New frontiers in biomaterials research for tissue repair and regeneration

The field of biomaterials has recently emerged to augment or replace lost or damaged tissues and organs due to the human body's limited ability to self-heal large defects. Historically, metallic components, polymers, ceramics, and composite materials were utilized as synthetic materials along with natural materials to assist in therapy.Various novel biomaterials were developed to respond to a significant amount of new medical challenges in the past decade. Therefore, there is a need to review these newly developed biomaterials and their potential to improve tissue repair and regeneration in a variety of applications. Here, we briefly review the different strategies and attempts to use novel biomaterials, including self-assembled and macromolecular biomaterials, hydrogels, metamaterials, decellularized tissues, and biomaterials obtained via synthetic biology, used either for tissue repair and regeneration or for therapeutic use by exploiting other mechanisms of healing. All these methods aim to create functional materials, devices, systems, and/or organisms with novel and useful functions on the basis of catalogued and standardized biological building blocks. This review details the various methods and introduces the applications of these biomaterials in tissue repair and regeneration, especially for bone, nerve, and skin applications.

Effect of surgical factors on the augmentation of cementinjectable cannulated pedicle screw fixation by a novel calcium phosphate-based nanocomposite

Bone cement-augmented pedicle screw system demonstrates great efficacy in spinal disease treatments. However, the intrinsic drawbacks associated with clinically used polymethylmethacrylate (PMMA) cement demands for new bone cement formulations. On the basis of our previous studies, a novel injectable and biodegradable calcium phosphate-based nanocomposite (CPN) for the augmentation of pedicle screw fixation was systematically evaluated for its surgical feasibility and biomechanical performance by simulated and animal osteoporotic bone models, and the results were compared with those of clinical PMMA cement. ASTM-standard solid foam and open-cell foam models and decalcified sheep vertebra models were employed to evaluate the augmentation effects of CPN on bone tissue and on the cement-injected cannulated pedicle screws (CICPs) placed in osteoporotic bone. Surgical factors in CICPs application, such as injection force, tapping technique, screw diameter, and pedicle screw loosening scenarios, were studied in comparison with those in PMMA. When directly injected to the solid foam model, CPN revealed an identical augmentation effect to that of PMMA, as shown by the similar compressive strengths (0.73 ± 0.04 MPa for CPN group vs. 0.79 ± 0.02 MPa for PMMA group). The average injection force of CPN at approximately 40-50 N was higher than that of PMMA at approximately 20 N. Although both values are acceptable to surgeons, CPN revealed a more consistent injection force pattern than did PMMA. The dispersing and anti-pullout ability of CPN were not affected by the surgical factors of tapping technique and screw diameter. The axial pullout strength of CPN evaluated by the decalcified sheep vertebra model revealed a similar augmentation level as that of PMMA (1351.6 ± 324.2 N for CPN vs. 1459.7 ± 304.4 N for PMMA). The promising results of CPN clearly suggest its potential for replacing PMMA in CICPs augmentation application and the benefits of further study and development for clinical uses.