Osteo-mucosal engineered construct: In situ adhesion of hard-soft tissues.

OBJECTIVES: The aim of this work was to combine engineered hard and soft tissue, adopting a new method for interfacial adhesion of osteo-mucosal construct. We hypothesized that the chemical procedure involved in this method not only adheres the components, but also improves the cell growth inside them. METHODS: 3D-printed functionally-graded porous hard-tissue scaffolds were characterized, functionalized by aminolysis and tyrosinase, and accommodated by human osteoblast cells. Introducing amino groups through aminolysis and inducing dopaquinones by tyrosinase can take part in the Michael additions to cause the adhesion. Subsequently, fully-differentiated engineered oral mucosa was formed directly on the surface of hard tissue. Constructs were assessed in term of morphology, structure, chemical composition, histology, and cytocompatibility. Interfacial adhesion was compared to a control group prepared by using a biological glue for the attachment of the soft and hard tissues. RESULTS: The data confirmed higher proliferation of osteoblast cells via aminolysis and improved osteoblast cells distribution and differentiation by incorporation of tyrosinase in collagen. There was evidence of multilayered, stratified epithelium on the osteo-mucosal model with viable fibroblasts and osteoblasts within the lamina propria and bone tissue layers. Our method of adhesion resulted in cohesive debonding within the engineered soft tissue; while in the control group, adhesive debonding and complete separation of the oral mucosa from the hard tissue was observed. Although the shear strength of the osteo-mucosal model (157.6 kDa ± 25.1) was slightly higher than that of the control group (149.4 kDa ± 23.1), there was no statistically significant difference between them (p > 0.05). However, the advantage of our in situ adhesion approach is the absence of a barrier like glue which can disrupt direct cellular communications between tissues. SIGNIFICANCE: This study provides a novel method of directly combining tissue-engineered human bone with oral mucosa, which has the potential to improve cell-ingrowth and tissue integration. This engineered tissue construct, after further optimization, can be used clinically as a graft material in various oral surgeries and can also be employed as an in vitro model to investigate many aspects of oral diseases and examine dental materials and oral health care products as a replacement of in vivo models.

Pressure-Assisted Coating of Ceramics on 3D-Printed Polymeric Scaffolds.

Pressure-assisted coating (PAC) is introduced to coat 3D-printed polymeric scaffolds with ß-tricalcium phosphate (ß-TCP) for tissue engineering applications. The method consists of four steps: infiltration of ceramic particles into the porous structure of the polymeric scaffold, dehydration of the slurry, compaction of ceramic particles around the scaffold, and heat treatment. The optimal coating is obtained at an infiltration speed of 400 mm/min followed by complete dehydration, compaction under ca. 8 MPa pressure, and subsequent heat treatment at 65 °C. The outcome is a uniformly coated scaffold with no deformation or structural defects, as confirmed by micro-CT analysis and laser and scanning electron microscopy. Scaffolds coated using the PAC method present superior interface bonding strength compared to those coated with a biomimetic approach. The contact angle decreased from 75.2 ± 1.4° for the uncoated scaffold to 39.6 ± 9.6° for the PAC specimen. PAC also increased the surface roughness from 0.66 ± 0.08 to 6.89 ± 0.26 µm and doubled the number of attached cells on the 3rd day of culture. The described method is applicable to different structures, object sizes, pore sizes, and shapes. For instance, in-depth coating of a 10 mm × 10 mm (D × H) cone with a 58 ± 4 µm-thick layer of ß-TCP can be achieved using PAC. The method can be used to coat other polymers, such as poly(lactic-co-glycolic acid) (PLGA). Successful coating of ß-TCP on 3D-printed PLGA scaffolds is also presented as a proof of concept.