Functionally Graded Bioactive Composites Based on Poly(vinyl alcohol) Made through Thiol-Ene Click Reaction.

Functionally graded materials (FGMs) composed of a polymer matrix embedded with calcium phosphate particles are preferred for bone tissue engineering, as they can mimic the hierarchical and gradient structure of bones. In this study, we report the design and development of a FGM based on thiolated poly(vinyl alcohol) (TPVA) and nano-hydroxyapatite (nano-HA) with graded bioactivity, cell compatibility, and degradability properties that are conducive for bone regeneration. The polymer matrix comprises crosslinked poly(vinyl alcohol) with ester and thioether linkages formed via the thiol-ene click reaction, avoiding undesired additives and byproducts. Freshly precipitated and spray-dried HA was mixed with the TPVA hydrogel, and layers of varying concentrations were cast. Upon lyophilization, the hydrogel structure yielded porous sheets of the graded composite of TPVA and nano-HA. The new FGM showed higher values of tensile strength and degradation in phosphate buffer saline (PBS) in vitro, compared to bare TPVA. The bioactive nature of the FGM was confirmed through bioactivity studies in simulated body fluid (SBF), while cytocompatibility was demonstrated with human periodontal ligament cells in vitro. Cumulatively, our results indicate that based on the composition, mechanical properties, bioactivity, and cytocompatibility, the fabricated TPVA-HA composites can find potential use as guided bone regeneration (GBR) membranes.

Calcium sulfate-based bioactive cement for periodontal regeneration: An In Vitro study.

BACKGROUND AND OBJECTIVE: Various types of osteoconductive graft materials are used for the management of alveolar bone defects arising out of periodontal disease. Inorganic, self-setting, bioactive bone cements are suggested to be most appropriate because they can conformally fill the bone defect and resorb progressively along with the regeneration of the host site. A new calcium sulfate-based bioactive bone cement (BioCaS) is developed, having simplicity and effectiveness for bone grafting applications. The response of primary human periodontal ligament (hPDL) cells to this material is investigated through in vitro cell culture model so as to qualify it for the repair of periodontal infrabony defects. METHOD: The BioCaS was designed as powder-liquid combination with in-house synthesized high purity calcium sulfate hemihydrate incorporating hydrogen orthophosphate ions. hPDL cells were isolated, cultured and characterized using optimized primary cell culture techniques. The cytotoxicity and cytocompatibility of the BioCaS samples were evaluated using the hPDL cells, with hydroxyapatite ceramic material as control. Osteogenic differentiation of the hPDL cells in presence of BioCaS was also evaluated using Alizarin red staining, Alizarin red assay, Von Kossa staining and Masson's trichrome staining. RESULTS: The primary cell culture techniques yielded a healthy population of periodontal ligament cells, with fibroblast morphology and characteristic marker expressions. The hPDL cells exhibited good viability, adhesion and spreading to the BioCaS cement in comparison to sintered hydroxyapatite. In addition, the cells differentiated to osteogenic lineage in the presence of the BioCaS cement, without extraneous osteogenic supplements, confirming the inherent bioactivity of the cement. CONCLUSION: The new BioCaS cement is a potential candidate for the repair of periodontal defects.

Self-assembling polymeric dendritic peptide as functional osteogenic matrix for periodontal regeneration scaffolds-an in vitro study.

OBJECTIVE: Regeneration of periodontal defects is challenging as it necessitates the formation of complex tissue structure with cementum, periodontal ligament, and alveolar bone. Rather than the conventional barrier membranes, scaffolds mimicking extracellular matrix (ECM) can achieve faster healing as they promote migration, adhesion, and differentiation of native progenitor cells. This work explores the possibility of a functional osteogenic matrix based on self-assembling peptide appended dendritic polydiacetylene in regenerating diseased periodontia. METHOD: The amino acid lysine was appended onto a diacetylene core, which was converted to a polymeric dendritic lysine matrix (Lys-PDA) through photopolymerization. This bioactive matrix was evaluated in vitro for the viability, adhesion, spreading, and differentiation of cultured human periodontal ligament (hPDL) progenitor cells. Its osteogenic differentiation was analysed by histologic staining and expression of osteogenic markers (alkaline phosphatase and Osteonectin). Electrospun polycaprolactone (PCL) mat, a candidate barrier material, was fabricated and functionalized with Lys-PDA matrix, and the cell viability, adhesion, and spreading of hPDL cells were evaluated. RESULTS: The dendritic Lys-PDA matrix well supported the hPDL cell growth and differentiation. The cells were viable and showed good cytoskeletal organization. Early expression of osteogenic markers and mineralization was noted in vitro in the presence of Lys-PDA matrix. The electrospun PCL mat functionalized with Lys-PDA maintained the viability, morphology, and spreading of the hPDL cells. SIGNIFICANCE: The ECM mimetic dendritic peptide matrices are capable of hosting and differentiating cells which can lead to the regeneration of periodontal tissue architecture. They could be used in conjunction with barrier membranes for better results.