retrospective observational clinical audit. MATERIALS AND METHODS: A total of 50 pediatric traumatic cataract cases that underwent lens removal and IOL implantation (IFIOL or PCIOL) with or without corneal or corneoscleral tear repair between January 2009 and December 2013 were analyzed. After meeting the eligibility criteria, their pre- and postoperative visual outcomes and complication rates were recorded. Data were analyzed descriptively. RESULTS: Out of 50 children, IFIOL and PCIOL implantations were performed in one eye of each of 25 children. Their mean age was 11 ± 4 years (range 4-18 years). Primary (cataract removal with lens implantation) and secondary (corneal tear repair followed by cataract removal with lens implantation) procedures were performed in 19 (76%) and six (24%) children in the IFIOL group and in 21 (84%) and four (16%) children in the PCIOL group, respectively. There was an improvement in best corrected visual acuity postimplantation in both the IFIOL and the PCIOL group, and no significant difference in the logarithm of the minimum angle of resolution of best corrected visual acuity was observed between the two groups over 36 months. Only three eyes in the IFIOL group developed complications: one eye developed secondary glaucoma, one disenclavation of IOL haptic, and one cystoid macular edema. CONCLUSION: Both IFIOL and PCIOL implantations have good visual outcomes and minimal postoperative complications; therefore, IFIOL can be used as an alternative to PCIOL in children with traumatic cataract with inadequate capsular support.

Human cardiomyocyte interaction with electrospun fibrinogen/gelatin nanofibers for myocardial regeneration.

Myocardial infarction is the major cause of death in many industrialized nations as it leads to end-stage heart failure. Tissue engineering (TE) approaches for treatment of the infarcted tissue have gained huge attention over the recent years and research in this direction mainly aims for the optimization of a biomaterial scaffold with suitable cell source for tissue regeneration. In this regard, we fabricated completely natural polymeric scaffolds using fibrinogen and gelatin in two different weight ratios and performed cross-linking [Fib/Gel(1:4)-CL; Fib/Gel(2:3)-CL] while cross-linked fibrinogen scaffolds were used as the control. The fiber diameters of the fabricated scaffolds were obtained in the range of 150-300 nm. Chemical characterization of the scaffolds confirmed the presence of both the proteins and showed the absence of any chemical reactions between them. The tensile strength and the stiffness values of Fib/Gel(1:4)-CL matrices were found to be 0.0125 and 0.46 MPa, respectively, which were much similar to the innate properties of the native myocardium. Cell culture studies using human cardiomyocytes revealed higher cell proliferation on Fib/Gel(1:4)-CL scaffolds compared to cell proliferation on Fib/Gel(2:3)-CL scaffolds, which was even higher than the cell proliferation on cross-linked fibrinogen scaffolds. Moreover, the cardiomyocytes seeded on composite substrates expressed the typical functional cardiac proteins such as alpha-actinin, troponin I, connexin-43, and myosin heavy chain, and could be potential for application in cardiac TE.