Poly(l-lactide)/polycaprolactone based multifunctional coating to deliver paclitaxel/VEGF and control the degradation rate of magnesium alloy stent

Advances in the Fabrication of Polycaprolactone-Based Composite Scaffolds for Bone Tissue Engineering: From Chemical Composition to Scaffold Architecture

Thermoplastic polymer-based materials, which feature essential biological properties and opportunities to implement the cutting-edge additive manufacturing technologies aimed at obtaining high-precision 3D models, have attracted intense interest for porous and bioresorbable bone tissue implants development. Among the wide range of materials, polycaprolactone was found to provide a balance between the biodegradation rate and biocompatibility with various tissues. Recent advances in the fabrication of polymer-polymer and polymer-inorganic composites have opened new ways to improve biological and mechanical outcomes and expanded the range of applications for bone and cartilage restoration, including the development of conductive composites for electrostimulation. While the chemical composition of the manufactured scaffolds played a vital role in their general biological performance and biocompatibility with bone tissue, the micropattern and roughness of the surface were shown to be additional stimuli for stem cell differentiation. More challenges came from the fabrication technique suitable for the proposed scaffold design. Here we summarize the key challenges and advances in fabrication and approaches to the optimization of certain chemical, morphological, or geometrical parameters of polycaprolactone-based scaffolds for bone tissue engineering applications.

ECM derivatized alginate augmenting bio-functionalities of lyophilized mat for skin and liver wound treatment

Peptides and molecular residues sourced from the fragmentation of the extracellular matrix (ECM) can exacerbate a plethora of cellular functions. We selected a natural ECM-derived complex peptide mixture to functionalize sodium alginate. Three alginate derivatives (sodium alginate conjugated with ECM) SALE-1, SALE-2, and SALE-3 were synthesized using the lowest (10 % w/w), moderate (50 % w/w), and highest (100 % w/w) concentrations of ECM. Thereafter, they were used to fabricate three groups of mat scaffolds EMAT-1 (ECM derivatized alginate thrombin-mat), EMAT-2, and EMAT-3, respectively by the freeze-drying process. To enhance the hemostatic activity, thrombin was loaded onto the scaffolds. Another group, AT, without any derivatized alginate was additionally included in order to comparative analysis. Physical characteristics revealed that the porous mat scaffold showed enhancement in degradation and swelling ability with the increase in ECM content. The higher cell proliferation, migration, and cell viability were noticed in the higher ECM-containing samples EMAT-2 and EMAT-3. In vivo studies using rodent hepatic and rabbit ear models were carried out to ensure the hemostatic ability of the scaffolds. EMAT-2 and EMAT-3 demonstrate excellent liver regeneration ability in rat models. Moreover, the rat cutaneous wound model depicted that EMAT-3 dramatically elevated the skin's healing ability, thereby rendering it an excellent candidate for future clinical application in wound healing.

Biocompatibility and corrosion resistance of drug coatings with different polymers for magnesium alloy cardiovascular stents

Recently, advances in enhancing corrosion properties through various techniques, and the clinical application of biodegradable cardiovascular stents made from magnesium (Mg) alloys face challenges to corrosion resistance, blood compatibility, and biocompatibility. Drug-eluting stents (DES) offer a solution to enhance the corrosion resistance of Mg alloys while simultaneously reducing the occurrence of restenosis. In this study, WE43 Mg alloy was pretreated using electropolishing technology, and different polymers (PEG and PLLA) were used as drug-polymer coatings for the Mg alloy. At the same time, PTX, an anticoagulant, was incorporated to achieve drug coating of different polymers on WE43 Mg alloy. The corrosion resistance of different polymer-drug coatings was assessed using a plasma solution. Furthermore, in vitro and in vivo tests were used to evaluate the blood biocompatibility of these coatings. The results indicated the PTX-PEG-coated WE43 Mg alloy exhibited the highest corrosion resistance and the most stable drug release profile among the tested coatings. Its hemolysis rate of 0.6 % was within the clinical requirements (<5 %). The incorporation of PEG prevents non-specific protein adsorption and nanoparticle aggregation, enhancing the surface hemocompatibility of WE43 Mg alloy. Therefore, the PTX-PEG coating shows promising potential for application in the development of drug-coated Mg alloy.

Recent developments in ureteral stent: Substrate material, coating polymer and technology, therapeutic function

The ureteral stent is an effective treatment for clinical ureteral stricture following urological surgery, and the functional coating of the stent could effectively inhibit bacterial colonization and other complications. The present review provides an analysis and description of the materials used in ureteral stents and their coatings. Emphasis is placed on the technological advancements of functional coatings, taking into consideration the characteristics of these materials and the properties of their active substances. Furthermore, recent advances in enhancing the therapeutic efficacy of functional coatings are also reviewed. It is anticipated that this article will serve as a valuable reference providing insights for future research development on new drug-loaded ureteral stents.

An agarose-based TOCN-ECM bilayer lyophilized-hydrogel with hemostatic and regenerative properties for post-operative adhesion management

This study used a unique approach by developing a bilayer system that can simultaneously accomplish non-adhesion, hemostatic, and tissue regenerative properties. In this system, agarose was used as a carrier material, with an agarose-TEMPO-oxidized cellulose nanofiber (TOCN), (AT) layer acting as a non-adhesion layer and an Agarose-Extracellular matrix, (AE) layer acting as a tissue regenerative layer. Thrombin was loaded on the AE layer as an initiator of the healing process, by hemostasis. AT 1:4 showed 79.3 % and AE 1:4 showed 84.66 % cell viability initially confirming the biocompatible nature of the layers. The AE layer showed cell attachment and proliferation on its surface whereas on the AT layer, cells are visible but no attachment was observed. Furthermore, in vivo analysis was conducted. The non-adhesive layer was grafted between the cecum and peritoneal wall which showed that (AT 1:4) displayed remarkable non-adhesion properties as compared to a commercial product and the non-treated group. Hemostasis and tissue regeneration ability were evaluated using rat liver models. The bleeding time of AE 1:4TH was recorded as 160 s and the blood loss was 5.6 g. The results showed that (AE 1:4) displayed effective regeneration ability in the liver model after two weeks.