Self-crosslinkable hyaluronate-based hydrogels as a soft tissue filler.

With increasing interest in aging and skin care, the use of fillers to increase the volume of soft tissue volume is increasing globally. However, the side effects caused by the residual chemical crosslinking agents present in these fillers limit the effective application of commercialized filler products. Therefore, the development of a novel crosslinking system with a non-toxic chemical crosslinking agent is required to overcome the limitations of commercial hyaluronate (HA)-based fillers. In this paper, a new injectable hydrogel with enhanced mechanical properties, tissue adhesion, injectability, and biocompatibility is reported. The HA derivatives modified with catechol groups (HA-DA) were crosslinked by self-oxidation under in vivo physiological conditions (pH 7.4) without chemical crosslinkers to form hydrogels, which can be further accelerated by the dissolved oxygen in the body. The fabricated HA-DA filler showed excellent mechanical properties and could be easily injected with a low injection force. Further, the HA-DA filler stably attached to the injection site due to the tissue adhesion properties of the catechol groups, thus leading to an improved displacement stability. In addition, the HA-DA filler showed excellent cell viability, cell proliferation, and biocompatibility. Therefore, the HA-DA hydrogel is a novel soft tissue filler with great potential to overcome the limitations of commercial soft tissue fillers.

Bio-plotted hydrogel scaffold with core and sheath strand-enhancing mechanical and biological properties for tissue regeneration.

Three-dimensional bio-plotted scaffolds constructed from encapsulated biomaterials or so-called "bio-inks" have received much attention for tissue regeneration applications, as advances in this technology have enabled more precise control over the scaffold structure. As a base material of bio-ink, sodium alginate (SA) has been used extensively because it provides suitable biocompatibility and printability in terms of creating a biomimetic environment for cell growth, even though it has limited cell-binding moiety and relatively weak mechanical properties. To improve the mechanical and biological properties of SA, herein, we introduce a strategy using hydroxyapatite (HA) nanoparticles and a core/sheath plotting (CSP) process. By characterizing the rheological and chemical properties and printability of SA and SA/HA-blended inks, we successfully fabricated bio-scaffolds using CSP. In particular, the mechanical properties of the scaffold were enhanced with increasing concentrations of HA particles and SA hydrogel. Specifically, HA particles blended with the SA hydrogel of core strands enhanced the biological properties of the scaffold by supporting the sheath part of the strand encapsulating osteoblast-like cells. Based on these results, the proposed scaffold design shows great promise for bone-tissue regeneration and engineering applications.

3D Printing of Bone-Mimetic Scaffold Composed of Gelatin/ß-Tri-Calcium Phosphate for Bone Tissue Engineering.

3D printed scaffolds composed of gelatin and ß-tri-calcium phosphate (ß-TCP) as a biomimetic bone material are fabricated, thereby providing an environment appropriate for bone regeneration. The Ca2+ in ß-TCP and COO- in gelatin form a stable electrostatic interaction, and the composite scaffold shows suitable rheological properties for bioprinting. The gelatin/ß-TCP scaffold is crosslinked with glutaraldehyde vapor and unreacted aldehyde groups which can cause toxicity to cells is removed by a glycine washing. The stable binding of the hydrogel is revealed as a result of FTIR and degradation rate. It is confirmed that the composite scaffold has compressive strength similar to that of cancellous bone and 60 wt% ß-TCP groups containing 40 wt% gelatin have good cellular activity with preosteoblasts. Also, in the animal experiments, the gelatin/ß-TCP scaffold confirms to induce bone formation without any inflammatory responses. This study suggests that these fabricated scaffolds can serve as a potential bone substitute for bone regeneration.