Hyaluronate-alginate hybrid hydrogels modified with biomimetic peptides for controlling the chondrocyte phenotype.

Hyaluronate-based hydrogels have been widely exploited as synthetic extracellular matrices in many tissue engineering applications, including cartilage tissue engineering. Hyaluronate-based hydrogels are typically prepared by chemical cross-linking reactions, in which chemical reagents may induce side effects, unless they are completely removed after the cross-linking reaction. We thus suggest the utilization of hybrid materials composed of hyaluronate as a main chain and alginate for physical cross-linking to simply form hydrogels in the presence of calcium ions under physiological conditions. In this study, we hypothesized that the introduction of biomimetic peptides to hyaluronate-alginate hybrid (HAH) hydrogels could be useful to regulate the chondrocyte phenotype, including chondrogenic differentiation. HAH was modified with the arginine-glycine-aspartate (RGD) peptide as a cell-matrix interaction motif and/or histidine-alanine-valine (HAV) as a cell-cell interaction motif. The HAV peptide is known to bind to cadherin, which is a key factor involved in homophilic cell-cell interactions as well as chondrogenesis. The viability and growth of mouse chondrocytes (ATDC5 cells) increased significantly when cultured on RGD-modified HAH hydrogels. Cell aggregates formed on HAV-modified HAH hydrogels, resulting in enhanced chondrogenic differentiation via enhanced cell-cell interactions by HAV modification. Interestingly, a synergistic effect of HAV and RGD peptides within HAH hydrogels on chondrogenesis was found in 3-D experiments in vitro. This approach to utilizing physically cross-linkable hyaluronate-based hydrogels presenting biomimetic peptides has potential applications in tissue engineering, including cartilage regeneration.

Physical properties of a novel small-particle hyaluronic acid filler: In vitro, in vivo, and clinical studies.

BACKGROUND: Infraorbital region is one of the most important regions that show the signs of aging. In recent years, hyaluronic acid (HA) fillers have been used to correct this region for esthetic treatments. Although HA fillers with various physical properties are used, limited research has been performed to compare their efficacy. OBJECTIVE: We aimed to compare three HA fillers to determine which is the most appropriate filler for the correction of the infraorbital region and evaluate the correction of such by performing a clinical test using CLEVIEL Fine. METHODS: We performed in vitro and in vivo tests using one new HA filler and two other commercial HA fillers. We compared the rheological properties, resistance to degradation, and in vivo duration test results of the three fillers. Nine patients participated in the clinical test using CLEVIEL Fine for 24 weeks. RESULTS: CLEVIEL Fine showed good rheological and physical characteristics for the infraorbital region. It had a low elasticity and cohesiveness, low incidence of postinjection swelling, high tanδ, narrow particle distribution, and small particle size. Further, it showed better resistance to the enzymes and radicals in the in vitro test than the other two HA fillers and a similar duration in the mouse test. In the clinical test, all patients showed good elasticity and hydration in the infraorbital region for 24 weeks. CONCLUSIONS: CLEVIEL Fine was proven to be safe and effective based on the in vitro, in vivo, and clinical study results.

Introduction of N-cadherin-binding motif to alginate hydrogels for controlled stem cell differentiation.

Control of stem cell fate and phenotype using biomimetic synthetic extracellular matrices (ECMs) is an important tissue engineering approach. Many studies have focused on improving cell-matrix interactions. However, proper control of cell-cell interactions using synthetic ECMs could be critical for tissue engineering, especially with undifferentiated stem cells. In this study, alginate hydrogels were modified with a peptide derived from the low-density lipoprotein receptor-related protein 5 (LRP5), which is known to bind to N-cadherin, as a cell-cell interaction motif. In vitro changes in the morphology and differentiation of mouse bone marrow stromal cells (D1 stem cells) cultured in LRP5-alginate hydrogels were investigated. LRP5-alginate gels successfully induced stem cell aggregation and enhanced chondrogenic differentiation of D1 stem cells, compared to RGD-alginate gels, at low cell density. This approach to tailoring synthetic biomimetic ECMs using cell-cell interaction motifs may be critical in tissue engineering approaches using stem cells.

Alginate hydrogels modified with low molecular weight hyaluronate for cartilage regeneration.

Alginate is a typical biomaterial that forms hydrogels in the presence of calcium ions and has often been utilized in tissue engineering approaches. However, it lacks biofunctionality in the form of interactions with cells and proteins. Hyaluronate, a main component of glycosaminoglycans, provides CD44-specific interactions with chondrocytes but typically requires chemical cross-linking agents to fabricate hydrogels, which may cause unexpected side effects in the body. In this study, we propose the design and fabrication of a hybrid structure of alginate and hyaluronate useful for cartilage regeneration. Alginate was used as a backbone, and hyaluronate with a low molecular weight was introduced to the backbone to fabricate alginate-hyaluronate hybrid coupled by ethylenediamine. We hypothesized that alginate-hyaluronate hybrid (AH) could maintain its ability to form gels in the presence of calcium ions and could be useful for cartilage regeneration as an injectable system. Characteristics of AH hydrogels containing various composition ratios of hyaluronate to alginate were investigated, and the chondrogenic potential of ATDC5 cells encapsulated within AH hydrogels was evaluated in vitro. Consequently, AH hydrogels having a defined polymer composition and mechanical stiffness were useful to successfully regulate chondrogenic differentiation and to maintain the chondrocytic cell phenotype, which may lead to many useful applications in cartilage regeneration.