Development of 3D Printed pNIPAM-Chitosan Scaffolds for Dentoalveolar Tissue Engineering.

While available treatments have addressed a variety of complications in the dentoalveolar region, associated challenges have resulted in exploration of tissue engineering techniques. Often, scaffold biomaterials with specific properties are required for such strategies to be successful, development of which is an active area of research. This study focuses on the development of a copolymer of poly (N-isopropylacrylamide) (pNIPAM) and chitosan, used for 3D printing of scaffolds for dentoalveolar regeneration. The synthesized material was characterized by Fourier transform infrared spectroscopy, and the possibility of printing was evaluated through various printability tests. The rate of degradation and swelling was analyzed through gravimetry, and surface morphology was characterized by scanning electron microscopy. Viability of dental pulp stem cells seeded on the scaffolds was evaluated by live/dead analysis and DNA quantification. The results demonstrated successful copolymerization, and three formulations among various synthesized formulations were successfully 3D printed. Up to 35% degradability was confirmed within 7 days, and a maximum swelling of approximately 1200% was achieved. Furthermore, initial assessment of cell viability demonstrated biocompatibility of the developed scaffolds. While further studies are required to achieve the tissue engineering goals, the present results tend to indicate that the proposed hydrogel might be a valid candidate for scaffold fabrication serving dentoalveolar tissue engineering through 3D printing.

Development and characterization of colloidal pNIPAM-methylcellulose microgels with potential application for drug delivery in dentoalveolar tissue engineering strategies.

Incorporation of growth factors, signaling molecules and drugs can be vital for the success of tissue engineering in complex structures such as the dentoalveolar region. This has led to the development of a variety of drug release systems. This study aimed to develop pNIPAM-methylcellulose microgels with different synthesis parameters based on a 23 full factorial design of experiments for this application. Microgel properties, including volume phase transition temperature (VPTT), hydrodynamic size, drug loading and release, and cytocompatibility were systematically evaluated. The results demonstrated successful copolymerization and development of the microgels, a hydrodynamic size ranging from ∼200 to ∼500 nm, and VPTT in the range of 34-39 °C. Furthermore, loading of genipin, capable of inducing odontoblastic differentiation, and its sustained release over a week was shown in all formulations. Together, this can serve as a solid basis for the development of tunable drug-delivering pNIPAM-methylcellulose microgels for specific tissue engineering applications.

The development of a 3D printable chitosan-based copolymer with tunable properties for dentoalveolar regeneration.

Dentoalveolar tissue engineering is an emerging yet challenging field, considering the lack of suitable materials and difficulty to produce patient-specific hydrogel scaffolds. The present paper aims to produce a 3D printable and tuneable biomaterial by copolymerizing a synthesized water-soluble chitosan derivative called maleic anhydride grafted chitosan (MA-C) with gelatin using genipin, a natural crosslinking agent. Development and testing of this material for 3D printing, degradation, and swelling demonstrated the ability to fabricate scaffolds with controlled physical properties based on pre-determined designs. The MA-C-gelatin copolymer demonstrated excellent biocompatibility, which was verified by analyzing the viability, growth and proliferation of human dental pulp stem cells seeded on MA-C-gelatin constructs through live/dead, alamar blue and DNA quantification assays. Based on the present findings, the proposed material might be a suitable candidate for dentoalveolar tissue engineering, while further research is required to achieve this goal.

A tunable gelatin-hyaluronan dialdehyde/methacryloyl gelatin interpenetrating polymer network hydrogel for additive tissue manufacturing.

Methacryloyl gelatin (GelMA) is a versatile material for bioprinting because of its tunable physical properties and inherent bioactivity. Bioprinting of GelMA is often met with challenges such as lower viscosity of GelMA inks due to higher methacryloyl substitution and longer physical gelation time at room temperature. In this study, a tunable interpenetrating polymer network (IPN) hydrogel was prepared from gelatin-hyaluronan dialdehyde (Gel-HDA) Schiff's polymer, and 100% methacrylamide substituted GelMA for biofabrication through extrusion based bioprinting. Temperature sweep rheology measurements show a higher sol-gel transition temperature for IPN (30 °C) compared to gold standard GelMA (27 °C). Furthermore, to determine the tunability of the IPN hydrogel, several IPN samples were prepared by combining different ratios of Gel-HDA and GelMA achieving a compressive modulus ranging from 20.6 ± 2.48 KPa to 116.7 ± 14.80 KPa. Our results showed that the mechanical properties and printability at room temperature could be tuned by adjusting the ratios of GelMA and Gel-HDA. To evaluate cell response to the material, MC3T3-E1 mouse pre-osteoblast cells were embedded in hydrogels and 3D-printed, demonstrating excellent cell viability and proliferation after 10 d of 3Din vitroculture, making the IPN an interesting bioink for the fabrication of 3D constructs for tissue engineering applications.

IL-1ß favors osteoclastogenesis via supporting human periodontal ligament fibroblasts.

The balance between bone formation and bone resorption in inflammatory diseases is often disturbed. Periodontitis, a chronic inflammation of the tooth gums, leads to unwanted bone loss as a response to inflammatory compounds such as interleukin-1ß (IL-1ß). This excessive bone loss reflects an increased osteoclast formation and activity. Osteoclast formation is a multistep process driven by osteoclastogenesis supporting cells such as periodontal ligament fibroblasts. The inflammatory factors can induce osteoclastogenesis, probably also by affecting the periodontal ligament fibroblast. In this study we investigated how pre-culture of periodontal ligament fibroblasts with IL-1ß affected osteoclastogenesis. Fibroblasts were pre-cultured with IL-1ß and/or dexamethasone, a commonly used anti-inflammatory compound, before being co-cultured with peripheral blood mononuclear cells (PBMCs). Pre-culture with IL-1ß (1-100 ng/ml) resulted in an increased number of adhered PBMCs as well as an increased mRNA expression of intercellular adhesion molecule-1 (ICAM-1), macrophage colony stimulating factor (M-CSF) and IL-1ß. Pre-culture with IL-1ß also caused retraction of fibroblasts and an augmented formation of TRACP(+) multinucleated cells. Our data suggest that stimulation of fibroblasts with IL-1ß has a long-lasting effect, leading to a significantly increased osteoclastogenesis. These results provide new insights for understanding excessive bone loss in periodontitis.