Clinical Applications of Additive Manufacturing Models in Neurosurgery: a Systematic Review

Introduction Three-dimensional (3D) printing technologies provide a practical and anatomical way to reproduce precise tailored-made models of the patients and of the diseases. Those models can allow surgical planning, besides training and surgical simulation in the treatment of neurosurgical diseases. Objective The aim of the present article is to review the scenario of the development of different types of available 3D printing technologies, the processes involved in the creation of biomodels, and the application of those advances in the neurosurgical field. Methods We searched for papers that addressed the clinical application of 3D printing in neurosurgery on the PubMed, Ebsco, Web of Science, Scopus, and Science Direct databases. All papers related to the use of any additive manufacturing technique were included in the present study. Results Studies involving 3D printing in neurosurgery are concentrated on three main areas: (1) creation of anatomical tailored-made models for planning and training; (2) development of devices and materials for the treatment of neurosurgical diseases, and (3) biological implants for tissues engineering. Biomodels are extremely useful in several branches of neurosurgery, and their use in spinal, cerebrovascular, endovascular, neuro-oncological, neuropediatric, and functional surgeries can be highlighted. Conclusions Three-dimensional printing technologies are an exclusive way for direct replication of specific pathologies of the patient. It can identify the anatomical variation and provide a way for rapid construction of training models, allowing the medical resident and the experienced neurosurgeon to practice the surgical steps before the operation.

Mesenchymal stromal exosome–functionalized scaffolds induce innate and adaptive immunomodulatory responses toward tissue repair

Designing scaffolds capable of inducing and guiding appropriate immune responses holds promise for tissue repair/regeneration. Biofunctional scaffolds were here prepared by immobilizing mesenchymal stromal exosomes onto fibrous polyester materials and allowed cell-mediated delivery of membrane-bound vesicles. Quantitative cell-level analyses revealed that immune cells dominated the uptake of exosomes from scaffolds in vivo, with materials and exosomes acting as the recruiter and trainer for immune cells, respectively, to synergistically promote beneficial macrophage and regulatory T cell responses in skin wounds in mice. Adaptive T helper cell responses were found active in remote immune organs, and exosome-laden scaffolds facilitated tissue repair in large skin injury models. This study demonstrated important mechanisms involved in local and systemic immune responses to biological implants, and understanding tissue-reparative immunomodulation may guide the design of new biofunctional scaffolds.

Metallic Glasses and Their Composites

Metallic glasses and their crystal/glass composites find ever more applications in such fields as mini transformers, microelectromechanical devices, pressure sensors, precision surgical instruments, biological implants and sportive goods (springs, diaphragms, membranes, knife blades, electromagnetic wave shields, optical mirrors, power inductors, Coriolis flow meters, etc.). The book reviews recent research and suggests future developments, e.g. in the area of dual-phase composite/hybrid materials.

Influence of Laminin Coating on the Autologous In Vivo Recellularization of Decellularized Vascular Protheses

Decellularization of non-autologous biological implants reduces the immune response against foreign tissue. Striving for in vivo repopulation of aortic prostheses with autologous cells, thereby improving the graft biocompatibility, we examined surface coating with laminin in a standardized rat implantation model. Detergent-decellularized aortic grafts from donor rats (n = 37) were coated with laminin and systemically implanted into Wistar rats. Uncoated implants served as controls. Implant re-colonization and remodeling were examined by scanning electron microscopy (n = 10), histology and immunohistology (n = 18). Laminin coating persisted over eight weeks. Two weeks after implantation, no relevant neoendothelium formation was observed, whereas it was covering the whole grafts after eight weeks, with a significant acceleration in the laminin group (p = 0.0048). Remarkably, the intima-to-media ratio, indicating adverse hyperplasia, was significantly diminished in the laminin group (p = 0.0149). No intergroup difference was detected in terms of medial recellularization (p = 0.2577). Alpha-smooth muscle actin-positive cells originating from the adventitial surface invaded the media in both groups to a similar extent. The amount of calcifying hydroxyapatite deposition in the intima and the media did not differ between the groups. Inflammatory cell markers (CD3 and CD68) proved negative in coated as well as uncoated decellularized implants. The coating of decellularized aortic implants with bioactive laminin caused an acceleration of the autologous recellularization and a reduction of the intima hyperplasia. Thereby, laminin coating seems to be a promising strategy to enhance the biocompatibility of tissue-engineered vascular implants.

Application of synthetic and biological implants for fixation of rectovaginal septum in rectocele repair

OBJECTIVE. Comparative assessment of results was made in application of synthetic and biological implants for rectocele repair. MATERIAL AND METHODS. The patients (n = 61, aged 34-61 years old) underwent operation concerning an isolated rectocele at the period from 2012 to 2015. Diamond-shaped plasty was performed using transvaginal approach. Synthetic composite mesh was used in 33 patients of the first group and biologic implant was applied in 28 women of the second group. RESULTS. Defecography showed reduction of middle size of rectocele in both groups in term of one year after surgery. However, the difference was insignificant in patients with biological implants. According to individual comparative analysis, the patients (n =9 (32,1 %) of the second group had the same size of rectocele as it was in preoperative period, but only 3 (9,1 %) patients of the first group had the same proportion. CONCLUSIONS. The anatomic results were significantly worse after application of biological implants, which appeared to be less reliable.