A thermosensitive chitosan/corn starch/β-glycerol phosphate hydrogel containing TGF-β1 promotes differentiation of MSCs into chondrocyte-like cells

Pharmaceutical electrospinning and 3D printing scaffold design for bone regeneration

Bone regenerative engineering provides a great platform for bone tissue regeneration covering cells, growth factors and other dynamic forces for fabricating scaffolds. Diversified biomaterials and their fabrication methods have emerged for fabricating patient specific bioactive scaffolds with controlled microstructures for bridging complex bone defects. The goal of this review is to summarize the points of scaffold design as well as applications for bone regeneration based on both electrospinning and 3D bioprinting. It first briefly introduces biological characteristics of bone regeneration and summarizes the applications of different types of material and the considerations for bone regeneration including polymers, ceramics, metals and composites. We then discuss electrospinning nanofibrous scaffold applied for the bone regenerative engineering with various properties, components and structures. Meanwhile, diverse design in the 3D bioprinting scaffolds for osteogenesis especially in the role of drug and bioactive factors delivery are assembled. Finally, we discuss challenges and future prospects in the development of electrospinning and 3D bioprinting for osteogenesis and prominent strategies and directions in future.

Recent Advances of Chitosan-Based Injectable Hydrogels for Bone and Dental Tissue Regeneration

Traditional strategies of bone repair include autografts, allografts and surgical reconstructions, but they may bring about potential hazard of donor site morbidity, rejection, risk of disease transmission and repetitive surgery. Bone tissue engineering (BTE) is a multidisciplinary field that offers promising substitutes in biopharmaceutical applications, and chitosan (CS)-based bone reconstructions can be a potential candidate in regenerative tissue fields owing to its low immunogenicity, biodegradability, bioresorbable features, low-cost and economic nature. Formulations of CS-based injectable hydrogels with thermo/pH-response are advantageous in terms of their high-water imbibing capability, minimal invasiveness, porous networks, and ability to mold perfectly into an irregular defect. Additionally, CS combined with other naturally-derived or synthetic polymers and bioactive agents has proven to be an effective alternative to autologous bone and dental grafts. In this review, we will highlight the current progress in the development of preparation methods, physicochemical properties and applications of CS-based injectable hydrogels and their perspectives in bone and dental regeneration. We believe this review is intended as starting point and inspiration for future research effort to develop the next generation of tissue-engineering scaffold materials.

Effects of different concentrations of type-I collagen hydrogel on the growth and differentiation of chondrocytes

The objective of this study was to analyze the effects of type-I collagen hydrogel of different concentrations on the growth and differentiation of rabbit chondrocytes. Articular cartilage from New Zealand white rabbits was harvested and cultured. Second-generation chondrocytes were collected for in vitro culture with 10, 7, and 5 mg/ml type-I collagen hydrogel, respectively (denoted as groups A, B, and C). After in vitro culture for 1 day, chondrocytes were stained with fluorescein diacetate (FDA)/propidium iodide (PI), and cell viability was observed by laser confocal microscopy. After in vitro culture for 14 days, the histological patterns were observed by H&E and toluidine blue staining. The expression of chondrocyte-related genes were measured by real-time quantitative RT-PCR. After in vitro culture for 1 day, FDA/PI staining showed that the cell density of group A was significantly higher than that of group B and C. After in vitro culture for 14 days, H&E staining showed that chondrocytes showed obvious aggregation in group A, partial proliferation and aggregation in group B, and uniform distribution in group C. Toluidine blue staining showed that chondrocytes in group A had aggregation areas and some were stained purple-red, fewer chondrocytes were aggregated with different staining around them in group B, and the aggregation of chondrocytes was not obvious. However, the distribution of chondrocytes was uniform with different staining in group C. After in vitro culture for 2 weeks, the levels of polymerized proteoglycan and type-II collagen mRNA were not significantly different between the three groups (P>0.05). The levels of type-I collagen, type-X collagen, and Sox9 mRNA in group A were significantly higher than those in group B and C (P<0.05). In conclusion, high concentration type-I collagen hydrogel can promote chondrocyte fibrosis and upregulation of type-I collagen, type-X collagen, and Sox9 mRNA.

Alginate-hyaluronic acid-collagen composite hydrogel favorable for the culture of chondrocytes and their phenotype maintenance

Articular cartilage has limited regeneration capacity, thus significant challenge has been made to restore the functions. The development of hydrogels that can encapsulate and multiply cells, and then effectively maintain the chondrocyte phenotype is a meaningful strategy to this cartilage repair. In this study, we prepared alginate-hyaluronic acid based hydrogel with type I collagen being incorporated, namely Alg-HA-Col composite hydrogel. The incorporation of Col enhanced the chemical interaction of molecules, and the thermal stability and dynamic mechanical properties of the resultant hydrogels. The primary chondrocytes isolated from rat cartilage were cultured within the composite hydrogel and the cell viability recorded revealed active proliferation over a period of 21 days. The mRNA levels of chondrocyte phenotypes, including SOX9, collagen type II, and aggrecan, were significantly up-regulated when the cells were cultured within the Alg-HA-Col gel than those cultured within the Alg-HA. Furthermore, the secretion of sulphated glycosaminoglycan, a cartilage-specific matrix molecule, was recorded higher in the collagen-added composite hydrogel. Although more in-depth studies are required such as the in vivo functions, the currently-prepared Alg-HA-Col composite hydrogel is considered to provide favorable 3-dimensional matrix conditions for the cultivation of chondrocytes. Moreover, the cell-cultured constructs may be useful for the cartilage repair and tissue engineering.