Silane-modified hydroxyapatite nanoparticles incorporated into polydioxanone/poly(lactide-co-caprolactone) creates a novel toughened nanocomposite with improved material properties and in vivo inflammatory responses.

The interface tissue between bone and soft tissues, such as tendon and ligament (TL), is highly prone to injury. Although different biomaterials have been developed for TL regeneration, few address the challenges of the TL-bone interface. Here, we aim to develop novel hybrid nanocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL), and hydroxyapatite (HA) nanoparticles suitable for TL-bone interface repair. Nanocomposites, containing 3-10% of both unmodified and chemically modified hydroxyapatite (mHA) with a silane coupling agent. We then explored biocompatibility through in vitro and in vivo studies using a subcutaneous mouse model. Through different characterisation tests, we found that mHA increases tensile properties, creates rougher surfaces, and reduces crystallinity and hydrophilicity. Morphological observations indicate that mHA nanoparticles are attracted by PDO rather than LCL phase, resulting in a higher degradation rate for mHA group. We found that adding the 5% of nanoparticles gives a balance between the properties. In vitro experiments show that osteoblasts' activities are more affected by increasing the nanoparticle content compared with fibroblasts. Animal studies indicate that both HA and mHA nanoparticles (10%) can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. In summary, this work highlights the potential of PDO/LCL/HA nanocomposites as an excellent biomaterial for TL-bone interface tissue engineering applications.

Natural, synthetic and commercially-available biopolymers used to regenerate tendons and ligaments.

Tendon and ligament (TL) injuries affect millions of people annually. Biopolymers play a significant role in TL tissue repair, whether the treatment relies on tissue engineering strategies or using artificial tendon grafts. The biopolymer governs the mechanical properties, biocompatibility, degradation, and fabrication method of the TL scaffold. Many natural, synthetic and hybrid biopolymers have been studied in TL regeneration, often combined with therapeutic agents and minerals to engineer novel scaffold systems. However, most of the advanced biopolymers have not advanced to clinical use yet. Here, we aim to review recent biopolymers and discuss their features for TL tissue engineering. After introducing the properties of the native tissue, we discuss different types of natural, synthetic and hybrid biopolymers used in TL tissue engineering. Then, we review biopolymers used in commercial absorbable and non-absorbable TL grafts. Finally, we explain the challenges and future directions for the development of novel biopolymers in TL regenerative treatment.

The Technological Advancement to Engineer Next-Generation Stent-Grafts: Design, Material, and Fabrication Techniques.

Endovascular treatment of aortic disorders has gained wide acceptance due to reduced physiological burden to the patient compared to open surgery, and ongoing stent-graft evolution has made aortic repair an option for patients with more complex anatomies. To date, commercial stent-grafts are typically developed from established production techniques with simple design structures and limited material ranges. Despite the numerous updated versions of stent-grafts by manufacturers, the reoccurrence of device-related complications raises questions about whether the current manfacturing methods are technically able to eliminate these problems. The technology trend to produce efficient medical devices, including stent-grafts and all similar implants, should eventually change direction to advanced manufacturing techniques. It is expected that through recent advancements, especially the emergence of 4D-printing and smart materials, unprecedented features can be defined for cardiovascular medical implants, like shape change and remote battery-free self-monitoring. 4D-printing technology promises adaptive functionality, a highly desirable feature enabling printed cardiovascular implants to physically transform with time to perform a programmed task. This review provides a thorough assessment of the established technologies for existing stent-grafts and provides technical commentaries on known failure modes. They then discuss the future of advanced technologies and the efforts needed to produce next-generation endovascular implants.